| At present,the problem of crop planting density characteristics of physiological and ecological and resources use efficiency theoretical were relatively weakness.In order to study coupling of irrigation and nitrogen application optimizing the mechanism of maize planting density physiological and ecological characteristics,by measuring the change of characteristics of physiological and ecological index in maize growth period under different irrigation and nitrogen application ratio.Reveal the coupling of irrigation and nitrogen application maize planting density optimizating yield,water and nitrogen use efficiency for innovation irrigation and fertilizer application regime and planting technology to provides important scientific basis in oasis irrigation.Main conclusions are as follows.(1)The photosynthetic rate,chlorophyll content and other physiological indexes with the increase of planting density were decreased.It also had significant effect on filling layer light transmittance,LAI and other ecological indexes during maize growth period.Compared with high planting density treatment,the photosynthetic rate of maize under the medium planting density treatment increased by 15.9%,the chlorophyll of maize under the low planting density treatment increased by 10.2%,However,compared with medium planting density,the medium-lower layer light transmittance under the high planting density treatment reduced by 17.7%,the LAI under the medium planting density treatment increased by 9.1% in the growth period.The results indicated that optimized planting density could significantly increase the light intensity of middle layer and improve the leaf area index and chlorophyll content in the whole growth period.Within the same nitrogen application,compared with the irrigation of 20% reduction,the photosynthetic rate,chlorophyll content and leaf area index under the conventional irrigation treatment increased by 6.7%,4.8% and 18.7%,separately;under the same irrigation treatments,compared with the no nitrogen application,the photosynthetic rate and chlorophyll content under the medium nitrogen application treatment increased by 30.8% and 31.2%,the medium lower layer light transmittance under the medium nitrogen application treatment decreased by 32.6%,the leaf area index under the high and medium nitrogen application treatments increased by 60.4% and 58.0% in growth period,respectively.The results indicated that the rational combination of irrigation and nitrogen application could regulate group structure of the maize planting density,increase the LAI,improve light intensity of the middle layer and enhance photosynthesis in the growth period.(2)The soil water content of 0-120 cm soil layer with the increase of planting density,irrigation amount and nitrogen application were increased during maize growth period,increased planting density significant decreased soil nitrogen content in 0-80 cm soil layer at mature stage.The soil water content of the high planting density treatment was 6.4% higher than that of the medium planting density during the maize growth period.Under the same nitrogen application treatments,compared with the irrigation of 20% reduction,the soil water content under the conventional irrigation treatment increased by 3.8%;under the same irrigation treatments,compared with the no nitrogen application,the soil water content under the high nitrogen application treatment increased by 3.6%.The results indicated that reasonable combination of irrigation and nitrogen application could significantly improve the soil water content and water consumption of maize crop with high planting density.In the 0-40 cm soil layer,compared with the medium planting density,soil nitrate nitrogen and ammonium nitrogen accumulation under high planting density decreased by 14.1%,8.2%,under the same irrigation treatments,compared with the medium nitrogen application,soil nitrate nitrogen and ammonium nitrogen accumulation under high nitrogen application treatments increased by 11.4%,11.6%.In the 40-80 cm soil layer,compared with the medium density,soil nitrate nitrogen and ammonium nitrogen accumulation under the high density treatment decreased 14.3%,6.3%,compared with the irrigation of 20% reduction,the nitrate nitrogen and ammonium nitrogen accumulation under conventional irrigation treatment decreased by 12.9%,16.4%,compared with the medium nitrogen application,the nitrate nitrogen and ammonium nitrogen accumulation amount under high nitrogen application treatment increased by 16.2%,8.2%.The results showed that rational application of irrigation and nitrogen application could significantly reduce the nitrogen residue in 0-80 cm soil layer of maize crops with high planting density.(3)The planting density were increased had significant increased of dry matter accumulation growth rate,dry matter accumulation and yield effect of maize,but high planting density treatments had decreased yield.Compared with the medium planting density treatment,dry matter accumulation maximum growth rate and dry matter accumulation index in high planting density treatment increased by 12.4%,8.8%.Compared with the high planting density,the grain yield under medium planting density treatment increased by 11.2%,respectively.The results showed that increasing planting density could improve the dry matter accumulation maximum growth rate and dry matter accumulation of maize crop.Under the same nitrogen application treatments,compared with the irrigation of 20% reduction,dry matter accumulation maximum growth rate,grain yield and under conventional irrigation treatment increased by 4.6%,6.8%,respectively.Under the same irrigation treatments,compared with the medium nitrogen application,dry matter accumulation maximum growth rate and dry matter accumulation under the high nitrogen application treatments increased by 9.6%,3.9%.The results showed that the reasonable coupling of water and nitrogen could significantly improve the dry matter accumulation rate and increased the dry matter accumulation and grain yield at mature stage.(4)The planting density were increased had significant increased water use efficiency and nitrogen use efficiency of maize growth period,but high planting density treatments had decreased water use efficiency.The water use efficiency under medium planting density treatment increased by 9.7%,12.9% than that in low planting density and high planting density treatments.The nitrogen use efficiency under high planting density treatment increased by 37.4%,12.6% than that in low planting density and high planting density treatments.Under the same nitrogen application treatments,the nitrogen use efficiency of conventional irrigation treatment was 2.7% higher than irrigation of 20% reduction treatment;under the same irrigation treatments,compared with the no nitrogen application treatments,the water use efficiency under high nitrogen application and medium nitrogen application treatments increased by 38.9 %,37.5%,respectively.The nitrogen use efficiency of medium nitrogen application treatments increased by 27.2% than that of high nitrogen application treatments.The results indicated that optimized irrigation and nitrogen management could improve the water use efficiency and nitrogen use efficiency of maize crops with high planting density. |
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