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ThesisItem Open Access Influence of composting methods on compost maturity and quality(Department of Agronomy, College of Horticulture, Vellanikkara, 2015) Harsha, Narayanan; KAU; Anitha, SOne of the important factors affecting the successful use of compost for agricultural purpose is compost maturity because immature compost can be detrimental to plant growth and soil environment. Compost obtained from many of the rapid methods is found to be coarser and need to be evaluated for maturity and quality prior to its agricultural use. Although the practical applicability and benefits of composting methods are widely known, there has been very limited effort towards scientific documentation and evaluation of the biodegradation process, along with quality evaluation of its end product and post application efficiency. The present study was proposed against this backdrop to study the influence of various composting methods on its end product quality, particularly in terms of its stability and maturity status and to evaluate whether the compost obtained from these methods can be directly used as manure. An investigation entitled ‘Influence of composting methods on compost maturity and quality’ was conducted at Plant Propogation and Nursery Management Unit, Vellanikkara to study the effect of composting methods on compost maturity and quality and evaluate the suitability of compost obtained from various composting methods as organic manure on the growth and yield performance of bhindi crop. The experiment consisted of eight methods of composting (T1-Aerobic composting using cowdung, T2- Aerobic composting using Bacillus subtilis (KAU culture), T3- Composting using effective microorganisms, T4- Composting with Trichoderma and worms, T5 - Vermicomposting, T6- Varanasi composting, T7- Heap and T8- Pit method of composting). The compost obtained from all the composting methods helped to attain physical, chemical and biological parameters of compost maturity at varying degree. The highest yield was recorded in varanasi composting followed by aerobic composting using cowdung. Based on the recovery percentage, the highest compost recovery was noticed in aerobic composting using cowdung. The nutrient content of compost obtained from all the composting methods was in the permissible limit. Even though the quantity of compost produced was less using microbial culture, compost produced has attained all the maturity parameters. In the absence of cowdung, composting using Bacillus subtilis (KAU culture), and Trichoderma and worms can be used as substitute for cowdung. Germination studies using compost extract and compost as potting mixture revealed that the compost produced were not phototoxic in nature and the heavy metal content was in the permissible limit. Based on the compost yield and better parameters of maturity, aerobic composting, varanasi composting and vermicomposting were found superior. The experiment to evaluate the suitability of compost as organic manure in the performance of bhindi crop consisted of nine treatments including compost obtained from eight different composting methods and farm yard manure. The organic manure requirement of the crop was substituted by compost and the quantity was decided based on nitrogen equivalent basis of farm yard manure requirement of bhindi (12t/ha). Crop performance was significantly higher with varanasi compost, vermicompost and compost using effective microorganisms. There was significant increase in available soil nutrient content after the addition of compost as compared to the initial content in all the treatments.ThesisItem Open Access Nutrient management for coconut based multi-storeyed cropping system in a typical coastal sandy zone(Department of agronomy, College of agriculture, Padannakkad, 2015) Farsanashamin, P; KAU; Anilkumar, A SThe investigation entitled “Nutrient management for coconut based multi-storeyed cropping system in a typical coastal sandy zone” was carried out during January 2014 – March 2015 to develop appropriate cost effective practices for enhancing nutrient use efficiency, productivity and profitability of coconut based multi-storeyed cropping system involving a combination of coconut (C), noni (IC), banana (IC) and long pepper (IC). The experiment was laid out in Randomized Block Design with 8 treatments and 5 control plots with two replications. The treatments were T1: 100% NPK (C) + 100% NPK (IC), T2: 100% NPK (C) + 75% NPK (IC), T3: 2/3rd NPK (C) + 100% NPK (IC), T4: 2/3rd NPK (C) + 75% NPK (IC), T5: 1/3rd NPK (C) + 100% NPK (IC), T6: 1/3rd NPK (C) + 75% NPK (IC), T7: Basin management (C) + 100% NPK (IC), T8: Basin management (C) + 75% NPK (IC). In addition, sole crops of coconut (T9), long pepper (T11), banana (T12) and noni (T13) were maintained as control plots under 100% NPK