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Open Access
Nutrients and tillage interactions in rice fallow cowpea (Vigna unguiculata L. Walp.) production
(Department of Agronomy, College of Agriculture, Vellanikkara, 2020) Vandana, G Pai; KAU; Prameela, P
An experiment entitled “Nutrients and tillage interactions in rice fallow cowpea production” was conducted during 2017-2019 at College of Horticulture, Vellanikkara of Kerala Agricultural University, Thrissur. The study consisted of two experiments. Experiment-1 was a pot culture study undertaken during 2017, to find out optimum dose of potassium and magnesium sulphate for cowpea. The experiment was laid out in CRD with 14 treatments and three replications. The treatments included three levels of K2O (10, 20 and 40 kg/ha), and four levels of MgSO4 (40, 60, 80 and 100 kg/ha). Apart from K: MgSO4 @ 10:80 kg/ha (KAU package of practices) and soil test based nutrition (K: MgSO4 @12:80 kg/ha) were also included. Nitrogen and P2O5 were applied at the rate of 20 and 30 kg/ha, respectively, uniformly to all pots. A bush type variety of cowpea Anaswara released from Kerala Agricultural University was used in the study. In the pot culture experiment, application of K2O: MgSO4 @ 40: 40 kg/ha and 40:100 kg/ha resulted in taller plants. At 60 DAS, POP based nutrient application registered more number of branches (12.7 /plant), which was on par with K2O: MgSO4 @ 10:60 (T2), 20:40 (T5), 20:100 (T8), 40:40 (T9), 40:80 (T11), 40:100 (T12) kg/ha as well as to soil test based nutrition (T14). Highest number of root nodules (201) and higher dry matter production at harvest (44 g/plant) was observed in application of K: MgSO4 @ 40:100 kg/ha (T12). An increase in dry matter production of cowpea was observed with magnesium sulphate nutrition. Various levels of K and Mg resulted in significant variation in chlorophyll a and total chlorophyll content. Application of potassium and MgSO4 @ 40:60 kg/ha resulted in higher number of pods and grain yield (40.3 g/plant) and it was statistically comparable to T11 and T12 (K2O: MgSO4 @ 40:80 & 40:100 kg/ha). Based on grain yield, treatments K: MgSO4 @ 20:60 kg/ha, 20:80 kg/ha, 40:60 kg/ha, 40:80 kg/ha were selected for field trial along with soil test based nutrition as control. The second experiment aimed at assessing the effect of various tillage practices, and varied doses of potassium and MgSO4 on growth and yield of cowpea and to work out economic viability. Field experiments were undertaken in rice fallow during 2017 and 2018 (November/December - March/April). Soil of the filed was high in organic carbon, available N, but deficient in available P, K, and Mg. The experiment was laid out in RBD and the treatments were factorial combinations of three types of tillage and varied doses of potassium and magnesium sulphate and it was replicated thrice. Zero tillage (ZT- M1), minimum tillage (MT- M2) and conventional tillage (CT- M3) were the major factors and five nutrient doses (S1-S5) were soil test based nutrition (S1- 11-13 kg K2O/ha along with 80 kg MgSO4/ha), 20 kg K2O/ha along with 60 kg/ 80 kg MgSO4/ha (S2 & S3) and 40 kg K2O/ha along with 60 kg/ 80 kg MgSO4/ha (S4 & S5). N and P2O5 were applied at the rate of 20 kg/ha and 30 kg/ha in all plots. Seeds were dibbled at spacing of 30 cm x 15 cm. In zero tillage, herbicide glyphosate was sprayed @ 0.85 kg/ha two weeks before sowing. In minimum tillage, strip tillage using spade was adopted at a spacing of 30 cm. In conventional tillage, land was ploughed twice followed by formation of small ridges and furrows at a spacing of 30 cm. The plot size was 6 m x 4.2 m. Germination percentage of cowpea (at 7 DAS) was significantly higher in conventional tillage (79 %), whereas, it was very low in zero till (44 %) and intermediate in MT (58 %). Tillage systems and potassium, magnesium sulphate doses had no significant effect on plant height of cowpea, and at 60 DAS average height was 47.5 cm, 52.9 cm and 48.4 cm under zero tillage, minimum tillage and conventional tillage, respectively. At 45 DAS and 60 DAS minimum tillage resulted in higher number of branches per plant whereas, plants in conventional tillage showed earliness in 50 % flowering. Significantly higher LAI was recorded in zero tillage, followed by minimum and conventional tillage. Application of K: MgSO4 @ 40:80 kg/ha also resulted in higher LAI. Zero tillage along with K: MgSO4 @ 40:80 kg/ha (M1S5) recorded the highest LAI. Tillage had no significant effect on chlorophyll a, chlorophyll b, and total chlorophyll content and on chlorophyll a/b ratio. Whereas, potassium and magnesium sulphate application had significant effect on chlorophyll content. Application of K: MgSO4 @ 20:60 kg/ha and K: MgSO4 @ 40:80 kg/ha resulted in higher as well as comparable chlorophyll a and total chlorophyll content. Among interactions ZT with K: MgSO4 @ 12:80 kg/ha (soil test) and CT along with K: MgSO4 @ 20:60 kg/ha higher chlorophyll a content. Dry matter production at early growth stage was higher under conventional tillage, followed by minimum tillage and zero tillage. Whereas, at 75 DAS, highest dry matter was registered under minimum tillage (3240 kg/ha). However, at 90 DAS, both minimum and conventional tillage resulted in higher as well as comparable dry matter (2043 kg/ha and 2085 kg/ha). Root length and root spread were higher under zero tillage followed by MT and CT. Application of K: MgSO4 @ 40:60 kg/ha also resulted in higher root spread. Zero tillage with K: MgSO4 @ 40:60 kg/ha (45.2 cm) resulted in longest roots and higher root spread (2695 cm2). Conventional tillage along with supply of K and MgSO4@ 40 and 80 kg /ha registered shortest roots and lower root spread. Pooled analysis showed that, among various tillage systems, significantly higher grain yield was realized under minimum tillage (735 kg/ha). This was followed by conventional tillage (648 kg/ha) and zero tillage (618 kg/ha) which were on par. Among varied potassium and magnesium doses, application of K: MgSO4 @ 40:60 kg/ha was found to be the best (grain yield of 806 kg/ha). Hence combination of minimum tillage along with K: MgSO4 @ 40:60 kg/ha resulted in the highest grain yield (915 kg/ha). Uptake of nutrients at 30 DAS followed the order of CT>MT>ZT. At harvest, higher uptake of potassium, and magnesium was noted in K: MgSO4 @ 40:60 kg/ha under minimum tillage. There was no significant variation with respect to grain protein content of cowpea due to various tillage practices whereas higher content was registered with application of K: MgSO4 @ 40:80 kg/ha (26.2 %).
