Study the amount of dry matter remobilization and current photosynthesis in different seed sizes of four wheat (Triticum aestivum L.) cultivars in Rasht

In order to study the effect of seed size on the production and dry matter accumulation and remobilization of assimilates to the grain of four bread wheat cultivars, an experiment was carried out in 2012-2013 in research farm of Rice Research Institute. A factorial experiment arrangement in randomized complete block design with three replications was used. Treatments in this study consist of four levels of seed diameter size (2.25- 2.5 mm, 2.5- 2.75 mm, 2.75- 3 mm and larger than 3 mm) and cultivars (Kohdasht, Moghan 3, Morvarid and native genotype). Results showed that cultivar had significant effect on amount of current photosynthesis, rate of yield accumulation and grain yield. Seed size had a significant effect on amount of dry matter remobilization, remobilization efficiency, contribution of remobilization, contribution of current photosynthesis, rate of grain yield accumulation, rate of biological yield accumulation, biological yield and grain yield. Seed with size greater than 3 mm had the maximum amount of dry matter remobilization (345.17 g.m-2), remobilization efficiency (32.28%) and contribution of remobilization (68.53%), while the seeds with size 2.25- 2.5 mm had the maximum contribution of current photosynthesis (55.5%). Morvarid cultivar and seed size 2.25- 2.5 mm had the lowest rate of biological yield accumulation (60.41 Kg.ha-1.day-2), biological yield (10542 Kg.ha-1), rate of grain accumulation (17.77 Kg.ha-1.day-2) and grain yield (3101.3 Kg.ha-1). The interaction of experimental treatments was significant in no one characteristic. Therefore, Native genotype and 2.75- 3 mm seed size due to better distribution of assimilates in important yield characteristics were more suitable.