Effect of Weed Competition on Growth and Yield of Blackgram (Vigna mungo L.)

Abstract

A study of the effects of weed competition on the growth and yield of black gram cv. BC-48 was undertaken at the Phgitsanulok Field Crops Research Station during the wet and dry seasons of 1986. In unweded treatments yield loss form the rainfed wet-season crop was up to 49 percent, whild in the dry-season under irrigation the yield loss was up to 63 percent. Weed competition reduced height, number of branches per plant and pod number perplant. Number of seeds per pod and seed weight did not respond statistically to weed competition. For the dryseason crop, the pre-emergence herbicide metolachlor applied at 0.75 kg a.i. ha-1 when combined with hand weedings at 15 and 30 days-after-sowing (DAS) gave the highest yield of 1.65 t ha-1, compared with 0.62 tonnes ha-1 for the unweeded treatment. In the wet-season study, the highest yield of 1.27 tonnes ha-1 was achieved from the treatments with two hand weedings, at 15 and 30 DAS; the unweeded control plot gave a mean yield of 0.65 toones ha-1.