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Kerala Agricultural University, Thrissur
The history of agricultural education in Kerala can be traced back to the year 1896 when a scheme was evolved in the erstwhile Travancore State to train a few young men in scientific agriculture at the Demonstration Farm, Karamana, Thiruvananthapuram, presently, the Cropping Systems Research Centre under Kerala Agricultural University. Agriculture was introduced as an optional subject in the middle school classes in the State in 1922 when an Agricultural Middle School was started at Aluva, Ernakulam District. The popularity and usefulness of this school led to the starting of similar institutions at Kottarakkara and Konni in 1928 and 1931 respectively.
Agriculture was later introduced as an optional subject for Intermediate Course in 1953. In 1955, the erstwhile Government of Travancore-Cochin started the Agricultural College and Research Institute at Vellayani, Thiruvananthapuram and the College of Veterinary and Animal Sciences at Mannuthy, Thrissur for imparting higher education in agricultural and veterinary sciences, respectively. These institutions were brought under the direct administrative control of the Department of Agriculture and the Department of Animal Husbandry, respectively. With the formation of Kerala State in 1956, these two colleges were affiliated to the University of Kerala. The post-graduate programmes leading to M.Sc. (Ag), M.V.Sc. and Ph.D. degrees were started in 1961, 1962 and 1965 respectively.
On the recommendation of the Second National Education Commission (1964-66) headed by Dr. D.S. Kothari, the then Chairman of the University Grants Commission, one Agricultural University in each State was established. The State Agricultural Universities (SAUs) were established in India as an integral part of the National Agricultural Research System to give the much needed impetus to Agriculture Education and Research in the Country. As a result the Kerala Agricultural University (KAU) was established on 24th February 1971 by virtue of the Act 33 of 1971 and started functioning on 1st February 1972. The Kerala Agricultural University is the 15th in the series of the SAUs.
In accordance with the provisions of KAU Act of 1971, the Agricultural College and Research Institute at Vellayani, and the College of Veterinary and Animal Sciences, Mannuthy, were brought under the Kerala Agricultural University. In addition, twenty one agricultural and animal husbandry research stations were also transferred to the KAU for taking up research and extension programmes on various crops, animals, birds, etc.
During 2011, Kerala Agricultural University was trifurcated into Kerala Veterinary and Animal Sciences University (KVASU), Kerala University of Fisheries and Ocean Studies (KUFOS) and Kerala Agricultural University (KAU).
Now the University has seven colleges (four Agriculture, one Agricultural Engineering, one Forestry, one Co-operation Banking & Management), six RARSs, seven KVKs, 15 Research Stations and 16 Research and Extension Units under the faculties of Agriculture, Agricultural Engineering and Forestry. In addition, one Academy on Climate Change Adaptation and one Institute of Agricultural Technology offering M.Sc. (Integrated) Climate Change Adaptation and Diploma in Agricultural Sciences respectively are also functioning in Kerala Agricultural University.
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ThesisItem Open Access Concurrent growing of green manure crops in dry and wet seeded rice(Department of Agronomy, College of Horticulture, Vellanikkara, 2008) Anitha, S; KAU; Jose, MathewAn investigation entitled ‘Concurrent growing of green manure crops in dry and wet seeded rice’ was conducted at Agricultural Research Station, Mannuthy to develop a comprehensive technology package for the system of concurrent growing of green manure crops in direct seeded rice. The investigation consisted of four experiments viz., Experiment Ia - Concurrent growing of green manure crops in dry seeded rice, Experiment Ib - Residual effect of concurrent growing of green manure crops in dry seeded rice, Experiment IIa - Concurrent growing of daincha in wet seeded rice and Experiment IIb - Residual effect of concurrent growing of daincha in wet seeded rice. The experiment on concurrent growing of green manure crops in dry seeded rice consisted of two green manure crops (horse gram and cowpea), three methods of incorporation (Incorporation by cono weeder, desiccation by 2,4 - D spray @1.0 kg ha-1 and allowing for self decomposition) and two levels of nitrogen (100 and 75% of recommended N) and a control without green manure crops . Among the two green manure crops, cowpea was the best in supplying the required quantity of green matter with 25 per cent savings of N fertilizer and a substantial reduction in weed incidence. All the three methods of incorporation were found to be equally effective. Hence in places where there is a difficulty in self decomposition, cowpea can be effectively incorporated by conoweeder or by spraying 2, 4-D. The cowpea variety used in this study was a short duration bush type variety facilitating additional pod yield from cowpea before it was incorporated. Concurrent growing of cowpea along with dry seeded rice is a viable system as it resulted in increased productivity, profitability and sustainability dry seeded rice. In the experiment to study the residual effect of concurrent growing of green manure crops in dry seeded rice, the main plots of dry seeded rice crop during the 1st crop season were divided into two sub plots and applied 100 and 75 per cent N to the subplots. The results revealed that concurrent growing of green manure crops were effective in increasing the yield and sustaining soil fertility status compared to pure crop of rice receiving 5 t ha-1 of FYM and 100 per cent of the recommended nitrogen. But there was no savings of N fertilizer to the succeeding transplanted rice crop as the highest yield of succeeding rice was achieved only when it received 100 per cent of the recommended N. The profitability of the rice- rice cropping system was the highest with concurrent growing of cowpea in dry seeded rice. The experiment on concurrent growing of daincha in wet seeded rice consisted of two stages of incorporation of daincha (20 DAS and 30DAS), three methods of incorporation (Incorporation by cono weeder, desiccation by 2, 4 - D spray @1.0kg ha-1 and Desiccation by Chlorimuron ethyl+ met sulfuron methyl spray @ 4.0 g ha-1 met sulfuron methyl spray @ 5 g ha-1) and two levels of nitrogen (100 and 75% of recommended N) and a control without daincha. Results indicated that concurrent growing of daincha can be successfully practiced in wet seeded rice with improved productivity. Incorporation of 30 days old daincha employing any of the three methods of incorporation was equally effective in increasing the productivity and profitability of wet seeded rice. Incorporation of daincha at 30 DAS could add about 14 t ha-1 of green matter with minimum investment and resulted in 70 per cent weed suppression. Concurrent growing of daincha receiving both 100 and 75 per cent of recommended N produced significantly higher yield than pure crop of rice receiving 5 t ha-1 of FYM and 100 per cent of the recommended nitrogen. Hence there was a saving of 25 per cent N without affecting the yield. The highest yield was obtained when 100 per cent of recommended N was applied to the system. The treatments for the experiment to study the residual effect of concurrent growing of daincha in wet seeded rice were similar to that of dry seeded rice. The results showed that concurrent growing of daincha and its incorporation at 30 DAS