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2020 - 202218
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Subject: Agronomy × End date: 2023 × Start date: 2020 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Integrated nutrient management in minisett cultivation of elephant foot yam {Amorphophallus paeoniifolius (Dennst.) Nicolson}
    (Department of Agronomy, College of Agriculture, 2022) Dhanalakshmi V N.; Rajasree G
    The study entitled “Integrated nutrient management in minisett cultivation of elephant foot yam [Amorphophallus paeoniifolius (Dennst.) Nicolson]” was conducted at the Instructional Farm, College of Agriculture, Vellayani, Thiruvananthapuram to standardise the minisett size in elephant foot yam and to investigate the effect of integrated nutrient management practices on growth, yield, quality and economics of cultivation and to study the rooting and tuberisation pattern of minisett planted elephant foot yam. The investigation consisted of two experiments; standardisation of minisett corm size and integrated nutrient management practices (field experiment) and rooting and tuberisation pattern study (pot culture) and was undertaken during April to November 2018 and 2019. The first experiment was laid out in RBD with 15 treatment combinations and a control, replicated thrice. The treatments comprised three minisett corm sizes (s1-200 g, s2-300 g and s3-400 g) and five integrated nutrient management practices (i1-100 per cent NPK, i2-75 per cent NPK with 50 per cent N substitution through coir pith compost, i3-75 per cent NPK with 50 per cent N substitution through coir pith compost + PGPR mix-I + AMF, i4-50 per cent NPK with 50 per cent N substitution through coir pith compost, i5-50 per cent NPK with 50 per cent N substitution through coir pith compost + PGPR mix-I + AMF). The minisett corms and control corms (1 kg) of elephant foot yam var. Gajendra were planted at a spacing of 60 x 60 cm and 90 x 90 cm respectively. The recommended dose of N, P and K (100:50:150 kg NPK ha-1 ) for elephant foot yam was modified based on soil test data. Substitution of N with coir pith compost was carried out on N equivalent basis, and P and K were given through chemical sources. The pot culture experiment was laid out in CRD with 14 plants per treatment with the same treatments as the field experiment. The number of days taken for 100 per cent sprouting of seed corms varied between minisett corms and control corms and the latter sprouted early. The minisett corm s3 (400 g) recorded taller plants, higher leaf area index, pseudostem 281 girth and canopy spread. Application of 100 per cent NPK (i1) as chemical fertilizer produced taller plants and higher canopy spread during later stages compared to INM practices. Among the INM treatments, i3 (75 % NPK with 50 % N substitution through coir pith compost + PGPR mix-I + AMF) found superior with respect to growth attributes such as plant height and canopy spread. The treatment combination s3i1 (400 g + 100 % NPK as chemical fertilizer) produced taller plants and recorded higher canopy spread. Among the interactions including INM practices, taller plants were produced by s3i3 and s3i5 and higher canopy spread was recorded with s3i2, s3i3 and s3i5. Control plants (1 kg) showed taller plants, higher pseudostem girth and canopy spread at all stages of observation. The s3 recorded higher yield attributes, corm yield (48.81 and 50.57 t ha-1 during first year and second year, respectively) and pooled corm yield (49.69 t ha1 ). The treatments, i1 (100 % NPK) recorded significantly the highest yield attributes and yield. Among the different INM practices, i3 recorded higher yield attributes and corm yield (38.26 and 45.37 t ha-1 during first year and second year, respectively), while corm yield in pooled mean analysis (41.82 t ha-1 ) was also higher in this treatment. The s3i1 (400 g + 100 % NPK as chemical fertilizer) produced significantly the highest yield attributes and yield among all the treatments. Among the INM combinations, s3i3 recorded higher yield attributes, corm yield and higher pooled mean of corm yield (51.29 t ha-1 ). Control recorded higher yield attributes than minisetts. Pooled analysis of corm yield ha-1 indicated that s3i1, s3i2, s3i3 and s3i5 were superior to control and s2i1, s2i2, s2i3 and s3i4 were on par with control. Quality attributes like starch, total sugar, crude protein and crude fibre content of corm were non significant with respect to the treatments. Higher dry matter content was obtained in i4 (50 % NPK with 50 % N substitution through coir pith compost). The lower content of oxalic acid was recorded with i5 and i4 and the higher content was in i1 (100 % NPK). The minisett corm s3 recorded superior results for nutrient content, uptake and nutrient harvest indices. The INM treatment, i3 recorded higher nutrient content and uptake, however the highest was recorded in i1 among all the treatments. The treatment s3i1 (400 g + 100 % NPK 282 through chemical fertilisers) recorded significantly the highest K uptake. Among the combinations including INM practices, s3i3 recorded higher K uptake during second year. The combinations, s3i1, s3i2, s3i3, s3i4 and s3i5 were found superior to control in case of nutrient uptake. Soil chemical properties after the field experiments were not significantly affected by the treatments. The treatment s3i1 (400 g + 100 % NPK) recorded the highest net income and BCR during both the years. The highest net income and BCR were recorded from s3i2 during first year and s3i3 during second year, and the two year mean of net income and BCR were also highest in the case of INM treatment s3i3. In pot culture study, chemical properties of potting medium at monthly intervals up to harvest were not significantly affected by the treatments except for organic carbon content. The treatment i3 (75 % NPK with 50 % N substitution through coir pith compost + PGPR mix-I + AMF) recorded higher organic carbon content at 5 MAP. The minisett corm s3 excelled in rooting pattern and root anatomical parameters. Higher number of roots per plant was recorded in i2 and i3, however, these treatments were on par with i1 (100 % NPK). Higher weight of roots per plant was observed in i5, i4 and i3 and, root anatomical parameters were superior in i3. The interactions, s3i5, s3i4 and s3i3 recorded the highest weight of roots per plant. Higher root parameters were recorded in control than in minisetts and, in case of number of roots per plant s3i1, s3i2 and s3i3 at 4, 6 MAP and harvest, and s3i1 at 5 MAP recorded on par results with control. In the case of weight of roots per plant, s3i3 was on par with control at harvest. The roots of plants applied with AMF showed mycelial network from 3 MAP up to the harvest, and in the maximum growing stage of 5 MAP, vesicles were found in between the cells of the roots of AMF applied plants. Higher root colonization was observed in s3i3 at 5 MAP. Corm initiation was observed between 1 MAP and 2 MAP in control and between 2 MAP and 3 MAP in all other treatments. The s2 (300 g) during 3-4 MAP and s3 (400 g) during all other stages had significantly the highest corm bulking rate (CBR). Higher corm bulking efficiency (CBE) was recorded in s2 during 3-4 MAP, s1 during 4-5 MAP and 6 MAP-harvest and s3 during 5-6 MAP. 283 The INM treatment i3 showed superior results for CBR and CBE, however, higher CBR and CBE were recorded in i1 (100 % NPK) among all the treatments. The s3i1 (400 g + 100 % NPK)showed the highest CBR and CBE during 4-5 MAP and 5-6 MAP among all the treatments. Among the INM interactions, s3i3 during 3-4 MAP and 5-6 MAP; s3i2 during 4-5 MAP and s3i4 during 6 MAP-harvest recorded higher CBR. The s2i3 during 3-4 MAP, s1i3 during 4-5 MAP, s3i3 during 5-6 MAP and s1i5 during 6 MAP-harvest recorded higher CBE. Higher corm weight per plant was recorded with s3. The i1 recorded the higher corm weight per plant among all the treatments, and at 5 MAP, i1 was on par with i3. Among the INM treatments i2 at 3 MAP and i3 at all other stages recorded higher corm weight per plant. Among interactions, s3i3 produced higher corm weight, however, among all the treatments the highest corm weight was noted in s3i1 at all stages except at 4 MAP. Control produced significantly higher corm weight per plant than minisetts. Uptake of nitrogen at 3 MAP and uptake of phosphorus at harvest were higher in s3. The INM treatment i3 recorded higher microbial population and dehydrogenase activity in the potting medium and among the interactions, higher dehydrogenase activity was recorded with s3i3. Significant and positive correlations were observed between corm weight per plant vs. root anatomical parameters and nutrient uptake vs. root anatomical parameters. It is evident from the present study that planting of 400 g minisett corm resulted in better growth, yield and quality of elephant foot yam. Application of 75 per cent NPK with 50 per cent N substitution through coir pith compost + PGPR mix-I [@ 10 g per pit (dry cow dung: PGPR mix-I in 50:1 proportion) - at planting and 2 MAP] + AMF (@ 10 g per pit - at the time of planting) in elephant foot yam resulted in superior growth, yield and quality under INM system. Planting of 400 g minisett and application of 75 per cent NPK with 50 per cent N substitution through coir pith compost + PGPR mix-I + AMF under an INM system could be recommended for economic production of minisett elephant foot yam. Rooting and tuberisation of elephant foot yam were found superior in planting of 400 g minisett corm with application of 75 per cent NPK with 50 per cent N substitution through coir pith compost + PGPR mix-I + AMF.
