Effect of Methanol Spraying on Physiological Characteristics, Oil and Protein Yields of Soybean (cv. Williams) under Deficit Irrigation
Vahid Bayat, Farzad Paknejad, Mohammad Reza Ardakani, Saeed Vazan, Jafar Azizi, Saeed Mafakheri
Abstract
Most agricultural areas are located in arid zones a nd drought is one of the most critical limiting fac tors of photosynthesis and crop yields, hence, treatment s like methanol spraying can partly reduce damage from water stress. To investigate the effects of times and number of methanol spraying on some physiological characteristics of soybean under defi cit irrigation, a factorial split-plot experiment based on a randomized complete block design with four rep lications was done at Karaj, Iran, in 2010. The fir st factor was drought stress in two levels (based on d epletion of a 1=40% and a 2=70% of available soil moisture). The second factor was spraying times of methanol in two levels (in the morning at b 1=8-10 AM and in the evening at b 2=19-21 PM). Third factor was foliar application num ber of methanol with three levels (each c 1=7, c 2=14 and c 3=21 days, Methanol spray was applied 5, 3 and 2 tim es during growth season of soybean, respectively). All treatm ents were sprayed with 21% (v/v) methanol concentration. 2 g lit -1 glycine was added to prepared solutions. In this st udy, grain yield, oil and protein percentage and yields, relative water content (RWC) , leave chlorophyll content were determined. Result s indicated a significant different (at 0.01probabili ty level) between different levels of water stress on all evaluated traits and normal irrigation showed more favorable effects on measured parameters. Soybean grain yield under normal and deficit irrigation wer e 3187 and 1526 kg ha -1 , respectively. However, no significant difference (P>0.05) was shown between d ifferent times of methanol spraying over studied characteristics. In contrast, measured traits were significantly affected by the number of methanol application. Moreover, results demonstrated that si gnificant differences exists (p>0.05) between interaction effects a◊b, a◊c, b◊c and a◊b◊c in all traits evaluated. In normal and deficit irrigation maximum grain yield was produced by methanol sprayi ng every other week in the evening and every 7 days in the morning, respectively. Grain yield wer e positively correlated with relative water content (RWC) (r=+0.89**) and chlorophyll content (r=+0.94* *). It seems by measuring these traits can predict yield at a certain period.