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ThesisItem Open Access Herbigation in Okra (Abelmoschus esculentus (L.) Moench)(Department of Agronomy, College of Agriculture, Vellanikkara, 2021) Minu, Mariya Issac; KAU; Mini, AbrahamHerbigation is the method of application of herbicides through irrigation water. Conventional method of herbicide application takes considerable time and expensive due to the increasing cost of manual labour. Also, heavy wind at the time of spraying and improper application causes more herbicide loss, environmental pollution and drift injury to the nearby fields especially on sensitive crops. Herbigation ensures no additional costs of application. Okra is one of the important vegetable crop of Kerala. Weed competition during early stage of crop growth significantly lowers crop yields. Heavy weed infestation in okra is mainly due to wider spacing, slower crop growth during early stages, high fertilizer use and frequent irrigation. Therefore, the present study was undertaken with a view to study the effect of herbigation through drip irrigation system in okra and also to evaluate the economic feasibility of the system. The experiment was conducted at Water Management Research Unit, Vellanikkara from December 2019 to April 2020. The experiment was laid out in RBD with ten treatments and three replications. Treatments comprised of herbigation and conventional spraying of oxyfluorfen applied in two doses (0.15 kg ha-1 & 0.20 kg ha-1) at two different time of application , a hand weeded control and an unweeded control. The okra variety used was Arka Anamika. Predominant grasses seen in the plots were Panicum maximum, Digitaria sanguinalis, Brachiaria miliformis, Digitaria bicornis and Axonopus compressus. Predominant broad leaved weeds were Ageratum conyzoides, Euphorbia hirta, Mollugo disticha, Cleome burmanii, Trianthema portulacastrum, Alternanthera bettzickiana, and Synedrella nodiflora. The sedges present were Cyperus spp., and Bulbostylis barbata in the experimental field. Observations on weed count showed that application of oxyfluorfen was effective in controlling both grass and broad leaved weeds. Maximum weed control efficiency was observed in conventional spraying with oxyfluorfen @ 0.20 kg ha-1 two days before sowing followed by hand weeding at 30 DAS with 91.31 per cent at 20 DAS; conventional spraying with oxyfluorfen @ 0.15 kg ha-1 two days before sowing followed by hand weeding at 30 DAS with 90.08 per cent at 50 DAS and hand weeded control recorded 90.59 per cent at 80 DAS. Lowest weed index was recorded from herbigation with oxyfluorfen @ 0.15 kg ha-1 two days before sowing followed by hand weeding at 30 DAS followed by the treatment conventional spraying with oxyfluorfen @ 0.15 kg ha-1 two days before sowing followed by hand weeding at 30 DAS. Even though, conventional spraying recorded lesser weed count and weed dry weight, the yield was less due to the scorching of crop foliage. During herbigation, herbicide is applied through drip to the crop root zone, due to which weeds in the interspaces that can germinate in water stress conditions will grow. While in conventional spraying, the entire cropped area come in contact with herbicide and results in complete control of weeds. The nutrient removal by weeds was maximum in unweeded control. Herbigation with oxyfluorfen @ 0.15 kg ha-1 two days before sowing followed by hand weeding at 30 DAS was on par with hand weeded control in terms of plant height, number of leaves and leaf area. It also recorded highest number of fruits per plant (17.8), average fruit weight (13.73 g), fruit yield per plant (243.90 g) and fruit yield (13.02 t ha-1). It was on par with hand weeded control (13.04 t ha-1), conventional spraying with oxyfluorfen @ 0.15 kg ha-1 two days before sowing followed by hand weeding at 30 DAS and herbigation @ 0.20 kg ha-1 two days before sowing followed by hand weeding at 30 DAS. Weed competition resulted in 58.97 per cent yield reduction in okra. Unweeded control recorded significantly lower fruit yield (5.35 t ha-1). Both conventional spraying and herbigation with oxyfluorfen @ 0.15 kg ha-1 two days before sowing followed by hand weeding at 30 DAS were equally effective in controlling weeds. Herbigation with oxyfluorfen @ 0.15 kg ha-1 two days before sowing followed by hand weeding at 30 DAS resulted in higher gross return, net return and B: C ratio (1.97) which was closely followed by conventional spraying with oxyfluorfen @ 0.15 kg ha-1 two days before sowing followed by hand weeding at 30 DAS (1.89). The result of the study revealed that the farmers can adopt either herbigation or conventional spraying of oxyfluorfen according to their convenience because both treatments performed equally well. Herbigation can be