Effect of herbicide spray-time on yield, quality and net photosynthesis of wheat

A field experiment was conducted to study the effect of 2,4-D butyl and sigma spray-time on the yield components, grain yield, quality and leaf net photosynthetic rate (Pn) of high quality wheat “Linyou 145”. Results show that Pn decreases under three spray-time of 2,4-D butyl, and decreasing rank increases with spring-time delay. Leaf and flag leaf Pn during early and middle filling stages drops compared with the control 1~15 days after sigma application in three spray-time. 2,4-D butyl applied in three spray-time shows little effect on filling parameters. Sigma prolongs filling period (S) and effective filling period (Se) but decreases average filling rate (R) and effective filling rate (Rs). Herbicide spray-time has greater effects on 1000-kernel weight and per-hectare ear than per-ear kernel. Yield decreases with later 2,4-D butyl spray. Sigma sprayed on Nov. 15 and March 20 increases flag leaf Pn during late filling stage compared with the control, and respectively increases yield by 157.44 kg·hm^-2 and 222.34 kg·hm^-2, but yield decreases by 512.71 kg·hm^-2 when sprayed on April 4. Wheat quality is improved when 2,4-D butyl is sprayed on Nov. 15 and March 20, but decreases when 2,4-D butyl is used on April 4 and sigma used in three spray-time. In summary, 2,4-D butyl and sigma sprayed on April 4 has a more obvious effect on wheat quality than sprayed on Nov. 15 and March 20. Sigma sprayed on April 4 produces the lowest yield and quality of wheat.