was effective in increasing the yield of succeeding rice and sustaining soil fertility status compared to pure crop of rice receiving 5 t ha-1 of FYM and 100 per cent of the recommended nitrogen. The highest yield of succeeding rice was achieved only when it received 100 per cent of the recommended N hence there was no savings of N fertilizer to the succeeding transplanted rice crop. Concurrent growing of daincha in wet seeded rice increased the profitability of the rice- rice cropping system. Concurrent growing of green manure crops in dry and wet seeded rice is a management alternative to reduce the production cost and to increase the yield of rice and is a practical model for sustainable rice production.ThesisItem Open Access Herbicide mixtures for weed management(Department of Agronomy,College of Agriculture, Vellayani, 2016) Sheeja, K Raj; KAU; Elizabeth, K SyriacThe experiment entitled "Herbicide mixtures for weed management in direct seeded puddled rice Oryza saliva L." was carried out at College of Agriculture, Vellayani, during the period from 2013 - 2016, to assess the bioefficacy of two post emergence herbicide mixtures viz., bispyribac sodium + metamifop and penoxsulam + cyhalofop butyl in direct seeded rice; to study the residual effect in soil; to investigate the impact on microbial and earth worm population, soil enzyme activity and weed seed bank and also to assess the in vitro sensitivity to soil borne pathogen, Rhizoctonia solani, bio control agents and bio fertilizer organisms. Field experiment was undertaken during first and second crop seasons of 2014-15 at Nemom block at farmer's field. The experiment was laid out in RED with 12 treatments and three replications. Bispyribac sodium + metamifop @ 60, 70, 80 and 90 g ha"*,penoxsulam + cyhalofop butyl @ 120, 125, 130 and 135 g ha"*, bispyribac sodium @ 25 g ha"', penoxsulam @ 22.5 g ha"', hand weeding twice and weedy check constituted the treatments. The higher three tested doses of penoxsulam + cyhalofop butyl v/z.,125, 130 and 135 g ha ' and the highest tested dose of bispyribac sodium + metamifop viz., 90 g ha"' were better than other weed management treatments in improving the growth and yield attributes of rice. Pooled analysis indicated the superiority of penoxsulam + cyhalofop butyl @ 135 g ha"' which recorded the highest grain yield (8463 kg ha ' ) and it was statistically on par with its lower doses (130 and 125 g ha*'). Straw yield was not significantly influenced by the weed control treatments. Penoxsulam + c^lofop butyl @ 135 g ha"' recorded the highest net returns (93744 ha *) and B: C ratio (2.43), which was on par with its lower dose (130 g ha"'). Penoxsulam + cyhalofop butyl @ 135 g ha"' was more effective in reducing the total density of weeds. With regard to the control of sedges and BLW, penoxsulam + cyhalofop butyl was more effective, but with respect to grasses, both the herbicide mixtures were more or less similar in effectiveness. Penoxsulam + cyhalofop butyl @ 135 and 136 registered higher weed control efficiency and lower weed index than other treatments. Uncontrolled weed growth caused a yield reduction of 50.38 per cent. Herbicide treatments significantly reduced the nutrient uptake by weeds and enhanced the nutrient uptake by crop over weedy check. The higher doses of penoxsulam + cyhalofop butyl (125,130 and 135 g ha"') and bispyribac sodium + metamifop (70, 80 and 90 g ha*') were more effective in maintaining higher nutrient content in soil. Dynamics of soil microbial population, earthworm population, soil enzyme status and organic carbon content of soil consequent to the application of herbicide mixtures revealed that, both penoxsulam + cyhalofop butyl and bispyribac sodium + metamifop at their tested doses did not have any inhibitory effect. Results of screening trial revealed that maize was the most sensitive indicator plant for both the herbicide mixtures. Dry weight and fresh weight of maize shoot were adjudged as the best parameters for assessing the residual effect of bispyribac sodium + metamifop and penoxsulam + c>^Iofop butyl in soil respectively. Pot culture bioassay studies revealed that the tested herbicide mixtures and their doses did not have any residual effect. In vitro sensitivity studies of bispyribac sodium + metamifop and penoxsulam + cyhalofop butyl to Rhizoctonia solani pointed out that both the herbicide mixtures inhibit the growth of Rhizoctonia solani. Studies on the in vitro effect of herbicide mixtures to Trichoderma viride indicated that bispyribac sodium + metamifop was safe to the fungus, whereas penoxsulam + cyhalofop butyl was moderately toxic. Compatibility studies revealed that both the herbicide mixtures were highly compatible with Psetidomonas fluorescenSy Azospirillum lipoferum and Azotobacter chroococciim. Weed seed bank assay results indicated the effectiveness of the higher doses of penoxsulam + cylialofop butyl (135, 130 and 125 g ha'') in depleting the seed bank compared to other treatments. The present study revealed the superiority of heibicide mixtures over individual herbicides in the management of weeds in wet seeded rice. Application of penoxsulam + cyhalofop butyl @ 135 or 130 g ha*', at 15 DAS could be adjudged as the most economic and ecofriendly weed management practice for wet seeded rice as evidenced by high weed control efficiency, net returns and B: C ratio; environmental safety, high inhibitory effect to Rhizoctonia solani and good compatibility with bio control agents and bio fertilizer organisms.ThesisItem Open Access Invasion impact of greater club rush (Scirpus grossus L.f) on wetland rice ecosystem(Department of Agronomy, College of Agriculture, Vellayani, 2017) Gayathri Karthikeyan, P; KAU; Sansamma GeorgeThe study entitled “Invasion impact of greater club rush (Scirpus grossus L. f) on wetland rice ecosystem” was conducted at College of Agriculture, Vellayani during 2015-2017. The objectives were to study the invasive characteristics, habitat affinity and distribution of greater club rush, to assess its invasion impact on biodiversity and ecosystem functioning of the wetland ecosystem and also to develop an ecofriendly management strategy for recovering the invaded fields. To achieve the objectives, the study covered four aspects, i.e. Part I. Weed mapping and habitat analysis, Part II. Study of invasive characteristics of greater club rush, part III. Invasion impact on biodiversity and ecosystem functioning of wetlands, Part IV. Management of greater club rush. A preliminary survey on the presence of the emergent hydrophyte in Thiruvananthapuram district indicated that the invasion was mainly concentrated in some pockets in the wetlands adjoining the Vellayani fresh water lake. Hence, the wetland ecosystem of the Vellayani lake watershed was selected as the geographical unit for conducting the investigation. Under Part I, the extent of greater club rush invasion in the wetlands of Thiruvananthapuram district was assessed and mapped using Global Positioning System (GPS) and Geographical Information System (GIS). As per local enquiries, the invasion was noticed for the first time about 15 - 20 years back and was spreading fast in waterlogged paddy fields. However, it was not clear how this alien weed was introduced and naturalised in Kerala. The results of the weed mapping studies revealed that greater club rush invasion was concentrated mainly in the north - western side of wetlands adjoining the Vellayani lake. From the drainage and land use maps, it was inferred that there was a flood plain formed in the locality due to indiscriminate wetland reclamation resulting in impeded drainage. The total area under invasion was approximately 65 ha (47.70 per cent of the rice