Open Access
Response of sweet potato [Ipomoea batatas (L.) Lam.] to secondary nutrients
(Department of Agronomy, College of Horticulture, Vellanikkara, 2020) Nengparmoi, TH; KAU; Prameela, P
Sweet potato is an important food crop with short duration and high nutrient requirement. As the deficiency of secondary nutrients is generally encountered in highly leached acid soils of Kerala and the research on supplementation of these nutrients in enhancing the productivity of sweet potato is limited, the present study entitled “Response of sweet potato [Ipomoea batatas (L.) Lam.] to secondary nutrients” was carried out. The objective was to assess the influence of secondary nutrients on growth, yield and quality of sweetpotato. The experiment was conducted from September 2019 to January 2020 at Agronomy Farm, College of Horticulture, Vellanikkara, Thrissur. The experiment was laid out in RBD with 11 treatments replicated thrice. The treatments included five levels of magnesium sulphate i.e., 0, 40, 60, 80 and 100 kg/ha along with N: P2O5 : K2O @ 75:50:75 kg/ha (KAU POP) and N : P2O5 : K2O @ 65:12:20 (soil test based). A high yielding sweet potato variety ‘Sree Kanaka’ was used. Growth parameters like vine length, leaf area, and total dry matter accumulation per plant were significantly influenced by nutrient management. Higher doses of N: P2O5 : K2O (75:50:75) irrespective of MgSO4 dose (0 to 100 kg/ha) showed higher values for these parameters compared to treatments receiving lower doses of N : P2O5 : K2O (65:12:20) along with MgSO4. At 30 days after planting (DAP), vine length ranged from 40.5 cm to 55.6 cm and it increased to 2.5m by 90 DAP. At this stage, all the treatments exhibited comparable vine length irrespective of nutrient doses, except T3 (65:12:20 + MgSO4 @ 60 kg/ha) and T7 (75:50:75 + MgSO4 @ 40 kg/ha) which registered higher values and differed significantly from others. Higher and comparable total dry matter accumulation was also observed in treatments where N : P2O5 : K2O @ 75:50:75 along with varying doses of MgSO4 was applied. The highest leaf area index of 3.48 was noticed in treatment T8 which received N : P2O5 : K2O (75:50:75) with MgSO4 @ 60 kg/ha and the lowest was seen in organic management (T11). Chlorophyll content at 60 DAP was not significantly influenced by varied doses of nutrients applied. Marketable tuber yield ranged from 19.8 to 35.9 t/ha and the treatments T7 (75:50:75 + MgSO4 @ 40 kg/ha) (35.9 t/ha) and T11 (organic management) (32.2 t/ha) resulted in higher tuber yields and were on par. Application of lower dose of N: P2O5: K2O based on soil test values resulted in lower yields compared to recommended dose. The highest harvest index of 0.72 was observed in T11 (Organic management) followed by T7 (0.60). Unmarketable tuber yield ranged from 1.0 to 1.7 t/ha. Higher and comparable unmarketable yield was observed in treatments T2 (65:12:20 + MgSO4 @ 40 kg/ha) and T3 (65:12:20 + MgSO4 @ 60 kg/ha) which received lower doses of N : P2O5 : K2O and MgSO4 and registered lower marketable yield. The unmarketable yield was the lowest in superior treatment T7 (75:50:75 + MgSO4 @ 40 kg/ha). Quality parameters of sweet potato tuber i.e. total, reducing and non-reducing sugar, crude fibre and crude protein were also estimated. In general, higher and comparable reducing sugar and total sugar content was observed in treatments which received higher doses of N : P2O5 : K2O and in tubers from organic nutrient management. Content of non-reducing sugar, crude fibre and crude protein did not vary significantly and the average values were 6.7, 2.6 and 14.3 % respectively. The soil chemical parameters in post-harvest soil showed a decline in pH and EC except in organic management where an increase in soil pH could be observed. The organic carbon was influenced by nutrient management however, it was in medium range in all the treatments. The average N, P and K uptake by sweet potato was 281, 10 and 156 kg/ha respectively, and the corresponding values for calcium, magnesium and sulphur were 20, 13 and 17 kg/ha respectively. Application of recommended dose of N : P2O5 : K2O along with 40 kg/ha magnesium sulphate resulted in the highest gross return (Rs. 5,38,500), net return (Rs. 4,05,619) as well as B:C ratio (4.1). Organic nutrient management system was the next best treatment with a net return of Rs. 2,88,050 and B:C ratio of 2.5. Hence N : P2O5 : K2O @ 75:50:75 along with 40 kg/ha of magnesium sulphate can be recommended in soils deficient in Mg for enhancing productivity of sweet potato. The results also indicate that organic nutrient management also will be economically viable in sweet potato production if premium price can be assured for the produce.
