اثر عوامل محيطي طي نمو بذر روي پايه مادري ذرت بر بنيه بذر هيبريد حاصله

Effect of Environment Factors During Seed Development of Female Inbred Parent on Vigor of the Hybrid Corn Seed

Seed vigor decreases under unsuitable environmental conditions and this is one of the most important problems in seed formation during prematurity and preharvest periods. Good seed vigor is a desired characteristics that affects plant growth and seedling uniformity. The aim of this investigation was to study the effective factors on seed vigor of single cross hybrid 704, during periods after pollination. A factorial experiment was conducted in the form of randomized complete block design with three replications in the Field of Islamic Azad University of Fasa during summer 2000. The studied factors were water deficit and levels of nitrogen application. Water deficit levels consisted of control, early water deficit and late water deficit after flowering, respectively. Nitrogen levels was considered as control, 92kgN/ha and 184kgN/ha. Kernel endosperm dry weight was determined during several weeks after pollination to explain the seedling dry weight of germinated kernel. The results showed that maximum endosperm dry weight of early water deficit treatment was less than late water deficit and control by 39.70 mg and 68.27 mg, respectively. No nitrogen application decreased total endosperm and, pericarp dry weight by 11.48% (P < 0.05). Seedling dry weight in optimum soil water deficit was less than early and late water deficit in germination initiation, but seedling dry weight of the control was increased in later weeks. Water deficit effect was greater than no nitrogen effect on seedling dry weight as early water deficit effect was 0.85 time of dry weight for no nitrogen. There was no significant difference in seedling dry weight between the levels of nitrogen application (92 and 184 kgN/ha) at 5% probability level. Regression of total endosperm and pericarp dry weight on seedling dry weight from kernel germination until harvest was significant at 5% probability level. This regression was also significant with nitrogen application. Seedling dry weight was minimum in early water deficit with no nitrogen.