fallows). During the mapping studies, it was also observed that the ownership of a major portion of these paddy fields was vested with absentee landlords who leave the land uncultivated for a long time thus providing open niches for further spread of the weed. Correlation studies on weed density and dry weight with soil and water parameters of the invaded fields indicated that the weed has high level of habitat tolerance and ecological flexibility and was able to thrive under a wide range of field conditions. Under Part II, the invasive nature of greater club rush was assessed by observing the growth and development characteristics of the weed under field conditions. From the results, it was inferred that, tall stature (1.52 m), dense growth habit (342.23 ramets m-2), low light infiltration (4.36 per cent), high relative growth rate (0.028 g g-1 day-1), efficient propagation (rhizomes, stolons and corms combine for multiplication and perennation), huge biomass (30 t ha-1) and abundance of aerenchyma along with ecological flexibility imparts intense competitiveness for greater club rush making it a successful invader. The major part of the study was to assess the impact of greater club rush invasion on the wetland ecosystem (Part III). Based on the weed mapping and habitat analysis, three heavily infested padasekharams, located within a distance of 5 km were selected for the impact study and monitored for two years. The methodology used was Multisite comparison of the co- existing flora and fauna community, between invaded vs uninvaded sites. Alterations in nutrient cycling and microbial activity due to the invasion were studied by collecting and analyzing soil samples from selected sites during three seasons. The results indicated that greater club rush invasion was depleting the diversity of native vegetation in the wetland ecosystem in terms of species richness and also density. Soil seed bank studies also confirmed the negative impact of the invasion on flora diversity. However, the invaded fields were observed to be rich in faunal diversity and an ideal home for several water birds especially purple moorhen. The thick stand of the weed was found to provide refuge to small animals like rats and snakes also; and these in general were causing trouble to rice farmers in adjacent areas. Contrary to several earlier reports, the impact on the ecosystem functioning parameters was negligible, probably due to occasional flooding and sedimentation in the selected locality. To develop an eco-friendly strategy for managing the weed, an experiment was undertaken in a heavily infested paddy field (Part IV) with eight treatments and three replications and the design was RBD. The treatments were: T1 - (Bensulfuron methyl + Pretilachlor) @ 660g ha-1 on the next day of tilling., T2 - (Bensulfuron methyl + Pretilachlor) @ 1320g ha-1 on the next day of tilling, T3 –Azimsulfuron @ 35g ha-1 at 3-5 leaf stage , T4 -Azimsulfuron @ 70 g ha-1 at 3-5 leaf stage, T5 - (Glyphosate @ 1.0 kg ha-1 + 2, 4 – D sodium salt @ 2.0 kg ha-1) at active growth stage, T6 - (Glyphosate @ 0.5 kg ha-1 + 2, 4 – D @ 1.0 kg ha-1) at reproductive stage, T7 -Tillage (Farmer’s practice) and T8 – Control (Uninterrupted weed growth). Among the various treatments, application of Glyphosate @ 0.5 kg ha-1 + 2, 4 – D @ 1.0 kg ha-1 at the reproductive stage was found to be the best, giving complete weed kill with no further regrowth. The opportunities for utilising the weed and thereby managing it were also investigated during the study. The results revealed that greater club rush with its huge biomass production (>30 t ha-1) could remove many of the heavy metals (arsenic, copper, zinc, lead, chromium, cobalt, nickel and chromium) from contaminated soils more efficiently than water hyacinth which is a well known phytoremediator. The nutritive value of the weed biomass (crude protein - 7.5 per cent, crude fibre- 26.79 per cent) was shown to be comparable with that of guinea grass (crude protein - 8 to14 per cent, crude fibre - 28 to 36 per cent). The K/(Ca+Mg) ratio was 1.39 which is considered to be within safe limits in a livestock feed. However being a phytoextractor, further studies needs to be done for justifying its use as a forage. The study revealed that greater club rush has high level of ecological flexibility and competitiveness which make it a successful invader. The weed has already invaded considerable area of wetland rice ecosystem and is likely to spread further in areas left fallow for long periods. It was found that the invaded fields could be efficiently recovered by application of a tank mixture of glyphosate @ 0.5 kg ha-1 + 2, 4 – D sodium salt @ 1.0 kg ha-1 at the reproductive stage. The major negative impact of the invasion on ecosystem was the decline in species richness and density of native weed community. At the same time, the thick weed growth provided ideal habitat for many faunal species. The weed was found to have the potential to be used for phytostabilisation of heavy metal contaminated soils and the luxuriant biomass had reasonable nutritive value also. The overall conclusion is that greater club rush invasion can become a potential threat to the wetland rice ecosystem, if left undisturbed.ThesisItem Restricted Acidity amelioration and nutrient management practices for mitigating yield constraints of rice in Vaikom Kari(Department of Agronomy, College of Agriculture, Vellayani, 2017) Devi, V S; KAU; Kumari Swadija, OAn investigation entitled “Acidity amelioration and nutrient management practices for mitigating yield constraints of rice in Vaikom Kari” was carried out as two field experiments in Vaikom Kari soils of Kuttanad during the period from 2014 to 2017 to standardize acidity amelioration and nutrient management practices for rice to overcome yield constraints in Vaikom Kari and to work out the economics of cultivation. Experiment I entitled “Evaluation of acidity amelioration practices for rice in Vaikom Kari” was conducted in farmer’s field in Kallara panchayat in Kottayam district during November 2014 to March 2015. The experiment was laid out in RBD with seven treatments in three replications with rice var. Uma. The treatments included lime, dolomite and rice husk ash (RHA) applied as two splits- as basal + 30 DAS or as basal + one week before third dose of fertilizer application and a control without ameliorants. Lime, dolomite or RHA, irrespective of time of application, could produce taller plants with higher LAI and tiller number at maximum tillering (MT), panicle initiation (PI) and harvest stages. The same treatments recorded higher number of panicles m-2 and 1000 grain weight and lower sterility percentage. Lime, dolomite or RHA as basal + 30 DAS produced significantly higher grain yield over control. Grain yield was significantly and positively correlated with LAI at MT and PI stages and panicle number m-2. Higher straw yield was obtained with lime or dolomite as basal + 30 DAS and RHA treatments. Application of lime, dolomite or RHA as basal + 30 DAS resulted in higher dry matter production at harvest. Soil ameliorants improved the uptake of macronutrients and micronutrients. Uptake of N and K were significantly higher for lime, dolomite or RHA applied as basal + 30 DAS while dolomite as basal + 30 DAS recorded the highest P uptake. The highest uptake of Ca was found with lime as basal + 30 DAS and that of Mg and S with dolomite as basal + 30 DAS. The highest uptake of Mn and Zn were observed with lime as basal + 30 DAS, Cu with RHA as basal + 30 DAS and that of B with lime, dolomite or RHA applied as basal + 30 DAS. The control treatment and RHA applied as basal + one week before PI registered lower Na uptake and both RHA treatments registered