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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 Root Distribution patterns of Banana and Colocasia in Coconut Gardens(Department of Agronomy, College of Horticulture, Vellanikkara, 1994) Suja Eapen, KAU; Abdul Salam, MAn investigation was undertaken at the College of Horticulture, Vellanikkara during 1993-94 to study the root disribution patterns of banana and colocassia in coconut gardens. The experiments were aimed to study the root distribution patterns of banana var. Palayankodan growth in the open and in the coconut garden under rainfed and irrigated conditions. It was also aimed to study the variation in the root distribution patterns of colocasia var. Cheuchempu grown in the coconut garden and in the open. A 32p plant injection technique and a direct profile excavation technique were employed to study the root distribution patterns. The salient results of the investigation are abstracted below. BANANA Root production of banana grown in the open was considerably more compared to that grown in coconut garden. Rainfed banana produced more roots compared to irrigated banana. The root distribution patterns of banana vary with growing condition. In the coconut garden, the root system of rainfed banana was spreading and that of irrigated banana was compact. When grown in the open condition, the root system of rainfed banana was compact and that of irrigated banana was spreading. The active root zones of rainfed banana grown in the open, irrigated banana grown in the open, rainfed banana grown in the coconut garden and irrigated banana grown in the coconut garden were the root zones comprising L0-60 D0-60, L0-60 D0-80, L0-80 D0-60 and L0-60 D0-60 respectively. COLOCASIA Root production of colocasia was more with the plants grown in the open compared to that grown in the coconut garden. Root distribution patterns of colocasia differ between the plants grown in the coconut garden and in the open. The root system of colocasia grown in the coconut garden is deep compact and that of the plants grown in the open is deep spreading. The active root zone of colocasia in the open and in the coconut garden are the root zones comprising L0-20 D0-40 and L0-10 D0-40 respectively. 32P plant injection technique is an efficient method for root system studies in both banana and colocasia.ThesisItem Open Access Foliar absorption of nitrogen and phosphorus by cashew(Department of Agronomy, College of Horticulture, Vellanikkara, 1994) Mini Abraham, KAU; Abdul Sala, S MAn investigation was undertaken at the College of Horticulture, Kerala Agricultural University, Vellanikkara during 1993-'94 to study the foliar absorption of nitrogen and phosphorus by cashew. The main objectives of the study were to develop a method to study the foilar absorption of 14c-urea and 32p and to identify the factors affecting foliar absorption of nitrogen and phosphorus by cashew. It was also aimed to compare the root absorption with foliar absorption and to study the leaf anatomy of cashew in relation to foliar absorption. The experiment was done using three month old cashew seedlings and six year old cashew trees (var.Anakkayam-l). The salient findings are abstracted below. A leaf washing technique was developed to quantify the foliar absorption of 14c-urea and 32p• Accordingly a sequential washing programme involving four washings each with 50 ml of 2 per cent teepol was found to be reasonable to quantify the foliar absorption of 14C-urea and 32P in cashew. Factors affecting foliar absorption of urea and phosphorus by cashew have been identified. Leaf age, leaf surface, duration allowed for absorption, time of application in a day, month of application in an year and presence of a surfactant in the spray solution are certain important factors that are found to decide the extent of absorption of foliar applied 14C-urea and 32P in cashew. Greater absorption of foliar applied urea was obtained when nutrient solution was sprayed in 0.05 per cent teepol between 11 00 hours and 14 00 hours, directing the spray to the lower surface of terminal leaves of latest flush during March and by giving a minimum absorption period of seven days. The efficiency of foliar applied phosphorus was increased by spraying around 11 00 hours to the lower surface of basal leaves of latest flush during December and by giving a minimum absorption period of six days. Root absorption from solution culture was more compared to foliar absorption in the case of 14C-urea and 32P .The absorption efficiency of 32P both through root and leaf was low compared to 14C-urea. The cashew leaves contain thicker cuticle. on the upper surface with no stomata and thinner cuticle on the lower surface with large number of stomata. The latest flushes of a six year old cashew tree (var. Anakkayam-1) during flushing account for 80 per cent of total leaf area in the crown.ThesisItem Open Access Enhancing the Nitrogen Use Efficiency in Bhindi With Nitrification Inhibitors(Department of