Effect of methanol on yield, dry matter remobilization and grain filling process of wheat (Triticum aestivum L.) under irrigation withholding

In arid and semi-arid regions, drought stress as the main factor and salinity stress as a secondary factor reduces plant growth and yield. Water limitation can damage pigments and plastids, reduce chlorophyll a, b, rate and grain filling period. One of the important strategies for increasing carbon dioxide concentration in plants is using chemicals such as methanol that can increase the concentration of CO2 in a plant and improves photosynthesis rate and growth under water deficit conditions. Methanol is considered as quasi-essential for plant growth and development, and alleviates toxic effects caused by various environmental stresses in plants. The aim of this study was to investigate the effects of methanol on the agro –physiological traits (i.e., chlorophyll content and grain filling period) and yield of wheat under water limitation condition

 A factorial experiment was conducted based on randomized complete block design with three replications at the research farm of Faculty of Agriculture and Natural Resources of University of Mohaghegh Ardabili, during 2015-2016. Factors experiment were included irrigation levels (full irrigation as control, irrigation withholding in 50% of booting and heading stages as severe and moderate water limitation respectively, according with 43 and 55 BBCH code) and methanol foliar application at four levels (foliar application with water as control and foliar application 10, 20 and 30% volume of methanol). Foliar application with methanol was done in two stage of period growth (Stem elongation and Flag leaf development).

Results showed that the maximum contribution of dry matter remobilization from air parts (20.52%) and contribution of stem reserves in grain yield (16.42%) were obtained with irrigation withholding at booting stage and no foliar application. The maximum grain filling period and effective grain filling period (33.62 and 29.33 days respectively) were obtained in full irrigation and foliar application of 30% volume of methanol and its minimum was obtained at no foliar application under irrigation withholding in booting stage. Also, results showed that there were an increase about 46.98%, 194.17%, 37.54%, 69.82%  and 15.96%  in grain yield, leaf area index, chlorophyll index, current photosynthesis and contribution of current photosynthesis in grain yield respectively in full irrigation and foliar application of 30% volume of methanol in comparison with no foliar application of methanol under irrigation withholding in booting stage. Based on the results this study, foliar application of 30% volume of methanol can be applied as a proper method to increase grain yield under water limitation conditions.