higher Al uptake. There was significant and positive correlation of grain yield with uptake of nutrients except Fe, Zn and Al. Lime and dolomite treatments were more effective in reducing soil acidity and improving dehydrogenase activity and nutrient availability in the soil. The ameliorated plots showed higher organic carbon status compared to control. Lime as basal + one week before PI and dolomite treatments recorded higher soil available N at seedling stage and at tillering and PI stages, any treatment except control could register higher available N in the soil. Any liming material applied as basal + 30 DAS improved soil available P status. No significant effect of treatments on available K was observed. Lime or dolomite treatments resulted in higher availability of Ca while dolomite treatments registered higher availability of Mg in the soil. At all stages except harvest, the control plots recorded significantly higher status of available S and Fe and lower status of Mn in the soil. Significant and positive correlation of pH with available Ca and negative correlation with available Fe was observed at all stages of crop growth. Soil available Cu status was the highest with control at PI stage and with dolomite at harvest stage. Dolomite treatments recorded higher available B in the soil. The highest Na content in the soil was registered by dolomite treatments at seedling stage and by control at tillering stage. There was an increase in the availability of Na at all stages of experimentation but the content was below the critical level of toxicity. Soil exchangeable Al status was significantly higher in the control. Lime, dolomite or RHA applied as basal + 30 DAS gave higher net income and BCR while the control recorded the lowest net income and BCR. Experiment II entitled “Standardization of nutrient management practices for rice in Vaikom Kari” was conducted during August to December 2015 and 2016 in farmers` fields in Thalayazham panchayat in Kottayam district. The experiment was laid out in RBD with 16 treatments (formulated based on the results of the Experiment I) in three replications with rice var. Uma. The treatments were dolomite, lime + MgSO4 or RHA + MgSO4 along with 100% POP alone or with 100% POP + foliar spray of 13:0:45 (1%) or borax (0.5%) or 13:0:45 + borax at PI stage. Lime + MgSO4 + 75% POP + 13:0:45 + borax as well as lime without MgSO4 + 100% POP combined with 13:0:45 or borax or both were also included as treatments. The treatments involving dolomite and lime with or without MgSO4 produced taller plants, higher tiller number m-2 and higher LAI during both the years. Dolomite + POP + 13:0:45 produced the highest number of panicles m-2. Higher test weight and lower sterility percentage were observed with dolomite + POP + 13:0:45 and dolomite + POP + 13:0:45 + borax. Higher grain yield of 5.42 and 5.57 t ha-1 during 2015 and 2016 respectively were produced by dolomite + POP + 13:0:45 followed by dolomite + POP + 13:0:45 + borax and lime + MgSO4 POP + 13:0:45. Grain yield was significantly and positively correlated with LAI at MT and PI stages and with panicle number m-2. Pooled analysis also proved the significance of the above treatments in producing higher grain yield. Lower yields were produced by the treatments involving RHA and 75% POP during both the years and in the pooled data. In general, higher straw yields were noticed with the treatments involving dolomite or lime along with foliar spray of 13:0:45 or 13:0:45 + borax. Higher dry matter production was noticed with dolomite + POP along with 13:0:45 or borax during first year and with dolomite + POP or lime + MgSO4 + POP along with 13:0:45 or 13:0:45 + borax during second year. In general, higher uptake of macronutrients and micronutrients was observed with dolomite or lime + MgSO4 treatments along with 100% POP during both the years. Uptake of Na was the highest with RHA + MgSO4 + POP + 13:0:45 during first year and with dolomite treatments during second year. Higher Al uptake was observed with lime + POP + 13:0:45 with or without MgSO4. Significant and positive correlation of grain yield with uptake of P, K, Ca, Mg, S, Mn, Zn, Cu and B and negative correlation with Fe was observed during first year. During second year, the yield was significantly and positively correlated with uptake of nutrients except Na and Al. The treatments involving dolomite, lime with or without MgSO4 performed better in ameliorating soil acidity than RHA treatments during both the years. The treatments involving RHA showed higher EC values. All the treatments except those involving RHA helped in improving dehydrogenase enzyme activity in the soil during the cropping period. The initial soil organic carbon status was maintained during the cropping period due to nutrient management practices. Availability of N in the soil improved due to treatments involving dolomite + POP during seedling stage and due to those involving lime + POP without MgSO4 at other stages. The treatments involving dolomite + POP and lime + POP with or without MgSO4 recorded higher available P during all crop stages. In general, higher status of available K was registered by the treatments involving RHA or lime without MgSO4. All treatments involving lime or dolomite registered higher soil available Ca and those involving dolomite or lime + MgSO4 showed higher availability of Mg in the soil. In general, available S in the soil decreased from initial status during the cropping period. The treatments involving dolomite registered lower status of soil available Fe and higher status of available Mn and B. Higher status of available Zn was registered by the treatments involving dolomite or lime + MgSO4. The treatments involving dolomite, lime + MgSO4 or RHA + MgSO4 along with POP registered higher available Cu in the soil. Dolomite treatments recorded lower status of Na and exchangeable Al in the soil. Soil pH was significantly and positively correlated with available P and significantly and negatively correlated with available Fe and exchangeable Al in the soil. The economics of cultivation in terms of net income and BCR were the highest with dolomite + POP + 13:0:45 during both the years which was closely followed by dolomite + POP + 13:0:45 + borax. The treatments involving RHA and 75% POP registered lower net income and BCR. The results of the study revealed the superiority of dolomite for ameliorating soil acidity in Vaikom Kari soil compared to lime or rice husk ash. Split application of dolomite as basal dose and at 30 DAS proved more effective than application as basal dose and one week prior to fertilizer application at panicle initiation stage. Soil acidity amelioration with dolomite @ 500 kg ha-1 (300 kg as basal dose and 200 kg ha-1 at 30 DAS) and soil application of 90:45:45 kg NPK ha-1 (full P as basal and N and K in three equal splits at 20 DAS, 35 DAS and PI stage) along with foliar spray of 13:0:45 (1%) or combined spray of 13:0:45 (1%) and borax (0.5%) at panicle initiation stage resulted in higher productivity and profitability from rice cultivation in Vaikom Kari soil.ThesisItem Open Access Precision farming in banana (musa AAB nendran ) for productivity enhancement(Department of Agronomy, College of Agriculture, Vellayani, 2017) Pintu Roy, Vattakunnel; KAU; Sheela, K RAn investigation entitled “Precision farming in banana (Musa AAB Nendran) for productivity enhancement” was undertaken during 2014-2017 to assess the influence of land management practices and lime application on growth and yield of banana, to standardize the fertigation schedule for yield improvement, to work out the economics and to study the nutrient dynamics under soil and fertigation systems of nutrient application. The study