Production potential of amaranthus under irrigation and nitrogen levels

Abstract

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.