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ThesisItem 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, PAn 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 %).ThesisItem 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, ACowpea 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.ThesisItem 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, MenonSacciolepis 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.ThesisItem Open Access Management of high temperature stress in aerobic rice(oryaza sativa L.)(Department of Agronomy, College of Horticulture, Vellanikkara, 2020) Saravana Kumar, M; KAU; Prameela, PRice production is subject to many biotic and abiotic stresses of which rise in temperature is a crucial one in the present context of global warming. Hence, a study on management of high temperature stress in aerobic rice was taken up at the Department of Agronomy, College of Horticulture, Vellanikkara with the main objective of assessing the varietal response to high temperature as well as to find out sensitivity of various growth phases of rice to elevated temperature. In two pot culture experiments conducted in the first year of study (Dec 2017- Mar 2018), selected aerobic and wetland rice varieties were exposed to temperature 2-3 ℃ higher than ambient air temperature at different growth phases. A field experiment to study the effect of nitrogen and potassium nutrition in mitigating high temperature stress was carried out in second year of study during Jan 2019 – April 2019. Four aerobic rice varieties [Swarnaprabha, Sharada (MAS 946-1), Vaishakh and MDU-6] were included in Experiment I and four wetland rice varieties (Kanchana, Jyothi, Uma and Aiswarya) were tested in Experiment II. Temperature stress (2-3 ℃ above ambient) was artificially imposed at three different growth stages of rice i.e., from tillering to panicle initiation, panicle initiation to flowering and flowering to maturity. For imposing temperature stress, portable chambers with the dimensions of 2 m x 2 m x 1.5 m with top covered with UV stabilized polythene sheet and sides covered with polythene sheet, were fabricated (Singh, 2010) leaving a gap of 15cm from the ground level at the base for free air passage. Each variety was maintained under ambient condition throughout the crop growth period as control (i.e., without stress). High temperature during vegetative phase enhanced the growth parameters in all varieties. Among rice varieties, Vaishakhh and Aiswarya exposed to stress from tillering to panicle initiation (PI) showed increased plant height, tiller number, leaf area index and dry matter production compared to stress at other stages and control. Earliness in flowering was observed when stress was imposed from tillering to PI stage in all varieties and they produced higher number of panicles under ambient temperature compared to elevated temperature condition. It was found that in varieties Sharada and Aiswarya, comparable number of productive tillers was seen when stress was imposed at various growth phases compared to plants grown under ambient condition. The highest number of filled grains per panicle in both aerobic and wetland rice varieties were recorded under ambient condition. The highest reduction in filled grains per panicle and 1000 grain weight was observed when high temperature stress was imposed from flowering to maturity and this resulted in grain yield reduction in all the varieties. At this stage the varieties Vaishakh and Aiswarya ii produced higher number of filled grains per panicle, indicating varietal suitability to high temperature. These varieties produced higher grain yield compared to other varieties when stress was imposed at this sensitive stage (Vaishakh-13.81g/hill and Aiswarya-13.35g/hill). The performance of these two varieties were superior under ambient condition also. Physiological parameters such as photosynthetic rate, stomatal conductance, transpiration rate, chlorophyll content, relative water content (RWC), soluble protein, nitrate reductase activity, membrane stability index (MSI), proline and superoxide dismutase (SOD) decreased under high temperature whereas increase in malondialdehyde (MDA) content was observed. Grain yield was positively correlated with chlorophyll content, membrane stability index and soluble protein content, but negatively correlated with MDA and proline content. The varieties Vaishakh and Aiswarya showed high values of transpiration rate, soluble protein, nitrate reductase acitivity, SOD and canopy air temperature difference under high temperature compared to other varieties, which points to their tolerance to high temperature. Higher proline content was observed for Swarnaprabha, Vaishakh and Kanchana when exposed to high temperature. Variation in heat units like GDD, HTU and PTU were not significant under heat stress compared to control. The third experiment was laid out in randomized block design with six treatments which included two rice varieties Vaishakh and Aiswarya grown with three N and K2O levels (60:30 kg, 90 :45 kg , 120:60 kg N:K2O/ha). Phosphorus was applied uniformly @ 30 kg/ha to all treatments basally. High temperature stress was imposed during flowering to maturity period by using portable polythene chamber. The study revealed that increase in N and K levels from 60:30 kg N: K2O/ha to 120:60 N:K2O kg /ha resulted in increased growth and yield attributes and grain yield along with a remarkable increase in RWC, chlorophyll content and MSI. Also, application of 90 kg N and 45 kg K2O produced comparable grain yield to that of 120 kg N and 60 kg K2O/ha in both Vaishakh (2485 kg/ha) and Aiswarya (2401 kg/ha) . The increase in grain yield over recommended dose of 60:30 kg N: K2O/ha was about 20 per cent. Hence, it can be inferred that yield reduction due to high temperature stress in aerobic system of rice cultivation can be managed to some extend by nitrogen and potassium nutrition. The net return was also high with application of N: K2O @ 90:45 kg /ha when compared to 60:30 N: K2O kg/ha.ThesisItem Open Access Crop-weather-nutrient relations in cassava under drought stress(Department of Agronomy, College of Horticulture, Vellanikkara, 2020) Sreelakshmi, K.; KAU; Meera Menon, VDue to global warming