implemented in fields in which already fertigation is carried out because it doesn’t involve any additional costs.ThesisItem Open Access Integrated weed management in green gram (Vigna radiata (L.) Wilczek)(Department of Agronomy, College of Agriculture, Vellanikkara, 2021) Saveri Gopakumar; KAU; Meera V MenonWeeds are known to cause substantial yield losses in green gram, owing to the slow initial growth of the crop and severe competition by weeds. Although hand weeding has been proved effective in reducing weed infestation, unavailability of timely labour and high labour costs have created practical difficulties in adopting manual weeding on a large scale, thus increasing the dependency on chemical weed control using herbicides. However, continuous use of herbicides results in problems like environmental contamination and resistance development. The present study entitled “Integrated weed management in green gram [Vigna radiata (L.) Wilczek]” was undertaken with the objective of developing an economically viable integrated weed management strategy that provided broad spectrum weed control in green gram. The field experiment was carried out from December 2020 to March 2021 at Kotteppadam rice field under the Department of Agronomy, College of Agriculture, Vellanikkara. The experiment included eight treatments replicated thrice in a randomized block design (RBD). The treatments were: stale seed bed for 14 days followed by (fb) shallow digging (T 1 ), stale seed bed for 14 days fb shallow digging fb oxyfluorfen at 0-3 DAS (T 2 ), oxyfluorfen at 0-3 DAS fb hand weeding at 25 DAS (T 3 ), imazethapyr at 0-3 DAS fb hand weeding at 25 DAS (T 4 ), imazethapyr + imazamox at 0-3 DAS fb hand weeding at 25 DAS (T 5 ), diclosulam at 0-3 DAS fb hand weeding at 25 DAS, hand weeding at 20 DAS and 40 DAS (T 7 ) and unweeded control (T 8 ). The major broad leaved weeds observed were Melochia corchorifolia, Aeschynomene indica, Grangea maderaspatana, Phyllanthus amara, Heliotropium indicum, Mimosa invisa and Mimosa pudica, whereas Brachiaria mutica, Digitaria ciliaris, Echinochloa colona, Oryza sativa and Cynodon dactylon were the predominant grasses. Hand weeding resulted in the lowest weed density as well as weed dry matter production at all stages of observation. All the pre-emergence herbicidesintegrated with hand weeding were also equally effective, among which imazethapyr+ imazamox fb hand weeding and diclosulam fb hand weeding recorded the highest weed control efficiency of 97 per cent. Similarly, nutrient removal by weeds was the lowest in hand weeding, which was statistically similar to all the treatments where herbicide application was integrated with hand weeding. Stale seed bed provided effective control of weeds only during the early stages of crop growth. Weed density, weed dry matter production, nutrient removal by weeds and weed index were invariably the highest in unweeded control. Number of branches/plant, number of pods/plant, grain yield and haulm yield of green gram were higher in hand weeding and the treatments where herbicide application was integrated with hand weeding. Uncontrolled weed growth resulted in yield losses up to 70 per cent in green gram, which was reduced to 5.82 per cent and 8.22 per cent in imazethapyr + imazamox fb hand weeding and diclosulam fb hand weeding respectively. These treatments registered high grain and haulm yields of 549 kg and 1296 kg, and 535 kg and 1271 kg respectively. Although the application of pre-emergence herbicides resulted in a reduction in the soil microbial count at flowering as compared to the untreated plots, the population recovered by harvest stage in the plots treated with oxyfluorfen, imazethapyr and imazethapyr + imazamox. However, diclosulam was found to have a pronounced inhibitory effect on the soil microbial population at harvest as well. Available N, P and K contents in soil were found the lowest in unweeded control. Although the gross returns were the highest in hand weeding, imazethapyr + imazamox fb hand weeding and diclosulam fb hand weeding registered the highest net returns of Rs. 9,126/ha and Rs. 8,733/ha, respectively. Accordingly, B:C ratio was also the highest in imazethapyr + imazamox fb hand weeding (1.28) and diclosulam fb hand weeding (1.27). Thus, application of these two pre-emergence herbicides followed by hand weeding at 25 DAS proved highly successful in achieving season- long weed control in green gram, thereby enhancing the yields and fetching higher monetary returns.ThesisItem Open Access Response of high yielding varieties of pearl millet (Pennisetum glaucum (L.) R. Br.) to major nutrients(Department of Agronomy, College of Agriculture, Vellanikkara, 2021) Murshida, S; KAU; Prameela, PPearl millet or bajra is a major millet grown in the tropics for