Agronomy, College of Agriculture, Vellayani, 1994) Bindu Kurup, S; KAU; Pushpakumary, RAn experiment was conducted at the Instructional Farm, College of Agriculture, Vellayani inorder to find out the effect of nitrification inhibitors in enhancing the nitrogen use efficiency in bhindi. The treatments consisted of four levels of nitrogen viz., 50 kg ha-1, 100 kg ha-1, 200 kg ha-1 and 300 kg ha-1 and three nitrification inhibitors viz., urea, neem cake and mahua cake. Phosphorus and potassium were applied as per package of practices recommendation. The results revealed that nitrogen levels significantly influenced most of the growth and yield contributing characters, yield of bhindi, uptake of nutrients and available nutrient status of soil. Biometric observations like number of leaves, branches, root spread, DMP, LAI, RGR, NAR and CGR increased with increasing levels of nitrogen and the maximum was produced by the highest levels of nitrogen (300 kg ha-1). F1 produced the maximum height and F2 the longest tap root. Time of 50 per cent flowering and number of flowers per plant was maximum with the highest levels of nitrogen (F4). Whereas other yield contributing characters like number of fruits per plant, percentage of fruit set, length and girth of fruit, fruit yield per plant and total yield of bhindi was maximum with F2 (100 kg N ha-1 ). Quality aspects like crude protein and ascorbic acid content of fruits, uptake of nutrients by plant and fruit as also maximum with the highest levels of nitrogen (F4). However, the height of the first bearing node and chlorophyll content of leaves remain unchanged with increasing levels of nitrogen. The optimum level of nitrogen to get maximum fruit yield and net profit was worked out as 142 kg N ha-1 . Nitrification inhibitors caused significant variation in some of the characters like root spread, LAI RGR, NAR, CGR, number of flowers and fruits per plant, percentage of fruit set, length and girth of fruit, crude protein content and ascorbic acid content of fruit, uptake of nutrients by plant and fruit and available nutrient status of soil. In all these cases neem cake blended urea recorded the highest value followed by mahua cake blended urea. From the economic point of view, the maximum net profit of Rs. 11787.74 was obtained for neem cake blended urea and among nitrogen levels, 100 kg N ha-1 recorded the highest net profit of Rs. 16017.50. Thus neem cake blended urea at 100 kg N ha-1 can be suggested as the best economic dose of nitrogen for getting maximum yield and net profit.ThesisItem Open Access Utilization of phosphorus from green manure by rice(Department of Agronomy, College of Horticulture, Vellanikkara, 1994) Pushpa, Joseph; KAU; Mercy, GeorgeAn investigation was undertaken at the College of Horticulture, Vellanikkara, during 1993 – 1994 to study the utilization of phosphorus from green manure by rice. The main objectives of the study were to assess the contribution of phosphorus released from labeled green manure to the phosphorus nutrition of rice and to study the effect of incorporation of green manure on the utilization of applied fertilizer and native soil phosphorus. The effect of incorporated green manure on the dry matter yield of rice was also investigated. The green manure used was Sesbania aculeate. 32p labelled green manure was produced by growing sesbania in sand culture for 50 days. When the plants were 15 days old 32p (carrier free) was applied with water at 30 µCikg-1 sand. The labeled plant material was used for the incubation study and pot culture experiment. The results obtained from the incubation experiment conducted to study the dynamics of P mineralization from green manure revealed that the release pattern of Bray – 1 extractable P was similar both in 0.25 and 0.5 per cent green manure amended soil irrespective of the quantity of green manure added. The available P content of the green manure amended soil was relatively higher at the initial day of incubation, gradually decreased till 25th day and thereafter increased. The contribution of P from green manure and native soil also followed similar trend. As extracts of soil immediately after amending with labeled green manure showed 32p activity, it is possible that Bray – 1 reagent extracted inorganic P from the green manure. The P release from green manure and soil was the least at the 30th day of incubation and then showed an increasing trend for both levels of green manure incorporation. Till 30th day more P was released from 0.5 per cent green manure incorporation, later showed a reverse trend. To study the effect of incorporation of green manure on P utilization by rice, a pot culture experiment was done with 32p labeled green manure and amophos. The results revealed that per cent P derived from fertilizer (% Pdff) increased upto 20 days after transplating and thereafter it decreased, whereas the per cent phosphorus derived from green manure (% Pdfg) was very low during the initial stages, and thereafter it increased considerably. So a