The Regulation Of Ridge-Furrow Rainwater Harvesting Planting With Fertilization On Light Energy Utilization Of Winter Wheat In Semi-arid Area

Ridge and furrow rainwater harvesting planting system is gradually implemented in semi-arid areas because it can effectively improve the soil water temperature environment,promote crop growth,and have the effect of stabilizing production and increasing production.It has great practical significance to improve the light energy utilization rate of winter wheat and improve the ridge and furrow rainwater harvesting planting technology through reasonable fertilization.The study set four fertilization gradients(N₀P₀,N 0 kg hm^-2:P₂O₅ 0 kg hm^-2;N₉₀P₆₀,N 90 kg hm^-2:P₂O₅60 kg hm^-2;N₁₈₀P₁₂₀,N 180 kg hm^-2:P₂O₅120 kg hm^-2;N₂₇₀P₁₈₀,N 270 kg hm^-2:P₂O₅ 180 kg hm^-2)under the rainwater harvesting planting mode（conventional flat as the control）in a typical semi-arid area（Pengyang County,Ningxia）from 2017 to 2019.We analyzed the effects of fertilization amount on the photosynthetic physiological characteristics of winter wheat leaves,light energy utilization of canopy,yield composition,fertilizer utilization and economic benefits.The main results and conclusions are as follow.（1）Compared with conventional flat,rainwater harvesting can effectively improve the relative water content（RWC）,relative chlorophyll content（SPAD）,net photosynthetic rate（Pn）0.23%-13.87%,transpiration rate（Tr）0.36%-10.01%,stomatal conductance（Gs）1.69%-20.25%,leaf water use efficiency（WUE_L）0.05%-8.04%,maximal fluorescence（Fm）0.13%-11.99%,potential activity of photosystemⅡ（Fv/Fo）1.34%-19.44%,photosystem II maximum photochemical efficiency（Fv/Fm）0.12%-3.36%,actual photochemical efficiency（ΦPSII）0.05%-21.74%,photosynthetic electron transport rate（ETR）1.46%-31.04%.Fertilization significantly increased Pn,Tr,Gs,WUE_L,RWC,SPAD,Fm,Fv/Fo,Fv/Fm,ΦPSII,ETR,and the highest level appeared at N₁₈₀P₁₂₀,and there was no significant difference between N₂₇₀P₁₈₀.（2）Compared with conventional flat,rainfall harvesting can increase leaf area index（LAI）,photosynthetically active radiation capture rate（Ca R）in the upper and middle part of the canopy,and decrease photosynthetically active radiation penetration rate（Pe R）in the lower and middle part of the canopy,to increase photosynthetically active radiation interception accumulation（IPAR）0.44%-3.67%in the heading-maturity period of winter wheat.In addition,LAI,upper and middle Pe R of winter wheat increased with the increase of fertilization amount,and the lower and middle Pe R decreased with the increase of werh3fertilization amount.When the fertilization amount N₁₈₀P₁₂₀,the IPAR reached the highest.（3）In the growth season of 2017-2019,the yield of rainwater harvesting planting is5.04%higher than conventional flat,and the number of grains per ear is 8.15%.With the increase of fertilization,the average increase of grain yield,panicle number,panicle number and grain weight under the rain harvesting cultivation was 21.41%,5.03%,11.98%and 3.53%compared with that under the no fertilization of N₀P₀.Compared with conventional flat,rainwater harvesting can improve fertilizer utilization efficiency.The order of fertilizer partial productivity and agricultural efficiency was N₉₀P₆₀>N₁₈₀P₁₂₀>N₂₇₀P₁₈₀.（4）Compared with the conventional flat,the average net income of rainwater harvesting planting was 450 yuan·hm^-2.With the increase of fertilization,the net income increased first and then decreased.The net income of applying N₁₈₀P₁₂₀was the largest,which was 5150 yuan·hm^-2.In summary,applying N₁₈₀P₁₂₀(N 180 kg hm^-2:P₂O₅120 kg hm^-2)to winter wheat production in semi-arid areas can significantly improve the photosynthetic capacity of winter wheat flag leaves,optimize the canopy structure of winter wheat,and improve grain yield,fertilizer utilization and economic benefits,which is an efficient fertilization strategy suitable for winter wheat production in semi-arid areas.