DETERMINATION OF CRITICAL PERIOD OF WEED COMPETITION AND EFFECT OF PLANT DISTRIBUTION PATTERNS ON WEEDS AND SESAME CROP (SESAMUM INDICUM L.) PRODUCTIVITY

four field experiments were conducted at Agricultural Research Station of Ismailia governorate, Agricultural Research Center, Egypt, in two studies during the two consecutive summer seasons of 2013 and 2014. First study (two experiments) was carried out to determine the critical period for weed control (CPWC) and its effect on weed infestation, sesame yield and its components. Each experiment included twelve treatments of weed removing after 3, 5, 7, 9 and 11 weeks and for the whole season; and weed interference with sesame plants for 3, 5, 7, 9 11 weeks and for the whole season. Second study (another two experiments) was done to evaluate the effect of planting distances (pd), planting distribution pattern and hand hoeing on weed infestation and on sesame yield and its component. The main findings of the first study was that the predicted CPWC in presence of mixed weed populations was found to expand from the 3rd to 11th weeks after planting (WAP). Existence of weed species infestation at fresh weight of 16.7 and 19.4 ton per faddan for whole seasons caused a highly significant reduction of sesame yields which estimated by 75.6% and 77.5% per faddan for first and second seasons respectively, compared to those obtained from weed free treatment for the whole seasons. The weed-free for the whole season treatment, gave significant increase in plant height, length of fruiting zone, number of capsules per plant and total seed yield per Fadden in both seasons. In the second study, planting distribution patterns at 10, 20 and 30 cm with a seeding rate of 1, 2 and 3 seeds per hill respectively, with respecting the recommended planting rate of 70000 plants per faddan revealed that planting of sesame at 10 cm and one seed per hill caused a significant reduction in the number and fresh weight of weeds and has resulted in highest sesame plant height, the number of capsules per plant and seeds yield per faddan in both seasons, compared to either of 20 or 30 cm distribution patterns, or to the weedy check in both seasons. These results demonstrated that planting distance at 10 cm with single plant per hill integrated with hand hoeing twice at 15 and 30 days after planting (DAP) are crucial for the highest sesame yield production per faddan