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    ThesisItemOpen Access
    Productivity enhancement of blackgram (Vigna mungo (L.) Hepper) intercropped in coconut gardens
    (Department of Agronomy, College of Agriculture,Vellayani, 2021) Pooja, A P; Ameena, M
    The research work entitled ‘Productivity enhancement of blackgram (Vigna mungo (L.) Hepper) intercropped in coconut gardens’ was undertaken at College of Agriculture, Vellayani during 2018-2021. The study aimed to identify shade tolerant blackgram varieties suitable for coconut gardens, to study the effect of foliar nutrition and plant growth regulators on growth and yield of the shade tolerant blackgram varieties intercropped in coconut garden and to work out the economics of cultivation. The investigation was carried out as two experiments: (i) screening of blackgram varieties for shade tolerance, and (ii) performance evaluation of shade tolerant varieties under foliar application of nutrients and growth regulators in rainfed coconut garden. The first experiment was conducted during Rabi 2019-20 in coconut garden having a light intensity equivalent to 50 per cent of that under open condition (56.25 klux), planted at a spacing of 7.6 m x 7.6 m. Seeds of 12 promising blackgram varieties collected from different research stations of south India (Sumanjana, DU 1, DBGV 5, VBN 5, VBN 6, VBN 8, Rashmi, CO 6, TAU 1, TAU 2, Blackgold and AKU 15) and three cultures (Culture 4.5.8, Culture 4.5.18 and Culture 4.6.1), were raised in micro plots laid out in randomized block design with three replications. The crop was raised as per KAU package of practices. The results of the study revealed significant variation in growth characters among the varieties screened for shade tolerance under partial shade in coconut garden. Plants of DBGV 5 were significantly taller (96.89 cm) with higher initial number of leaves at all the stages and was on par with Sumanjana and CO 6. Higher leaf area index (LAI) and leaf area duration were recorded in CO 6 (5.77, 65.66 days) and DBGV 5 (5.36, 58.40 days) followed by Sumanjana. Early flowering was observed in Sumanjana (34.33 days) and DBGV 5 (36.33 days). The variety DBGV 5 had the highest photosynthetic rate and resulted in significantly more pods per plant (23.67) which was on par with CO 6, VBN 5, VBN 6, Sumanjana and Rashmi. DBGV 5 produced the highest seed yield per plant (5.44 g) followed by VBN 5 and Sumanjana. Haulm yield per plant was higher for DBGV 5 (19 g) and was on par with VBN 5, Sumanjana and CO 6. The variety DBGV 5 produced the highest seed yield (1183 kg ha-1 ) followed by VBN 5, Sumanjana and CO 6. A higher harvest index of 0.24 was recorded by Sumanjana which was on par with DBGV 5 and VBN 6. Among the varieties screened, five varieties which performed better in terms of yield per unit area under the partial shade in coconut garden viz., DBGV 5, VBN 5, Sumanjana, CO 6 and VBN 6 were selected for experiment II undertaken in summer 2020 followed by the confirmatory trial during Rabi 2020 -21. The experiment was laid out in split plot design with five varieties (v1 - Sumanjana, v2 - DBGV 5,v3 - VBN 5,v4 - VBN 6,v5 - CO 6) as main plot treatments and six foliar sprays of nutrients and plant growth regulators as subplot treatments (f1: 19:19:19 (1%) at 45 and 60 DAS, f2: SOP (0.5%) at 45 and 60 DAS, f3: NAA 40 mg L-1 and salicylic acid 100 mg L-1 at pre-flowering (30-45 DAS) and 15 days later, f4: f3 + f1, f5: f3 + f2 and f6: Control - KAU POP). Among the varieties, Sumanjana (v1) grew taller during both the seasons and was comparable with CO 6 and DBGV 5 at harvest. Sumanjana produced higher number of branches with more number of leaves during both the seasons. At flowering, higher LAI, number and dry weight of nodules per plant were realized by Sumanjana and was on par with CO 6 (v5) in summer and DBGV 5 (v2) in Rabi. Sumanjana exhibited the highest crop growth rate (CGR) and relative growth rate (RGR) during both the seasons at 45-60 DAS. However, DBGV 5 recorded the highest net assimilation rate (NAR) between 30-45 DAS and 45-60 DAS during both the seasons. The highest chlorophyll content was recorded by DBGV 5 (1.96 mg g-1 fresh tissue) during summer and by Sumanjana (2.36 mg g-1 fresh tissue) during Rabi. The highest stomatal conductance (30.22 m moles m-2 s -1 and 28.34 m moles m-2 s -1 ) and lower stomatal index (15.16% and 13.34%) were recorded in Sumanjana during both the seasons. The variety Sumanjana flowered earlier compared to other varieties during both the seasons and produced the highest number of pods per plant (27.30 and 26.54). Hundred seed weight was significantly higher for DBGV 5 (5.01 g and 4.92 g) and remained at par with Sumanjana (4.99 g and 4.88 g) during both the seasons. Seed yield, haulm yield and total dry matter production (TDMP) were higher for Sumanjana and comparable with DBGV 5 during both the seasons. Sumanjana recorded higher NPK uptake during both the seasons followed by DBGV 5. The subplot factor foliar spray had significant effect on growth, physiological and yield attributes of blackgram varieties. Foliar spray of 19:19:19 (1%) at 45 and 60 DAS + foliar spray of NAA 40 mg L-1 and SA 100 mg L-1 at pre-flowering and 15 days later (f4) resulted in significantly taller plants, more number of branches and leaves. The highest CGR, RGR (at 45-60 DAS), LAI, number and dry weight of nodules per plant at flowering were recorded in f4 during both the seasons. During summer, f3, f4 and f5 recorded higher NAR between 45-60 DAS. Higher chlorophyll content and stomatal conductance were recorded by f4 during both the seasons. Plants supplied with f3 attained 50 per cent flowering earlier and was on par with f5 during both the seasons. Highest number of pods per plant, 100 seed weight, seed yield, haulm yield and TDMP were recorded by f4 during both seasons. The grain protein content was improved by f4 and was on par with f3, f1 and f5. The NPK uptake was higher in f4 and was on par with f3 and f5 during summer. Significantly higher organic carbon, available N and P was recorded in f4. Among the treatment combinations, Sumanjana (v1) with f4 produced taller plants at two months after sowing (MAS), higher number of branches and leaves per plant during summer and Rabi. Leaf area index, number of nodules and dry weight of nodules at flowering were higher for v1f4 followed by v2f4. Sumanjana in combination with f4 measured significantly higher CGR and RGR (at active growth stages), highest chlorophyll content, stomatal conductance and lower stomatal index during both the seasons. The variety Sumanjana with f4 produced superior number of pods per plant (30.24 and 29.40) and hundred seed weight during summer and Rabi. A higher seed yield was realized in v1f4 (1750 kg ha-1 ) which was on par with v2f4 (1713 kg ha-1 ) during summer. Seed yield was the highest (1700 kg ha-1 ) in v1f4 during Rabi. Haulm yield and TDMP recorded were higher for v1f4 and was on par with v2f4 during both the seasons. The available N status in soil was higher during both the seasons in v1f4 with the highest NPK uptake during Rabi. Sumanjana and DBGV 5 with f4 realized higher mean net income (₹ 70411 ha-1 and ₹ 61256 ha-1 ) and mean B: C ratio (2.04 and 1.95). The present study identified DBGV 5 and Sumanjana as shade tolerant blackgram varieties with superior growth and yield attributes under partial shade and could be recommended for intercropping in coconut garden. Further, the yield of the shade tolerant varieties could be enhanced by recommended dose of nutrients as per KAU package supplemented with foliar spray of 19:19:19 (1%) at 45 and 60 DAS + foliar spray of NAA 40 mg L-1 and SA 100 mg L-1 at preflowering (35 DAS) and 15 days later. Sumanjana and DBGV 5 raised under partial shade in coconut garden with recommended dose of nutrients supplemented with the above said foliar spray realized higher mean net income and mean B: C ratio.