consisted of two experiments carried out simultaneously for two years from March 2015 to May 2017 in the farmer’s field at Pirappancode, Thiruvananthapuram. The first experiment on “Soil management and fertigation studies in banana” was laid out in split plot design with 12 treatment combinations and two controls each replicated thrice. The main plot treatments were the combinations of land management practices (l1- conventional land management and l2- land management for precision farming) and lime application{c1 – as basal at the time of pit preparation and c2 – applied in 2 splits (1/2 basal+1/2 at 4 MAP)} and the sub plot treatments were three levels of fertigation (n1-60 % recommended dose (RD) of N & K; n2- 100 % RD of N & K and n3-140 % RD of N & K). The two controls maintained were KAU adhoc recommendation for precision farming (control 1) and KAU POP (control 2). Lime requirement was calculated based on initial pH and applied as per the treatment. As the P status of the soil was high, P was applied @ 75 % RD for all treatments except control 1. Basal application of FYM @ 15 kg plant-1 and two bunch sprays with 3 % SOP were given uniformly for all the treatments. Precision land management practice (L2) improved growth attributes viz. LAI and total dry matter production (TDMP) and yield attributes like number of fingers in D hand (9.89) during first year and number of fingers bunch-1 (67.71) during second year. L2 also improved quality attributes like TSS and total sugar during second year and reducing sugar and total P uptake during both the years. Pooled analysis indicated the superiority of precision land management practice on yield (28.3 t ha-1). Basal application of lime (C1) resulted in higher LAI, TDMP, number of fingers bunch-1 (67.78), number of fingers D hand-1 (11.08), D finger weight (163.26 g), bunch weight (11.27 kg) and total K uptake during second year. Quality parameters viz. TSS, and sugar acid ratio during first year and pulp peel ratio during second year were also more for C1. Basal application of lime significantly increased the second year yield (28.19 t ha-1) and pooled yield (28.96 t ha-1). Higher growth attributes viz. LAI and TDMP and NPK uptake were observed with N2 during first year and N3 during second year. However, N2 and N3 were on par with respect to N uptake during first year and P uptake during second year. Among yield attributes, weight of D finger (223.71 g) was more with N2 during first year and higher number of fingers bunch-1 was obtained with N2 (66.66) and N3 (68.19) during second year. Fertigation of 60 % RD of N & K significantly improved fruit quality. Pooled yield was higher with fertigation of 100 % and 140 % RD of N & K (28.68 t ha-1 and 27.63 t ha-1 respectively). All treatment combinations resulted in improved growth and yield over control 2. Precision land management and basal application of lime with fertigation of 60, 100 or 140 % RD of N & K recorded higher yield (30.38, 30.87 and 28.77 t ha-1 respectively). Fertigation treatments and adhoc recommendation resulted in yield improvement by 30.83 % and 21.61 % respectively over soil application. Precision land management practices and fertigation of 100 % RD of N & K significantly improved water use efficiency (WUE) and water productivity during the first year while fertigation of 100 % and 60 % RD of N & K recorded higher water productivity application during second year. Application of entire quantity of lime as basal enhanced WUE during both the years. Drip irrigation enhanced WUE and water productivity over basin irrigation. Compared to soil application of 100 % RD of N & K, fertigation with the same nutrient level resulted in higher nutrient use efficiency and agronomic efficiency. All treatment combinations recorded higher gross income, net income and B: C ratio when compared with controls. Among the combinations, precision land management with basal application of lime and fertigation with 60 % RD of N & K recorded higher B: C ratio (3.75). The second experiment on “Nutrient dynamic studies in banana” was carried out with the treatment combinations involving fertigation of 100 % RD of N&K (l1c1n2, l1c2n2, l2c1n2 and l2c2n2) of the first experiment along with controls. Observations on pH, organic carbon (OC), primary, secondary and micro nutrient status in both soil and plant were taken at bimonthly interval. Dynamics on soil pH duirng first year and NH4-N and S during both the years indicated an initial increase upto 4 MAP followed by a decline at 6 MAP and again a slight increase at harvest stage of the crop. However for pH during second year and K content during first year, a slight decrease was noticed towards the harvest stage. In general, an increasing trend in NO3-N content in the soil was observed from initial stage to harvest stage of the crop. An increasing trend in OC and P contents were also observed in the soil. In general, build up of Ca and Mg in the soil was noticed after two years of experimentation. Changes in soil pH and nutrient content under fertigation and soil application of fertilizers indicated that soil application resulted in higher pH during first year while fertigation enhanced pH during second year especially during grand growth phase (6 MAP). The OC content recorded varying response during both the years. Fertigation resulted in higher NO3-N content in soil throughout the growth stages except at 6 MAP during first year and 6 MAP and at harvest during second year. Soil application of fertilizers resulted in higher K content in the soil throughout the growth stages during first year while fertigation enhanced K availability during early crop growth stages during second year. Availability of Ca and Mg in the soil was more for fertigation compared to soil application of fertilizers especially during grand growth phase. Fertigation improved S availability only at 4 MAP and at harvest. Correlation study revealed significant and positive correlation of bunch weight with Mg content and N/K ratio in the soil during first year and N, K, Ca and Mg contents and N/P, Mg/P, Ca/Fe and Ca/Mn ratios during second year. Significant and positive correlation of bunch weight was also observed with K, Mn and B contents in the plant during first year and Ca and Cu contents and Ca/Fe and Ca/Mn ratios during second year. The results of the present study revealed that precision land management practice (deep ploughing to a depth of 50 cm, raised beds to a height of 30 cm, taking pits and planting) along with basal application of FYM, P (based on soil P status) and lime (based on soil pH) and fertigation of 60 % RD of N & K (urea @ 390 g plant-1 and MOP @ 450 g plant-1) is the best management practice to increase yield and profitability of Nendran banana. Fertigation can be given at weekly interval starting from the first month of planting. Soil nutrient dynamics was found to be influenced by rainfall pattern, growth stage of crop and nutrient interactions. In general, fertigation improved the nutrient availability over soil application.ThesisItem Open Access Tillage and nutrition for productivity enhancement in tannia (Xanthosoma sagittifolium"(L.) schott)(Department of Agronomy, College of Agriculture, Vellayani, 2017) Atul Jayapal; KAU; Kumari Swadija, OAn investigation entitled ‘Tillage and nutrition for productivity enhancement in tannia (Xanthosoma sagittifolium (L.) Schott)’ was undertaken at College of Agriculture, Vellayani to identify ideal tillage system for productivity enhancement in tannia, to study the effect of soil conditioners and to compare the effects of integrated and organic nutrition on growth, yield and quality of tannia and to work out the economics of cultivation. The field experiments were