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Subject: Agronomy × Author: KAU × End date: 1991 × Start date: 1991 ×
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    ThesisItemOpen Access
    Production potential of amaranthus under irrigation and nitrogen levels
    (Department of Agronomy, College of Agriculture, Vellayani, 1991) Rajan, S; KAU; Oomen, M
    An experiment was conducted at the Instructional Farm, College of Agriculture, Vellayani, during the summer seasons of 1989 and 1990 to study the response of amaranthus to different water management practices and nitrogen doses. The trial was laid out in split-plot design with three replications. The main plot treatments consisted of a combination of two varieties (red and green ) and four irrigation treatments. (Irrigation at IW/CPE ratio of 0.75, 1.00 and 1.25 and the farmer’s practice of daily irrigation). Sub plot treatments consisted of four levels of nitrogen (50, 75,100 and 125 kg N/ha). The study revealed that amaranthus responded well to frequent irrigations and higher levels of nitrogen. Red variety of amaranthus was superior to green variety in most of the growth and yield attributing characters studied. Biometric characters like height, girth of stem, number of branches, number of leaves, LAI, and dry weights of leaves, stem and roots were favourably influenced by frequent irrigations and higher nitrogen levels. Total yields were also higher in more frequently irrigated treatments and at higher nitrogen levels. The moisture content of leaves was not influenced by irrigation and nitrogen treatments. However nitrogen exerted, significant influence on the moisture content of stem. Protein content of red variety was maximum and as the frequency of irrigation and levels of nitrogen were increased, protein content of plant increased and the maximum was recorded at daily irrigation treatment and at 125 kg N/ha. A relatively higher fibre content was noted in red variety. The effect of irrigation treatments on the fibre content of plants were not conclusive but the nitrogen fertilization tended to decrease the fibre content of plants. The red variety recorded a comparatively higher uptake of nutrients. The uptake of N, P and K were enhanced by frequent irrigations and nitrogen application upto 125 kg/ha. Available N, P, K status of the soil after the experiment was reduced by red variety. Higher irrigation treatments reduced the N and k content of soil after the experiment. But the nitrogen fertilization increased the nitrogen content and reduce the potassium content of the soil after completing the experiment. However the effects of different irrigation and nitrogen treatments on available phosphorus content of the soil after the experiments were found to be inconsistent during the two seasons. The red variety showed maximum water use efficiency then the green variety. Field water use efficiency was higher in the less frequently irrigated treatments (IW/CPE) of 0.75 and 1.00) and at higher nitrogen fertilizations (125 and 100kg N/ha). The results of economic analysis revealed that net income and benefit cost ratio were maximum for red variety and these were increased by more frequent irrigations and Nitrogen fertilizations up to 125 kg N/ha.
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    ThesisItemOpen Access
    Nitrate Reductase Activity in Cocoa (Theobroma cacap L.)
    (Department of Agronomy, College of Horticulture, Vellanikkara, 1991) Rekha Bhaskar; KAU; Balachandran, P V
    An investigation on the nitrate reductase activity in cocoa (Theobroma cacao L.) was conducted at the College of Horticulture, Vellanikkara during the period 1990-1991. Forty plants belonging to the shade trial, thirty accessions of the H VI series and twenty hybrids and their parents were used for the study. All the plants used in the study belonged to the Cadbury-KAU Co-operative Cocoa Research Project. Genotypic and seasonal variations in NRA and NRA in different parts of cocoa plant were studied. The effect of N03-N and shade on NRA were also investigated. Heritability of NR, heterosis and relationship between NRA and yield were also worked out. Based on genotypic differences in NRA, the thirty accessions were grouped into three categories of low, medium and high activity. The highest NRA was observed in October with two lesser peaks in June and August respectively. The season x genotype interaction was found to be significant. Among the plant parts studied, viz., leaf, petiole .and pod, 'nitrate reductase activity was exhibited only by the leaf. There was significant increase ,in mean NRA with increase in NO3-N levels. Under irrigated condition, NRA increased with decrease in shade intensity. NRA at 0% shade intensity was superior to that at 50% and 75% shade levels, while the least activity was observed at 25% shade level. Under rainfed condition, high NRA was observed at 75% shade level followed by those at 25%, 0% and 50% shade levels. Heritability in the broad sense was found to be high in cocoa. In general, all the hybrids studied showed negative relative heterosis and heterobeltiosis. No significant correlation between NRA and yield could be obtained in this study.
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    ThesisItemOpen Access
    Nutritional requirement of arrow root as pure crop
    (Department of Agronomy, College of Agriculture, Vellayani, 1991) Remesan, K K; KAU; Oommen, M
    A field experiment was conducted in garden lands of Instructional Farm of College of Agriculture, Vellayani, to study the effect of N, P and K on growth, yield and quality of arrow root and uptake pattern of major nutrients. The treatments in the experiment consisted of four levels of nitrogen (0, 50,100 and 150 kg/ha N). Four levels of phosphorus (0, 25, 50 and 75 kg/ha P2O5) and four levels of potassium (0, 50, 100 and 150 kg/ha K2O). The experiment was laid out in 43 partially confounded factorial in RBD with two replications. Different growth attributes like height of plants, number of leaves, number of suckers per plant, leaf area index were maximum at higher levels of nitrogen and potassium. The total drymatter production was highest by the application of 150 kg N. 75 kg P2O5 and 150 kg K2O per hectare. The highest value of rhizome number, length of rhizome and girth of rhizome were obtained by the application of 100 kg/N, 75 kg P2O5 and 150 kg/ha K2O. Maximum mean rhizome weight was with 150 kg n/ha, 75 kg P2O5 and 150 kg K2O per hectare. Fresh weight of plants was maximum with highest levels of nitrogen, phosphorus and potassium. Rhizome yield was maximum when nitrogen, phosphorus and potassium were applied at the rate of 150, 75 and 150 kg/ha respectively. Highest levels of nitrogen, phosphorus and potassium increased the starch, yield and protein content of rhizome. Nitrogen nutrition increased the crude fibre content of rhizome, but potassium application decrease the fibre content. The plant uptake of nitrogen, phosphorus and potassium was maximum at highest level of these nutrients. Maximum benefits cost ratio and net return were obtained by the application of 150 kg/ha N, 75 kg/ha P2O5 and 150 kg/ha K2O.