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    ThesisItemOpen Access
    Irrigation scheduling and water stress mitigation strategies in upland rice (Oryza sativa L.)
    (Department of Agronomy, College of Agriculture, Vellayani, 2021) Gritta, Elizabeth Jolly; KAU; Sajitha Rani, T
    The study entitled “Irrigation scheduling and water stress mitigation strategies in upland rice (Oryza sativa L.)” was carried out as two field experiments at the Instructional Farm, College of Agriculture, Vellayani from 2017 to 2020 to identify a suitable variety and irrigation method for upland rice, to standardize irrigation scheduling and to assess the effect of moisture stress mitigation strategies on the growth, yield and economics of upland rice. Experiment I entitled “Identification of suitable variety and standardization of irrigation method” was conducted from January 2019 to May 2019. The experiment was laid out in split plot design with five main plot treatments and two sub plot treatments, in four replications. The treatments included sprinkler irrigation at 100% PE, sprinkler irrigation at 75% PE, drip irrigation at 100% PE, drip irrigation at 75% PE and hose irrigation (farmer’s practice-irrigation given thrice in a week) as main plot treatments and rice varieties Uma and Prathyasa as sub-plot treatments. The height of the plant, number of tillers m -2 , leaf area index and dry matter production were observed to be significantly the highest for the variety Prathyasa irrigated using sprinkler irrigation at 100% PE and hose irrigation was significantly inferior to all other methods of irrigation. The variety Prathyasa irrigated using sprinkler irrigation at 100% PE also recorded the highest number of panicles m -2 (226.00), number of grains per panicle (159.75) and grain yield (4.37 Mg ha -1 ). The highest RLWC and consumptive use (434.25 mm) by the crop was observed in the variety Uma irrigated using sprinkler at 100% PE, followed by drip irrigated plots at 100% PE. The highest crop water use efficiency (1.53 kg m -3 ) was observed in the variety Prathyasa irrigated using hose method and the highest field water use efficiency (0.95 kg m -3 ) was observed in the variety Prathyasa irrigated using sprinkler at 100% PE. 282The economics of cultivation in terms of net returns ( ₹ 1,32,465.50 ha -1 ) and B:C ratio (2.67) were observed to be the highest in the variety Prathyasa irrigated using sprinkler irrigation plots at 100% PE, followed by the variety Prathyasa irrigated using drip irrigation at 100% PE. Field experiment II entitled “Standardization of irrigation scheduling and moisture stress mitigation strategies for upland rice” was conducted during January 2020 to April 2020. The experiment was laid out in split plot design with four main plot treatments and five sub plot treatments in five replications (the best treatment from the experiment I - sprinkler method of irrigation at 100% PE and the variety Prathyasa were used for the experiment II). The main plot treatments included approaches of scheduling irrigation: IW/CPE of 0.8, critical growth stage approach, irrigation to maintain soil moisture at 100% FC and irrigation to maintain soil moisture at 75% FC. The sub-plot treatments included field application of hydrogel polymer (20 kg ha -1 ), seed treatment with hydrogel polymer (10 g kg -1 ), hydrogel polymer (field application @ 2.5 kg ha -1 + seed treatment @10g kg -1 ), foliar application of PPFM (1%) and absolute control. The plant height, number of tillers m -2 , leaf area index and dry matter production were observed to be significantly higher in the plots irrigated at 100% FC, treated with hydrogel polymer (field application @ 2.5 kg ha -1 + seed treatment @10 g kg -1 ), which was followed by the plots irrigated to maintain 2 cm depth of water at critical stages of crop growth. The number of days for 50% flowering, the number of panicles m -2 (233.20), length of panicle (20.36 cm), weight of panicle (3.07 g), number of grains panicle -1 (169.20), grain yield (5.00 Mg ha -1 ) and straw yield (8.07 Mg ha -1 ) were the highest in the plots irrigated at 100% FC and treated with hydrogel polymer (field application @ 2.5 kg ha -1 + seed treatment @10g kg -1 . . The consumptive use by the crop was significantly the highest in the plots irrigated at 100% FC (1265.60 mm) and treated with hydrogel polymer (field application @ 2.5 kg ha -1 + seed treatment @ 10g kg -1 ).The crop water use efficiency recorded the highest value (0.69 kg m -3 ) in the plots irrigated at IW/CPE 283of 0.8 and treated with hydrogel polymer (field application @ 2.5 kg ha -1 + seed treatment @ 10g kg -1 ) and a significantly higher field water use efficiency (0.58) was recorded in the plots irrigated at IW/CPE of 0.8 and treated with hydrogel polymer (field application @ 2.5 kg ha -1 + seed treatment @ 10g kg -1 ) The highest B: C ratio (2.92) and net returns ( ₹ 1,58,000.00 ha -1 ) were obtained from the plots irrigated at 100% FC and treated with hydrogel polymer (field application @ 2.5 kg ha -1 + seed treatment @ 10g kg -1 . The results of the study revealed suitability of the variety Prathyasa, irrigated using sprinkler irrigation at 100% PE for higher yield and monetary returns under upland conditions. It also reflected the suitability of irrigating upland rice at 100 % FC as an effective approach of scheduling irrigation, along with the application of hydrogel polymer (field application @ 2.5kg ha -1 + seed treatment @ 10 g kg -1 ) as the most suitable moisture stress mitigation strategy for upland rice cultivation for enhanced yield and economic returns under water stress conditions.