Open Access
Chemical Priming for improving salinity tolerance in rice
(Department of Agronomy, College of Agriculture, Vellanikkara, 2020) Liz J, Kappen; KAU; Deepa, Thomas
Measures to improve abiotic stress tolerance in plants is gaining importance due to raised concerns on climate change and food security issues all over the world. Though different methodologies for combating abiotic stress like conventional breeding and molecular breeding have been in existence, they are often limited by time and biosafety concerns respectively. Chemical priming is a cost-effective approach in managing abiotic stress. It is reported that use of chemicals, both synthetic and natural, prior to stress events can enhance tolerance to abiotic stresses such as salinity and drought. Application of chemical agents externally can impart a minor stress which will help to generate stress signals that can lead to certain biological changes resulting in increased stress tolerance in later stages of the crop. Rice is a crop badly affected by salinity. Use of chemicals such as beta amino butyric acid (BABA), sodium nitroprusside and calcium chloride as seed primers to improve salinity tolerance may turn promising. With this objective a study was formulated with three experiments. The experiments were screening rice varieties for salinity tolerance, effect of seed priming on germination of rice varieties under salt stress condition and field trial to assess the effect of priming in rice fields with saline water intrusion. The First experiment was a lab study to screen three rice varieties namely Jyothi, Uma and Vytilla-10 at five salinity levels i.e., non-saline, 3 dS/m, 6 dS/m, 9 dS/m and 12 dS/m. Based on the results it was concluded that at 16 DAS with salinity level of 6 dS/m variety Vytilla-10 was highly tolerant (score 1). Variety Jyothi was found susceptible at 6 dS/m (score 7) whereas variety Uma was moderately tolerant (with score 5). At 21 DAS, varieties Uma and Vytilla-10 were found to be susceptible at salinity levels of 6 and 9 dS/m respectively with a score of 7. Objective of second experiment was to assess whether chemical priming could improve salinity threshold of the three varieties. The design used was two factorial CRD with three replications. The treatments were four priming chemicals and two salinity levels. Based on the results of the first experiment, threshold salinity level for Jyothi, Uma and Vtyilla-10 were estimated. Jyothi and Uma were susceptible at 6 dS/m, while Vytilla-10 was susceptible at 9 dS/m. Therefore, in second experiment variety Jyothi, salinity levels of 6 dS/m and 9 dS/m, for variety Uma salinity levels of 6 dS/m and 9 dS/m and for Vytilla-10 salinity levels 9 dS/m and 12 dS/m were taken. Each variety was primed using three chemicals, namely beta amino butyric acid (BABA 1 Mm/L), sodium nitroprusside (SNP,100 μM) and calcium chloride (CaCl2, 2%), water priming was included as control. The efficacy of each priming chemical was analyzed based on germination percentage, growth parameters and visual salt injury symptoms. Priming seeds with calcium chloride was found to influence both the growth parameters and salinity tolerance of seedlings. Based on the results of second experiment, a field trial was undertaken to assess the efficacy of priming chemicals as seed primers and as foliar spray. An experiment was laid out at Rice Research Station, Vytilla in factorial RBD with three replications. The treatments were three priming chemicals namely beta amino butyric acid (BABA), sodium nitroprusside (SNP) and calcium chloride (CaCl2), with water priming as control and three foliar sprays at weekly intervals, fortnightly intervals and weekly water spray. Rice variety Vytilla-10 was used for the study. The seedlings were transplanted to main field and foliar spraying of priming chemicals was done at weekly intervals at 30, 37 and 45 DAS, fortnightly intervals at 30, 45 and 60 DAS as well as weekly water spray. Calcium chloride seed priming was found effective in increasing plant height at 60 DAT, leaf area index, number of panicles, percentage of filled grains, thousand grain weight, yield, proline content in leaf and chlorophyll content (at 60 DAT). Most of the growth and yield parameters were influenced by weekly spray of calcium chloride. More tillers/m2 was observed in seedlings primed using SNP and weekly foliar spraying of SNP was effective in increasing tillering. Total chlorophyll content was found to increase with SNP seed priming and foliar spraying of SNP at fortnightly intervals was found most effective at 60 DAT to increase chlorophyll content. Grain filling was found to increase with BABA seed priming and weekly foliar spray of the same chemical was highly effective. Priming rice seeds with 2 % calcium chloride and foliar spraying of calcium chloride at 2 % on a weekly basis was found to be a reliable method to combat salinity stress and for improving growth, yield and yield attributes of rice.