conducted in the Instructional Farm attached to College of Agriculture, Vellayani from August 2014 to May 2015 and repeated during May 2015 to February 2016. The field experiment was laid out in split plot design with 24 treatment combinations and four replications. The main plot treatments consisted of four tillage systems (l1- conventional tillage followed by pit system, l2- conventional tillage followed by mound system, l3- deep tillage followed by pit system and l4- deep tillage followed by mound system) and sub plot treatments were combinations of two soil conditioners along with a control (s1- control, s2- coir pith @ 500 g plant-1 and s3- rice husk @ 500 g plant-1) and two nutrient management practices (n1- integrated nutrient management (INM) – FYM @ 25 t ha-1 + 80:50:150 kg NPK ha-1 and n2- organic nutrition- FYM @ 37.5 t ha-1 + wood ash @ 2 t ha-1).In the case of INM, half the quantity of FYM and full P were applied as basal dose and remaining FYM and full N and K were applied in three equal splits each at two, four and six months after planting along with interculture and earthing up. For organic nutrition, 2/3rd quantity of FYM was given as basal dose and remaining FYM and wood ash were given in three equal splits each at two, four and six months after planting along with interculture and earthing up. Dolomite @ 1 t ha-1 was applied uniformly to all plots at land preparation. Growth characters like plant height, leaf number plant-1and leaf area index were improved by deep tillage followed by pit system of planting. Application of coir pith as soil conditioner profoundly influenced growth characters. Organic nutrition was found superior to INM in improving growth characters. Yield components like cormel number plant-1, cormel and corm yield plant-1 and cormel: corm ratio were significantly higher due to deep tillage followed by pit system of planting. Application of coir pith as soil conditioner registered significantly higher values of yield components. Organic nutrition proved its superiority over INM in influencing the yield components. Cormel yield was found to be significantly and positively correlated with leaf area index at five months after planting, cormel number plant-1 and cormel : corm ratio. Significantly higher cormel yield (5.15 t ha-1) and corm yield (7.73 t ha-1) were obtained due to deep tillage followed by pit system. Deep tillage resulted in 24 per cent increase in yield over conventional tillage and pit system of planting registered 28 per cent increase in yield over mound system. Coirpith as soil conditioner resulted in higher cormel yield of 4.51 t ha-1 (11 per cent increase in yield over control) and corm yield of 6.99 t ha-1. Organic nutrition significantly improved cormel yield (4.52 t ha-1 which was 12 per cent higher than due to INM) and corm yield (7.07 t ha-1) compared to INM. Pooled analysis indicated that interaction of deep tillage followed by pit system with coir pith as soil conditioner and organic nutrition (l3s2n2) recorded the highest cormel yield (5.77 t ha-1) and the same treatment, but with rice husk as soil conditioner (l3s3n2) recorded the highest corm yield (8.3 t ha-1). Deep tillage followed by pit system, application of coir pith as soil conditioner and organic nutrition compared to INM recorded significantly higher dry matter production and harvest index. Quality characters of cormel like dry matter, starch and protein contents were improved due to deep tillage followed by pit system among tillage systems, application of coir pith as soil conditioner and organic nutrition compared to INM. In general, a shelf life of one month for cormel was observed without any microbial decay, sprouting and appreciable physiological loss in weight. Higher uptake of N, P and K were noticed due to deep tillage followed by pit system. Coir pith as soil conditioner proved its superiority in enhancing nutrient uptake. Uptake of nutrients was significantly higher under organic nutrition than under INM. Tillage systems, soil conditioners and organic nutrition profoundly influenced the physico-chemical properties of the soil after the experiment. Bulk density was lowered and porosity and water holding capacity were improved due to deep tillage, application of rice husk as soil conditioner and organic nutrition. Correlation study revealed significant and negative correlation of yield with bulk density and significant and positive correlation with porosity and water holding capacity of the soil. Organic nutrition resulted in significantly higher status of organic carbon and available N, P and K in the soil compared to INM. Significantly higher net income and benefit cost ratio could be realized due to deep tillage followed by pit system among tillage systems, application of coir pith as soil conditioner and organic nutrition compared to INM. Considering interaction effects, deep tillage followed by pit system without soil conditioner under organic nutrition (l3s1n2) registered higher net income and benefit cost ratio. It is evident from the present study that deep tillage to a depth of 30 cm followed by pit system of planting is ideal for productivity enhancement in tannia. Application of coir pith as soil conditioner and organic nutrition improved the growth, yield and quality of tannia.Deep tillage followed by pit system and organic nutrition (FYM @37.5 t ha-1 + wood ash @ 2 t ha-1) can be recommended for economic production of tannia. Wherever coir pith or rice husk is available at a cheaper rate, it can be applied as soil conditioner @ 500 g plant-1 for enhanced productivity of tannia.ThesisItem Open Access Integrated weed management under system of rice intensification (SRI)(Department of Agronomy, College of Horticulture, Vellanikkara, 2011) Musthafa, Kunnathadi; KAU; Abraham, C TAn experiment was conducted to assess the performance of system of rice intensification (SRI) vis-à-vis conventional system with special emphasis on weed problems under SRI and to develop an economic weed management strategy. Aiming at reducing drudgery while using manual cono weeder, it was also envisaged to develop the prototype of a self propelled cono weeder. The field studies laid out in randomized block design with 16 treatments in three replications were conducted at RARS, Pattambi in Palakkad district and in farmers’ fields at Alappad Kole in Thrissur district, during the Mundakan seasons of 2007 and 2008. The soil at Pattambi was lateritic sandy clay loam with pH 4.96 and medium fertility, and that at Alappad Kole was clayey in texture with pH 5.0 and of high fertility. At both locations, the density and dry weight of weeds at 45 and 60 days after transplanting (DAT) were higher in all the SRI treatments especially when weed control was done through repeated cono weeding. At Pattambi, weed density and weed dry weight were the lowest in conventional system with post emergence herbicides, which recorded lower nutrient removal by the weeds and the lowest weed index and also higher gross return, net return and B:C ratio. The weed density and dry weight in the SRI fields were the lowest with pre emergence herbicide followed by hand weeding at 30 DAT, but the use of post emergence herbicides showed higher B:C ratio. At Alappad Kole, the weed density and dry weight, both at 45 and 60 DAT, were the lowest in conventional system with cono weeding at 10 DAT followed by post emergence herbicides. Cono weeding followed by hand weeding, pre emergence herbicides followed by hand weeding as well as the use of post emergence herbicides were also equally effective in controlling the weeds 233 in the conventional system, and were on par in the B:C ratios. In the SRI plots cono weeding at 10 DAT followed by post emergence herbicides