both food and fodder. Many high yielding varieties of pearl millet are now available for cultivation. But, the performance of these varieties and the nutrient requirement of pearl millet were not assessed in Kerala. Hence, the study entitled “Response of high yielding varieties of pearl millet [Pennisetum glaucum (L.) R. Br.] to major nutrients” was carried out with the objective of assessing the performance of selected prominent high yielding varieties of pearl millet and their response to major nutrients. The experiment was carried out at Agronomy Farm, Department of Agronomy, College of Agriculture, Vellanikkara during the period from November, 2020 to February 2021. Treatments were the combinations of nutrient levels (N: P 2 O 5: K 2 O @ 60: 30: 30, 70: 35: 35, 90: 45: 45 kg/ha and absolute control) and four varieties released from various research institutes [Co (Cu) 9, Co 10, ABV 04 and Dhanashakthi]. The design was factorial RBD with 16 treatments and three replications. The biometric parameters like plant height, length and width of leaf blade, Leaf Area Index and dry matter production of pearl millet were significantly influenced by the application of different N: P 2 O 5: K 2 O levels. The plants which got higher fertilizer doses of 90: 45: 45 and 70: 35: 35 N: P 2 O 5: K 2 O kg/ha had taller plants and registered higher dry matter production. The variety Co (Cu) 9 was taller with more leaf area index and dry matter production whereas, Dhanashakthi was inferior. But, it had superior leaf width and leaf-stem ratio. The application of fertilizers had a significant influence on grain yield, yield parameters and straw yield of bajra. The highest grain weight per earhead (36.93 g) and grain yield (3360 kg/ha) were registered in plants that received 90: 45: 45 N: P 2 O 5: K 2 O kg/ha. The grain yield at fertilizer level of 90: 45: 45 N: P 2 O 5: K 2 O kg/ha showed only a marginal increase of 7.5 per cent compared to 70: 35: 35 N: P 2 O 5: K 2 O kg/ha (3107kg/ha). The straw yield at 90: 45: 45 and 70: 35: 35 N: P 2 O 5: K 2 O kg/ha were comparable (10391 and 10753 kg/ha, respectively). 1The varieties ABV 04, Co 10 and Dhanashakthi had superior and comparable grain yield ranging from 3026 to 3188kg/ha and the performance of Co (Cu) 9 was inferior with 2201kg/ha. Lower straw yield was noticed in variety Dhanashakthi (6430 kg/ha) that was comparable to Co 10 (8096kg/ha). The other two varieties ABV 04 and Co (Cu) 9 registered superior straw yield of 10191 and 11390 kg/ha, respectively. The longest earhead was for variety Co (Cu) 9 and the shortest was for variety Dhanashakthi (19.44 cm). The lowest weight of grains per earhead (29.27 g) and test weight (7.99 g) were recorded for variety Co (Cu) 9. The variety Dhanashakthi had higher test weight (13.35 g) as well as Harvest Index (0.34). The straw yield was comparable in varieties Co (Cu) 9 (11,390 kg/ha) and ABV 04 (10,191 kg/ha). The average crude protein content was 11.37 per cent and the varietal differences were non-significant. Crude fiber was comparable in ABV 04, Dhanashakthi and Co (Cu) 9 with an average content of 2.33 per cent. The crude fiber content at varied levels of primary nutrients were comparable. The highest and superior nitrogen uptake was recorded by the application of 90: 45: 45 N: P 2 O 5: K 2 O kg/ha (437 kg/ha) with 51 per cent increase compared to absolute control. P uptake at 90: 45: 45 N: P 2 O 5: K 2 O kg/ha (126 kg/ha) was on par to that at 70:35:35 N: P 2 O 5: K 2 O level. But, K uptake was comparable at three N: P 2 O 5: K 2 O levels with an average of 358 kg/ha. Significantly lower uptake of primary nutrients were registered in absolute control. The application of fertilizers enhanced the gross and net returns along with benefit- cost ratio in pearl millet cultivation. The highest B: C ratio (1.78) and net returns (Rs. 53,186 /ha) from bajra cultivation registered in N: P 2 O 5: K 2 O level of 70: 35: 35 N: P 2 O 5: K 2 O kg/ha, followed by the highest dose. Hence, it can be concluded that a fertilizer dose of 70: 35: 35 N: P 2 O 5: K 2 O kg/ha can be recommended for pearl millet cultivation in Kerala. The varieties ABV 04, Co 10 and Dhanashakthi can be recommended for grain purpose, whereas varieties Co (Cu) 9 and ABV 04 are ideal for straw and fresh herbage. ABV 04 is a good variety with respect to both grain and straw yield.ThesisItem Open Access Potassium-magnesium interaction in coleus [Solenostemon rotundifolius (Poir.) J.K. Morton] productivity(Department of Agronomy, College of Agriculture, Vellanikkara, 2021) Aswani, S; KAU; Prameela, PAn experiment entitled ‘Potassium-magnesium interaction in coleus [Solenostemon rotundifolius (Poir.) J.K.Morton] productivity’ was conducted during the period from July to November 2020 at Agronomy