9 Effects of supplemental irrigation and source limitation on grain quality of Iranian bread wheat genotypes Saeid Jalali-Honarmand 1* , Mohsen Saeidi 1 , Ali Rasaei 1 and Elaheh Peik 1 1 Department of Agronomy and Plant Breeding, Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran *Corresponding author: crops_physioresearcher@yahoo.com; sjhonarmand@yahoo.com Abstract The wheat’s bread is one of the main foods to supply daily diet that its quality is affected by different stress and environmental conditions. This study was carried out to investigate the effects of different irrigation treatments (supplemental irrigation at anthesis and grain filling stages and non-irrigation as control) and source limitation (current photosynthetic limitation) at 14 days after anthesis on traits related to baking quality of bread wheat genotypes (Karim, Cross Albourz, Sivand and Pishtaz). The results showed that the effects of irrigation, source limitation and genotypes were significant on the gluten index, total gluten, wet gluten and strong gluten. Also the falling number was affected by treatments except genotypes. The supplementary irrigation had positive effect on bread wheat traits and between the genotypes Sivand and Cross Albors had highest amount of gluten index and strong gluten. The most appropriate falling number was related to Karim genotype and without source limitation condition. Key words: Gluten Index, Falling number, Wet gluten, Wheat. Introduction Nowadays increasing of food demand and water deficit has created a challenge for food security in the world (Zwart and Bastiansen, 2004). Among the crops, wheat is a strategic cereal in the world and it is also a major food cereal and a cheapest source of the people in Iran that provides more than 40-45 and 50 percent of the daily calories and protein (respectively) of people (Iran-Nejad and Shahbaziyan, 2005). The mainly consuming of wheat is in the form of bread. The bread quality can be affected by grain genetic and environmental effects like soil condition, irrigation, weather, seed storage and seed content (Finney et al., 1987). Also in relation to quality of wheat flour: grain protein content, wet gluten value, gluten index (which describes the ratio of strong gluten to total gluten) and alpha amylase activity are factors that affect on it (Huebner et al., 1997). The gluten is formed about 78-85 percent of total protein in wheat grain, which is composed of gliadin and glutenin. Dough with high glutenin content has good stability and elasticity. In fact, the ratio of glutenin to gliadin determines the quality of dough/bread (Hamada et al., 1982). Water deficit has significant effect on many biochemical changes in wheat grain (Ashraf, 2010). Genotypes with tolerance to drought stress have higher values of traits related to baking quality. Water deficit and high temperature during post-anthesis and grain filling stages can be reduced accumulation of starch and increase the concentration of protein in the grains that are growing (Sowers et al., 1994; Zhang et al., 2010). There are two sources to supply assimilate for grain filling: (I): Current photosynthesis of leaf, which is the major source and (II): remobilization of storage matter at late period of gain filling. Assimilate availability directly has relationship with leaf photosynthetic activity and decreasing in leaf photosynthesis can be caused the quality and quantity of grain (Kuanar et al., 2010). This experiment was conducted to investigate the effects of post-anthesis current photosynthetic limitation and supplemental irrigation on some characteristics related to baking quality in some bread wheat genotypes. Results Effects of supplemental irrigation According to the results, the effect of supplemental irrigation was significant on baking quality traits (P < 0.01) (Table 1). Application of supplemental irrigation reduced the falling number value (9.5%) but increased the amount of parameters related to gluten (Table 2). Effects of source limitation All of the baking quality traits were affected by limitation of leaf current photosynthesis (P ≤ 0.01) (Table 1). As be showed (Table 2), under normal photosynthesis conditions the values of baking quality are higher than limited current photosynthesis (Table 2). Situation of traits between genotypes The amount of gluten and other traits related to it were differ between genotypes but the falling number had not significant difference between the genotypes (Table 1) (Table 2). The correlation between quantity and quality of gluten (total gluten and gluten index, respectively) was positive and significant (P < 0.94). Also, the falling number had negative correlation with other traits (Table 3). Plant Knowledge Journal Southern Cross Publishing Group ISSN: 2200-5390 AUSTRALIA EISSN: 2200-5404 5(1):9-12 (2016)