Crop-weed competition studies in French bean (Phaseolus vulgaris L.)
J.S. Mishra, V.P. Singh and V.M. Bhan, National Research Centre for Weed Science, Maharajpur, Adhartal, Jabalpur 482004, (MP) India.
Field studies were conducted during 1994-95 and 1995-96 to determine the critical period of weed control in the French bean crop at Jabalpur, India. The treatment consisted of either allowing weeds to infest the crop for increasing duration after planting or maintaining plots weed free for increasing duration after planting. The major weeds infesting the French bean crop were chicory (Cichorium intybus L.), common lambsquarters (Chenopodium album L.), common vetch (Vicia sativa L.), and strawberry clover (Trifolium fragiferum L.).
Competition with the weeds throughout the crop season reduced the seed yield of French bean by 83.3%. Allowing the plots to remain weedy up to 30 days after sowing (DAS) reduced the seed yield by 4.6% but when the weeds were allowed to grow in association with the crop for further 15 days (up to 45 DAS), the reduction of seed yield was 29.05%. This marked reduction was due to severe competition offered by weeds. Seed yield was increased when the initial weed free duration was extended up to 60 days and further increase in the duration of weed free had no beneficial effect on the grain yield. Hence, the critical period of weed control occurred between 30 and 60 DAS.
Plant Protection Quarterly (2000) 15 (3) 90-91.