Farm, College of Agriculture, Vellanikkara, Thrissur, with the objective to assess the effect of potassium and magnesium sulphate application on tuber yield of coleus. Potassium (K2O) was applied @ 60 kg/ha (soil test based), 100 kg/ha (PoP recommendation) and a check (no potassium). Magnesium sulphate doses tried were 0 kg/ha, 10 kg/ha, 20 kg/ha, 40 kg/ha. The treatments consisted of twelve different combinations of K2O and magnesium sulphate which was replicated thrice in RBD design. The soil of the experimental field was medium in potassium and low in magnesium status. Magnesium sulphate was soil applied at 30 days of planting and in the case of lower dose of 10 kg/ha, it was foliar applied (2 per cent spray). N and P2O5 were applied as per PoP recommendation of 60:60 kg/ha. Coleus variety Nidhi was used for the study. Growth parameters such as plant height, dry matter production of aerial portion, dry matter production of tubers as well as total dry matter production were significantly influenced by potassium application. However, LAI and root to shoot ratio at vegetative stage did not vary significantly with potassium dose. Taller plants were observed with potassium application @ 60 and 100 kg/ha at 60 DAP.But at 90 DAP lower value of plant height was registered at higher level of 100 kg/ha K2O. Magnesium sulphate application also influenced plant height at 90 DAP taller plants were observed in plants which received 40 kg/ha of MgSO4. Varied levels of potassium as well as magnesium sulphate did not bring about variation in chlorophyll content of coleus leaves. However, interaction of potassium and magnesium sulphate on leaf chlorophyll content was significant and higher values were observed when K2O was applied @ 60 kg/ha along with MgSO4 @ 20 or 40 kg/ha. Dry matter production (DMP) of aerial portion increased with increasing levels of K2O. At 60 DAP and at harvest plants which received 60 or 100 kg/ha potassium registered higher and comparable aerial DMP. Magnesium sulphate application did not show any significant influence on DMP at 90 DAP. However at harvest, aerial DMP with the application of 40 kg magnesium sulphate was superior to other levels which were at par statistically. Tuber yield showed significant increase with increase in rate of potassium applied and showed an increase of 19 per cent when 100 kg of K2O was applied compared to control (13.80, 14.94 and 16.46 t/ha, at 0, 60 & 100 kg/ha K2O, respectively). Various levels of magnesium sulphate applied did not show any influence on tuber yield. However interaction effect of K and Mg was significant and best combination was 60 K2O with 40 kg MgSO4, 100 kg K2O with 10 or 40 kg magnesium sulphate, which registered statistically comparable yields. Magnesium and potassium levels had no influence on yield of unmarketable tuber. Application of K2O @ 100 kg/ha recorded higher DMP of tuber and total DMP over 0 and 60 kg potassium. Effect of magnesium sulphate application on dry matter production of tuber and total dry matter production was non significant. However interaction effect of potassium and magnesium sulphate was significant with respect to tuber DMP. Higher and superior values were registered under 100 kg of K2O with 10 kg MgSO4 and 40 kg MgSO4. Higher K uptake was noticed when K2O was applied @ 60 kg/ha with 40 kg/ha MgSO4 which was on par with K2O at 100 kg/ha with MgSO4 at 10 kg/ha or 40 kg/ha. Potassium and magnesium sulphate application did not cause significant variation in N, P and secondary nutrient uptake by coleus. Net returns as well as B-C ratio were higher for K2O application @ 100 kg/ha along with MgSO4 @ 40 kg/ha or 10 kg/ha. The results of the study indicate that for better productivity in coleus, potassium may be applied at the rate of @ 100 kg/ha, even in soils with medium status of available K. Also, K- Mg balance is important and hence in soils deficient in magnesium and medium in potassium, soil application of magnesium sulphate @ 40 kg/ha or foliar spray @ 10 kg/ha at 30 DAP, together with K2O dose of 100 kg/ha can enhance the productivity of coleus.ThesisItem Open Access Non-chemical weed management in chilli (Capsicum annuum L.)