FOLIAR METHANOL APPLICATIONS TO COTTON IN THE SOUTHEASTERN UNITED-STATES - LEAF PHYSIOLOGY, GROWTH, AND YIELD COMPONENTS

Foliar methanol applications have previously been reported to dramatic ally increase yields of a variety of crops under arid conditions, incl uding cotton (Gossypium hirsutum L.). Whether methanol is effective in the southeastern USA is not known. In addition, the agronomic and phy siological events contributing to the increase are not understood. The refore, we conducted a series of experiments in 1993 to study the effe cts of methanol on the gas exchange, water relations,development, grow th, and yield of field-grown cotton at three locations in the southeas tern USA. Conventional management and irrigation procedures were used. Methanol solutions in water, with and without urea and iron, were app lied over the top at midday to cotton. Four to eight applications were made from flowering to late bell filling. Both single-leaf and canopy photosynthesis rates taken 2 h to 6 d after treatment were unaffected by methanol or the nutrients. At one site, CO2 compensation point was determined, but did not differ among treatments. This finding does no t support previous claims that methanol reduces photorespiration. Tran spiration and water potential also were not affected by foliar applica tions of 15 or 30% methanol (v/v). Foliar methanol applications also d id not result in faster development of the crop and did not increase y ield at any of the locations. Our results do not indicate any positive effect of foliar methanol applications on cotton in the southeastern USA.