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Author: KAU × Author: Rajan, S × Start date: 1990 × Type: Thesis ×
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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
    Leaf litter addition and nutrient recycling in two clones of rubber (Hevea brasiliensis Muell. Arg.) at Vellanikkara estate of Kerala Agricultural University
    (Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 1994) Rajan, S; KAU; Nazeem, P A
    The present study deals with the quantification of leaf litter addition and nutrient recycling in two clones of rubber in the Vellanikkara Estate of kerala Agricultural University , Trichur . Two different methods of collection were adopted for litter collection in both the clones RRII 105 and RRII 118. Wintering was found to start on 23rd November, 1993 for clone RRII 105 and continued till 12th February , 1994 whereas in RRII 118 wintering strated by 25th November, 1993 and continued till 17th February , 1994. Peak leaf fall was noticed in the month of January for RRII 105 whereas it was in the month of February in the case of RRII 118. Thus clonal variation do exist for the wintering pattern. The total leaf litter production was estimated to the 4954.297 kg for RRII105 and 4584.558 kg for RRII 118. The nutrients contributed through leaf litter during wintering in the clone RRII 105 were 72 kg N, 2 kg p, 57 kg K, 59 kg ca and 12kg mg whereas for the clone RRII 118 it was 61kg N, 2kg p, 43kg k , 79 kg ca and 9kg mg . The clone RRII 105 contributed more litter as well as nutrients than the clone RRII 118. Contrary to the previous years the nutrient levels in the leaf litter did not follow a regular pattern during the wintering period . The presence of green leaves shed due to high wind velocity resulted in an increased level of nutrients in some collection s. It was also observed that the contribution of N, K and Ca were more during the wintering period whereas p was more prior to peak wintering and Mg was more after peak wintering. Comparison of nutrient status in soil samples collected from the area enclosed by net and outside sites showed that removal of leaf litter resulted in relatively lower levels of soil nutrients in the top soil . The leaf area worked out during the study was 6.44 for the clone RRII 105 and 5.53 for clone RRII118. The study also revealed that enclosing the trees with net is the best method to quantify the leaf litter addition . The expensive and cumbersome procedure of providing nets cannot be replaced by collecting the leaf litter from a marked area provided with 15 cm high fencing . The leaf litter accumulated in the fenced area was always less and varied from 27 to 71 per cent of the quantity of litter collected by providing net to cover the canopy all around the trees.