besides sole crop of coconut (T10-basin management). The results of the field experiment revealed that all the growth parameters in long pepper were significantly influenced by treatment effects. The treatment T2 at 4 MAP and T3 at 8, 10 and 12 MAP; T8 at 12 MAP; and T2 at 6 MAP, T3 at 8, 10 and 12 MAP recorded significantly higher values of total vine length, number of branches per vine and total number of leaves per vine respectively. Total spike number per plant, total fresh and dry spike yield and total alkaloid content also showed significant difference due to treatment effects and the treatment T3 recorded the highest value. Nutrient content of leaf and fruit, dry matter production per plant and physiological parameters were not significantly influenced by the treatment effects. In banana, biometric characters, yield components, yield, plant nutrient status and physiological parameters were found to be unaffected by treatment effects. However, the performance of banana in multi-storeyed cropping system was found better compared to sole cropping. The highest bunch weight was recorded in treatment T3. The treatment T3, recorded the highest number of fruits and fruit weight in noni. Nitrogen content in noni fruit was significantly influenced by the treatment effects and the highest per cent was recorded in T3. Litter fall in noni was unaffected by treatment effects but the phosphorus accumulation in soil through litter fall was found to be significant and the treatment T4 contributed the highest quantity of phosphorus to the system. Among the physiological parameters, leaf temperature showed significant influence and the treatment T13 recorded the highest leaf temperature while the treatment T8 recorded the lowest value. Studies on nutrient release pattern of noni leaf litter revealed that 53.3% N, 81.8% P and 61.9% K were released in to the system over a period of seven months. Pooled analysis of the productivity of coconut over a period of three years confirmed the significance of the treatment T8 which was on par with T7. With respect to copra content also, the treatment T7 registered the highest value. Plant analysis data showed that nutrient concentration in index leaf was unaffected by treatment effects except sulphur. The treatments significantly influenced the maximum water holding capacity of soil and T8 recorded the highest value. Available P2O5, Ca, Mg and Mn in soil were significantly influenced by the treatment effects and the highest values were recorded in T3, T8, T11 and T4 respectively. Rhizosphere microflora was enumerated and the highest number of bacteria, fungi and actinomycetes were recorded in T8, T11 and T12 respectively. Total energy output was estimated in the cropping system and the highest output was registered by the treatment T3 which was on par with T8. Economic analysis of the system revealed that gross returns, net returns and B:C ratio were significantly influenced by treatment effects and the highest values were recorded in T8. The treatment T8 ( Basin management of coconut with in situ green manuring, recycling of palm waste, FYM application @ 50 kg + 5 kg ash + 25 g Azospirillum per palm per year combined with the application of 75% of the recommended dose of NPK each for the component crops viz. noni, banana and long pepper) was found worthwhile for popularization in relation to sustainable yield index, partial nutrient balance with respect to P & K and BCR for coconut based multi-storeyed cropping systems of the coastal sandy zones.ThesisItem Open Access Fertigation in sprinkler irrigated upland rice (Oryza sativa L.)(Department of Agronomy, College of Horticulture, Vellanikkara, 2015) Shahanila, P P; KAU; Prameela, PUpland rice cultivation is now being promoted by the Kerala government in the context of diminishing area and production of rice. Although traditionally raised as rainfed crop in the first crop season, upland rice can also be grown throughout the year, if irrigation is provided. Micro irrigation techniques are now gaining popularity because of scarcity of water and high water use efficiency. Irrigation through micro sprinklers is advantageous for upland rice. The present study was undertaken to standardize the irrigation and nutrient requirement of high yielding rice variety grown in upland situation. The experiment was conducted at the Instructional Farm of KAU, Vellanikkara during February to June 2014. The trial was laid out in split plot design with four main plots and three subplots and replicated thrice. The treatments consisted of four levels of irrigation; irrigation @ 75% pan evaporation (Ep) (I1), 100% pan evaporation (I2), 125% pan evaporation (I3) and life saving irrigation (I4) at 5cm depth at required stages and three fertilizer levels; 90:45:45 N, P2O5, K2O kg/ha (F1), 70:35:35 N, P2O5, K2O kg/ha (F2) and 60:30:30 