Synergistic responses of drip-irrigated wheat crop to chitosan and/or silicon under different irrigation regimes

Abstract

Water scarcity is considered as a key restriction for food production worldwide. Chitosan (Chi) and silicon (Si) play a crucial role in plants metabolic processes under normal or stress conditions. Field experiments were done at the Res. Station, Nat. Res. Cen., El-Nubaria Province, Egypt, in 2014/15 and 2015/16 seasons in a split-plot based on randomized complete block design with three replications, for assessing the defensive role of Chi and/or Si on wheat growth, yield, some physio-anatomical attributes and water use efficiency under different irrigation regimes. The experimental treatments included three irrigation water regimes (100, 70, and 40% of drip irrigation water requirement "IWR") as the main factor, as well as Chi and/or Si (water, 125 mg L−1 Si, 250 mg L−1 Chi, and 125 mg L−1 Si+250 mg L−1 Chi) as the sub-factor.Water deficit significantly decreases plant growth, yield, photosynthetic pigment, and relative water content; whereas significantly induced noticeable changes in leaf and stem anatomy as well as organelle's ultrastructure. Application of Chi + Si gave the highest plant growth and yield attributes, maintaining plant water status, along with improved physiological trials under irrigation regimes. Additionally, the application of Chi + Si under severe drought showed an ameliorative effect on cell ultrastructure compared with drought-affected plants only including well-developed chloroplasts, increased plastoglobules and maintained nucleus and mitochondria structure.Overall, this investigation proposes that the application of 125 mg L−1 Si plus 250 mg L−1 Chi twice at 50 and 70 days from sowing had potential to mitigate the water deficit effects, improving water use efficiency as well as increasing the wheat yield and its quality.