| In order to explore the impact of shading,nitrogen fertilizer and their interaction on wheat,using Xin dong 20 as material,set up S1:jointing stage 10%-heading stage 25%,S2:jointing stage 20%-heading stage 50%,S3:jointing stage 30%-heading stage 75%,S0:0%four shading levels,with the whole growth period of no fertilizer（F0）,jointing stage（after shading）nitrogen 103.5 kg/hm2（F1）,138 kg/hm2（F2）and172.5 kg/hm2（F3）four levels of fertilization,studied the regulation effect of shading,nitrogen fertilizer and their interaction on the winter wheat growth and yield.This experiment mainly shows:（1）Nitrogen levels and shading intensity have significant effect on winter wheat yield.Under the same shading condition,with the increase of nitrogen application the number of grains per spike increased first and then decreased;the number of harvested panicles increased and the grain weight decreased.Under the same fertilization conditions,with the increase of shade intensity the spike number,grain number and grain weight were decreased.Shading and nitrogen interaction significantly affect the grain number and grain weight（P<0.05）,impact on spike number is not significant.Nitrogen levels and shade intensity significantly affected the yield of winter wheat（P<0.05）.Under the same shading condition,with the increase of nitrogen application the,winter wheat yield increased first and then decreased,when the amount of nitrogen increased from F2 to F3,the yield decreased;with the increase of shade intensity the yield decreased.Different shading and nitrogen treatments on yield had significant interaction effects,nitrogen treatment showed positive effects on yield,shading shows a negative effect on yield,and the shading effect is greater than the effect of nitrogen fertilizer.（2）At the flowering stage,in S0,S1 and S3 shading,with the increase of nitrogen,winter wheats flag leaf photosynthetic rate increased first and then decreased,in the S2 shading treatment flag leaf photosynthetic rate increased with the increase of nitrogen.Under the same nitrogen conditions,at different growth stages,with the increasing intensity of shading winter wheats flag leaf photosynthetic rate decreased;shading and nitrogen interaction significantly affect the winter wheats flag leaf photosynthetic rate.Under the same shading condition,the chlorophyll content of flag leaves in winter wheat increased with the increase of nitrogen application rate.Under the same nitrogen conditions,with the increase of shade intensity the chlorophyll content of flag leaf of winter wheat decreased.Under the same shading condition,the leaf area index of winter wheat increased with the increase of nitrogen application rate.Under the same nitrogen conditions,with the increase of shade intensity the leaf area index of winter wheat were increased firstly and then decreased.（3）Shading has a significant influence on the spike number and spike rate of tiller（P<0.05）,no significant effect on the highest number of stems,tillers and panicle weight proportion;Nitrogen fertilizer had significant effects on panicle number,maximum number of stems,tiller percentage,panicle weight and panicle weight of main stem.Under the same shading condition,fertilizing significantly increased the panicle number,maximum stem number,tillering rate and tiller percentage（P<0.05）.The panicle weight of main stem decreased with the increase of nitrogen application rate.Under the same nitrogen conditions,with the shading intensity increased the spike number,the highest number of stems were decreased.（4）Nitrogen levels and shading intensity have significant effect on winter wheats dry matter accumulation（P<0.05）.at anthesis,filling stage and heading stage increased with the increase of nitrogen rate;The amount of dry matter accumulation after anthesis increased first and then decreased with the increase of nitrogen application rate.In different periods,Shading decreased the winter wheats dry matter accumulation.As time goes by,the dry matter accumulation of stems,leaves and shells of winter wheat decreases gradually,and the dry matter accumulation in grain increases.Under the same shading condition,with the increase of nitrogen,in different periods of vegetative organs dry weight were increased.Under the same nitrogen conditions,shading were reduced in different periods of vegetative organs dry matter weight.In S0,S1 and S2 shading conditions,with the increase of nitrogen,translocation amount of dry matter in vegetative organs before anthesis,translocation ratio of dry matter in vegetative organs before anthesis and contribution of dry matter translocation amount in vegetative organs to kernel before anthesis were increased;but In the S3 shading condition,with the increase of nitrogen they are decreased.Under the same nitrogen conditions,assimilation amount of dry matter after anthesis and the contribution rate to grain increased first and then decreased with the increase of nitrogen application rate. |