N, P2O5, K2O kg/ha (F3). Biometric characters such as plant height and tiller number per hill were higher in the irrigation schedule of 125% pan evaporation at all the crop growth stages. There was no significant difference among fertilizer levels with regard to plant height and tiller number at 30 DAS and at harvest. The quantity of irrigation water significantly influenced the yield and yield attributes of rice. The highest number of panicles per hill, filled grains per panicle, total biomass production, grain and straw yield were in the highest irrigation level of 125% pan evaporation. Nitrogen and phosphorus contents in rice were not altered with irrigation levels at 30 DAS. The phosphorus content showed an increasing trend with increase in irrigation level from 75% to 125% pan evaporation. At 60 DAS, the highest nitrogen content was observed in irrigation at 75% pan evaporation and the highest phosphorus content was under 125% pan evaporation. Nitrogen and phosphorus content in grains were altered by moisture regime whereas potassium content was not influenced. In straw, phosphorus and potassium contents were altered by irrigation levels and higher contents were registered in 100% pan evaporation and life saving irrigation respectively. The uptake of all the three basic nutrients showed an increasing trend with increase in irrigation level and the highest uptake was recorded under the high irrigation level of 125% pan evaporation. Only nitrogen uptake was significantly influenced by fertilizer levels and the highest uptake was registered with a fertilizer dose of 90:45:45 N, P2O5, K2O kg/ha. Field water use efficiency showed a decreasing trend with increase in irrigation level and it was higher for crop grown under 75% pan evaporation irrigation level. The results of moisture studies indicated that rice extracted more moisture from the top 30 cm soil layer. In general, weed density was high under sprinkler irrigation. Panicum maximum (Guinea grass) was the only monocot weed found in the experimental plot. Borreria hispida, Melochia corchorifolia, Centrosema pubescens, Calopogonium mucunoides, Cleome spp. were the dicot species. Density of monocots and weed dry weight was higher in 125% pan evaporation irrigation whereas density of dicot weeds were higher in 75% pan evaporation. Throughout the crop growth stages, weed density was not significantly influenced by fertilizer levels. In the present study, the highest return from sprinkler irrigated upland rice was obtained with an irrigation regime of 125% pan evaporation and fertilizer dose of 60:30:30 N, P2O5, K2O kg/ha.ThesisItem Open Access Standardization of media for tray nursery technique in rice(Department of Agronomy, College of Horticulture, Vellanikkara, 2015) Greeshma, V Mathew; KAU; Latha, A (Guide)Rice is the principal food crop of Kerala. But the cultivated area of rice in Kerala is drastically decreasing year after year. The major reason for reduction in area is the high cost of cultivation due to increased wage rate prevailing in the state. Mechanization has become imperative to sustain and make rice cultivation economically viable as well as ecologically harmonious. Manual transplanting is labour intensive and mechanical transplanting using tray nursery which is a low cost technology can be adopted in rice cultivation. The success of mechanical transplanting depends on the success of nursery. The soil media used for raising tray nursery limits the easy transportation of the nursery and substitution of the growing media with light weight, cheap and easily available materials will lead to the commercial production of paddy mat nursery for easy transportation and wider acceptance of the technology. The present study entitled “Standardization of media for tray nursery technique in rice” was conducted during 2013-2015 at Agricultural Research Station, Mannuthy with the objectives of standardizing the media for tray nursery technique in rice and to evaluate its efficiency under field condition. The study was carried out in two experiments. The variety used was Jyothi. The design of the Experiment I was CRD with 18 treatments replicated five times. The components viz. four levels of rice husk charcoal, seven levels of soil and two levels of vermi compost or coir pith compost were mixed as per the treatments. Observations on mean germination time, growth characters of seedlings, mat characteristics, physico-chemical properties of media, nutrient contents and uptake by the seedlings were recorded. Economics of nursery was also calculated. The media comprised of 80% RHC + 20% VC, 60% RHC + 20% soil + 20% VC, 80% RHC + 10% soil + 10% VC and 80% RHC + 20% CC were found to be superior with respect to biometric characters. The mats with light weight were produced by the media of 80% RHC + 20% CC and 80% RHC + 20% VC. The stronger mats were