Response of Chlorophyll Fluorescence,Photosynthetic Characteristics and Yield of Yannong 19 to Sowing Date and Density

In order to understand the impact of sowing date and density on photosynthetic effect and yield of wheat,the effect of six sowing dates and four kinds of planting densities on wheat variety of Yannong 19( Semi-winter and inclined to winterness) was studied. The results showed that the leaf area index of wheat at heading and middle of filling stages was increased with the increasing of planting density under the same sowing date,and the sowing dates of October 10( S2,normal sowing date) and October 17( S3,moderately late sowing) had the highest values. Under the same planting density,the highest values of chlorophyll content at different growth stages and each chlorophyll fluorescence parameter( Fo,Fm,Fv/ Fm,ETR and ΦpsⅡ) at middle of filling stage were all appeared at the sowing dates of October 10 and October 17,and they decreased with the increasing of plant density under the same sowing date. The photosynthetic rate,stomatal conductance,intercellular CO2concentration and transpiration rate of wheat were obviously influenced by sowing date and planting density,and they performed the best under reasonable sowing date of October 10 and October 17 and suitable density of 120 × 104/ ha and 210 × 104/ ha. The two-year high yield combinations of sowing date and density were S2M1,S2M2,S3M1 and S3M2,and the yields of 2011 were 7 892. 8,7 978. 6,7 996. 2,8 020. 6 kg / ha,of 2012 were 7 911. 5,7 978. 6,7 970. 1,8 032. 9 kg / ha,respectively.Correlation analysis revealed that the leaf area index of wheat had a quadratic parabola relationship with yield,and chlorophyll content,photosynthetic rate and actual photochemical efficiency were positively correlated to yield with the shape of a straight line. The study indicated that the suitable sowing date of Yannong 19 in Huaibei area was October 10- October 17,and the reasonable density was the basic seedling 120- 210 × 104/ ha.