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    ThesisItemOpen Access
    Productivity enhancement of blackgram (Vigna mungo (L.) Hepper) intercropped in coconut gardens
    (Department of Agronomy, College of Agriculture,Vellayani, 2021) Pooja, A P; KAU; Ameena, M
    The research work entitled ‘Productivity enhancement of blackgram (Vigna mungo (L.) Hepper) intercropped in coconut gardens’ was undertaken at College of Agriculture, Vellayani during 2018-2021. The study aimed to identify shade tolerant blackgram varieties suitable for coconut gardens, to study the effect of foliar nutrition and plant growth regulators on growth and yield of the shade tolerant blackgram varieties intercropped in coconut garden and to work out the economics of cultivation. The investigation was carried out as two experiments: (i) screening of blackgram varieties for shade tolerance, and (ii) performance evaluation of shade tolerant varieties under foliar application of nutrients and growth regulators in rainfed coconut garden. The first experiment was conducted during Rabi 2019-20 in coconut garden having a light intensity equivalent to 50 per cent of that under open condition (56.25 klux), planted at a spacing of 7.6 m x 7.6 m. Seeds of 12 promising blackgram varieties collected from different research stations of south India (Sumanjana, DU 1, DBGV 5, VBN 5, VBN 6, VBN 8, Rashmi, CO 6, TAU 1, TAU 2, Blackgold and AKU 15) and three cultures (Culture 4.5.8, Culture 4.5.18 and Culture 4.6.1), were raised in micro plots laid out in randomized block design with three replications. The crop was raised as per KAU package of practices. The results of the study revealed significant variation in growth characters among the varieties screened for shade tolerance under partial shade in coconut garden. Plants of DBGV 5 were significantly taller (96.89 cm) with higher initial number of leaves at all the stages and was on par with Sumanjana and CO 6. Higher leaf area index (LAI) and leaf area duration were recorded in CO 6 (5.77, 65.66 days) and DBGV 5 (5.36, 58.40 days) followed by Sumanjana. Early flowering was observed in Sumanjana (34.33 days) and DBGV 5 (36.33 days). The variety DBGV 5 had the highest photosynthetic rate and resulted in significantly more pods per plant (23.67) which was on par with CO 6, VBN 5, VBN 6, Sumanjana and Rashmi. DBGV 5 produced the highest seed yield per plant (5.44 g) followed by VBN 5 and Sumanjana. Haulm yield per plant was higher for DBGV 5 (19 g) and was on par with VBN 5, Sumanjana and CO 6. The variety DBGV 5 produced the highest seed yield (1183 kg ha-1 ) followed by VBN 5, Sumanjana and CO 6. A higher harvest index of 0.24 was recorded by Sumanjana which was on par with DBGV 5 and VBN 6. Among the varieties screened, five varieties which performed better in terms of yield per unit area under the partial shade in coconut garden viz., DBGV 5, VBN 5, Sumanjana, CO 6 and VBN 6 were selected for experiment II undertaken in summer 2020 followed by the confirmatory trial during Rabi 2020 -21. The experiment was laid out in split plot design with five varieties (v1 - Sumanjana, v2 - DBGV 5,v3 - VBN 5,v4 - VBN 6,v5 - CO 6) as main plot treatments and six foliar sprays of nutrients and plant growth regulators as subplot treatments (f1: 19:19:19 (1%) at 45 and 60 DAS, f2: SOP (0.5%) at 45 and 60 DAS, f3: NAA 40 mg L-1 and salicylic acid 100 mg L-1 at pre-flowering (30-45 DAS) and 15 days later, f4: f3 + f1, f5: f3 + f2 and f6: Control - KAU POP). Among the varieties, Sumanjana (v1) grew taller during both the seasons and was comparable with CO 6 and DBGV 5 at harvest. Sumanjana produced higher number of branches with more number of leaves during both the seasons. At flowering, higher LAI, number and dry weight of nodules per plant were realized by Sumanjana and was on par with CO 6 (v5) in summer and DBGV 5 (v2) in Rabi. Sumanjana exhibited the highest crop growth rate (CGR) and relative growth rate (RGR) during both the seasons at 45-60 DAS. However, DBGV 5 recorded the highest net assimilation rate (NAR) between 30-45 DAS and 45-60 DAS during both the seasons. The highest chlorophyll content was recorded by DBGV 5 (1.96 mg g-1 fresh tissue) during summer and by Sumanjana (2.36 mg g-1 fresh tissue) during Rabi. The highest stomatal conductance (30.22 m moles m-2 s -1 and 28.34 m moles m-2 s -1 ) and lower stomatal index (15.16% and 13.34%) were recorded in Sumanjana during both the seasons. The variety Sumanjana flowered earlier compared to other varieties during both the seasons and produced the highest number of pods per plant (27.30 and 26.54). Hundred seed weight was significantly higher for DBGV 5 (5.01 g and 4.92 g) and remained at par with Sumanjana (4.99 g and 4.88 g) during both the seasons. Seed yield, haulm yield and total dry matter production (TDMP) were higher for Sumanjana and comparable with DBGV 5 during both the seasons. Sumanjana recorded higher NPK uptake during both the seasons followed by DBGV 5. The subplot factor foliar spray had significant effect on growth, physiological and yield attributes of blackgram varieties. Foliar spray of 19:19:19 (1%) at 45 and 60 DAS + foliar spray of NAA 40 mg L-1 and SA 100 mg L-1 at pre-flowering and 15 days later (f4) resulted in significantly taller plants, more number of branches and leaves. The highest CGR, RGR (at 45-60 DAS), LAI, number and dry weight of nodules per plant at flowering were recorded in f4 during both the seasons. During summer, f3, f4 and f5 recorded higher NAR between 45-60 DAS. Higher chlorophyll content and stomatal conductance were recorded by f4 during both the seasons. Plants supplied with f3 attained 50 per cent flowering earlier and was on par with f5 during both the seasons. Highest number of pods per plant, 100 seed weight, seed yield, haulm yield and TDMP were recorded by f4 during both seasons. The grain protein content was improved by f4 and was on par with f3, f1 and f5. The NPK uptake was higher in f4 and was on par with f3 and f5 during summer. Significantly higher organic carbon, available N and P was recorded in f4. Among the treatment combinations, Sumanjana (v1) with f4 produced taller plants at two months after sowing (MAS), higher number of branches and leaves per plant during summer and Rabi. Leaf area index, number of nodules and dry weight of nodules at flowering were higher for v1f4 followed by v2f4. Sumanjana in combination with f4 measured significantly higher CGR and RGR (at active growth stages), highest chlorophyll content, stomatal conductance and lower stomatal index during both the seasons. The variety Sumanjana with f4 produced superior number of pods per plant (30.24 and 29.40) and hundred seed weight during summer and Rabi. A higher seed yield was realized in v1f4 (1750 kg ha-1 ) which was on par with v2f4 (1713 kg ha-1 ) during summer. Seed yield was the highest (1700 kg ha-1 ) in v1f4 during Rabi. Haulm yield and TDMP recorded were higher for v1f4 and was on par with v2f4 during both the seasons. The available N status in soil was higher during both the seasons in v1f4 with the highest NPK uptake during Rabi. Sumanjana and DBGV 5 with f4 realized higher mean net income (₹ 70411 ha-1 and ₹ 61256 ha-1 ) and mean B: C ratio (2.04 and 1.95). The present study identified DBGV 5 and Sumanjana as shade tolerant blackgram varieties with superior growth and yield attributes under partial shade and could be recommended for intercropping in coconut garden. Further, the yield of the shade tolerant varieties could be enhanced by recommended dose of nutrients as per KAU package supplemented with foliar spray of 19:19:19 (1%) at 45 and 60 DAS + foliar spray of NAA 40 mg L-1 and SA 100 mg L-1 at preflowering (35 DAS) and 15 days later. Sumanjana and DBGV 5 raised under partial shade in coconut garden with recommended dose of nutrients supplemented with the above said foliar spray realized higher mean net income and mean B: C ratio.
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    ThesisItemOpen Access
    Input optimization for short duration Red gram [Cajanus cajan (L.) Millsp.]
