Effects Of Calcium Fertilizer On Yield Formation Of Peanut And Its Physiological Basis Under Intercropping Condition

As a result of resource and environmental constraints,peanut planting area has been reduced year by year.The 3:4 intercropping mode of corn and peanut has become an important intercropping mode in the Huang-Huai-Hai region because it can achieve the goal of stabilizing grain and increasing oil.Because the growth and yield of intercropping peanut were mainly affected by the low light environment,the key of high yield and high efficiency cultivation technology of intercropping peanut was how to reduce the effect of intercropping and improve the ability of peanut shade tolerance.In this study,under the field condition of maize peanut 3:4 intercropping and peanut monoculture,Denghai 605 and Huayu 25 were selected as the experimental materials to study the differences of canopy climate factors between intercropping and monoculture in the growth period and in different periods of a day?In addition,different calcium treatments(CaO 0kg.hm^-2?150kg.hm^-2?300kg.hm^-2?450kg.hm^-2)were used to study the effects of calcium on the accumulation and transportation of photosynthetic products in different organs and the formation of yield and the physiological mechanism of calcium regulation.The main results are as follows:1.The intercropping of maize and peanut decreased the light intensity and increased the relative humidity of peanut canopy.Path analysis showed that canopy light intensity,canopy environmental humidity at pod setting stage and canopy environmental humidity at full fruit stage were the main climatic and ecological factors limiting pod yield of intercropping peanut.2.Intercropping significantly reduced the leaf area per plant,leaf area coefficient,dry matter accumulation per plant and dry matter accumulation of population in the middle and late growth stages of peanut,and calcium application alleviated the decrease.According to the regression equation,it was concluded that the suitable calcium application rate was 306?329kg.hm^-2.In this experiment,The best treatment which pod yield was the highest was that applied CaO 300kg.hm^-23.Intercropping inhibited the absorption and accumulation of calcium in stems and leaves,and promoted the absorption and accumulation of calcium in underground organs of peanut.Calcium application was beneficial to increase the biomass of peanut,increase the calcium content of stem,root,fruit needle,shell and kernel,increase the calcium distribution rate of peanut leaves,reduce the calcium distribution rate of peanut stem,and maintain the utilization rate of calcium fertilizer.Application of calcium increased the efficiency of calcium production,agronomic utilization of calcium fertilizer and partial productivity of calcium fertilizer.4.Intercropping resulted in the decrease of net photosynthetic rate,stomatal conductance and transpiration rate,and the decrease of carbon metabolism enzyme activity,which affected the number of full fruit per plant and 100 fruit weight,and finally reduced pod yield.Under the condition of this experiment,the application of calcium effectively improved the agronomic characters of peanut,improved the photosynthetic performance and carbon metabolism enzyme activity of leaves,increased the antioxidant enzyme activity of the last three leaves of the main stem of peanut,reduced the membrane permeability of peanut leaves,and maintained a high chlorophyllin content and fluorescence emission intensity at the late growth stage.Under the condition of supplementary light source,the photosynthetic rate of peanut functional leaves in intercropping middle row could reach the level of peanut monoculture without calcium fertilizer.The results showed that under intercropping condition,calcium application could partly alleviate the adverse effect of intercropping on peanut yield.5.Calcium application could increase the number of stomata and area index per unit area of peanut leaves,thicken the leaves,compact palisade tissue,increase the number of vascular bundles in leaves and stems,increase the number of chloroplasts per cell,and increase the size of chloroplasts and starch grains.The results showed that the negative effects of intercropping on stomata,leaf and stem cell structure of peanut could be alleviated by calcium application.This may also be the physiological mechanism of calcium application in peanut intercropping.In conclusion,canopy light intensity and canopy humidity were the main microecological factors limiting flower production in intercropping.Calcium application can alleviate the adverse effects of intercropping on peanut plant morphology,anatomical structure,growth and yield formation;increase the calcium content of peanut leaves,improve the photosynthetic production capacity and related enzyme activities of peanut leaves,improve the activity of antioxidant enzymes,delay aging,reduce the degree of membrane peroxidation,and improve the stability of cell membrane and cell structure.Under the condition of this experiment,the intercropping application of CaO 300kg.hm^-2is the most suitable amount of calcium.