Open Access
Perfomance of high yielding varieties of finger millet [Eleusine coracana (L.)] (Gaertn)
(Department of Agronomy, College of Agriculture, Vellanikkara, 2020) Kishore, Neeruganti; KAU; Prameela, P
An experiment entitled “Performance of high yielding varieties of finger millet (Eleusine coracana (L.) Gaertn)” was undertaken during the period from July 2018 to January2019 at the Agronomy Farm, College of Agriculture, Vellanikkara, Thrissur.The objective of the experiment was to evaluate the performance of some prominent high yielding varieties of ragi suitable for Kharif and Rabi seasons in central Kerala. Randomized block design was adopted with nine varieties and three replications in both seasons. The plot size was 5 m x 4 m and the seeds were line sown at a spacing of 25 cm x 15 cm. The high yielding varieties included were VR 708 (Champavathi), Vakula, Hima, Maruthi and PR 202 (Godavari) (released from Andhra Pradesh), GPU 48, GPU 28 and KMR 201 (released from Karnataka) and Co15 (released from Tamil Nadu). All the management practices were done as per Package of Practices Recommendations of KAU. Observations on growth parameters were taken at 30 DAS, flowering and at harvest. Quality parameters of grain (crude protein, crude fibre, Ca and Fe), yield and yield attributes were also recorded. Varietal differences were significant with respect to plant height. In Kharif, when plant height was recorded at harvesting, GPU 28 (109.71 cm) and PR 202 (111.07 cm) were superior to all other varieties with statistically comparable values. The shorter varieties were GPU 48 (77.75 cm) and VR 708 (78.39 cm). At this stage in Rabi, CO15 had the tallest plants (100.41 cm). However, PR 202 also had statistically comparable plant height (98.65 cm). VR 708, Maruthi and GPU 48 were statistically on par and were inferior to other varieties with plant height in the range 72.17cm to 73.99cm. The varieties differed significantly with respect to total number of tillers in both the seasons. In general, Rabi crop had a greater number of basal tillers than the Kharif crop. The average number of basal tillers was 5.80 in Kharif and 6.80 in Rabi. In Kharif, variety VR 708 (9.27) was statistically superior with respect to basal tillers produced than other varieties. Variety Vakula produced only 3.6 tillers per plant. In Rabi, the greater number of tillers were produced by VR 708 (10.27) and CO15 (9.93). Total number of tillers showed an increase in most of the varieties, and in Hima and Vakula, a sharp increase in tiller number during Rabi was registered compared to Kharif. Seasonal differences were not pronounced in many varieties with respect to days to flowering but variation to the extent of up to 11 days was noticed in variety GPU 28. On an average, the days to 50 per cent flowering was 69 in Kharif and 72 in Rabi season. In Kharif season, PR 202 took the longest period for 50 percent flowering (79 days). The calcium content in ragi grain showed wide variability among varieties ranging from 326mg/100g to 564 mg/100g over the seasons and Fe content was in a narrow range of 6.25 – 8.91 mg/100g. There was no significant difference in fibre content of various varieties. More productive tillers were produced by CO15 and the minimum number of productive tillers were produced by Maruthi. Wide variations in finger length was observed among varieties and the values ranged from 5.30cm to 11.87 cm in Kharif and 6.23 to 11.97 cm in Rabi season. Vakula had the highest value in both seasons and was significantly superior to all others. The test weight ranged from 1.53 to 3.53 g in Kharif and from 1.51 to 3.25 g in Rabi among the varieties. Variety PR 202 had the highest 1000 grain weight of 3.53g. The average straw yield was 3592 kg/ha in Kharif whereas a higher value of 4010 kg/ha was realized in Rabi. The highest straw yield was for KMR 201(5100 kg/ha & 5141 kg/ha in Kharif and Rabi)) which was on par with GPU 48 (4578 kg/ha) in Kharif. The straw yields were low in Maruthi (3059.7 kg/ha), Vakula (3388.8 kg/ha) and VR 708 (3550 kg/ha) in both seasons. Among the nine varieties tried, six varieties - GPU 48, GPU 28, Hima, CO15 , PR 202 (Godavari) and KMR 201 performed better in Kharif as well as in Rabi season. The variety KMR 201 was found to be superior in terms of yield in both the seasons (3008.3 and 2737 kg/ha, respectively), whereas the white seeded variety Hima was found to be ideal for Rabi season due to its superior yield of 3092 kg/ha . Variety CO15 showed more adaptability to Kharif with grain yield of 2355 kg/ha and the performance was poor in Rabi (1833.33 kg/ha). Three varieties VR 708, Vakula and Maruthi are not ideal varieties for Kerala especially for Kharif season
Open Access
Weed management for upland rice
(Department of Agronomy, College of Horticulture, Vellanikkara, 2020) Basila, Y; KAU; Anitha, S
Rice is one of the principal food crops in Asia and can be grown in wetland and upland conditions. Upland rice is grown in rainfed, naturally well drained soils with bunded or unbunded fields without surface water accumulation. Moisture stress, weed infestation, poor soil fertility and incidence of pests and diseases are major problems in upland rice cultivation. Among these, weeds are considered to be most serious. Hence an effective and timely control of weed is essential to achieve higher productivity in upland rice. Field experiment was conducted at Agronomy Farm, College of Horticulture, Vellanikkara from June 2019 to September 2019 to develop cost effective weed management strategy for upland rice. The experiment was laid out in RBD with eight treatments and three replications. Treatments were T₁: Brown manuring (Cowpea) by application of 2,4-D on 25 DAS, T₂: In situ green manuring (Cowpea), on 25 DAS, T₃: Oxyfluorfen on the day of sowing fb HW at 30 DAS, T₄: Oxyfluorfen on the day of sowing fb bispyribac sodium on 20 DAS, T₅: Pyrazosulfuron on 6 DAS fb HW at 30 DAS, T₆: Pyrazosulfuron ethyl on 6 DAS fb bispyribac sodium on 20 DAS, T₇: Hand weeded control and T₈: Unweeded control. Dominant grass weed species observed were Echinochloa colona, Digitaria sanguinalis, Eleusine indica, Panicum maximum, Setaria spp, and Brachiaria spp. Dominant broad-leaf weed species were Alternanthera bettzickiana, Mitracarpus hirtus, Euphorbia hirta, Euphorbia geniculata, Ludwigia perennis, Scoparia dulcis, Ageratum conyzoides, Phyllanthus amara, Cleome burmannii, Commelina benghalensis, Lindernia crustacea, Catharanthus pusillus, Trianthema portulacastrum, Mollugo disticha and Hemidesmus indicus. Cyperus iria was the only sedge observed in the experimental field. Lowest weed dry matter production was recorded in hand-weeded control at 20 and 45 DAS. Application of oxyfluorfen fb HW at 30 DAS was as effective as hand weeded control and resulted in lesser weed count, weed dry matter, weed index and high weed control efficiency. Application of oxyfluorfen fb HW at 30 DAS resulted in maximum WCE of 92.60 % at 20 DAS and 98.58 % at 45 DAS. Lowest weed index was resulted from oxyfluorfen fb HW at 30 DAS (5.02 %) and was on par with pyrazosulfuron-ethyl on 6 DAS fb HW at 30 DAS (10.35 %). In situ green manuring and brown manuring resulted in significant reduction in weed dry matter production and high WCE at early stages of crop growth as compared to unweeded control, but it was not as effective as herbicide application. Application of oxyfluorfen fb HW at 30 DAS resulted in highest number of tillers per hill, leaf area index and number of hills/m². Hand-weeded control resulted in significantly higher grain yield (2888 kg/ha) and was on par with application of oxyfluorfen fb HW at 30 DAS (2743 kg/ha) and pyrazosulfuron-ethyl fb HW at 30 DAS (2589 kg/ha). Weed competition resulted in 78.05 % yield reduction in upland rice. Oxyfluorfen fb HW at 30 DAS resulted in highest straw yield (5898 kg/ha), which was on par with pyrazosulfuron-ethyl fb HW at 30 DAS (5886 kg/ha) and hand-weeded control (5415 kg/ha). Unweeded control resulted in significantly lower grain yield (634 kg/ha) and straw yield (943 kg/ha). Application of oxyfluorfen fb HW at 30 DAS resulted in higher N uptake by rice at all stages of observation and higher P uptake at harvest. At 30 DAS, application of pyrazosulfuron-ethyl fb bispyribac sodium resulted in higher P and K uptake by rice. At 60 DAS, the treatment brown manuring resulted in higher P uptake and application of oxyfluorfen fb bispyribac sodium resulted in higher K uptake by rice. At harvest, application of pyrazosulfuron-ethyl fb HW at 30 DAS resulted in higher K uptake by rice. Less N, P and K removal by weeds was observed in treatments oxyfluorfen fb HW at 30 DAS and hand-weeded control. Brown manuring resulted in higher organic carbon and soil microbial biomass carbon. Higher soil N and P availability was recorded in plots sprayed with oxyfluorfen fb bispyribac sodium and higher soil K availability was in pyrazosulfuron-ethyl on 6 DAS fb HW at 30 DAS. Application of oxyfluorfen 23.5 EC @ 0.15 kg/ha on the day of sowing fb HW at 30 DAS resulted in higher gross return, net return and B: C ratio, which was on par with pyrazosulfuron-ethyl 10 WP @ 0.03 kg/ha on 6 DAS fb hand weeding at 30 DAS. Hence, either of these pre-emergence herbicides followed by one hand weeding at 30 DAS can be recommended for a cost effective weed management in upland rice.
Open Access
Agro techniques for bush type vegetable cowpea (Vigna unguiculata (L.) Walp.) under open precision farming
(Department of Agronomy, College of Horticulture, Vellanikkara, 2020) Chijina, K; KAU; Latha, A
Cowpea is an important legume vegetable crop known as vegetable meat because of high protein content (24.8 %). The average productivity of cowpea in India is 607 kg/ha (ICAR, 2020) which is considered to be low. Productivity of the crop can be enhanced through selection of appropriate varieties and advanced technologies in management of nutrients and water. Since the research work on cowpea under open precision farming in Kerala is meagre, an attempt was made to standardise the agro techniques for enhancing the yield and profit to the growers. The research work on the topic “Agro techniques for bush type vegetable cowpea (Vigna unguiculata (L.) Walp.) under open precision farming” was undertaken in the Department of Agronomy, College of Horticulture, Vellanikkara during 2017- 2019. The project was aimed to standardize optimum spacing and irrigation requirement of bush type cowpea for enhanced growth and yield under open precision farming. It also aimed to develop a fertigation schedule and to study the response of biofertilisers and foliar nutrition on bush type vegetable cowpea. The first experiment on “Evaluation of genotypes and optimization of spacing for enhanced growth and yield of bush type vegetable cowpea under open precision farming” was laid out with five genotypes viz. Lalita, VU-5, Bhagyalakshmi, Kashi Kanchan, Pusa Komal and Anaswara and three spacings viz. 60 cm x 30 cm, 45 cm x 30 cm and 30 cm x 15 cm, replicated thrice. Among the genotypes Lalita performed better in terms of growth characters and yield and the poor performance was recorded by genotype VU-5. The wider row spacing of 60 cm x 30 cm had a significant superior effect on growth characters and yield of cowpea. The best treatment of genotype Lalita and wider spacing of 60 x 30 cm were selected for the subsequent experiments. The second experiment on “Standardization of source of nutrients and levels of fertigation in bush type vegetable cowpea under open precision farming” was carried out with four levels of fertilizers and three sources of nutrients replicated thrice under open precision farming. The levels of fertilizers were arrived based on the nutrient uptake pattern. The fertigation was given at twenty equal splits doses with conventional and water soluble fertilizers and their combination. The results revealed that there was no significant difference between the levels of fertilizers with respect to growth and yield of cowpea and the application of 20:30:10 kg N, P2O5, K2O per hectare was found to be sufficient for the comparable performance of cowpea with other levels. Fertigation through conventional fertilizers viz. urea, diammonium phosphate and muriate of potash had comparable effect with water soluble fertilizers and their combination in terms of growth and yield of cowpea. The third experiment on “Standardization of irrigation schedule and response of biofertilisers on bush type vegetable cowpea under open precision farming” was conducted to standardize the schedule of drip irrigation and to study the response of biofertilisers and foliar nutrition on bush type vegetable cowpea under open precision farming. Drip irrigation at 100 per cent Ep recorded higher fresh pod yield which was on par with 80 per cent Ep. Water productivity was significantly influenced by irrigation levels and higher water productivity was recorded with drip irrigation at 80 per cent Ep. Combined application of 60 per cent of the recommended dose of fertilizers (20:30:10 kg N, P2O5, K2O / ha) through fertigation as conventional fertilizers and 40 per cent through foliar application using water soluble fertilizers recoded higher fresh pod yield as well as quality characteristics compared to fertigation alone. It is concluded that genotype Lalita at wider spacing of 60 cm x 30 cm was found promising for enhanced growth and yield of bush type vegetable cowpea under open precision farming. Fertigation with conventional fertilizers viz. urea, diammonium phosphate and muriate of potash at the rate of 20:30:10 kg N, P2O5, K2O per hectare found optimum in term of growth and yield under open precision farming. Combined application of 60 per cent of the recommended dose of fertilizers (20:30:10 kg N, P2O5, K2O /ha) through fertigation with conventional fertilizers viz. urea, diammonium phosphate and muriate of potash and 40 per cent through foliar nutrition using water soluble fertilizers with drip irrigation schedule at 80 per cent Ep was found superior for maximum water productivity, yield and profit of bush type cowpea under open precision farming.