noticed in the media of 80% RHC + 20% CC and 40% RHC + 40% soil + 20% VC. Based on the growth characteristics, mat characters and nutrient uptake by the seedlings, ten high ranking media were selected among 18 media from Experiment I for evaluating under field condition. The Experiment II was designed to evaluate the ten best performing media selected from Experiment I under field condition. The design was RBD with three replications. Observations on performance of transplanter, growth characters, yield attributes and yield were recorded. The nutrient contents of the crop were determined and uptake by the crop and economics of cultivation were computed. The performance of the transplanter with respect to the number of hills per metre run and the plant population per m2 at planting were comparable in all the media except the media 60% RHC + 20% soil + 20% VC. The optimum number of seedlings per hill and less number of missing hills per m2 were noticed in the media of 80% RHC + 20% VC, 60% RHC + 30% soil + 10% VC, 80% RHC + 20% CC and 20% RHC + 60% soil + 20% VC. The variation in biometric characters, yield attributes, yield, harvest index, nutrient contents of crop and uptake of nutrients by the crop did not produce significant variation under field condition. From the study, it was revealed that the media comprised of 80% RHC + 20% VC, 60% RHC + 30% soil + 10% VC and 80% RHC + 20% CC were found to be better for cheap, good qualty and light tray nursery production in terms of seedling and mat characteristics and performance of transplanter. These media were also noticed to be performing well and produced higher grain yield under field condition also.ThesisItem Open Access Stress induced source-sink modulation in yard long bean (Vigna unguiculata subsp. sesquipedalis (L.) Verdcourt)(Department of agronomy, College of agriculture, Vellayani, 2015) Anjana Babu, R S; KAU; Sheela, K RThe investigation entitled “Stress induced source-sink modulation in yard long bean (Vigna unguiculata subsp. sesquipedalis (L.) Verdcourt)” was carried out during January to May, 2014 at the Instructional Farm, College of Agriculture, Vellayani, Kerala. The objective was to assess the influence of moisture- nutrient stress and foliar nutrition on source-sink relationship, productivity and profitability of yard long bean. The experiment was laid out in split plot design with four replications. The main plot treatments included four different levels of irrigation viz., daily irrigation at 10 mm depth (I1), irrigation in alternate days (I2), irrigation once in 3 days (I3) and irrigation once in 3 days up to flowering and then in alternate days (I4) each at 20 mm depth. Combinations of nitrogen levels [recommended N (N0) and 25 per cent less of recommended N (N1)] and method of application [soil application of N and K in 4 splits (M1) and soil application of one-third N and K as basal followed by foliar application of 13:0:45 @ 0.5 per cent at fortnightly interval (M2)] formed the sub plot treatments. The adhoc recommendation for yard long bean (30:30:20 kg NPK ha-1) was adopted for this study. Farm yard manure @ 20 t ha-1 and full P were applied as basal dose, uniformly for all treatments. Daily irrigation at 10 mm depth recorded significantly higher values for growth parameters viz., functional leaves plant per plant and leaf area index (1.56). Chlorophyll content of leaves at flowering (1.47 mg g-1), crude protein content and N and P uptake were also superior in daily irrigated treatments. K uptake was found to be the maximum in irrigation once in three days and it was on par with daily irrigation. The major yield attributes like number of pods per plant and pod yield per plant and total pod yield were not influenced by levels of irrigation. A better source : sink ratio (0.75) was registered in I3 (irrigation once in three days at 20 mm depth) while, the harvest index was higher for I3 and I4. The water use efficiency and water productivity (14.58 and 6.84 kg ha.mm-1) were 115 found to be significantly superior in irrigation once in three days. Increasing the irrigation interval enhanced the proline accumulation in leaves and crude fibre in pods. Application of recommended dose (RD) of nitrogen registered significantly higher values for functional leaves at later crop growth and leaf area index. Leaf chlorophyll content was found to be superior in N0 while, proline content (2.57 μ mols g-1) was higher in N1. Uptake of N and K were superior in RD N. Reducing the nitrogen levels to 75 per cent of RD did not cause any reduction in yield attributes and yield. Lower source : sink ratio and higher P uptake were noted in application of 25 per cent less of RD N. Recommended dose of N registered the highest value of water productivity, whereas WUE was the highest at 25 per cent less RD N. Soil application of nutrients registered