| A field experiment with the split-plot design was conducted to study the effects of the application rates of nitrogen and growth regulator substances on the growth and grain yield of 2 winter wheat varieties.The result showed that seeds soaked with PP333 significantly increased the tiller number per plant at different N-application rates.The height of Xiaoyan 22 and Xiaoyan 6 were obviously decreased by spraying PP333 in jointing stage,and the decreasing rate of Xiaoyan 6(1.73 cm) was more obvious than that of Xiaoyan 22(1.57 cm).The leaf area and leaf SPAD value of the 2 cultivars were also increased by the PGRs during different growth phases;and the increase of leaf SPAD value was significant when the 6-BA was sprayed during the grain filling stage,which indicates the positive role of plant growth regulators(PGRs) in improving the grain filling by delaying the senescence of flag leaf and extending the function time of leaves.In addition,the grain number per plant,1 000-grain weight,and the yield were obviously improved by using PGRs in different growth phase.PP333BA increased wheat yield by 348.6 kg/hm2 and 601.2 kg/hm2 compared with PP333 and Water,respectively. |