recorded the lowest weed density and dry weight, however, use of post emergence herbicides recorded the highest net return and B:C ratio among the SRI treatments. Thus, considering the acute shortage and high wages for the labourers in Kerala, weed management through post emergence herbicides will be the preferable option for the farmers in both conventional and SRI systems of rice cultivation. Comparison between the two systems of rice cultivation at two different rice growing ecosystems showed that SRI improved the performance of individual hills through higher number of tillers hill-1, root length and root dry weight hill-1. On the other hand, the tiller number, dry matter production, root dry weight and productive tillers per unit area were higher in the conventional treatments. Owing to higher number of productive tillers per unit area the grain yield of conventional treatments was significantly higher than that of the typical SRI. At Pattambi, conventional system with post emergence herbicides recorded higher number of productive tillers m-2, panicle length, number of filled grains panicle-1, 1000 grain weight and grain yield (2877 kg ha-1), which was 33 per cent higher than the grain yield in the typical SRI. This treatment also recorded significantly higher B:C ratio (1.27) compared to that (0.91) of the typical SRI. However, the highest straw yield (2510 kg ha-1) at Pattambi was observed in ‘SRI with cono weeding at 10 DAT followed by post emergence herbicides’, which was on par with the typical SRI treatment. At Alappad Kole, higher number of productive tillers m-2, more filled grain percentage, highest 1000 grain weight, highest grain yield (6073 kg ha-1) and highest straw yield (5109 kg ha-1) were recorded by conventional system with cono weeding followed by hand weeding, which showed an increase of 93 per 234 cent in grain yield, with an additional yield of 2934 kg ha-1, and 109 per cent in straw yield over the typical SRI and recorded the highest gross return, net return and B:C ratio (2.46). Thus, the study showed the superiority of conventional system of rice cultivation at a spacing of 20 cm x 10 cm over the SRI system at a spacing of 30 cm x 30 cm at both the two different rice growing ecosystems studied viz., the sandy loam soils at Pattambi and the clayey soils at Alappad Kole. Prototype of the self propelled cono weeder was developed and field tested. It works satisfactorily in a single forward pass, and covers an area of 0.1 ha h-1. The field study showed that the self propelled cono weeder is effective for inter row weeding in rice, however, further refinement is needed to improve its weeding efficiency.ThesisItem Open Access Input optimization for medicinal rice (Oryza sativa L.) cv. Njavara.(Department of Agronomy, College of Agriculture, Vellayani, 2011) Sriramkumar, N; KAU; Geethakumari, V LThe investigation entitled “Input optimization for medicinal rice (Oryza sativa L.) cv. Njavara” was conducted at Instructional Farm, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, during the summer seasons of 2007 and 2008 (January to April) to standardize an ideal nutrient schedule under two moisture regimes for sustaining Njavara production in lowlands, to investigate the soil physical, chemical and biological properties as influenced by regimes and sources of nutrients and to work out the economics of Njavara cultivation. Both the experiments (submerged and saturated situations) were laid out in randomised block design with ten treatments each and three replications. The treatments comprised four nutrient regimes viz., N1 - 30:15:15, N2 - 30:30:30, N3 - 40:20:20 and N4 - 40:40:40 kg NPK ha-1, two nutrient sources viz., organic nutrient source (S1) and integrated nutrient source (S2) and two controls viz., absolute control (no nutrient was applied) (C1) and POP for local rice variety (C2). Growth components like plant height, leaf number plant-1, leaf area index (LAI), number of tillers m-2, culm strength and flag leaf area, yield and yield attributes like number of productive tillers m-2, panicle length, number of grains panicle-1, number of filled grains panicle-1, 1000 grain weight, harvest index, sterility percentage, dry matter partitioning, paddy grain ratio and grain husk ratio were recorded. Leaf chlorophyll content was also estimated. Uptake of nutrients (N, P, K, S, Fe, Mn and Zn) and economics of cultivation were computed. Biochemical components of grains such as total, free and sulphur containing amino acids, phenols, starch, amylose, amylopectin and protein content were estimated. Data on weed biomass, weed flora and crop duration were also recorded. Soil enzymes (urease, phosphatase and dehydrogenase), soil microbial population (bacteria, fungi and actinomycetes population) and soil fertility status (available nitrogen, phosphorus, potassium, sulphur, iron, zinc and manganese) were assessed before and after the crop. Effect of nutrient regimes Effect of nutrient regimes on all growth parameters was significant. Growth parameters like plant height, leaf number plant-1, leaf area index (LAI), number of tillers m-2, culm strength and flag leaf area were significantly higher in N2. N2 recorded leaf chlorophyll content which was significantly higher than N3 and N1 and was on par with N4. All yield attributes except 1000 grain weight were significantly influenced by nutrient regimes resulting in significant variation in the crop yield (grain and straw). Maximum grain yield was recorded in N2 (30:30:30 kg NPK ha-1) (2.78 and 2.66 t ha-1) which was on par with N4 (40:40:40 kg NPK ha-1) (2.67 and 2.58 t ha-1) and was significantly superior to N1 and N3 under submerged and saturated situations respectively. Duration of the crop did not show significant variation due to nutrient regimes. Total amino acid and protein content of grain were significantly influenced by nutrient regimes and were maximum in N2. Nutrient regimes significantly influenced N, P and K uptake. Uptake of N, P and K in N2 was significantly higher than that in the other three nutrient regimes. Nutrient regimes did not significantly influence uptake of S, Fe, Mn and Zn. Results of the study also revealed that Echinochloa colona (L.) Link, Isachne miliacea Roth ex Roem. et Schult; Cyperus iria L., Cyperus difformis L. Fimbristylis miliacea (L.) Vahl.; Marsilea quadrifoliata Linn., Monochoria vaginalis (Burm. f.) Presl. ex Kunth and Ludwigia perennis L were the most predominant weed species in the experimental field under both situations. Weed biomass at 20 and 40 DAS were not significantly influenced by nutrient regimes during both the years of experimentation. Nutrient regimes showed significant influence on available nitrogen, phosphorus and potassium status of the soil after the investigation. Available sulphur, iron, zinc and manganese status of the soil after the experiment revealed non-significant effect of nutrient regimes in both the years of study. Among the soil enzymes, urease activity was influenced significantly by the nutrient regimes and it was in the order N4 > N3 > N2 > N1. Bacterial population was influenced significantly by the nutrient regimes and it was in the order N4 > N3 > N2 > N1. Effect of nutrient sources Nutrient sources had significant influence on all the growth characters, yield attributing characters like number of grains panicle-1, number of filled grains panicle-1, harvest index as well as crop yield (grain and straw). Highest number of grains panicle-1, filled grains panicle-1 and crop yield (grain and straw) were realized in integrated nutrient source and they were significantly higher than that realized from organic source. Duration of crop did not differ significantly between the nutrient sources. Integrated