significantly higher yield (100.03 q ha-1) and uptake of nutrients over soil + foliar application. The biochemical characters viz., chlorophyll content and proline content were higher in soil + foliar application. The source : sink ratio and harvest index were favourably influenced by soil application of nutrients. WUE and water productivity (11.95 and 5.82 kg ha.mm-1 respectively) were superior in soil application of nutrients. Irrigation once in three days at 20 mm depth registered the highest B : C ratio. Among the methods of application, soil application was found more economical. From the study it could be inferred that daily irrigation is not necessary for yard long bean. Irrigation once in three days at 20 mm depth along with application of 25 per cent less of RD N (22.5 kg N ha-1) registered favourable source : sink ratio (0.70) and enhanced the B:C ratio (3.89). Soil application of nutrients recorded 10.25 per cent increase in yield and 15 per cent increase in B : C ratio compared to soil + foliar application.ThesisItem Open Access Flag leaf nutrition for enhancing resource use efficiency in rice (Oryza sativa L.)(Department of Agronomy, College of Agriculture, Vellayani, 2015) Surya, M S; KAU; Shalini Pillai, PThe experiment entitled “Flag leaf nutrition for enhancing resource use efficiency in rice (Oryza sativa L.)” was undertaken at the Instructional Farm, College of Agriculture, Vellayani, Thiruvananthapuram, during June to October, 2014. The main objectives of the study were to at assess the effect of flag leaf foliar nutrition on partitioning of photosynthates, growth and productivity of rice and to work out the economics of the practice in lowland rice ecosystem. The field experiment comprised [(5x3)+1] treatment combinations, laid out in randomised block design with three replications, using PTB 52 (Aiswarya) as the test variety. The treatments were 0.5 per cent each of S1 : potassium nitrate, S2 : calcium nitrate, S3 : magnesium sulphate, S4 : 19 : 19 : 19 complex and S5 : a combination S2 + S3 + S4, sprayed at three crop growth stages viz., G1 : Booting stage, G2 : Booting + Flowering stages and G3 : Booting + Flowering + Milk stages, as compared against a control (KAU POP for medium duration rice). The flag leaf nutrition treatments (s1g1 to s5g3) were given, over and above the KAU POP. The effect of nutrient sources used for flag leaf nutrition (FLN) was more pronounced than the growth stages chosen for FLN. Flag leaf area was significantly higher at booting (4.98 cm2) and flowering stages (8.11 cm2) with S1 (potassium nitrate @ 0.5 %), which was at par with S4 (19: 19: 19 complex). Foliar spraying of potassium nitrate @ 0.5 per cent at booting and flowering stages (s1g2) recorded the highest flag leaf area (9.08 cm2) at flowering stage and s2g3 resulted in the highest flag leaf area (11.65cm2) at harvest stage. FLN had no significant effect on the number of days taken for panicle exsertion. Latent tiller production (2.78 hill-1) was significantly higher with potassium nitrate @ 0.5 %. The relative growth rate recorded at booting (0.174 mg g-1 day-1), flowering (0.057 mg g-1 day-1) and harvest stages (0.028 mg g-1 day-1) was also superior with potassium nitrate. Net assimilation rate (NAR) recorded at booting stage was significantly higher for potassium nitrate (3.76 mg cm-2 day-1). But at flowering stage, 19:19:19 complex had the same effect with a NAR of 2.58 mg cm-2 day-1. FLN with 19:19:19 complex (S4) registered significantly higher chlorophyll content (2.58 mg g-1) in flag leaf blade at flowering stage. However, the carotenoid content was significantly superior (1.83 mg g-1) with potassium nitrate. All the yield attributes viz. productive tiller count (490.19), grain weight panicle-1 (2.18 g), number of spikelets panicle-1 (89.11), filled grains panicle-1 and thousand grain weight (28.55 g) were significantly superior with (potassium nitrate @ 0.5 %) as compared to KAU POP which recorded 417.24 productive tillers m-2, 82.57 spikelets panicle-1, 1.43 g grain weight panicle-1 and a thousand grain weight of 21.51 g. Further, sterility percentage was the lowest (11.94 per cent) with S1 compared to KAU POP (16.05 per cent). The effect of potassium nitrate was at par with 19: 19: 19 complex, with respect to sterility percentage and thousand grain weight. FLN with potassium nitrate @ 0.5 per cent recorded significantly higher grain yield (5.95 t ha-1) followed by 19: 19: 19 complex (5.01 t ha-1). The treatment combination, s1g1 (potassium nitrate at booting stage) recorded the highest yield of 6.28 t ha-1. The KAU POP recorded a grain yield of 4.41 t ha-1. Straw yield was also significantly higher with potassium nitrate. Grain yield recorded with flag leaf nutrition at booting + flowering stages (G2) (4.52 t ha-1) and booting + flowering + milk stages (G3) (4.68 t ha-1) were