SMOOTH AMARANTH INTERFERENCE WITH WATERMELON AND MUSKMELON PRODUCTION

Studies were conducted to determine the critical period of smooth amar anth interference in watermelon (Citrullus lunatus L.) and muskmelon ( Cucumis melo L. var. reticulatus). Best-fit linear or exponential regr ession models were used to predict the maximum period of competition a nd the minimum weed-free period for 10% yield loss, The maximum period of competition and minimum weed-free period was 0.50 and 2.97 weeks a fter watermelon emergence, respectively, and 1.0 and 3.9 weeks after m uskmelon emergence, respectively, The critical periods of smooth amara nth interference for the crops were between those intervals. In both c rops, late emerging smooth amaranth had little effect on total yield, Smooth amaranth introduced at crop emergence reduced total yield, The effect of competition on yield components, i.e., fruit number per hect are and fruit mass, varied by crop, Muskmelon fruit count was more sen sitive to smooth amaranth competition than was watermelon fruit count, Conversely, mass per fruit of muskmelon was less sensitive to this co mpetition than was mass per fruit of watermelon.