Bothena Omran⁽¹⁾ and  Ghiath A. Alloush*⁽¹⁾

(1). Department of Soil and Water Sciences, Faculty of Agriculture, Tishreen University, Latakia, Syria.

(*Corresponding author: Dr. Ghiath A. Alloush. Email: galloush@scs-net.org).

Received: 21/11/2019                               Accepted: 11/01/2020

Abstract

A pot experiment was conducted at a greenhouse during the growing season 2016/2017 to study the effect of water stress (FC=65 and 75%) on growth and productivity in the presence and absent of K fertilization (0 and 100 mg K/kg soil). Two control treatments at (0 and 100 mg K/kg soil) watered to 100% of FC were also included. Water stress was implemented during the whole life cycle of wheat crop and at three different wheat phonological stages: up to ending of tillering, up to beginning of spike heading, and up to beginning of grain filling. Water stress was then relieved and plants were watered to 100% of FC. Regardless of K application, water stress at 65 and 75% of FC decreased total number of tillers which mostly remained weak and unfertile compared to the control plants. The application of K to plants grown at 100% of FC increased the number of fertile tillers. Wheat plants subjected to 65 and 75% of FC water stress up to grain filling were unable to compensate for the lost fertile tillers after the stress was relieved. Whereas, stressed plants at tillering and spike emerging stages were able to compensate and increased number of fertile spikes not only similar, but even higher than those obtained for control plants. The decrease in grain weight per spike of main stem and tillers less apparent at 75% of FC, and that K application had no significant effect among treatments of the different water stress stages. The effect of water stress at different growth stages and K fertilization on the number of fertile tillers and weight of grain in spikes influenced grain productivity. Imposing continuous water stress led to decrease grain yield from 11.78 to 4.28 and 7.44 ton/ha at 65 and 75% of FC, respectively, in case of no K application. The decrease in grain yield for the same treatments were from 11.94 to 4.89 and 7.75 ton/ha in the presence of K application. In treatments subjected to water stress up to spike emerging stage yielded 7.44 and 8.58 ton/ha at 65 and 75% of FC  and no K application, and 7.77 and 9.16 ton/ha for the same treatments receiving K application. Water stress at 65 and 75% of FC at tillering stage had small reducing effect on grain yield and produced as much as 90 and 97% of the grain yield of the control plants without K application. Grain yield was 91 and 99% of the yield in the control treatments receiving K application.

Key words: Bead wheat,Water stress, Potassium, Grain yield, Grain protein

Full paper in Arabic: PDF