Abstract: We conducted an experiment with six planting date (06-10,06-12,06-14,06-16,06-18,06-20) combining six harvest date(10-04,09-28,10-10 ,09-25,10-07,10-01)of cultivar ( Zhengdan 958 and Xundan 20 respectively) in the field having medium soil fertility,and studied the effect of different planting and harvest date on matter production,radiation utilization efficiency(RUE) and yield. The objective to achieve high yield and high RUE at the same time,and obtain the quantitative value of yield when early sowing and delayed harvest for different cultivars. The main results showed that the growth period of 13 leaves to Bilking stage was obvious shortened when the planting date put off , and the growth period from sowing to Bilking could be shortened by 0. 4 day when the planting date was delayed for one day. LAI was influenced mainly by sowing date in thirteenth leaf to Bilking, and by length of growth period in maturity. Along with the delayed sowing and harvest date,the LAI had decreased significantly at Bilking and maturity stage. Along with the delayed sowing date,the dry matter amount and transformation rate of leaf, stem and sheath decreased significantly. Compared with late planting, matter amount and matter translocation rate were higher for early planting treatments (The first three sowing date).RUE was influenced mainly by length of growth period,and which was higher for longer growth period treatments. For Zhengdan 958,RUE was higher than Xundan 20. Planting and harvest date can strongly affect grain yields especially planting date. Grain number per spike,1000 grain weight and yield were significantly higher for early sowing+late harvest treatments(The first and the third sowing date).Every early sowing for 1 days or delayed harvest 1 day the average yield increased 196. 5 kg /ha or decreased 97.5 kg/ha. Compared to early sowing}late sowing has the disadvantages that the RUE and dry matter production are significantly less before Bilking stage. Even if growth period prolonged,it still can not make up the yield loss caused by the less matter production in early growth stage. For achieved high yield,the optimum eombination was 06-10,06-14 sowing and 10-04一10-07 harvest.

Key words: Summer maize, Planting date, Dry matter weight, RUE, Grain yield

CLC Number: 

• S513.01