Qualitative and Physical Properties of Barley Grain s under Terminal Drought Stress Conditions

Abstract

Drought stress is the major limitation for crop yie ld, which depending on the time of occurrence, could decrease the number of grain as w ell as their weight. Barley ( Hordeum vulgare L.) is one of the tolerant cereals that its grain components have an important role in human and animal nutrition; however, physical an d biochemical properties of grains affected through drought stress are still poorly un derstood. In this study, barley genotypes (n= 6) with different levels of drought t olerance were studied in a 2-year field experiment under well-watered and terminal drought stress conditions. In order to measure physical properties of grains, digital imag es were taken and some morphological features were obtained by using Image Analysis Tool box of MATLAB software. Biochemical properties of grains were also measured . Results proved that size, weight and also quality of the grains were significantly affec ted by drought stress (P< 0.01). Grain starch content decreased and protein content increa sed under drought stress at anthesis stage in all genotypes, but drought-sensitive genot ypes interestingly had more percentage increase in protein content. Furthermore, genotypes varied in total sugar, sucrose, glucose and fructose content. Drought stress affected grain size and finally 1,000-grain weight of barley genotypes by reducing area and minor axis le ngth of grains. Correlations between 1,000-grain weight and minor axis length, grain are a, starch and sucrose content were significant (P< 0.01). These results emphasized in both conditions that size-dependent features of grain particularly minor axis length an d area may be serving as useful traits for estimation of 1,000-grain weight and biochemica l properties in barley. Keywords: Grain size, Hordeum vulgare L., Image analysis, Protein, Starch.