at par. Grain to straw ratio (0.80) and harvest index (0.44) were superior with 19: 19: 19 complex @ 0.5 per cent. Index leaf (flag leaf) analysis recorded significantly higher N and P contents with S5 and K content with S1. The treatment s3g3 recorded the highest sulphur content in flag leaf. The treatment combination, s1g2 recorded significantly higher crude protein content (8.34 per cent) in grain. FLN had no effect on the incidence of pests and diseases. FLN with potassium nitrate @ 0.5 per cent (S1) recorded significantly higher N, P and K uptake. The treatment combination, s3g2 recorded significantly higher sulphur uptake. Nutrient use efficiency assessed in terms of nitrogen use efficiency, agronomic efficiency and apparent recovery efficiency were significantly higher with S1 followed by 19: 19: 19 complex. Gross income ( 1,35,127 ha-1), net income ( 70,102 ha-1) and benefit cost ratio (2.07) were significantly higher with S1, compared to KAU POP with a BCR of 1.65. The study revealed that KAU POP recommendation for high yielding medium duration wetland rice (FYM @ 5 t ha-1 + 90:45:45 kg NPK ha-1) supplemented with FLN of potassium nitrate @ 0.5 per cent concentration, 5 days prior to booting and 50 per cent flowering stages, resulted in significantly higher grain yield, nutrient use efficiency and profitability, in the rice variety Aiswarya. However, the photosynthate partitioning efficiency, assessed in terms of harvest index and grain to straw ratio were observed to be superior with 19:19:19 complex @ 0.5 per centThesisItem Open Access Biology and management of weedy rice (Oryza sativa f. spontanea)(College of Horticulture, Vellanikkara, 2015) Nimmy, Jose; KAU; Abraham, C TWeedy rice is the complex of morphotypes of Oryza species widely distributed in the commercial rice fields in more than 50 countries of Asia, Africa and Latin America, especially in areas where farmers have switched to direct seeding due to labour shortage and high cost. Taxonomically, Indian weedy rice is identified as Oryza sativa f. spontanea which belongs to the indica group. Invasion and spread of weedy rice in the cultivated rice fields have forced the farming community to abandon rice farming, leading to socio economic and ecological impacts in the rice bowls of Kerala. Management of weedy rice infestation is complex mainly because of its morphological similarities to cultivated rice and lack of herbicides for selective control of weedy rice in cropped fields. Hence, the present research programme was undertaken to estimate the extent of infestation of weedy rice in rice bowls of Kerala, to study the biology and ecology, and to chalk out strategies for integrated management of weedy rice. Survey conducted in the major rice belts of Kerala, viz., Kole, Kuttanad and Palakkad, revealed that more than 65 percent of the area has low to severe weedy rice infestation. In the major rice bowls of Kerala there was severe, moderate and low infestation of weedy rice in 26, 36 and 49 panchayaths, respectively,. The extent of infestation was more in Kuttanad in Alleppey, Kottayam and Pathanamthitta districts and Kole lands of Thrissur district. In Palakkad region, the infestation was more in panchayaths of Alathoor and Nemmara blocks. Survey revealed the presence of weedy rice variants with respect to morphological characters like number of tillers per plant, height of plant, length of ligule, panicle characters, colour of grains, and length and colour of awns. Studies conducted on the germination of weedy rice seeds revealed that there was no significant difference between the germination of weedy rice in the presence and absence of rice seeds in the soil. It was noticed that seed germination was higher at the surface and 2 cm depth of the soil and there was drastic reduction in the germination from deeper layers of 4-8 cm. Investigations on dormancy revealed that hull induced dormancy in weedy rice could be broken by exposing seeds to 20ºC for 48 hours, treating with 0.6% nitric acid for six hours, rupturing seed coat, or maintaining electrical conductivity of 5 dS m-1 for six hours in the growing media. Scanning electron microscope studies confirmed that lesser overlapping of lemma and palea contributed to quicker germination of half mature straw coloured weedy rice grains whereas, slow germination in black coloured mature seeds is due to the clear overlapping of lemma and palea. Presence of more number of stomata both on adaxial and abaxial surface, silica deposits and hairy out-growths on leaf, and high root volume in weedy rice contributed to its early vigour, growth and competitiveness. Management options found effective for the control of weedy rice in direct seeded puddled rice include (1) pre sowing surface application of oxyfluorfen @ 0.2 kg ha-1 three days before sowing in thin film of water (2) selective