Open Access
Biology and management of Sacciolepis interrupta (Wild.) Stapf in rice
(Department of Agronomy, College of Horticulture, Vellanikkara, 2020) Pujari Shobha, Rani; KAU; Meera V, Menon
Sacciolepis interrupta is a tropical grass weed which mimics rice crop at early stages of growth and of late has been appearing as a major weed in many rice growing areas. In India, it is reported in rice growing areas of eastern India and Kerala. In Kerala, the occurrence of S. interrupta was earlier confined to semi dry rice cultivation in Palakkad districts however, now it has been reported in wet seeded as well as transplanted rice culture in other parts of the State. Knowledge on biology and ecology of weeds and their interaction with crops play a key role in weed management. The research programme entitled ‘Biology and management of Sacciolepis interrupta (Willd.) Stapf in rice’, included field survey, laboratory, pot culture and field experiments to study the biology, growth, propagation, dormancy and germination requirements of S. interrupta. The study assessed the efficacy of different pre and post-emergence herbicides, individually as well as in an integrated manner, so as to develop an effective recommendation for management of S. interrupta in direct seeded rice. Surveys were conducted twice in the major rice tracts of Kerala viz., Kole, Kuttanad and Palakkad. The results of the survey suggested the probability of S. interrupta becoming a problem weed in rice tracts of Kerala, and attaining the status of a dominant weed like weedy rice. The density and dominance indices clearly indicated the severity of this weed in the surveyed areas. Based on morphological characters of different morphotypes found in the surveyed areas, S. interrupta could be grouped into three groups: A, B and C, which might have evolved as an adaptation to the existing habitat, cultural practices and climatic conditions. Group A (green variegated) refered to morphotypes from Palakkad with medium stature and narrow light green leaves and having green coloured panicles (4-6 nos./plant), oblong spikelets (311-348 spikelets/panicle), and spikelet length and width varying between 4.6-4.8 mm and 0.9-1.3 mm respectively. Group B (purple variegated) from Kole tract, with tall statured plants and narrow dark green leaves, had purple coloured panicles (4-6 nos./plant), and enlongated spikelets (311-348 spikelets/panicle), with spikelet length of 4.6-4.8 mm and width of about 0.9-1.3 mm. Kuttanad tract types were categorized into Group C (green-purple variegated), which were short statured, profuse tillering plants with broad dark green leaves having bicoloured green and purple panicles (6-8 nos./plant), oblong to bulged spikelets (378-391 spikelets/panicle), and short spikelets with length of 4.1-4.5 mm and width of 1.6-1.8 mm. Sacciolepis interrupta is a C4, grass weed having fibrous root system, and stems were erect or leaning with creeping or geniculate habit. Nodes were glabrous with roots at lower nodes. Leaves were lanceolate; either glabrous or sparsely pilose. The plant height varied from 70 to 112 cm, and inflorescence was an erect, compact, terminal panicle, about 8 to 30 cm long, of either interrupted or spiciform type. The spikelets were ovate or lanceolate, either green or green with violet variegations and about 2.1 to 4.8 mm long. The flowers of S. interrupta were violet or purple or white in colour. The seeds were very small, oval to oblong in shape, light brown to dark brown in colour, and 1000 seed weight varied from 2.2 g to 4.2 g. Germination studies revealed that seeds of S. interrupta were dispersed with high levels of induced dormancy and were able to germinate both in upland as well as flooded conditions. Seed germination was strongly influenced by seasonal variations in temperature and light. Higher temperatures of 330C to 380C with continuous light of 14 hours triggered germination. Seeds placed on soil surface and at 2 cm depth had higher rate of germination and emergence. Seed longevity studies revealed prolonged seed persistence of upto one year. A persistent seed bank due to secondary dormancy favoured the periodic reappearance of species and increase in the soil seed bank. Different methods of propagation i.e., by seeds, culm cuttings and root clumps were observed. High regeneration capacity of different plant parts promoted its survival and spread. Field experiments were conducted in 2017 and 2019 at Chithali, Palakkad in a farmers’ field where the infestation of Sacciolepis was very high. Different pre- and post-emergence herbicides and integrated methods were tested for management of S. interrupta. The pre-emergence herbicide treatments included oxyflourfen, pretilachlor, pendimethalin, oxadiargyl, stale seedbed for 14 days, hand weeding at 20 and 40 DAS, and unweeded control. Hand weeding was the most efficient method for control of S. interrupta. Stale seedbed was found to give efficient control of the weed by depleting the soil seed bank. Among pre-emergence herbicides, oxyfluorfen @ 0.15 kg/ha and oxadiargyl @ 0.10 kg/ha were found effective, however, weed control lasted only upto 30 DAS. The post-emergence treatments included cyhalofop-butyl, bispyribac sodium, penoxsulam, fenoxaprop–p–ethyl, two commericial pre-mix formulations triafamone + ethoxysulfuron and cyhalofop-butyl+ penoxsulam, hand weeding at 20 and 40 DAS, and unweeded control. Fenoxaprop-p-ethyl @ 0.06 kg/ha and cyhalofop-butyl @ 0.08 kg/ha was found to be better post-emergence herbicides, resulting in improved yield attributes and grain yield of 2299 kg/ha and 1983 kg/ha respectively. Integrated weed management treatments included stale seed bed + fenoxaprop–p–ethyl, stale seed bed + cyhalofop-butyl, stale seed bed + hand weeding, oxyfluorfen + fenoxaprop–p–ethyl, oxyfluorfen + cyhalofop-butyl, oxyfluorfen + hand weeding @ 45 DAS, hand weeding at 20 and 45 DAS and unweeded control. Stale seed bed followed by hand weeding at 45 DAS or pre-emergence application of oxyfluorfen @ 0.15 kg/ha followed by hand weeding at 45 DAS, could be recommended as an integrated method for control of S. interrupta, as these treatments gave significantly higher weed control efficiency and resulted in high grain yields and B:C ratios of 4239 kg/ha and 1.9; 4079 kg/ha and 1.8 respectively.