combind application of green manure and inorganic P fertilizer will meet the P requirement of the crop throughout the growth period. ‘% Pdfg’ increased with increasing rate of application of green manure. Per cent utilization of P from amophos was high during the initial stages of crop growth, later it decreased while the per cent utilization of P from green manure increased considerably after 20 days of transplanting. The per cent utilization decreased with increasing rate of application of green manure. With regard to crop growth characters, significant increase in plant height and tiller number were observed with the application of 0.25 per cent green manure along with amophos. Among the yield attributing characters, number of spikelets per panicle showed significant increase with the application of 0.25 per cent green manure in combination with amophos. Grain and straw yield were also the highest under the same treatment. Both grain and straw yield were significantly low when green manure alone was applied at the higher rate (0.5 per cent).ThesisItem Open Access Plantlet regeneration through somatic embryogenesis in cocoa (Theobroma cacao L.)(Department of Agricultural Botany, College of Horticulture, Vellanikkara, 1994) Jiji, Joseph; KAU; Mallika, V KInvestigations on 'Plantlet regeneration through somatic embryogenesis in cocoa' were undertaken in the Department of Agricultural Botany, College of Horticulture, Kerala Agricultural University, Vellanikkara during 1992-94. Studies were made to identify the most suitable medium, the most responsive genotype and most favourable conditions for embryogenesis in cocoa. Conditions for germination of embryoids to plantlet were also standardised. Among the different media tested for embryogenesis namely, MS, WPM and B5, MS medium was found to be the most ideal. Embryoids could be induced only from the tender cotyledon and embryonal axis of immature embryos of 100 days old pods. Other vegetative tissues like leaf, stem, petal, gynoecium, integumant etc. Yielded only non-embryogenic calli in media for somatic embryogenesis. An important finding in the present study was the standardisation of an ideal medium which favoured maximum embryogenesis from embryonic tissues. This medium was MS+ NAA 1.8 + thiamine 1 mg 1-1 + CW 15 per cent + sucrose 4 per cent. This is a modification of medium proposed for cocoa somatic embryogenesis by Adu-Ampomah et al. (1988). As already reported by other workers, the maximum embryogenesis occurred under dark incubation. The ideal incubation temperature was 30±20C. The embryoids originated singly or in clusters from the cotyledon explants. Most of the embryoids lacked a suspensor but some of them did have a suspensor. A typical embryoids had an embryonic axis and two cotyledons. However, aberrant forms were not uncommon with excessive proliferation of cotyledons as well as with disproportionate axes and cotyledons. The study helped to identify some genotype which showed maximum degree of embryogenesis. The Series I hybrid H 6.5 was found to be the ideal source of explant giving high frequency and intensity of embryogenesis as well as with larger sized embryoids having lesser percentage of abnormalities. The selfed progeny (S1) of this out-breeding crop exhibited minimum degree of embryogenesis. This indicates that the degree of embryogenesis may be associated with the vigour of the explant. Germination of embryoid to plantlet was a difficult process. Liquid media with 1/2 MS salts and 5 per cent sucrose was found to favour germination. A pretreatment was required to remove the inhibitors by washing and desiccation. Only embryoids of larger size (>4 mm) germinated properly to plantlet. The recovered plantlets were too small for field establishment. The most significant achievement in the present study was the plantlet regeneration from somatic embryoids and its planting out in the nursery. This was achieved by micrografting the embryoid derived plantlet to a three week old seedling rootstock. The presence of cotyledons was found to be inhibitory and at least a small leaflet in the embryoid derived plantlet was essential for success in micrografting.ThesisItem Open Access Nutrient- moisture interaction under phasic stress irrigation of sweet potato in summer rice fallows(Department of Agronomy, College of Agriculture,Vellayani, 1994) Muraleedharan, Nair; G, KAU; Muraleedharan, Nair; vA field experiment on sweet potato was laid out in the rice field fallowed during summer season at the Instructional Farm, College of Agriculture, Vellayani. The study was intended to work out of the irrigation schedule and fertilizer practice for sweet potato grown as a catch crop during the summer season of 1990 and 1991. The experiment was designed to economise the use of irrigation water as well as fertilizers by inducing phasic stress at certain phases of plant growth which are considered critical for sweet potato. The field experiment was laid out in a strip plot design replicated thrice with irrigation