nutrient source registered significantly higher nitrate reductase activity and root weight compared to organic source. Biochemical components such as total, free and sulphur containing amino acids, phenols, starch, amylose, amylopectin and protein content of grain did not differ significantly between nutrient sources. Highest uptake of N, P and K was in integrated nutrient source. Sources of nutrients did not influence uptake of S, Fe, Mn and Zn during both the years of experimentation. Weed biomass under different nutrient sources at both 20 DAS and 40 DAS differed significantly from one another. Weed biomass during both stages and both the years of experimentation was more in organic source compared to integrated nutrient source. Highest weed biomass was recorded in absolute control at both stages during both the years. Available nitrogen, available phosphorus and available potassium status of the soil after the experiment in the plots receiving integrated nutrient source and organic nutrient source differed significantly from each other. Available N, P and K status of the soil were higher in integrated nutrient source. Organic carbon, available sulphur, iron, zinc and manganese status of the soil after the experiment were not significantly influenced by nutrient sources. Urease activity and bacterial population in the soil were influenced significantly by nutrient sources. Highest activity of urease and bacterial population in the soil were recorded in organic source compared to integrated nutrient source. Phosphatase and dehydrogenase activity as well as fungal and actinomycetes population in the soil were not influenced by nutrient sources. Economics of crop production Gross income, net income and BCR were highest in N2S2. Application of FYM @ 5 t ha-1 along with 30:30:30 kg NPK ha-1 (50 % N as organic + 50 % N as chemical fertilizer) (N2S2) recorded a net profit of Rs 57,586 ha-1 and Rs 53,546 ha-1 under submerged and saturated situations respectively. The lowest gross income, net income and BCR were recorded in N1S1 (FYM @ 5 t ha-1 along with 30:15:15 kg NPK ha-1 as organic source). The ideal nutrient schedule for sustaining Njavara production in lowlands under both submerged and saturated situations is N2S2 - FYM @ 5 t ha-1 + 30:30:30 kg NPK ha-1 (50 % N as organic + 50 % N as chemical fertilizer). This nutrient system realised highest grain yield, straw yield and net income.ThesisItem Open Access Floristic diversity, autecology and competitive behaviour of weed flora in wetland rice ecosystem(Department of Agronomy, College of Agriculture, Vellayani, 2010) Sajith Babu, D; KAU; Sansamma GeorgeFloristic diversity, autecology and competitive behaviour of weed flora in the wetland rice ecosystem were studied by conducting a field survey and two field experiments. The field survey was conducted during the first and second crop seasons of 2003 in the rice fields of 30 panchayaths in Thiruvananthapuram district having more than 50 hectares of net sown area, covering all the four thaluks of the district. Weed flora was surveyed from both cultivated and fallow fields. The design adopted for conducting the floristic survey was Stratified Multistage Random Sampling and the methodology was Census Quadrate Method. The field experiments were conducted during the first crop seasons of 2003 and 2004 at College of Agriculture, Vellayani. The design adopted was Strip plot. The treatments included four levels of nutrient management and three levels of crop spacing and the number of replications was five. Part III of the investigation was an autecological study wherein the growth and development pattern of two of the major weed flora observed in the experimental area was studied by keeping an area of 1.2 X 4.2 m2 on the same side of all the plots in Part II. Perusal of the results of the field survey indicated that substantial diversity of weed flora existed in the wetland rice ecosystem in Thiruvananthapuram district of Kerala. In the cultivated rice fields, there were 46 weed specii during the first crop season and 49 species during the second crop season. In the rice fallows during the first crop season there were 43 specii while during the second crop season there were 54 specii. In the cultivated fields during both seasons, the most prominent species among the different classes of weeds (grasses, sedges and broad leaved weeds) were Isachne miliacea Roth ex Roem et Schult, Cyperus iria L. and Monochoria vaginalis (Burm.f.) Presl. Ex Kunth respectively. Isachne miliacea Roth ex Roem et Schult was the dominant grass weed in the fallows as well. However the dominant sedge weed in the fallows was Cyperus distans L.f. during the first crop season while it was Fimbristylis miliacea. during the second crop season. Monochoria vaginalis (Burm.f.) Presl. Ex Kunth and Ludwigia perennis topped the list of broad leaved weeds in the rice fallows during first and second crop seasons respectively. Results of the field experiment showed that weed growth in the rice field was influenced significantly by the sources and levels of nutrients as well as by crop spacing. During both the years at 20 and 40 DAT the weed density and dry weight were the lowest when the rice crop was treated with NPK @ 90:45:45 kg ha-1 applied with 25 per cent N as organic (N2) while at 60 DAT enhanced nutrient level (NPK @ 112.5:56:25:56.25 kg ha-1) applied with 25 per cent N as organic (N4) recorded the lowest value. During both the years, at all growth stages the weed density and dry weight were the lowest under the closer spacing of 15 X 15 cm (P1) The grain and straw yield were maximum under NPK @ 112.5:56:25:56.25 kg ha-1 applied with 25 per cent N as organic in combination with widest spacing (n4p3). Dead heart occurrence was minimum under the widest crop spacing The net income and Benefit : Cost ratio were the highest when rice crop was treated with 125 per cent of the recommended NPK with 25 per cent organic substitution in combination with widest spacing (n4p3) Autecological studies showed that the growth and development of Isachne miliacea Roth ex Roem et Schult. was significantly influenced by the management practices for the associated rice crop. The higher dose of NPK applied as chemical fertilizers only (N3) along with widest spacing (P3) stimulated all the vegetative parameters (shoot / root length and plant spread) of the weed. During both the years plants growing in rice fields treated with recommended dose of NPK with 25 per cent organic substitution (N2) and rice crop planted at wider spacing (P3) recorded delayed flowering but produced more seeds per panicle The root and shoot length of Cyperus iria L growing in rice fields treated with 100 per cent recommended NPK as chemical fertilizers (N1) with minimum spacing (P1) recorded the maximum value during the both years. Delayed flowering of the sedge was noticed under N2. The number of seeds produced per plant was significantly high under N4 and P3. The general trend was that addition of organic manures in rice delayed flowering but increased seed production in the associated sedge weed From the studies it may be concluded that by altering nutrient management and adjusting the plant population, the competitive ability and productivity of rice crop can be improved substantially. Though, closer spacing of 15 X 15 cm significantly reduced the density and dry weight of weeds, the wider spacing of 20 X 20 cm in conjunction with enhanced fertilizer dose of 112.5:56:25:56.25 kg NPK ha-1 applied with 25 per cent N as organic manures significantly enhanced the rice grain and straw yield. The treatment also resulted in significant enhancement in net income and B:C ratio in medium duration variety Aiswarya in first crop season.