Effects Of Water And Fertilizer Regulation On Interspecific Interaction Of Apple-maize Intercropping System

Taking a typical applexmaize intercropping system in the loess region of Shanxi Province,China as test object,the current study analyzed the photosynthetic and water use effect under different irrigation and fertilization regimes.in order to explore a suitable water and fertilizer management system for the intercropping system.There were three irrigation levels[low?W₁?,50%field capacity?Fc?;medium?W₂?,65%Fc;and high?W₃?,85%Fc],three fertilizer levels {F1[N?289 kg·hm-2?+P₂O₅?118 kg·hm-2?+K₂O?118 kg·hm-2?];F2[N?412.4 kg·hm-2?+P₂O₅?168.8 kg·hm-2?+ K₂O?168.8 kg·hm-2?],F3[N?537 kg·hm-2?+P205?219 kg·hm-2?+K₂O?219 kg·hm-2?]},and a control?CK,no irrigation and fertilization throughout the growing season?.The nine irrigation and fertilization treatment combinations were W₁F1,W₂F1,W₃F1 W₁F2,W₂F2,W₃F2,W₁F3,W₂F3,and W₃F3,respectively which were determined based on the water and nutrient requirements of maize and apple trees in Shanxi.?1?The results indicated that:Irrigation and fertilization can increase soil moisture content by 7.6%than ck at filling stage,and 10.9%at maturation stage.There was not significant difference among different distances from the tree in the plot,so reasonable irrigation and fertilization can alleviate water competition between different species in intercropping system.the application of water and fertilizer can increase soil moisture content in deep soil layer?30-60cm?significantly at maturation stage.Therefore,the application of water and fertilizers can significantly improve soil moisture content in intercropping system.improve the water retention performance,and relieve the moisture interspecific competition.?2?The contents of soil nitrate nitrogen,ammonium nitrogen,available phosphorus and available potassium were increased with the increase of irrigation and fertilizer application rate.The available nutrient contents of experiment treatment were significantly higher than that of control,and the content of nitrate nitrogen increased by 3.98%?70.69%,The content of ammonium nitrogen was increased by 22.22%?114.73%,the available phosphorus content was increased by 0.23%?35.20%,and the content of available potassium was increased by 6.58%?17.67%,While There was no significant difference in organic matter content between experimental and control treatment.With the increase of irrigation fertilization,the soil nitrate nitrogen gradually accumulated to the lower layer;other available nutrients showed obvious table poly phenomenon.Therefore,the water and fertilizer supply can significantly improve the content of available nutrient in the intercropping system,and mainly improve the soil nutrient content of the crop absorption layer?0?20cm?.But excessive fertilization and irrigation will exacerbate the leaching and deep leaching of soil nutrients,which is not conducive to plant growth.?3?the application of water and fertilizers considerably increased the peak value of net photosynthetic rate?Pn?,extended the stomatal opening period,influenced the lowest value of intercellular CO2 concentration?Ci?,and reduced the maximum value of water use efficiency?WUE?during the day.The limiting factors affecting photosynthesis were nonstomatal factors.Stomatal conductance?gs?and transpiration rate?Tr?were both significantly negatively correlated with the distance from tree line?P<0.01?.WUE and light use efficiency?LUE?were significantly positively correlated with the distance from the tree line?P<0.05?.But the gradient of experient treatment significantly greater than that of the control group.The effect of water and fertilizer on the chlorophyll content of crop leaves was weak,but the application of water and fertilizers had a strong effect on leaf water potential.and it weakened the difference of chlorophyll among different distances from the tree.The horizontal distribution of leaf water potential showed great difference with different irrigation levels.therefore,the application of water and fertilizers significantly improved the photosynthetic and Physiological in intercropping system,but also intensifies the competition between interspecifics,reduces the plant water use efficiency.?4?.The water use efficiency of crops was influenced by irrigation factors,and the crop growth index was influenced by fertilization factors..Excessive irrigation and fertilization will inhibit plant height,leaf area and yield increase.Irrigation water use efficiency and water use efficiency decrease with the increase of irrigation amount.The results showed that the optimum fertilization control measures was as follows:Fertilize N 144.5 kg · ha^-1,P₂O₅ 59 kg·ha^-1,K₂O 59 kg·ha^-1 at tassel period;Fertilize N 144.5kg·ha^-1,P₂O₅ 59 kg·ha^-1,K₂O 59 kg·ha^-1 at filling stage.And when the upper limit of irrigation was set to 85%of the field capacity,the intercropping system can obtain the best soil moisture status,photosynthetic performance and maximum yield.However,limited by irrigation infrastructure and resources,when the upper limit of irrigation is set to 50%of the field capacity,the intercropping system can obtain the best net economic benefit of the apple-maize intercropping system in the western Shanxi loess area.This study shows that a reasonable water and fertilizer regulation can improve soil moisture and nutrient content,improve photosynthetic physiological characteristics,alleviate interspecific competition and increase systemic economic benefits.However,excessive fertilization and irrigation can also cause environmental pollution and resources waste,even intensify interspecific competition.The results of this study can provide theoretical basis for correct water and fertilizer system and interspecific interaction mechanism in intercropping system in the loess region of west Shanxi province...