(Department of Agronomy, College of Agriculture, Vellanikkara, 2021) Fasna, P; KAU; Meera V, MenonOne of the major problems in any crop production system is weed infestation which causes reduction in both the yield and quality of produce. Although the use of herbicides provides effective and sustained weed control, it is not a preferred option because of environmental concerns. This is particularly true in the case of vegetables, some of which are consumed either partially cooked or raw. The research programme entitled ‘Non-chemical weed management in chilli (Capsicum annuum L.)’ was carried out with the objective of evaluation of non-chemical methods of weed management in chilli. The experiment was conducted at the Department of Agronomy, College of Agriculture, Vellanikkara from June 2020 to September 2020. The field was infested with broad leaf weeds, grasses and sedges. Randomized block design used for laying out the experiment, with seven treatments and three replications. The treatments were, T1: stale seed bed for 14 days followed by shallow digging and planting of chilli, followed by two hand weedings at 30 DAT and 60 DAT, T2: stale seed bed for 14 days followed by shallow digging and planting of chilli, followed by one hand weeding at 45 DAT, T3: black polythene mulch (30 microns), T4: straw mulch at 7.5 t/ha applied twice, at planting and one month after planting, T5: straw mulch at 7.5 t/ha applied twice, at planting and one month after planting followed by one hand weeding at 60 DAT, T6: hand weeding at 30 and 60 DAT and T7: unweeded control. Black polythene mulch (T3) recorded highest weed control efficiency and lowest weed density, weed dry matter production and weed index, whereas straw mulch when applied alone (T4) and when followed by one hand weeding (T5) were the next best treatments with high weed control efficiency and low weed index. The treatments hand weeding (T6), stale seed bed when followed by two hand weedings (T1) and one hand weeding (T2) were not effective in controlling weeds. The lowest weed control efficiency and the highest weed index values were recorded for the unweeded control (T7) at all stages of observation. Various weed management practices had significant effect on growth and yield parameters of chilli. At all stages of observation, the plant height of chilli in polythene mulching (T3) was found to be the greatest followed by straw mulching when done alone (T4) and when followed by one hand weeding (T5). Unweeded control (T7) had the lowest values. Chilli plants in polythene mulching (T3) recorded the highest number of fruits per plant (218) and fruit yield (22.44 t/ha), followed by straw mulching both when done alone (T4) (182 nos. and 18.89 t/ha respectively) and when followed by one hand weeding (T5) (177 nos. and 18.38 t/ha respectively). Hand weeding (T6) and stale seed bed when followed by two hand weedings (T1) recorded lower yields than straw mulching. Unweeded control (T7) recorded lowest values for fruit length, fruit girth, fruit weight, number of fruits per plant and fruit yield. The soil physico-chemical characteristics pH, EC, organic carbon, and available N, P and K were influenced by different weed management practices. The organic carbon content in soil was highest in polythene mulching (T3) at 60 DAT (1.45 %) and after the final harvest (1.49 %). At both stages of observation, straw mulching (T4) had highest values of available P (77 and 79 kg/ha respectively) and K (414 and 408 kg/ha respectively), whereas available N was found higher in black polythene mulch (T3) at 60 DAT (246 kg/ha) and in stale seed bed followed by one hand weeding (T2) after the final harvest (239 kg/ha). Considering the economics of cultivation, black polythene mulching (T3) recorded highest gross returns (Rs.22.44 lakhs/ha), net returns (Rs. 9.94 lakhs/ha) and B:C ratio (1.84) and was followed by straw mulching when done alone (T4) and when followed by a hand weeding (T5). Black polythene mulching was thus identified as the best non-chemical weed management technique in chilli, having highest weed control efficiency leading to enhanced growth and yield parameters and highest net returns and B:C ratio. Straw mulching when done alone or when followed by one hand weeding were the next best treatments with respect to weed control efficiency, growth, yield and net returns of chilli.ThesisItem Open Access Approaches to assess chlorpyrifos degradation in northern laterite soils of Kasaragod (AEU 11)(Department of Agronomy, College of Agriculture , Vellanikkara, 2022) Shakkira, KK; KAU; Sindhu, P VWeeds have been a persistent menace for farmers since the advent of agriculture. Among several methods adopted for controlling weeds, chemical control is the widely used and most effective. However, the extensive use of herbicides has led to the generation of a wide range of problems including development of herbicide resistant weeds. As a result, extensive research is being done to exploit non chemical methods of weed management. The mechanism of allelopathy has been suggested as a potential biorational method towards this goal. Hence the present study entitled “Allelopathy for weed management in field crops” was conducted during February-October 2021 in the Department of Agronomy, College of Agriculture, Vellanikkara, Kerala Agricultural University, Thrissur. The study consisted of two parts viz., screening Andrographis