Adversity Effect Of Continuous Cropping On Potatoes And Its Mitigation Methods

As China's population continues to grow,the demand for grain consumption in China is still on a rigid growth trend,Therefore,putting forward the strategy of potato staple food is conducive to alleviating the pressure of resources and environment,at the same time,it can guarantee the food security of our country,and it is of great significance to realize the sustainable development of agriculture.However,with the development of potato industry,the phenomenon of continuous cropping has become increasingly prominent,which leads to the accumulation of allelochemicals in soil.Potato plants will have serious autotoxic effects.Potato growth and development is poor,diseases and insect pests occur frequently,and soil pathogens accumulate and increase,resulting in a serious decline in stress resistance,yield and quality of crops.Therefore,exploring the mechanism and mitigation measures of continuous cropping on potatoes is a problem to be solved.In this experiment,Feueruita was used as material to plant potato for five consecutive seasons in pot experiment.Combined with different consecutive cropping methods under field conditions,the soil enzyme activities,physiological characteristics and plant growth and development of potato under different consecutive cropping years and different growth stages were discussed in order to provide theoretical basis for solving the obstacles of potato continuous cropping.The main results are as follows:1.The effects of continuous cropping on the morphological indexes and some enzymatic activities of potatoes in the first to third season were relatively small,and reached the maximum in the third season.The effects of continuous cropping on the area of leaves,plant height,fresh weight of leaves,fresh weight of roots and fresh weight of stems in the third to fifth season were stronger,but the effects of stem diameter and root volume were not obvious.Compared with the fourth season,the dry matter content of each organ decreased by 30.4%,49.8%,21.1%,27.8% and 47.7% in the fifth season,respectively.The decrease of average single tuber weight was the direct cause of yield decline.The decline was different in different growth stages,and the decline was more with the growth period as a whole.The activities of stress-resistant enzymes decreased as a whole,MDA content and membrane permeability increased,chlorophyll was less affected,soluble protein and soluble sugar content in potato leaves increased,soil enzyme activity decreased in different ranges,p-hydroxybenzoic acid content decreased,ferulic acid and vanillic acid increased.2.The application of EM fungi and biochar could alleviate the stress of continuous cropping on potatoes,promote the growth and development of potatoes,and plant height increased with the increase of biochar concentration.The application of EM fungi alone increased plant height by 31.9% and 41.2% respectively in two seasons.The plant height in two seasons reached the maximum value in A2B4 treatment.The application of biochar increased the fresh weight of leaves and roots of potatoes,but had little effect on the fresh weight of stems.The fresh weight of stem increased by 21.9% and 51.7% respectively after adding EM bacteria,which increased the dry matter quality of potato organs,increased the single potato weight,and increased the final yield.3.The activity of POD in potato leaves decreased by 53.9%,32.2% and 30.9% compared with the control group.The activity of SOD in budding stage and tuber swelling stage was increased.The activity of catalase was increased by applying EM fungi alone.The activity of POD in potato leaves was significantly decreased by applying EM fungi and biochar at all stages.The stress-resistant enzymes of potato leaves played a significant role in the early growth stage.The highest concentration of biochar was 26.7%,37.8% and 41.3% lower than that of the control group at each stage.With the increase of growth period,EM bacteria had little effect on MDA content of potato leaves at budding stage and tuber swelling stage,but had significant effect at maturity stage.Biochar and EM fungi can change the ratio of soluble protein to soluble sugar in potato leaves,reduce the relative membrane permeability of potato leaves,prevent the peroxidation of plasma membrane and maintain the function of leaf cells.EM fungi have stronger effect on maintaining the stability of leaf cell membrane when stress is strong.4.The application of biochar had different effects on soil enzyme activities.It increased sucrase,catalase,polyphenol oxidase and FDA hydrolase in soil,decreased acid phosphatase activity.The application of EM bacteria could improve all soil enzyme activities,and the promotion effect was stronger when applied with biochar at the same time.The contents of p-hydroxybenzoic acid,vanillic acid and ferulic acid in soil were reduced.5.Among the different continuous cropping patterns,the effect of continuous cropping obstacles on the potato rotation was the lowest,and the morphological indexes and dry matter quality were the highest.The root-shoot ratios were 0.121,0.121 and 0.116 in the three periods,respectively.The phenolic acid content of potato soil under potato rotation was the lowest as a whole.