    (Department of Agronomy, College of Agriculture,Vellayani, 2021) Anjana Devaraj, G; KAU; Sheeba, Rebecca Isaac
    The study entitled “Input optimization for short duration red gram [Cajanus cajan (L.) Millsp.]” was conducted at College of Agriculture, Vellayani during 2017 - 2020 with the objectives, to assess the suitability of two short duration varieties of red gram, standardize the spacing and nutrient management practices for short duration red gram and to examine the legume effect on succeeding fodder maize crop. The investigation was done as three experiments (i) assessment of the suitability of two short duration varieties and standardization of spacing and nutrient levels (ii) assessment of legume effect on fodder maize and (iii) nutrient scheduling in red gram. The experiment I was laid out in randomized block design (RBD) with three replications during Rabi season (November to March) in 2018 - 2019 and the confirmatory experiment, during 2019 - 2020. The treatments included combinations of varieties [v1: APK 1; v2: Vamban (Rg) 3], spacings [s1: 40 cm x 20 cm; s2: 60 cm x 30 cm] and nutrient levels [ n1: 40:80:40, n2: 30:60:30; n3: 20:40:20 kg NPK ha-1 ]. Half nitrogen (N), potassium (K) and full phosphorus (P) were given basally, remaining as top dressing, 30 days after sowing (DAS). Farmyard manure (FYM) was applied uniformly @ 12. 5 t ha-1 . The varieties, spacings and nutrient levels had significant influence on the growth characters of red gram at the different stages of observation. Variety Vamban (Rg) 3 (v2) recorded significantly taller plants, higher number of branches and root parameters compared to APK1 (v1) during both the years of experimentation. The wider spacing, s2 (60 cm x 30 cm), the highest nutrient level, n1 (40:80:40 kg NPK ha-1 ) and the combination, v2s2n1 resulted in superior values for plant height, number of branches per plant, root volume and root dry weight, while narrow spacing (40 cm x 20 cm) recorded the highest number and weight of nodules per plant. The interactions also exerted significant influence on growth parameters with the interactions involving v2, s2 and n1 recording higher values. The variety APK 1 showed earliness in flowering with significantly higher average pod weight, 100 seed weight, seed yield (1.04 t ha-1 ) and haulm yield (3.70 t ha-1 ). Narrow spacing and the highest nutrient level recorded superior values for average pod weight, seed and haulm yields. The interactions also resulted in significant variations in yield attributes and yield. Pooled analysis of yield data of the two years registered the highest seed yield (1.38 t ha-1 ) in v1s1n1 (APK 1 + 40 cm x 20 cm + 40:80:40 kg NPK ha-1 ). Maximum dry matter production (DMP), crop growth rate (CGR) and seed protein content were recorded in APK 1 and at the highest nutrient level. Among the spacings tried, wider spacing resulted in the highest DMP and seed protein, while CGR was higher in the narrow spacing. The partial factor productivity (PFP) for N, P and K were superior in the combination v1s1n1 in both years. Individual effects of the variety APK 1, narrow spacing and the highest nutrient level recorded maximum nutrient uptake and in the combinations of APK 1 or Vamban (Rg) 3 with 40 cm x 20 cm and 40:80:40 kg NPK ha-1 . Available soil N and microbial counts assessed after the experiment were the highest after APK 1. Wider spacing and the highest NPK level recorded maximum soil available nutrient status, while microbial counts, at narrow spacing. Soil nutrient balance sheet computed for N was positive during both years. The balance sheet for P was positive for all the treatment combinations involving wider spacing during the first year. During the second year, all treatments showed positive balance for P except v1s1n1, v1s1n2, v1s2n2 and v2s2n3. Nutrient balance for K was positive in treatments v1s1n1, v1s2n1 and v2s1n1 during the both years. Pooled mean of the economics of cultivation during the two years revealed maximum net returns per hectare (₹ 88621/-) and B:C ratio (2.03) in v1s1n1 (APK 1 + 40 cm x 20 cm + 40:80:40 kg NPK ha-1 ). The legume effect of red gram on fodder maize was assessed during Kharif season, June to August 2019. Crop residues (root + shoot + fallen leaves) of red gram were incorporated in situ and allowed to decompose for two months. The maximum quantity of residues (4.83 tha-1 ) was generated in the treatment combination T7, Vamban (Rg) 3 + 40 cm x 20 cm + 40:80:40 kg NPK ha-1 imposed in red gram, which was on par with T1, the combination, APK 1 + 40 cm x 20 cm + 40:80:40 kg NPK ha-1 (4.75 tha-1 ). There were no marked variations in the biochemical characters of residues, while C: N ratio was significantly narrower in T1 (18.2: 1) and T7 (18.9:1). Residue incorporation improved the soil chemical properties and at 60 days after residue incorporation (DAI), maximum soil pH and C pool (total organic carbon and labile carbon) were estimated in treatment T7, and recalcitrant organic carbon, in T1. Soil available N, P status and dehydrogenase activity were higher in T1, and available K, in T7 at 60DAI. Fodder maize seeds (variety, African tall) were sown during the third week of June in the residue incorporated plots. Green and dry fodder yields (33.61 and 11.37 t ha-1 respectively) were the highest in the treatment T7 which was on par with T1 (32.85 and 11.08 t ha-1 respectively). Soil available NPK status were found to decline from the initial status with fodder maize cultivation. The nutrient scheduling experiment was conducted during Rabi season, 2019 - 2020, in RBD with nine treatments and three replications. The variety APK 1, spacing 40 cm x 20 cm and nutrient level 40:80:40 kg NPK ha-1 found superior in Experiment I were adopted. The integrated nutrient management (INM) practices evaluated were T1: 100 % NPK as chemical fertilizers, T2: 100 % N + 50 % P + 100 % K + P solubiliser, T3: 100 % N + 100 % P + 50 % K + K solubiliser, T4: 100 % N + 50 % P + 50 % K + P solubiliser + K solubiliser, T5: T1 (50 % N foliar), T6: T2 (50 % N foliar), T7 : T3 (50 % N foliar), T8 : T4 (50 % N foliar) and T9 : Absolute control: No fertilizers. The entire dose of N was given as soil application in T1 to T4 and foliar spray of 50 per cent N in T5 to T8 with urea (2 %) at 30 and 45 DAS. Phosphorus and K solubilisers (Bacillus megaterium and Bacillus sporothermodurans respectively) were mixed with powdered FYM in the ratio 1: 50 separately, and 10 g of each mixture was added in soil one week after basal fertilizer application. The INM practice of 100 per cent N + 50 per cent P + 50 per cent K along with P and K solubilisers (T4) recorded significantly taller plants (109.70 cm), maximum number of branches (6.5) at harvest, whereas weight of nodules per plant at flowering (0.59 g) and root parameters were significantly the highest in treatment T8. Average pod weight (0.62 g) and seed yield (1.48 t ha-1 ) were superior in T4 and on par with the combination involving foliar nutrition, T8 (1.46 t ha-1 ). Integration of P and K solubilisers with chemical fertilizers (100 % N and 50 % P and K), registered 50 per cent higher yield than the absolute control. Among the agronomic indices, DMP at 100 DAS (34.18 g plant-1 ), CGR at 80 - 100 DAS (3.44 g m-2 day-1 ) were the highest in T4, and RGR, in T2 followed by T4. Substitution of 50 per cent Pand K with biofertilizers recorded maximum uptake of N, P and K and physiological efficiencies for the nutrients. Computation of nutrient balances with the INM practices adopted revealed the highest positive balance for N in T8, P in T4 and for K in T7. Economic analysis showed the treatment T to record the highest net return per hectare (₹ 94722 /-) and B: C ratio (2.05). Based on the results it could be concluded that the short duration red gram varieties, APK 1 and Vamban (Rg) 3 are suitable for cultivation in the southern laterites of Kerala. The variety APK 1 was superior in terms of yield and profit and can be recommended for planting at a spacing of 40 cm x 20 cm and an NPK dose of 40:80:40 kg ha-1 based on the soil test results. Evaluation of the legume effect of red gram revealed significant increases in soil fertility status with residue incorporation. Among the treatments imposed in red gram, irrespective of the variety, the residual effect realized with red gram planted at 40 cm x 20 cm spacing and fertilized with 40:80:40 kg NPK ha-1 was found to be superior in terms of fodder yield in the succeeding crop of maize. The integrated nutrient management practice that proved profitable in APK 1 involved application of 40:40:20 kg NPK ha-1 as chemical fertilizers along with P and K solubilisers, the entire dose in soil.
