EFFECTS OF WEED REMOVAL IN CLUSTERBEAN (CYAMOPSIS-TETRAGONOLOBA) UNDER DIFFERENT RAINFALL SITUATIONS IN AN ARID REGION

In dry land agriculture, intensity and type of weed pressure depend up on the rainfall pattern during the crop season. A two year field study was conducted to determine the effect of time of weed removal in clus terbean (Cyamopsis tetragonoloba (L.) Taub.). Treatments consisting of weed removal at 10, 20, 30, 40 and 50 days after sowing were compared with clean weeded and unweeded controls. The xerophytic weeds Gisekia pharnacioides (L.) M., Mollugo cerviana (L.) Ser. and Tribulus terres tris L. dominated in the low and erratic 1993 rainfall season while gr assy weeds such as Eragrostis pilosa (Beauv) were predominant in the 1 994 season with well-distributed rainfall. The number of weeds was max imum at 30 days after sowing (DAS) in 1993 and at 40 DAS in 1994. The dry weight of weeds increased up to 50 DAS in 1993 and up to harvest i n 1994. Removing weeds at 20 or 30 DAS increased the number of pods pe r plant, water use efficiency and seed yield of clusterbean. Water con sumption was higher in unweeded plots. Water use efficiency decreased with the increase in time of weed removal beyond 20 days after crop so wing.