Open Access
Micronutrient management of sweet corn (Zea mays var. saccharata) hybrids for yield and quality
(Department of Agronomy, College of Agriculture, Padannakkad, 2020) Deepa Mary, Varghese.; KAU; Vandana, Venugopal
An investigation entitled “Micronutrient management of sweet corn (Zea mays var. saccharata) hybrids for yield and quality” was undertaken with the objectives to evaluate the performance of sweet corn hybrids for yield and quality and to study the role of zinc and boron in increasing the productivity, quality and profitability of the crop. The study was carried out at College of Agriculture, Padannakkad and Regional Agricultural Research Station, Pilicode during 2019-2020. The experiment was laid out in factorial randomized block design with 12 treatments replicated thrice. The treatment combinations included three hybrids viz., H1- Sugar 75, H2- KSCH 333, H3- Misthi and four levels of micronutrient application viz., M1- RDN of Maize as per KAU POP (control), M2- RDN of Maize as per KAU POP + Spray of Boron as Solubor @ 0.15 per cent once at tasseling and silking, M3- RDN of Maize as per KAU POP + Spray of Zinc as ZnSO4 @ 1.0 per cent at 20 and 40 days after sowing and M4- RDN of Maize as per KAU POP + Spray of Boron as Solubor @ 0.15 per cent once at tasseling and silking + Spray of Zinc as ZnSO4 @ 1.0 per cent at 20 and 40 days after sowing. Perusal of the results on growth attributes revealed that sweet corn hybrids did not significantly influence plant height, number of leaves, leaf area, days to 50 per cent tasseling and silking, days to maturity and number of harvests. However, significant effects of hybrids were recorded in dry matter production. Highest dry matter accumulation was noticed in Sugar 75 (12027 kg ha-1) and was statistically on par with Misthi (9962 kg ha-1). Recommended dose of nutrients alone had resulted in highest plant height at 15 DAS and was on par with combined foliar application of zinc and boron. Leaf area was recorded maximum at 15 and 45 DAS in control plot and at 45 DAS, the treatment was on par with foliar application of zinc. Number of days taken for 50 per cent tasseling, silking and maturity was least in the control plot. Number of harvests did not differ significantly with micronutrient application. However, growth attributes did not show any significant variation between hybrids and their interaction with zinc and boron. Hybrids did not differ in any of the yield attributes recorded. However, total cob yield and green stover yield varied significantly with hybrids. Among the different hybrids tested, Sugar 75 was superior recording a cob yield of 11102 kg ha-1. Green stover yield was the highest in Sugar 75 (20667 kg ha-1) and was on par with Misthi (19111 kg ha-1). Among the yield attributes, the highest cob length was noticed in the control plot and was on par with foliar application of zinc and boron. Maximum cob girth was recorded in the control plot and was statistically on par with foliar application of zinc. Cob weight without husk was maximum when treated with recommended dose of fertilizers alone and was on par with foliar application of boron. Foliar nutrition with either zinc, boron or both had no influence on number of cobs per plant, number of kernel rows per cob, number of kernels per cob, hundred fresh kernel weight, cob weight with husk, total cob and stover yield. Visual symptoms of boron deficiency were observed in cobs irrespective of the treatments. The hybrids and their interaction with foliar application of micronutrients did not show significant influence on yield attributes. However, maximum cob yield (11640 kg ha-1) was recorded when recommended dose of nutrients alone were given and among interaction effects, the highest cob yield (13813 kg ha-1) was recorded when Sugar-75 was provided with recommended dose of nutrients alone and was on par with KSCH 333 and recommended dose of nutrients alone (13247 kg ha-1). Organic carbon and available boron content in the soil was not significantly influenced by hybrids, micronutrient application and their interaction. However, after harvest, there was an increase in the organic carbon content in the soil. Available boron content in the soil was in deficient range before and after the experiment. Chlorophyll content did not vary significantly with hybrids and micronutrient application. Highest chlorophyll content (2.44 mg g-1) was recorded when KSCH 333 was treated with recommended dose of fertilizers alone and was on par with all the interaction effects except when KSCH 333 was treated with foliar application of zinc and boron. Ascorbic acid content and moisture content was not significant among treatments. Among the hybrids, mean per cent damage by fall army worm was recorded the lowest in Misthi. Micronutrient application and their interaction with hybrids did not significantly influence the pest incidence. Highest net profit of ₹ 225710 ha-1 and BCR of 2.03 was realized with Sugar 75. Therefore, it can be concluded from the study that growing sweet corn hybrid Sugar 75 is beneficial for getting higher yield per unit area and maximum economic returns. Visual symptoms of boron deficiency were evident, reflected as unfilled kernel rows within the cobs of sweet corn. The study also reveals that boron is a critical nutrient that influences the yield and yield attributes in sweet corn. Foliar application of boron @ 0.15 per cent once at tasseling and silking did not meet the requirements of the crop when grown in boron deficient soil. Hence, foliar application of a nutrient alone cannot alleviate the nutrient deficiency in the crop when grown under limited soil nutrient supply.
