Journal of Crop Production and Processing

In order to evaluate the morphological characteristics and lodging-related traits and comparison of improved cultivars of rice plant resistance to lodging, a field experiment was carried out in randomized complete block design with three replications in 2012 at the Rice Research Institute of Iran )Rasht(. Rice cultivars were Kadus, Khazar, Gohar, Dorfak, Sepidrood and Deylam and local rice cultivar (Hashemi; susceptible to lodging as a control). Plant height, stem length, internode length for the first, second, third and fourth internodes, diameter, thickness and cross- section area of third and fourth internodes, ratio of fresh weight and dry weight of third and fourth internodes to internode length, breaking resistance, bending moment and lodging resistance of third and fourth internodes and pushing resistance were examined. Khazar cultivar with greater thickness of third and fourth internodes (4.11 and 4.26 mm), diameter of third and fourth internodes (8.33 and 9.46 mm), cross- section area of the third and fourth internodes (40.96 and 52.32 mm²) and ratio of fresh weight of third and fourth internodes to internode length (301.48 and 444.15 mg.cm^-1) and ratio of dry weight of third and fourth internodes to internode length (49.46 and 50.38 mg.cm^-1), breaking resistance of the third and fourth internodes (14.43 and 20.87 N, respectively) was found to be the most resistant cultivar. Khazar cultivar with a plant height of 121 cm was found to be the tallest among all studied cultivars. Considering the strong correlation found between thickness, stem diameter, cross- section area of third and fourth internodes and ratio of fresh weight and dry weight of third and fourth internodes to internode length with breaking resistance and pushing resistance, it seems that these traits could be considered as indirect indices in selection for higher resistance of rice cultivars to lodging.

In order to evaluate the effect of seed priming on lodging-related characteristics in direct seeding method, a study was conducted in a factorial randomized complete block design with four replicates in the research field of Rice Research Institute of Iran (Rasht) for two years. The first factor consisted of two rice cultivars (Khazar and Hashemi) and the second one consisted of ten levels of seed conditions encompassing, eight priming treatments including hydropriming, ascorbic acid, salicylic acid, CaCl₂, cold, cold + heat, seed coating, and non-primed dry seed, all sown with seed tap technology along with linear direct seeding of germinated seeds and transplanting (25-days-old seedlings). Agronomic and morphological characteristics and resistance to lodging indices were measured. The results showed that there were significant differences between two cultivars and ten levels of seed conditions in morphological traits and lodging resistance indices. Mean comparisons and correlation analyses showed that grain yield (5142 kgha^-1), resistance to fracture in third and fourth internodes (549 and 704 Newton, respectively) in Khazar were higher than those of Hashemi. There was a significant difference between planting methods (direct-seeded and transplanting) in terms of lodging resistance. Maximum indicators in the third and fourth internode bending momentum (1060 and 1708 gcm^-1) were observed in the transplanting method. Hydropriming treatment had significant effect on fourth internode thickness in cultivar Khazar. Priming treatments appeared to leave significant effect on resistance to lodging in different planting methods in a cultivar-specific manner.