Response of Root Characteristics and Dry Matter Partitioning in 40 Improved and Local Rice (Oryza sativa L.) Genotypes under Deficit Irrigation

Nowadays, the root characteristics as one of secondary traits along with grain yield are used to response evaluation of rice genotypes under deficit irrigation. Thus, to evaluate the root traits of 40 irrigated rice genotypes to water limited condition a pot experiment was performed in 2014 at Rice Research Institute (Rasht), Iran. Irrigation treatment was applied in two levels include control (traditional irrigation) and deficit irrigation (withholding irrigation at the booting stage). The results showed that deficit irrigation reduced root length from closely 45 to 28 cm, root area from 190 to 117 cm2 and root area density from closely 6 to 4 cm2cm-3. Under deficit irrigation, average of paddy yield and panicle weight decreased 25% and 18.5%, respectively. In this condition, root dry weight decreased, in other hand the shoot dry weight increased from 42.7 to 49.4 g. Genotypes classification carried out based on studied traits by the Ward's Minimum Variance test in both conditions (control and deficit irrigation) that separated the genotypes into four and three groups, respectively. In both situations, groups with lower amount for root traits had the higher paddy yield. Accordingly in deficit irrigation conditions, group III include 19 genotypes such as Gohar, Shiroudi and Khazar with low amount for root characteristics, had paddy yield higher than other groups. Comparison of groups showed that significant variation of root dry weight, shoot dry weight, panicle weight and paddy yield (about , , -19 and -14%, respectively) in local genotypes compare with improved genotypes. Therefore, it seems that although priorities of crop improvement in studied genotypes were to allocate more dry matter from the root to the shoot, but considerable diversity existed in terms of dry matter partitioning to different organs under deficit irrigation.