Foliar-applied methanol effects on cotton ( Gossypium hirsutum L.) gas exchange and growth

Abstract

Reports that foliar-applied methanol greatly enhanced growth of C 3 crops has stimulated considerable interest. Experiments were conducted to evaluate foliar application of methanol on cotton ( Gossypium hirsutum L.) growth, leaf gas exchange and water use. Aqueous solutions of 0 (control), 10, 20 and 30% (v/v) methanol were applied to well-fertilized and watered plants of cultivar G&P 74 + grown under field and greenhouse conditions. Foliar-applied methanol increased CO 2 assimilation ( A) and leaf conductance to CO 2 ( g) in both field and greenhouse experiments up to 3 weeks after application, but did not consistently change intercellular CO 2 concentration ( c i) or leaf water-use efficiency (LWUE, μmol CO 2/mol H 2O). Increasing the concentration of aqueous methanol above 10% solution did not further increase A or g in both field and greenhouse experiments. Dry matter accumulation, leaf area, fruit number, main stem node number and plant water use did not differ between the control and methanol-treated plants. Although these results indicate that methanol increases leaf gas exchange of cotton, they fail to validate previous reports of large increases in cotton growth and transpiration efficiency.