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    ThesisItemOpen Access
    Bio-efficacy of tank mixed herbicides and urea in wet seeded rice
    (Department of Agronomy, College of Agriculture, Vellanikkara, 2021) Thumu, Venkateswara Reddy; KAU; Meera, V Menon
    The use of herbicides has become an indispensable part of agriculture, particularly in rice cultivation, where weeds are the most harmful of the biotic constraints to production. A usual practice among rice farmers in the Kole lands of Kerala is the tank mixing of herbicides, for a broader spectrum of weed control, enhanced weed control efficiency and reduction in the cost of application. However, mixing of herbicides is done without any knowledge of the probable synergistic or antagonistic interactions on weed flora. Herbicides are also mixed with fertilizers like urea under the common belief that herbicidal efficiency is enhanced by this practice. Application of herbicides may affect various plant pathogens and microbial bioagents which occur naturally in the rice ecosystem. Information of the effect on main disease causing as well as beneficial microorganisms would help in selecting appropriate herbicides. Hence the major objectives of the research programme entitled “Bio-efficacy of tank mixed herbicides and urea in wet seeded rice” were to study the synergistic or antagonistic effect of tank mixing of commonly used herbicides, and to evaluate the efficiency of these herbicides on mixing with urea, on major weeds of rice. The effect of these herbicides on beneficial and pathogenic microorganisms were also investigated. Two field experiments were conducted at Alappad padasekharam in the Kole lands of Thrissur from October to January 2019-20 and 2020-21. The soil of experimental field was clayey in texture, high in organic carbon (1.1-1.3%), low available nitrogen (180-188 kg/ha), and medium phosphorus (20-21.5 kg/ha) and potash (152-159 kg/ha), with a soil pH of 4.5-4.7. The feasibility of mixing herbicides was evaluated in experiment I (Bio-efficacy of tank mixed herbicide combinations in wet seeded rice). There were fourteen treatments and they included tank mixtures and sequential applications of five herbicides viz., fenoxaprop-p-ethyl (0.06 kg/ha), (chlorimuron-ethyl + metsulfuron-ethyl) (0.004 kg/ha), carfentrazone ethyl (0.02 ii kg/ha), bispyribac-sodium (0.025 kg/ha), and (cyhalofop-butyl + penoxsulam) (0.15 kg/ha). These were compared with two broad spectrum herbicides, bispyribac-sodium (0.025 kg/ha) and (cyhalofop-butyl + penoxsulam) (0.15 kg/ha), as well hand weeded and unweeded controls. In experiment II (Bio-efficacy of tank mixed herbicides and urea in wet seeded rice), there were twelve treatments. Six herbicides, viz., cyhalofop butyl (0.08 kg/ha), (cyhalofop butyl + penoxsulam) (0.15 kg/ha), bispyribac-sodium (0.025 kg/ha), fenoxaprop-p-ethyl (0.06 kg/ha), carfentrazone ethyl (0.02 kg/ha) and (chlorimuron ethyl + metsulfuron methyl) (0.004 kg/ha) were applied with and without urea (1%) mixing. Hand weeded and unweeded controls were also included for comparison. Randomized Block Design with three replications was adopted for both experiments. Wet seeding of rice at the seed rate of 100 kg/ha was done. Nitrogen, phosphorus and potassium @ 90:35:45 kg/ha were supplied through urea, factomphos and muriate of potash (KAU, 2016). In experiment III (In vitro evaluation of herbicides on beneficial and pathogenic microorganisms) treatments included the effect of herbicides mentioned in experiment II which were evaluated under in vitro conditions with recommended, higher and lower doses on beneficial microbial bioagents (Trichoderma viride and Pseudomonas fluorescens) and pathogenic microorganisms (Rhizoctonia solani, Pyricularia oryzae and Xanthomonas oryzae pv. oryzae). Factorial Completely Randomized Block Design was adopted with 18 treatments and three replications each. Tank mixing of herbicides was found to be more effective than their sequential application for most of the combinations. Tank mixed combination of (cyhalofopbutyl + penoxsulam) with (chlorimuron-ethyl + metsulfuron-methyl) showed synergistic effect and had lowest weed density (32, 16 and 20 nos./m2 ), lowest weed dry matter production (14.68, 50.50 and 88.95 kg/ha), and highest weed control efficiency (91, 88, and 82%) at 15, 30 and 60 days after application respectively. The number of tillers per sq. m (411), number of panicles per sq. m (288), number of grains per panicle (103), percentage of filled grain (91.6) at harvest, nutrient uptake by rice at 60 DAS (105.06, 14.32 and 74.28 kg/ha of N, P and K respectively), grain iii yield (3.97 t/ha), net returns (Rs.71,406/ha) and benefit: cost ratio (2.25) were highest in the same treatment. The next best treatment was fenoxaprop-p-ethyl + bispyribac sodium. On tank mixing of herbicides with urea, bispyribac-sodium and urea interacted synergistically, resulting in highest weed control efficiency (82.5 and 78% at 15 and 30 days after application respectively), highest grain yield (5.03 t/ha), and profitability (Rs. 93,509/ha) over the other treatments. Mixing of (cyhalofop-butyl + penoxsulam) with urea could also be recommended for good results (grain yield of 4.94 t/ha and net returns of Rs.87,463/ha). In vitro evaluation of herbicides revealed that bispyribac-sodium and (cyhalofop-butyl + penoxsulam) had greatest inhibitory effect on pathogenic microorganisms Rhizoctonia solani and Pyricularia oryzae, but showed no effect on Xanthomonas oryzae pv. oryzae, and were less harmful to biocontrol agents Trichoderma viride and Pseudomonas fluorescens at recommended doses. Tank mix combination of (cyhalofop-butyl + penoxsulam) with (chlorimuronethyl + metsulfuron-methyl) was the best treatment with compatibility, efficient weed control, high grain yield and net returns. Tank mixing of bispyribac-sodium with urea 1% had synergistic effect resulting in highest weed control efficiency, production and profitability over the other treatments. Mixing of (cyhalofop-butyl + penoxsulam) with urea 1% could also be recommended for good results. Bispyribac-sodium and (cyhalofop-butyl + penoxsulam) were the best herbicides on in vitro evaluation in their effect on pathogenic microorganisms Rhizoctonia solani and Pyricularia oryzae, and at recommended doses were compatible with biocontrol agents Trichoderma viride and Pseudomonas flourescens.
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    ThesisItemOpen Access
    Resource management for source- sink modulation in chinese potato[Plectranthus rotundifolius (Poir.) Spreng.]
    (Department of Agronomy, College of Agriculture Vellayani, 2021) Arunjith, P; KAU; Sheeba, Rebecca Isaac
