Effects of Different Sowing Dates on Plant type and Yield Traits of Hybrid Rice Variety Yiyou 673

Interval sowing experiment was executed with Yiyou 673 as testing material to explore the effects of different sowing time on the growth period, plant and leaf morphology and yield components. The results showed that the growth period of rice was shorten, the number of main stem leaves was reduced and the plant height was decreased with the delayed sowing date. At the same time, the number of effective panicles was reduced, while the seed setting rate was increased, and the grains per spike were firstly ascended and then declined gradually. Optimum sowing time for Yiyou 673 had been confirmed on 20th May, it had good plant and leaf morphology, big panicle with more grains and the highest yield. Yiyou 673 could gain higher yield for sowing on 1st May, but it would have lodging risk because of over high plant height in this period. Therefore, we should pay attention to strengthen the scientific cultivation of fertilizer management, drain paddy fields timely, combine the promotion and control, develop strong roots and stalks so as to enhance the capacity of lodging.