drying of weedy rice panicles with nonselective broadspectrum herbicides glufosinate ammonium or glyphosate @ 15 % - 20 % concentration at 60-65 DAS using specially designed wick applicator/wiper device (3) stale seed bed technique with (wet tillage in between two stales under heavy infestation) application of broad spectrum herbicide followed by flooding for exhausting soil seed bank (4) straw burning after harvest of infested fields followed by zero tillage in succeeding crop and (5) soil solarisation for more than 30 days during summer months using 100 micron transparent polythene sheets. A novel hand held wiper device was developed for the direct contact application of nonselective broadspectrum herbicides for selective drying of weedy rice panicles at 60-65 days after sowing, when rice and weedy rice plants maintain height difference of 20 cm. The device was filed for Indian Patent at Patent Office, Chennai (Application No. 1763/CHE/2014 dated 01.04.2014). Effective and economical management of weedy rice is possible by the integrated use of different options for management depending on the intensity of infestation. Various weedy rice management options standardized in the present study were demonstrated in farmers’ fields in a participatory mode. The demonstrations have given good results and many farmers have already adopted the package for the integrated management of weedy rice.ThesisItem Open Access Herbicide based weed management for semi dry rice (Oryza sativa L.)(College of Agriculture, Vellayani, 2015) Arya, S R; KAU; Ameena, MAn investigation entitled “Herbicide based weed management for semi dry rice (Oryza sativa L.)” was conducted during the period May to September 2014 at farmer’s field in Nemom block, Thiruvanthapuram. The main objectives of the study were to evaluate the weed control efficiency of new generation herbicides in semi dry rice, to assess their selectivity and influence on growth and yield, to work out the economics and to develop a weed management strategy for semi dry rice. The field experiment comprised of eleven treatments replicated thrice (Variety: Uma) was laid out in randomised block design. The treatments were T1: bensulfuronmethyl + pretilachlor @ 60 + 600 g a.i. ha-1 (pre - emergence), T2: T1 + hand weeding at 40 DAS, T3: T1 + azimsulfuron @ 30 g a.i. ha-1 (post emergence), T4: pyrazosulfuron ethyl @ 25 g a.i. ha-1 (pre - emergence), T5: T4 + hand weeding at 40 DAS, T6 : T4 + azimsulfuron @ 30 g a.i. ha-1 (post emergence), T7 : oxyfluorfen @ 0.15 kg a.i. ha-1 (pre - emergence), T8 : T7 + hand weeding at 40 DAS, T9 : T7 + azimsulfuron @ 30 g a.i. ha-1 (post emergence) and two controls: T10: hand weeding at 20 and 40 DAS and T11: weedy check. Result of the study revealed substantial reduction in weed population and biomass in all the herbicide treated plots compared to weedy check. Weed composition of the experimental field indicated the dominance of broad leaved weeds followed by sedges and grasses with considerable variation in weed flora during dry and flooded condition. Hand weeding at 20 and 40 DAS (T10) recorded lowest weed density, weed dry weight and highest weed control efficiency. Absolute frequency (Af) for all weed species throughout the crop growth stages was also lower under hand weeding while higher values of importance value (IV) and summed dominance ratio (SDR) for sedges and broad leaved weeds were recorded in weedy check (T11). Pre-emergent herbicide application followed by either hand weeding at 40 DAS (T2 and T5) or application of post emergent herbicides (T3 and T6) recorded higher weed control efficiency and lower nutrient removal in comparison with hand weeding twice (20 and 40 DAS). None of the herbicides produced any phytotoxic symptoms on rice plant. However, crop density and growth was lower at the initial stages in oxyfluorfen treated plots. This indicated that bensulfuron methyl + pretilachlor and pyrazosulfuron can be treated as safe pre-emergent herbicides for dry sown (semi dry) system of rice cultivation. Result of the study also indicated the safety of the herbicides on microbial activity as evidenced by the increase in soil dehydrogenase activity in herbicides applied plots. The yield attributes of rice viz., number of productive tillers m-2 and filled grains panicle-1 were significantly influenced by the weed management practices T2, T3, T5, T6 and T10. Grain yield (4817.67 kg ha-1) and straw yield (7969.33 kg ha-1) were significantly higher in T2 (bensulfuronmethyl + pretilachlor @ 60 + 600 g a.i. ha-1 + hand weeding at 40 DAS) and remained on par with T3, T5, T6 and T10. Yield loss due to weeds was found to be 52.22 per cent. The most economically viable weed management practice was T6 (bensulfuronmethyl + pretilachlor fb azimsulfuron) with a B: C ratio of 1.76 which was on par with T3 (1.75). Grain yield, net income and B: C ratio were significantly lower in weedy check. It can be concluded that the most effective weed management practice for semi dry rice is pre-emergence application of either bensulfuron methyl + pretilachlor @ 60 + 600 g a.i. ha-1 or pyrazosulfuron ethyl @ 25 g a.i. ha-1 on the next day of sowing followed by post emergence application of azimsulfuron @ 30 g a.i. ha-1 at 25 DAS.ThesisItem Open Access Efficacy of mulches for weed management in okra (Abelmoschus esculentus (L.) Moench.)