in horizontal strips and fertility levels in vertical strips. Irrigation water at full CPE was given during tuber initiation phase (10-30 DAP), full CPE at tuber maturity phase (80-100 DAP) and full CPE at tuber initiation and tuber maturity phases. The crop received irrigation at ½ CPE during the rest of the period of plant growth. Nitrogen and potassium were applied @ 25, 50 and 75 kg ha-1 and a uniform dose of P2 O5 @ 50 kg ha-1 and lime @ 500 kg ha-1 were applied. A control plot that received NPK @ 75:50:75 kg ha-1 and FYM @ 10 t ha-1 was maintained for treatment comparison. Growth characters were recorded at an interval of 21 days from planting and it was observed that providing irrigation at full CPE during tuber initiation phase resulted in significant increase in vine length and number of leaves plant-1. Enhanced rate of application of Nitrogen promoted the growth of vines, number of branches plant-1 and number of leaves produced plant-1. Potassium did not exert any influence on these growth characters. Growth analysis studies showed that the LAI was maximum in plots that received irrigation at full CPE during tuber initiation phase. Nitrogen substantially influenced the LAI, higher levels being significantly superior to the lower levels. Higher levels of potassium also influenced the LAI. The NAR and specific leaf weight were the highest in plots that received irrigation at ½ CPE during tuber initiation phase. Both NAR and CGR were high in the early stage of plant growth and decreased towards harvest. Increased rates of nitrogen supply decreased the NAR and specific leaf weight whereas no definite trend could be observed on CGR> Higher levels of potassium had a favourable influence on NAR and CGR. The dry matter of leaves, shoots, fibrous roots and tubers were significantly enhances by providing full CPE during tuber initiation phase. Increasing the level of nitrogen, influenced the dry matter in the aerial parts. The influence of K on dry matter production was not consistent. Tuber bulking rate showed a positive trend under irrigation at full CPE during tuber initiation phase. Nitrogen levels at 50 and 75 kg ha-1 had an overlapping influence on tuber bulking rate and both remained superior to 25 kg ha-1. Scheduling of irrigation did not exert any influence on the length and girth of tuber. However, an increase in the length and a corresponding decrease in the girth were noticed at enhanced rates of nitrogen supply. The number of tubers plant-1 showed a significant improvement by providing irrigation at full CPE during tuber initiation phase. The total number of tubers plant-1 was increased by high rates of N, but did not influence the number of marketable tubers. Application of K at 50 kg ha-1 promoted the production of more tubers. Tuber yield was significantly influenced by irrigation wherein providing full CPE during tuber initiation phase resulted in superior yield of both total and marketable tubers. Tuber yield was maximum at 50 kg ha-1 each of nitrogen and potash. Vine yield was significantly enhanced by higher rates of applied nitrogen. The harvest index and utilization index were enhanced by the application of irrigation water at full CPE during tuber initiation phase. Application of N at 25 kg ha-1 resulted in the production of high starch content whereas the sugar content was increased upto the highest level of 75 kg ha-1. The uptake of nitrogen by vines and tubers showed a progressive increase by applying full CPE during tuber initiation phase. Application of higher levels of nitrogen invariably promoted the uptake of N, P and K by the plant. Application of potash at 50 or 75 kg ha-1 also resulted in higher uptake of potassium. The fertility status of the soil did not show a positive trend by scheduling of irrigation. The plots that received the lowest dose of nitrogen, invariably recorded the highest level of available phosphorus. Available potassium content was also high in plots that received higher rates of potash. Irrigation at full CPE during tuber initiation and/or tuber maturity phase recorded significantly higher water use efficiency and net returns as compared to including stress during tuber initiation phase. Nitrogen and potash both at 50 kg ha-1 recorded the maximum water use efficiency and net returns from sweet potato cultivation.ThesisItem Open Access Effect of nutrition as Influenced by irrigation on growth and yield of oil palm (Elaeis guineensis Jacq)(Department of Agronomy, College of Agriculture, Vellayani, 1994) Thomas, Varghese P; KAU; Sreedharan, CA field experiment was conducted in the oil palm plantations of the Central Plantation Crops Research Institute (CPCRI) Research Centre, Palode, Kerala to study the response of mature oil palm to fertilizer and irrigation applications with respect to growth, yield and uptake of nutrients. There were four levels of fertilizers viz: F0- 0:0:0, F1-600: 300: 600, F2- 1200: 600: 1200 and F3-1800: 900: 1800 g N : p20 : k20 palm-1 year-1. The three levels of irrigation were: I0-no irrigation, I1-45 1 palm-1 day-1 and I2-90 1 palm-1 day-1. The 4x3 factorial experiment was laid out in randomised block design with three replications. The study was also envisaged to establish the importance of leaf nutrient ratios of yield group of palms and its application in identifying nutrient limitations through the Diagnosis and Recommendation Integrated System (DRIS) approach in oil palm. The influence of various climatic parameters on yield of oil palm was studied by relating the monthly yield of oil palm in the field experiment with the monthly weather variables as far behind as 42 months before harvest. Fertilizer application of 1200 g N+600 g P2O5+ 1200 g K2O palm-1 year-1 was found to improve the growth characters such as annual leaf production, number of leaves on the crown, dry matter production of leaf, trunk and bunches, total dry matter production and the crop growth rate. Increase in yield attributes such as number of female inflorescences, sex ratio, average single fruit weight and the number of bunches at F2 level contributed to the significantly high FFB yield at F2 level of fertilizer application. Both palm oil and palm kernel oil production were also maximum at F2 level. For the uptake of nutrients N,P and K by palm parts as well as by the palm as a whole, the F2 level of fertilizer application was found to be the optimum. It was observed that 79% of the total uptake of N, 77% of P and 82% of K are removed annually through leaves and bunches from the system. A K-Mg antagonism was also detected in nutrient uptake. The yield of palm was found positively correlated with leaf production, leaf area, net assimilation rate, number of bunches produced, vegetative dry matter, P and K in soil and the total uptake of N, P and K by the palm. Both net income and benefit cost ratio were also found favorable at F2 level of fertilizer application. Irrigation at I2 level has resulted in increased leaf production, leaflets per leaf, leaf area, leaf dry matter, mesocarp dry matter and the bunch dry matter. Physiological parameters like relative water content, leaf water potential, stomatal resistance, leaf temperature and net photosynthesis were all favourable at I2 level of irrigation. Female flower production, sex ratio, single fruit weight and number of bunches produced were also more in I2 treatment. This has resulted in increasing FFB production at I2 level. Palm oil production was also more at I2 level. Total uptake of N, P, K and Ca were also found to be maximum at I2 level of irrigation. The net profit and benefit cost ratio were also maximum at I2 level. Leaf nutrient ratios of palms in different yield groups: were used to evolve parameters and norms for Diagnosis and Recommendation Integrated System (DRIS) in oil palm. The range of nutrient ratios within the zones of balance, moderate imbalance and imbalance were determined which were also illustrated through DRIS charts for three nutrient combinations. The DRIS approach was used to evaluate the nutrient balancing of the different treatments of the field. The order of relative importance of the five nutrients was determined using nutrient imbalance index (NII) values as indicated below: K> P> N> Mg> Ca The F2 level of fertilizer application in the experiment was found to be the most balanced among the tested fertilizer levels. The possibility of magnesium becoming a potential limiting nutrient at higher levels of fertilizer application has been brought out from the study. The superiority of balanced nutrition in increasing total dry matter production and bunch yield became evident from the study. The studies on climatic relationship with yield revealed that the pattern of variation in monthly yield remained the same inspite of irrigation throughout the summer months. The relationship of monthly yield of oil palm with monthly climatic parameters was evaluated up to a period 42 months before harvest. When eight climatic parameters were considered together, the influence of these weather parameters at seven specific lag periods viz. 1-4, 9-10, 13-16, 20-23, 25-28, 32-33 and 37-40 were found important for oil palm. Of these the lag 25-28 was found to be the most important as the relationship of climatic parameters with yield at this period was more. Relative humidity, maximum temperature and rainfall were identified as the most important variables influencing palm yield. Using results obtained from regression studies yield prediction models were constituted. It is concluded that yield prediction using the three or more variables is possible for oil palm 26-28 months in advance of harvest. The salient findings from the study is that a fertilizer dose of 1200g N+ 600 g P2O5+ 1200 g K2O palm-1 year-1 and irrigation level of 90 l palm-1 day-1 applied through drip system during the summer months are required to obtain maximum FFB yield from mature oil palm. The order of importance of nutrients for oil palm is determined as K> P> N> Mg> Ca. With the above level of fertilizer application the