Agrotechniques for seed production in vegetable cowpea (vigna unguiculata subsp. sesquipedalis (L) verdcourt/ var. Sharika

Abstract

A field experiment was conducted in the Instructional Farm of the College of Agriculture, Vellayani during the period extending from first week of January to third week of April 2001 to study the effects of different levels of nitrogen, potassium and spacing on the growth characters, yield and yield attributes, seed characters and seed quantity, nutrient uptake and economics of cultivation for seed production of vegetable cowpea (Vigna unguiculata subsp. sesquipedalis (L.) Verdcourt) var. Sharika. The soil of the experimental site was sandy clay loam in texture, acidic in reaction, low in available nitrogen, medium in available phosphorus and low in available potassium. The treatment consisted of two levels of spacing (S1 – 1 X 0.6m and S2 – 1.5 X 0.6m), three levels of nitrogen (N1 – 30 kg N ha-1, N2 – 45 kg N ha-1and N3 – 60 kg N ha-1) and three levels of potassium (K1 – 10 kg K2O ha-1, K2 – 15 kg K2O ha-1and K3 – 20 kg K2O ha-1). The experiment was laid out in factorial randomized block design. An abstract of the result is given below. Among the growth characters spacing had a significant effect on DMP,LAI at 30 and 60 DAS and LAD. For all these parameters the highest or the best values were given by the lowest spacing S1 (1 X 0.6m). Nitrogen and potassium were not able to influence any of the growth parameters in a significant way. Among the yield characters spacing was able to make an impact on pods per plant. Here S2 the wider spacing (1.5 X 0.6m) gave a significantly higher value. With regard to the seed characters second level of potassium (K2 – 15 kg K2O ha-1) has significantly influenced the weight of seeds per pod. The first level of spacing S1 (1 X 0.6m) has again influenced the NPK uptake of plants in a statistically significant way.

The interaction effect of potassium and spacing had significantly affected the growth character viz. LAI at 30 DAS. The treatment K3S1, i.e. 20 kg K2O ha-1 and 1 X 0.6m spacing was found to be the best among the combinations that influence the leaf area index. The interaction of nitrogen and potassium has significantly influenced another growth character viz. DMP. Here N3K1 i.e. 60 kg N ha-1 and 10 kg K2O ha-1was found to be the best among the treatment combinations. Interaction of nitrogen and potassium also influenced the seed character viz. pod to seed ratio. In this case N1K3 (30 kg N ha-1 and 60 kg K2O ha-1) gave the highest value. The interaction of nitrogen and potassium also significantly influenced the uptake of nitrogen and phosphorus. Both N1K2 (30 kg N ha-1 and 15 kg K2O ha-1) and N3K1 (60 kg N ha-1 and 10 kg K2O ha-1) had influenced the uptake of nitrogen and phosphorus in a significant way. The interaction of nitrogen, potassium and spacing were able to significantly influence the yield character viz. pods per plot. N1K2S1(30 kg N ha-1, 15 kg K2O ha-1 and 1 X 0.6m spacing), N2K1S1 (45 kg N ha-1, 10 kg K2O ha-1 and 1 X 0.6m spacing) were superior with regard to this character. Different levels of nitrogen, potassium, spacing and their interaction did not significantly influence other growth characters like length of vine, number of branches per plant, shoot root ratio, days to 50 per cent flowering, yield characters like weight of dried pods per plant and seed characters like hundred seed weight, seed yield per hectare, germination percentage, vigour index, root length of seedling, dry weight of seedling and seed viability. Maximum profit was obtained (Rs. 117501/-) for the treatment combination N1K2S1 i.e. 30 kg N ha-1, 15 kg K2O ha-1 and 1 X 0.6m spacing.