Effect of post-flowering water stress on yield and physiological characters of grain sorghum genotypes. Mohammad Mostafa1, Maryam Shahbazi2*, Azim Khazaei3, Jahanfar Daneshian3, Soheil Naddafi2 and Hashem Pourirandoust2

Abstract

<span style="font-size: medium;"><span><span lang="EN-MY">Drought</span></span><span lang="EN-MY"><span><span>is one</span></span><span><span>of the most important</span></span><span><span>factors limiting</span></span><span><span>crop production</span></span><span><span>in</span></span><span><span>arid and semi</span></span><span><span>arid</span></span><span><span>regions</span></span><span style="font-family: Calibri;">, such as </span><span><span>Iran.</span></span><span><span>In order to study drought stress in four grain sorghum varieties (Kimia, Sepideh, KGS15 and KGS23), an </span></span></span><span style="font-family: Calibri;"><span>experiment was laid in randomized complete block design with three replications in a split plot arrangement. Water treatments were considered the main plot at three levels: irrigation after 60 mm evaporation as well-watered, normal irrigation </span><span lang="EN-MY">till flowering</span><span> and then irrigation after 120 mm evaporation (mild water stress), and water withholding after flowering (severe water stress).</span><span lang="EN-MY"> There </span><span>were significant (P</span></span><span><span>£</span></span><span style="font-family: Calibri;"><span>0.05) decrease in grain yield, seed index, SPAD number and stomatal conductivity in post-flowering water stress, particularly in severe stress.</span><span>Sepideh cultivar had the highest yield reduction of 73%, and KGS23 genotype had the least yield reduction of 29%, but still it was a good genotype </span><span lang="EN-MY">if well</span><span>-watered and the best in moisture stress conditions</span><span lang="EN-MY">.</span><span> Sepideh and KGS15 had a greatly significant reduction in stomatal conductivity of flag leaves in severe water stress</span><span lang="EN-MY"> and </span><span>displayed premature leaf and stalk senescence. KGS23 as tolerant genotype with more elevated stomatal conductance under water stress probably had a more efficient water uptake by roots in comparison with the other genotypes.</span></span></span> <span lang="EN-MY"><span style="font-family: Calibri; font-size: medium;"> </span></span>