Open Access
Biology and management of goose weed (Sphenoclea zeylanica Gaertner) in wetland rice
(Department of Agronomy, College of Agriculture, Vellayani, 2020) Mallu Sai Sarath Kumar, Reddy.; KAU; Ameena, M
An investigation entitled ‘Biology and management of goose weed (Sphenoclea zeylanica Gaertner) in wetland rice’ was conducted at College of Agriculture, Vellayani during 2018-2020. The major objectives were to study the biology of the weed, its allelopathic effect on crop and also to develop an effective and economic management strategy using herbicides in wet seeded rice. The field experiment was undertaken at IFSRS, Karamana during kharif 2019. Weed biology was studied by observing randomly selected sample plants in weedy check plots starting from the emergence of the weed. The field experiment was laid out in randomized block design with eight treatments and three replications. The weed control treatments included T1: bensulfuron methyl + pretilachlor @ 60+600 g ha-1 at 5 days after sowing(DAS), T2: pyrazosulfuron ethyl @ 25g ha-1 at 5 DAS, T3: bispyribac sodium @ 25 g ha-1 at 15-20 DAS, T4 :penoxsulam + cyhalofop butyl 6% OD at 150 g ha-1 at 20 DAS, T5: metsulfuron methyl + chlorimuron ethyl @ 4g ha-1 at 20 DAS, T6: ethoxysulfuron @ 15 g ha-1 at 20 DAS, T7 : hand weeding at 20 and 40 DAS, T8 : weedy check ( unweeded control) and the treatments T1 to T6 were followed by hand weeding at 35-40 DAS. The lab experiment on allelopathic effect of goose weed on germination and growth of rice seedlings was evaluated with treatments T1: Fresh leaves aqueous extract 10%, T2: Dry leaves aqueous extract 10%, T3: Fresh stem aqueous extract 10%, T4: Dry stem aqueous extract 10%, T5: Fresh inflorescence aqueous extract 10%, T6: Dry inflorescence aqueous extract 10%, T7: Fresh whole plant aqueous extract before flowering 10%, T8: Fresh whole plant aqueous extract after flowering 10%, T9: Distilled water (control). The data on weed biology identified goose weed as an annual. The weed seeds took 3-7 days for germination, 15 days for flowering and 36 days for first spike maturity with an average duration of 69 days in wet seeded rice fields. The weed was observed to propagate by seeds with enormous seed production potential. The average dry matter produced per plant and total dry matter production were to the tune of 26.24 g per plant and 3.75 t ha-1 respectively in the weedy check. The weed was analysed to contain 1.306, 0.087 and 1.695 per cent N, P and K respectively. In the field experiment, Sphenoclea zeylanica was the dominant weed flora during all the growth stages of the crop. Initially, a lower weed density was recorded in T1, but taken over by T4 at 30, 45 and 60 DAS. The weed dry weight was the lowest in T1 at 15 and 30 DAS (0.08 and 6.41 g m-2), whereas at 45 and 60 DAS, T4 recorded the lowest values (1.35 and 4.61 g m-2). T1 registered lesser relative weed density of S. zeylanica up to one month and later by T4. Unweeded plot showed dominance of the weed over other flora with a relative density of 70.33 per cent. Though weed control efficiency was higher in T1 upto 30 DAS (99.28 and 96.22 per cent), T4 recorded higher values during critical stages of crop growth at 45 and 60 DAS (99.54 and 98.85 per cent). T4, T1 and T5 recorded minimum NPK removal and to be precise only one tenth of N removal registered in weedy check in comparison to others due to lower weed dry matter accumulation Among the weed management practices tested, T1 recorded higher plant height at 30, 60 DAS and at harvest. Both T1 and T4 recorded higher yield and yield attributes like number of panicles m-2(320 and 308.3), number of grains panicle-1 (173 and 177), grain yield (5461 and 5355 kg ha-1) and straw yield (7710 and 7646 kg ha-1). Bensulfuron methyl + pretilachlor @ 60+600 g ha-1 at 5 DAS followed by hand weeding at 35-40 DAS turned out to be the most economic weed management practice with a higher B: C ratio of 1.83. This was followed by penoxsulam + cyhalofop butyl 6% OD at 150 g ha-1 at 20 DAS followed by hand weeding at 35-40 DAS with a B: C ratio of 1.77. Higher nutrient uptake by the crop was noticed in bensulfuron methyl + pretilachlor (T1), T4 and T5 due to higher dry matter production. The extent of yield reduction due to presence of weeds in wet seeded rice was estimated to be 57 per cent. The study on allelopathic influence of goose weed revealed strong inhibitory influence for its dry leaves and dry inflorescence on germination percentage (92.67 and 80%) and dry weight (96.98 and 96.12%) of rice seedlings. Shoot length, root length, fresh weight, dry weight and vigour index were also recorded the lowest in T2 and T6. From the results of the study, it could be concluded that Sphenoclea zeylanica could become a serious weed in wetland rice fields being a prolific seed producer with high dry matter production. Application of bensulfuron methyl + pretilachlor @ 60+600 g ha-1at 5 DAS followed by hand weeding at 35-40 DAS was found to be the most effective and economic management strategy. The inference of allelopathic studies indicated that dry leaves and inflorescence of goose weed have strong inhibitory influence affecting germination and growth of rice.

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