the risk of environmental stresses, especially of prolonged drought, are expected to increase in the coming years. Cassava (Manihot esculenta Crantz.) is a typical tropical plant with its distribution confined almost entirely to the tropical zone. The crop is sensitive to soil water deficit during the first three months after planting, and water stress during the later stages of crop growth causes reduced yield and quality of tubers. In case supplemental irrigation is not possible, some nutrients are found to play important roles in imparting drought resistance to the crop. With this background, the present investigation entitled “Crop-weather-nutrient relation in cassava under drought stress” was undertaken. Two separate experiments were conducted in the Agronomy farm of College of Horticulture Vellanikkara (10o 31’ N latitude and 76o 13’E longitude) in Thrissur District of Kerala. In experiment I, conducted in 2015-16, the response of four cassava varieties of varying durations viz..Vellayani Hraswa and Sree Vijaya of short duration and M4 and Sree Athulya of long duration, planted in May, October and December to variations in environmental conditions. In experiment II, the effect of foliar application of potassium, silicon and calcium along with major nutrients on short duration variety Vellayani Hraswa grown under drought stress was investigated in two years, viz., 2015-16 and 2016-17. The experiments were laid out in randomized block design, with net plot size of 5.4 m x 5.4 m and three replications. The crops were raised as per the package of practice recommendation of Kerala Agricultural University (KAU, 2011). In experiment I, the crops were grown under rainfed condition and were thus subjected to varying temperature, precipitation and solar radiation during the period of study. May planted crops received a total rainfall of 2450.37 mm, whereas October and December planted crops received rainfall amount of 2013.4 mm and 1781.7mm respectively. Considering the general growth habit, May and October planted crops recorded considerable greater growth compared to the December planted one. Progressive increase in plant height was observed during all the three planting seasons, with May planted varieties outperforming the other two plantings. Among the varieties, Sree Athulya a normal-duration variety and Sree Vijaya a short-duration variety were significantly taller. Leaf retention and number of leaves fallen were less for Sree Athulya planted in December planting season compared to other seasons. Among normal-duration varieties, M4 was seen to produce greater number of leaves than Sree Athulya throughout the growing period, whereas short-duration varieties Sree Vijaya and Vellayani Hraswa recorded more number of leaves only towards later stages. Values of physiological parameters were higher in May and October planted crops with high stomatal conductance and photosynthetic activity. Sree Athulya variety recorded higher crop growth rate for all the plantings. Cyanogenic glucoside content and bitterness of varieties were found to progressively increase in tubers from May to October to December plantings. For all seasons, higher yield, tuber length and girth, number of tubers and mean yield per plant were in May. Normal-duration variety Sree Athulya recorded significantly higher tuber length, tuber girth, number of tubers per plant and mean tuber weight per plant, which added to significantly greater yield per plant by the variety. Among the varieties, Sree Athulya recorded significantly higher yields followed by M4 and Sree Vijaya for all seasons, while Vellayani Hraswa recorded significantly lower yield. Sree Athulya recorded higher B:C ratio of 3.67 and 2.37 when planted in May and December plantings respectively. However, short duration variety Sree Vijaya was more profitable when planted in October. Correlation between yield and weather parameters suggested that yield influencing weather parameters at early crop establishment period were maximum temperature, minimum temperature, rainfall and relative humidity. Reduced maximum and minimum temperature, high rainfall and high relative humidity were seen to be desirable. The results placed Sree Vijaya and M4 as the most promising varieties for moisture stressed conditions followed by Sree Athulya. Even though Sree Athulya was drought tolerant and produced highest yield, qualitatively it could be regarded as only the second ordered variety since it cannot be used for edible purpose. In experiment II, field experiments were conducted with 10 treatments. The treatments consisted of the recommended package of practices (POP) for nutrients, POP along with KCl, CaCl2 and silicic acid separately and in combinations. Controls included POP with water spray and water spray alone. The total precipitation during 2015-16 was recorded to be 514.1mm. The 2016-17 cropping season experienced extreme dry condition with monthly rainfall of only 136.3 mm during the entire cropping period. Pooled analysis of data showed that combined application of nutrients as per package of practices along with KCl + CaCl2 + silicic acid (T8) had significant positive impact on plant height, leaf retention, root length, stomatal conductance, photosynthetic activity and relative leaf water content. Significantly higher HCN content in tubers was recorded in 2016-17 compared to 2015-16. The above treatment combination also resulted in significantly higher tuber girth, number of tubers, mean tuber weight and yield per hectare in 2015-16. Generally, yield of crop was comparatively low during 2016-17 cropping period due to insufficient rain. However, POP+ KCl + CaCl2 along with POP + KCl + silicic acid and POP + KCl + silicic acid + CaCl2 recorded higher fresh tuber yield. Tuber girth was highest in the treatment POP + KCl + silicic acid + CaCl2. Combination of all three nutrients along with recommended doses of N, P and K resulted in significant increase in the total uptake of primary and secondary nutrients compared to control. However nutrient uptake was limited in 2016-17. In general, foliar application of chemical treatments along with recommended package of practices were found to have a significant positive influence on cassava even under low rainfall conditions.