    The research work entitled ‘Resource management for source-sink modulation in Chinese potato [Plectranthus rotundifolius (Poir.) Spreng.]’ was undertaken at College of Agriculture, Vellayani during 2018 – 2021. The main objectives were to study the influence of planting methods, nutrient management practices and growth promoters on source-sink relationship, tuber yield and quality in Chinese potato, to assess the growth and yield responses of the crop to carbon dioxide (CO2) fertilization and to work out the economics. The investigation was carried out as two experiments: i) influence of planting methods, nutrient management practices and growth promoters on source - sink relationship, tuber yield and quality and ii) influence of CO2 fertilization on growth and yield responses in Chinese potato. The photo insensitive variety Suphala, released by Kerala Agricultural University (KAU), was used for the study. Experiment I was conducted during October 2019- February 2020 and repeated during 2020-2021 for confirmation. It was laid out in split plot design with five methods of planting as main plots and six combinations of two nutrient management practices and three growth promoters as sub plot treatments, in four replications. The methods of planting included were m1: bed method (30 cm x 15 cm), m2: bed method (30 cm x 30 cm), m3: ridge method (30 cm x 15 cm), m4: ridge method (30 cm x 30 cm) and m5: mound method (30 cm x 30 cm). The combinations comprised nutrient management practices (n1: 60:30:120 kg NPK ha-1 + PGPR Mix 1, n2: 60:30:120 kg NPK ha-1) and growth promoters (g1: humic acid @ 5 g L-1, g2: benzyl adenine @ 50 mg L-1 and g3: water spray). PGPR Mix 1 (2 %) was applied @ 5 g per plant, thrice, at the time of planting, 30 DAP and 60 DAP in n1 and growth promoters were sprayed 45 and 75 DAP. Other cultural operations were done as per package of practices of KAU. Bed method of planting at 30 cm x 15 cm (m1) produced significantly taller plants with higher leaf area index (LAI), dry matter production (DMP) and crop growth rate (CGR) in both the years. Planting at the wider spacing (30 cm x 30 cm) on beds (m2) or ridges (m4) resulted in higher and comparable values for number of branches and plant spread (N-S and E-W), while m2 showed superiority in the number of leaves and leaf area per plant at 45 and 90 DAP. The wider spacing, irrespective of the method of planting, revealed markedly higher relative growth rate (RGR) during 45-90 DAP and the trend remained similar in both years. Significantly higher net assimilation rate (NAR) between 45-90 and 90-135 DAP, and chlorophyll content were noted in m2. Higher chlorophyll content in m2 was on par with m4 during second year. Per plant tuber attributes (number of tubers, tuber yield, marketable tuber yield and average tuber weight) were found superior in bed planting at 30 cm x 30 cm. But, average tuber weight was comparable with m4 in the first year and with m4 and m5 in the second year. Per hectare tuber yields were significantly the highest in the bed method of planting at 30 cm x 15 cm spacing, during both the years with a pooled mean of 20.93 t ha-1. The treatment also showed the maximum uptake of N, P and K. Soil available N, P and K status were the highest in mound method at 30 cm x 30 cm (m5) and on par with m4 and m2. Bacterial, fungal and actinomycete population and dehydrogenase activity were higher in the bed/ridge method of planting at 30 cm x 15 cm spacing (m1 and m3). The combination of 60:30:120 kg NPK ha-1 + PGPR Mix 1 + humic acid (n1g1) resulted in significantly higher growth attributes (plant height, number of branches and plant spread) while at 135 DAP, n1g2 recorded the maximum number of leaves, leaf area per plant, LAI and delayed senescence in both the years. Physiological parameters (DMP, CGR, RGR, NAR) yield attributes, per hectare tuber yield, marketable tuber yield, percentage marketable tuber yield, N, P, K uptake, starch and protein content were superior in n1g1. The tuber yield and marketable tuber yield (pooled) were 21.10 and 18.34 t ha-1 respectively. Soil available N, P, K status, microbial count and dehydrogenase activity were markedly higher in treatments involving PGPR Mix 1 (n1) compared to that without PGPR Mix 1, nevertheless, remained comparable among n1g1, n1g2 and n1g3. Land configuration (bed/ridge) with planting at wider spacing and inclusion of PGPR and humic acid proved superior with respect to the number of branches, leaves per plant and leaf area. Leaf area index was significantly the highest in m3n1g1 in the first year and m1n1g1 in the second year at 90 DAP. The combination m4n1g1, produced the maximum number of tubers per plant (23.8) in the first year on par with m2n1g1 (23.6), whereas during the second year it was the highest (25.0) in m2n1g1. Maximum per plant tuber yield (189.48 and 198.95 g), marketable tuber yield (170.37 and 179.45 g) and percentage of marketable tubers (73.06 and 70.67) were noted in m2n1g1 during both years. The treatment combination m1n1g1 recorded the highest DMP and per hectare tuber yield with a pooled mean of 23.38 t ha-1. The percentage of marketable tuber yields increased by nearly 10 per cent over m1n2g3 in the two years. Potassium uptake was the highest in m1n1g1 and remained comparable with m1n1g2 in the second year. Irrespective of growth promoters applied, inclusion of PGPR Mix 1 (n1) resulted in higher soil available P and K status in the widely spaced planting and the maximum dehydrogenase activity and microbial counts were enumerated in the closely spaced planting on beds (m1). Bed method of planting at 30 cm x 15 cm spacing along with application of 60:30:120 kg NPK ha-1 + PGPR Mix 1 + humic acid (m1n1g1) was the most profitable resource management practice, pooled mean of economics of cultivation revealed maximum net returns and BCR of ₹ 651296 ha-1 and 3.83 respectively. The CO2 fertilization study was conducted in trenches (2 m x 1 m x 1 m) in completely randomized design with six treatments (substrates for CO2 evolution) replicated thrice, during November 2019- July 2020 and October 2020- March 2021. The treatments included, s0: no substrate, s1: cow dung, s2: coir pith, s3: cow dung + coir pith (2:1), s4: s2 + Pleurotus 1g kg-1 + N + P (2% w/w) and s5: s3 + Pleurotus 1g kg-1 + N + P (2% w/w). Cuttings of Chinese potato were planted directly in soil in the first year and in grow bags during the second year. Organic substrates (as per treatment) were spread at the trench base to a thickness of 5 cm, taking precautions to avoid direct contact of the substrates with the cuttings planted directly in soil. The trenches were kept covered with a dome prepared of 200 μ uv stabilised polythene sheet fixed on a metal frame, daily from 4.00 pm to 10.30 am. In all the substrate applied treatments, maximum release of CO2 (501 to 858 ppm) occurred during the first two weeks of application and thereafter it declined. The highest peak of CO2 concentration (858 ppm) at two weeks of application was observed in s5 followed by s3, (752 ppm). Relatively higher air and soil temperatures were observed in trenches during both the years of study. Significantly higher growth attributes at 30 DAP were observed in plants grown in the trench filled with cow dung and coir pith in 2:1 ratio (s3) comparable with treatments containing cow dung and additives (s5). The superiority of s5 on growth attributes were evident at the later stages of growth. Chlorophyll contents (1.147 and 1.193 mg g-1) were maximum in s3 applied trenches at 45 DAP, whereas s5 recorded superior values at 90 DAP (1.153 and 1.193 mg g-1). Initiation of senescence was significantly earlier in CO2 fertilized plants and the highest biomass per plant was recorded in s5. Nevertheless, despite an increased above ground biomass with elevated CO2, tuber development was not observed in any of the treatments. Based on the results of the experiments, it could be concluded that bed/ ridge method of land preparation with planting at 30 cm x 30 cm spacing in combination with an NPK dose of 60:30:120 kg ha-1 + PGPR Mix 1 + humic acid significantly improved the growth parameters (source) and yield attributes (sink) in Chinese potato. A closer planting (30 cm x 15 cm) on beds and application of 60:30:120 kg NPK ha-1 through chemical fertilizers, PGPR Mix 1 (2 %) @ 5 g per plant thrice, as basal, 30 and 60 DAP along with foliar sprays of humic acid @ 5 g L-1 (45 and 75 DAP) can be recommended for superior marketable tuber yields, higher net returns and B: C ratio. The results of the CO2 fertilization study indicated that elevated CO2 enhanced the vegetative growth in Chinese potato at the expense of tuber development.
