Methanol Does Not Influence Water Relations, Gas Exchange, or Growth in Cotton

J. J. Heitholt, M. W. van Iersel, D. M. Oosterhuis, and R. Wells


Research in the 1980's indicated low concentrations of organic solvents, such as methanol, could stimulate rooting of etiolated green gram (Vigna radiata L.) hypocotyls. In 1992, it was reported that foliar applications of 10 to 50% methanol to both horticultural and agronomic crops (including cotton, Gossypium hirsutum L.) had the potential to substantially enhance productivity. Since there is limited published data supporting this response, studies were performed to evaluate the effects of foliar-applied methanol on the physiology and agronomy of cotton. In 1993, field experiments were conducted near Stoneville, MS (cv. Deltapine 5415), Fayetteville, AR (cv. Deltapine 20), and Clayton, NC (cv. Deltapine 5690). Beginning at first flower and at weekly intervals thereafter, selected solutions were foliar-applied near midday under high irradiance. The treatments included: (1) untreated check [unsprayed or water only (Stoneville and Clayton only)], (2) a nutrient check, N (33 mM) + Fe (2 mM), (3) 30% methanol with N+Fe, (4) 30% methanol without N+Fe. All solutions contained a nonionic surfactant and application volumes ranged from 187 L ha-1 (Stoneville and Fayetteville) to 234 L ha-1 (Clayton). The average high temperature for the application dates was 35 C (Stoneville). Selected physiological and agronomic variables were determined periodically at each location. The experiments were arranged in randomized complete blocks with at least five replicates and data were analyzed separately by location. No significant differences (P > 0.05) were detected among treatments at any location. Measurements at Stoneville, averaged across treatments were as follows: leaf area index (LAI) during late flowering, 3.2; single-leaf CER, 25 µmol m-2 s-1; lint yield, 1070 kg ha-1; fiber strength, 205 kN m kg-1; and fiber micronaire, 4.66. Measurements at Fayetteville, averaged across treatments were as follows: midday leaf water potential, -1.03 MPa; LAI at cutout, 2.54; single-leaf CER, 27 µmol m-2 s-1; stomatal conductance, 1.07 cm s-1; transpiration, 5.5 mmol m-2 s-1; CO2-compensation point, 86 µmol mol-1; lint yield, 834 kg ha-1. Measurements at Clayton, averaged across treatments were as follows: flower production, 110 flowers m-2; midday canopy CER, 20 µmol m-2 s-1; lint yield, 1100 kg ha-1; lint percentage, 39%; and boll size, 4.1 g boll-1. Differences in photorespiration among treatments were not apparent in Fayetteville. Photorespiratory related variables were not measured at Stoneville or Clayton. The results indicate that foliar-applied 30% methanol is unlikely to benefit cotton.

Reprinted from Proceedings of the 1994 Beltwide Cotton Conferences pg. 1329
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998