paniculata, Plectranthus ambonicus and Tagetes minuta for their allelopathic potential, and evaluating alleloapathic effect of these plant extracts on weeds and the test crops rice, cowpea and green gram. Cold water, hot water and methanol extracts of these plants were prepared at six concentrations viz., 5 %, 10 %, 15 %, 20 %, 25 % and 30 % in a completely randomized design (CRD) in factorial arrangement with three replications. In the first experiment plants were screened for their allelopathic potential against upland weeds in 165 plastic trays (25 cm x 20 cm x 5 cm) that were filled to three-quarters with uniform quantity of soil (1.5 kg) collected from an open area. Best 10 treatment combinations from this experiment and a control with distilled water were carried over to the second experiment. The second experiment consisted of two parts; in petri plates to test the phytotoxic activity on test crops (cowpea, green gram and rice) and in pot culture study with test crops and weeds. Both studies were carried out in completely randomized design (CRD) in factorial arrangement with two factors and three replications. Factor A consisted of time of application (on the day of sowing and 6th day after sowing). Factor B consisted of the best 10 allelopathic treatments from experiment 1. Experiment on screening allelopathic plants for their potential to control upland weeds revealed the significant influence of the plants, the method of extraction and the concentration of extract on weed growth parameters such as weed density and weed dry weight. Broad leaved weeds were more sensitive to allelopathic extracts than grass weeds. Reduction in weed germination count and dry weight after one month of application was noticed with methanol extract of Tagetes minuta at 30 per cent concentration and was 6.67 nos./m2 and 21. 33 g/m2 respectively as compared to control (68.33 nos./m2 and 54. 25 g/m2 ). Pre mergence application of Andrographis paniculata methanol extract at 30 per cent concentration was the next best treatment. Allelopathic effect of plants was significant only for a short period of time i.e. up to one week after application, indicating absence of residual action. Germination indices and seedling growth parameters of test crops were adversely affected by the application of allelopathic extracts. Among test crops, cowpea and green gram were more sensitive to allelopathic extracts than rice. A notable delay in germination of test crops, in shoot and root length, and in fresh and dry weights were observed by the application of allelopathic treatments. Phytotoxicity symptoms were observed on test crops both under laboratory condition and in pot culture. Root decay and reduction in number of rootlets were observed by the pre emergence application of 30 and 25 per cent methanol extract of Tagetes minuta. When Tagetes minuta methanol extract was applied at 30 or 25 per cent as pre mergence treatment, germination of cowpea and green gram started on the 4th and 5th day after sowing as compared to the 2nd day in control. Root length reduction was more pronounced than shoot length reduction. The reduction was 43.29 and 41.46 per cent in cowpea, and 41.56 and 37.05 per cent in green gram, due to pre emergence application of 30 and 25 per cent methanol extract of Tagetes minuta in petri plates. In pot culture study, root reduction of 70.85 and 71.01 per cent in cowpea and green gram by the pre emergence application of 30 per cent methanol extract of Tagetes minuta as was observed. A notable delay in weed germination and weed dry weight reduction were observed by 30 and 25 per cent Tagetes minuta methanol extract applied as pre emergence treatment and their residual inhibitory effect in the soil persisted up to one week. Based on the results of the study, pre emergence application (on the day of sowing) of methanol and cold water extracts of Tagetes minuta and Andrographis paniculata at 30 per cent concentration can be recommended for control of broad leaved weeds in uplands.ThesisItem Open Access Response of sweet potato [Ipomoea batatas (L.) Lam.] to secondary nutrients(Department of Agronomy, College of Horticulture, Vellanikkara, 2021) Nengparmoi, T H; KAU; Prameela, PSweet 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.ThesisItem Open Access Chemical Priming for improving salinity tolerance in rice(Department of Agronomy, College of Agriculture, Vellanikkara, 2021) Liz J, Kappen; KAU; Deepa, ThomasMeasures 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.ThesisItem Open Access Perfomance of high yielding varieties of finger millet [Eleusine coracana (L.)] (Gaertn)(Department of Agronomy, College of Agriculture, Vellanikkara, 2021) Kishore, Neeruganti; KAU; Prameela, PAn 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