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    ThesisItemOpen Access
    Germination ecology and management of chinese sprangletop [Leptochloa chinensis (L.) Nees.] in wet seeded rice
    (Department of Agronomy, College of Agriculture, Vellayani, 2021) Lekshmi, Sekhar; KAU; Ameena, M
    An investigation entitled ‘Germination ecology and management of Chinese sprangletop [Leptochloa chinensis (L.) Nees.] in wet seeded rice’ was undertaken at the College of Agriculture, Vellayani during 2017-2020. The objectives were to study the habitat, germination ecology and distribution of Leptochloa chinensis in major rice growing tracts of Kerala; to test the efficacy of tank mix combinations of herbicides for the management of the weed; to test the sensitivity of the weed to herbicide combinations and to assess the mode of action of the herbicide combinations. The phytosociological survey was conducted to document the habitat, composition and distribution of L. chinensis in different rice tracts of Kerala viz., Palakkad, Kole and Kuttanad after selecting three severely infested padasekharams in each tract during 2018 and 2019. L. chinensis was found to occur in all the major rice growing tracts of Kerala and registered summed dominance ratio of 13.05, 12.40 and 17.49, respectively in Kuttanad, Kole and Palakkad (Kharif). Appraisal of weed vegetation analysis indices displayed the highest weed species richness (17) and Simpson’s diversity index in Kole and the lowest Shannon Wiener diversity index (2.09) in Palakkad. L. chinensis was the dominant weed in all these tracts with an abundance of 17.33, 17.0 and 16.36, respectively and the weed inhabited both upland and lowland situations, either in crop lands, field bunds, stream banks or waterways. Profuse growth of the weed was observed along the inner bunds separating individual fields. The weed was a prolific seed producer with seed production potential ranging from 7400-33,941 seeds per plant across the surveyed locations. Germination ecology experiments encompassed studies on weed phenology and germination of Chinese sprangletop. L. chinensis is an erect or creeping, annual or perennial grass that can grow upto a height of 120-150 cm, propagates both by seed and slips with very minute seeds (thousand seed weight of 0.10-0.18 g). The weed was noticed to develop through five phenological stages, viz., emergence, tillering, heading, flowering and maturity with an average duration of 10.6, 41.5, 73.5, 78.5 and 95 days, respectively. Investigations on germination ecology revealed that light was not an absolute requirement for germination of seeds of L. chinensis, but stimulated germination by 23 per cent. When exposed to alternating temperatures in light/dark, seeds germinated at 15°C to 35°C. The highest germination occurred at 25/15°C (87.2%), while at 35/25°C it was only 70.31 per cent. Germination of L. chinensis was significantly influenced by moisture regime; with zero germination under continuous flooding or with thin layer of water (3 cm) and 70 per cent germination on irrigating at alternate days. Seedling emergence was also significantly affected by seed burial depth. Seedling emergence was high (85%) for seeds placed on the soil surface, while no emergence was observed at burial depths of 2 cm or beyond. Slips placed at the surface recorded 100 per cent sprouting and the time taken for 50 per cent emergence increased with increase in burial depth. The seeds germinated upto nine months after harvest with the germination declining over time. The field experiments on management of L. chinensis were conducted during 2018 and 2019 Kharif at Integrated Farming System Research Station, Karamana. The experiment was laid out in randomized block design with 10 treatments and three replications. The treatments included T1: cyhalofop butyl @ 0.08 kg ha-1 , T2: penoxsulam + cyhalofop butyl (6% OD) @ 0.15 kg ha-1 , T3: cyhalofop butyl + carfentrazone ethyl @ 0.08 + 0.02 kg ha-1 , T4: bispyribac sodium @ 0.025 kg ha-1 , T5: bispyribac sodium + cyhalofop butyl @ 0.025 + 0.08 kg ha-1 , T6: bispyribac sodium + fenoxaprop-p-ethyl @ 0.025 + 0.06 kg ha-1 , T7: fenoxaprop-p-ethyl @ 0.06 kg ha-1 , T8: stale seedbed followed by (fb) glyphosate + oxyfluorfen @ 0.8 + 0.15 kg ha-1 at 15-20 days after land preparation fb cyhalofop butyl + carfentrazone ethyl @ 0.08 + 0.02 kg ha-1 , T9: unweeded control and T10: hand weeding twice at 20 and 45 days after sowing (DAS). The weed management practices had significant influence on L. chinensis count, dry matter production, control efficiency and nutrient removal at different stages of observation. Count of L. chinensis was zero in T6, T7, T8 and T10 at 15 days after treatment application (DATA) during both the years. The lowest count and dry matter production and the highest pooled control efficiency of L. chinensis (97.55 and 96.78 per cent, respectively at 30 and 45 DATA) was registered in T7. It was statistically on par with all other treatments except T4 and T9. Bispyribac sodium was not effective in controlling L. chinensis and resulted in lower control efficiency of 52.63, 38.68 and 42.43 per cent, respectively at 15, 30 and 45 DATA. However, its combination with fenoxaprop-p-ethyl (T6) or cyhalofop butyl (T5) resulted in higher control efficiency of L. chinensis at all stages of observation and recorded 100, 96.06 and 95.96 and 97.23, 92.37 and 94.55 per cent, respectively at 15, 30 and 45 DATA. Among the herbicide treatments, T6 registered the least total weed dry matter production at all stages and resulted in the highest pooled weed control efficiency of 98.20 and 89.70 per cent which was on par with T2 (96.61 and 83.86%) and T5 (95.40 and 84.81%) respectively at 30 and 45 DATA. The highest pooled grain yield (5.03 t ha-1 ) also was registered in T6 which was on par with T2 and T5 with 4.79 and 4.76 t ha-1 . Pooled data revealed that season long weed competition in wet seeded rice (WSR) with L. chinensis as a major weed caused a yield reduction of 59.95 per cent. Compared to the unweeded control, herbicidal treatments enhanced grain yield by 23.89-58.84 per cent, whereas herbicide combinations increased grain yield by 56-59 per cent in WSR. Pooled mean of the economics of cultivation registered maximum net returns per hectare (₹ 63,657 ha-1 ) and B:C ratio (1.81) in T6 followed by T2 (₹ 56,995 ha-1 and 1.73) and T5 (₹ 56,044 ha-1 and 1.72). The sensitivity of L. chinensis to herbicide combinations was tested at the field recommended dose and its lower doses using whole plant bioassay technique after identifying best combinations viz., bispyribac sodium + fenoxaprop-p-ethyl @ 0.025 + 0.06 kg ha-1 , bispyribac sodium + cyhalofop butyl @ 0.025 + 0.08 kg ha-1 , penoxsulam + cyhalofop butyl @ 0.15 kg ha-1 and cyhalofop butyl + carfentrazone ethyl @ 0.08 + 0.02 kg ha-1 . The experiment was laid out in completely randomized design (CRD) with eight treatments and three replications. Lower dose of bispyribac sodium + fenoxaprop-p-ethyl @ 0.020 + 0.04 kg ha-1 recorded the least survival (0%) of L. chinensis whereas, bispyribac sodium + cyhalofop butyl @ 0.020 + 0.06 kg ha-1 , cyhalofop butyl + carfentrazone ethyl @ 0.06 + 0.01 kg ha-1 and penoxsulam + cyhalofop butyl @ 0.10 kg ha-1 registered 26.66, 30.0 and 86.66 per cent survival, respectively. The experiment on mode of action of tank mix herbicide combination was laid out in CRD with four treatments and five replications. The treatments included T1: ALS inhibitor alone (bispyribac sodium @ 0.025 kg ha-1 ), T2: ACCase inhibitor alone (fenoxaprop-p-ethyl @ 0.06 kg ha-1 ), T3: ALS + ACCase inhibitor (bispyribac sodium @ 0.025 kg ha-1 + fenoxaprop-p-ethyl @ 0.06 kg ha-1 ) and T4: Control. Treatment T3 recorded lower amino acid content (0.1775 mg mL-1 ) than T1 (0.2904 mg mL-1 ) confirming that the combined application of an ALS + ACCase inhibitor could provide better control of L. chinensis compared to sole application of ALS inhibitor. The experiment on assessing the differential response of L. chinensis and Echinochloa colona to the broad-spectrum herbicide bispyribac sodium, revealed that amino acid content of L. chinensis was not influenced by the increasing concentration of bispyribac sodium. High content of amino acid was registered in L. chinensis (0.2904 and 0.3234 mg mL-1 ) compared to E. colona irrespective of the concentration of bispyribac sodium. However, in E. colona, the amino acid content (0.1520 and 0.0627 mg mL-1 ) was found to decrease with increasing concentration of bispyribac sodium. The present study identified L. chinensis as a major weed in all the major rice growing tracts of Kerala indicating its invasive potential under diverse environmental conditions owing to its prolific seed production, sprouting from weed slips on soil surface, extended period of seed viability and different mode of propagation. The results revealed that early and continuous flooding, deep tillage for burial of seeds and slips into the soil beyond 5 cm could suppress its emergence. The study identified fenoxaprop-p-ethyl @ 0.06 kg ha-1 as the most effective herbicide against L. chinensis to be sprayed at 15-18 DAS in WSR. In areas where L. chinensis is a dominant weed in the WSR, tank mix application of bispyribac sodium @ 0.025 kg ha-1 + fenoxapropp-ethyl @ 0.06 kg ha-1 at 15-18 DAS could be recommended for broad spectrum weed management. Whole plant bioassay of the above combination proved effective at its still lower dose and the differential response of L. chinensis to bispyribac sodium indicated herbicide combinations for managing the complex spectrum of weeds in wet seeded rice.
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    ThesisItemOpen Access
    Resource management for source- sink modulation in chinese potato[Plectranthus rotundifolius (Poir.) Spreng.]
    (Department of Agronomy, College of Agriculture, Vellayani, 2022-01-20) Arunjith, P; Sheeba, Rebecca Isaac