(College of Horticulture, Vellanikkara, 2015) Faras, Bin Muhammed U P; KAU; Sindhu, P VA major constraint in the production of vegetables in the humid tropics is heavy infestation of weeds. The extent of damage due to weeds varies with the crop and the nature of weeds. Okra [Abelmoschus esculentus (L.) Moench.] is an important vegetable crop grown throughout India in summer and rainy seasons. Being a widely spaced crop, weeds are always a problem for the successful cultivation of okra. Because of the high cost and drudgery involved, traditional methods especially hand weeding is on the decline. Chemical weed control is a cost effective option to manage this situation. However, depending only on chemicals is not advisable considering the ill effects due to continued use of chemicals. Mulching, a non chemical method of covering the land surface with organic or inorganic materials is commonly followed in many crops especially vegetables for managing weeds, conserving moisture and for many other benefits. The present experiment entitled “Efficacy of mulches for weed management in okra [Abelmoschus esculentus (L.) Moench.]” was conducted in the Department of Agronomy, College of Horticulture, Vellanikkara in the summer season of 2014 to compare the efficiency of different organic mulches for managing weeds of okra and to assess the effect of mulching on soil-plant micro site variations. Treatments included mulching with five organic mulches (mango leaves, coconut fronds, fresh weeds, paddy straw and newspaper), mulching with black polythene sheet, weed management by herbicide, hand weeding and unweeded control. Mulching with black polythene sheet greatly increased the plant height, while organic mulches did not show any significant effect. Organic mulches of newspaper, mango leaves and paddy straw facilitated higher uptake of nutrients by crops. Mulching with black polythene sheet, paddy straw and mango leaves favoured earliness in flowering. The number of fruits per plant was higher in plots mulched with black polythene sheet followed by hand weeding. Black polythene sheet mulching recorded highest fruit yield of 15.63 t/ha followed by hand weeding (12.02 t/ha). Among organic mulches, mango leaves recorded 10.06 t/ha yield which was higher than the yield in herbicide sprayed plot (9.56 t/ha). Mulching with newspaper resulted in a yield of 9.37 t/ ha. Mulching with paddy straw, mango leaves and newspaper resulted in 70 to 95 percent control of weeds at 30 DAS. The efficiency of organic mulches reduced to 30 to 50 percent at 60 and 90 DAS. Mulching with fresh weeds and coconut fronds failed to check weed emergence. Black polythene sheet was superior among the mulches throughout the crop period. Weed index of the treatments mulched with mango leaves and newspaper were found almost similar to that of pre emergent spray of pendimethalin. Nutrient removal by weeds was lower under organic mulches of newspaper and mango leaves. An increase in the soil pH was observed towards the harvest of the crop. The soil organic carbon content was also found to be increased due to use of organic mulches. Higher contents of available N and K were observed in mulched plots compared to bare soils of hand weeded and herbicide sprayed plots. However, available P status was not influenced by treatments. Organic mulches helped to reduce the soil temperature throughout the crop growth period. Higher moisture content was noticed in mulched plots compared to bare soil. Among them, paddy straw and coconut fronds exhibited greater influence. There was no significant difference in relative humidity at canopy level due to mulching. The treatments greatly influenced the population of bacteria, fungi and actinomycetes. In general, organic mulches, especially paddy straw favoured microbial population. The highest benefit-cost ratio of 2.77 was recorded in black polythene sheet mulching. The B:C ratio of mango leaf mulching and pre emergent spray of pendimethalin were almost same (2.73 and 2.72 respectively). Mulching with newspaper resulted in a B: C ratio of 2.49. From the experiment, it can be concluded that organic mulches of mango leaves and newspaper can be effectively utilized for weed management in okra. The results also suggest the possibility of replacing herbicides with organic mulches without affecting yield or benefit-cost ratio.