palms were found to have a more balanced nutrition. However continued application of fertilizers might possibly lead to magnesium deficiency unless corrective measures are adopted. Relative humidity, maximum temperature and rainfall are found to be the most important climatic parameters influencing oil palm yields. The influence of climatic parameters at seven lag periods 1-4, 9-10, 13-16, 20-23, 25-28, 32-33 and 37-40 were found to be more pronounced on palm yield. From these studies it became possible to predict oil palm yields 26-28 months in advance using models based on these weather parameters.ThesisItem Open Access Time of application of pre-emergence herbicides on phytotoxicity and weed control in semi-dry rice(Department of Agronomy, College of Horticulture, Vellenikkara, 1994) Susan Lee Thomas; KAU; Sreedevi, PA field experiment entitled 'Time of application of pre-emergence herbicides on phytotoxicity and weed control in semi-dry rice' was conducted during first crop season (Virippu) of 1933 i.e., from May to September at Agricultural Research Station, Mannuthy under the Kerala Agricultural University, Vellanikkara, Thrissur. The objective of the trail was to find out the best time of application of pre-emergence herbicided on phytotoxicity and weed control in semi-dry rice. The experiment was laid out in split plot design with three replications. Treatments included in the trail were pre-emergence application of herbicides such as pendimethalin, thiobencarb, butachlor and oxyfluorfen at 0, 3, 6 and 9 days after sowing with handweeded and unweeded plots as the controls. The dominant weeds found in the experiment field were Digitaria sanguinalis and Cynodon dactylon among grasses, Cyperus rotundus and Cyperus iria among sedges and Cleome viscosa and Ageratum conyzoides among broadleaved weeds. The population of grasses was reduced by the application of oxyfluorfen at 6 DAS and pendimethalin upto 6 DAS. Hanweeding was significantly superior than the herbicides in lowering the number of sedges and broadleaved weeds. At 30 DAS the highest weed control efficiency was recorded by oxyfluorfen. Though phytotoxic symptoms were developed in rice seedling where oxyfluorfen was applied at 6 and 9 DAS, it later recovered by about two weeks. Pendimethalin and oxyfluorfen treated plots gave the highest number of tiller/m2. Chlorophyll content of leaves and dry matter production of rice were more in pendimethalin treated plots. Yield attributing characters and yield were higher in plots treated with pendimethalin at 3 DAS. Total returns and return per rupee invested were higher in the case of pendimethalin at 3 DAS and oxyfluorfen at 9 DAS.ThesisItem Open Access Effect of incorporation of cropes residues on productivity of succeding rice crop(Department of Agronomy, College of Horticulture, Vellenikkara, 1994) Beena Jacob; KAU; Mercy GeorgeAn experiment was conducted at the Agricultural Research Station, Mannuthy during the summer and kharif seasons of 1993 to evaluate the effect of cowpea and groundnut residue incorporation on the productivity of succeeding rice crop in comparison to a green manure Sesbania rostrata and a pre-rice fallow under four levels of N (0, 35, 70, and 105 kg/ha). The experiment was laid out in a split plot design with four replications. Biomas yield on dry weight basis was higher for groundnut and sesbania (7.0 t/ha) while N accretion was higher from cowpea (133kg N/ha). Extractable ammonium in the soil was the highest in sesbania incorporated treatments and minimum in plots preceded by fallow. Sesbania underwent faster mineralization compared to residues and mineral-N accumulation reached a peak 15 days after incorporation. Cowpea residue and sesbania incorporation resulted in higher plant height and tiller production. The dry matter production of rice by incorporation of sesbania was on par with cowpea residue when 70 kg N/ha was applied for rice. Sesbania incorporated treatments recorded the highest leaf area index whereas chlorophyll content at boot leaf stage was maximum in cowpea residue treated plots. Number of spikelets per panicle and total number of spikelets per panicle were higher in sesbania incorporated treatments which was on par with that of cowpea residue treated plots. Grain yield was higher after sesbania (3.24 t/ha) and cowpea residue (3.23 t/ha) incorporation and sesbania along with 70 kg N/ha produced the highest grain yield of 3.74 t/ha. N, P and K contents of grain were maximum when rice was grown after cowpea residue incorporation. Total uptakes of N, P and K at harvest were also the highest after cowpea residue incorporation which was statistically similar to that of sesbania incorporation. Even though NPK uptake increased by application of 105 kg N/ha, they were on par with 70 kg N/ha. Groundnut-rice system and sesbania-rice system were comparable in retaining a higher level of soil fertility. Net income was higher from groundnut-rice system whereas return per rupee invested was higher for cowpea-rice system.
