| At present,continuous cropping obstacles are one of the problems that restrict the healthy and sustainable development of agriculture in China.For many years,the kidney bean planting has slowed its growth and development,reduced its yield and decreased its quality.Based on this,this study investigated the current situation and causes of continuous cropping obstacles in cowpea in Jiangxi Province and proposed to explore ways to effectively alleviate continuous cropping obstacles in cowpeas through biodiversity and green environmental protection technologies.The experiment used celery and gynura bicolor as a companion crop,garlic and mustard straw as decomposition materials and mustard extract to treat cowpea.By analyzing the effects on the growth and development,physiological indicators,soil physical and chemical properties,and microbial community structure of cowpea,this paper discussed its mechanism of action for alleviating continuous cropping obstacles of cowpea and provided a practical theoretical basis for practical production.The main results were as follows:1.In order to further understand the main causes and control situation of the obstacle of cowpea,six major cowpea producing areas were selected for investigation in Jiangxi province.The results showed that there were different levels of continuous cropping problems in the cowpeas in Jiangxi province.Among them,the degree of continuous cropping in the Xin’gan and Gao’an regions was relatively serious,and the average incidence of cowpea reached more than 27.4%.The investigation of fertilization and continuous cropping cowpea soil determination showed that the contents of ammonium nitrogen and available potassium in the main nutrients in the continuous cropping cowpea soil were significantly uneven,and partial fertilization,improper management of fertilizer and water resulted in unbalanced soil nutrients.In addition,correlation analysis of cowpea continuous cropping years,soil pH,electrical conductivity and incidence rate were carried out.Continuous cropping cowpea soil had acidification trend and negatively correlated with continuous cropping years.The trend of soil acidification in continuous cropping cowpea was negatively correlated with the duration of continuous cropping,and there was a significant difference.However,the soil electrical conductivity and incidence rate showed the opposite trend and was positively correlated with the continuous cropping years,and there was a significant difference.Based on the analysis of the causes of continuous cropping obstacles in cowpea,it was concluded that soil nutrient imbalance,soil secondary salinization,acidification,and soil-borne diseases were the main causes of continuous cropping obstacles in cowpea.2.The effect of growth and rhizosphere soil properties by celery and gynura bicolor as companion crops of continuous cropping cowpea were studied.The results showed that,compared with the monoculture control,the plant heights,stem diameters,shoot fresh and dry weights of cowpea were significantly increased by 24.0%,9.1%,16.1% and 16.0% in the celery treatment,respectively.At the same time,chlorophyll content,peroxidase(POD)and glutathione reductase(GR)and dehydrogenation ascorbic acid reductase(DHAR)activity also increased significantly,and catalase(CAT)activity also improved,but there was no significant difference with CK.The accompanied celery and gynura bicolor treatments could significantly increase soil enzyme activity(invertase,polyphenol oxidase and acid phosphatase),soil pH,and decrease soil conductivity.The accompanied treatment of celery could significantly increase the content of actinomycetes and reduce the content of fungus.Finally,both modes of companion significantly improved the yield of cowpea.3.The effect of different straw decomposition materials on the soil micro ecological environment of cowpea continuous cropping soil and the physiological indexes of cowpea seedlings were investigated in this experiment.The results showed that,compared with CK,garlic and mustard straw decomposition could significantly increase soil pH,reduce soil electrical conductivity,and increase soil enzyme activity in cowpea continuous cropping;and both could significantly increase the number of bacteria and actinomycetes and reduce the number of fungus in the soil.After planting cowpea,the mustard straw treatment significantly increased the plant height,stem diameter,fresh weight,dry weight,and strong seedling index of cowpea seedlings.There was no significant difference in growth index between garlic straw treatment and CK treatment.Both treatments could significantly increase the chlorophyll content of cowpea leaves;meanwhile,they also increased the activities of CAT,POD and superoxide dismutase(SOD),and significantly reduced the malondialdehyde(MDA)content.4.To explore physiological mechanism of the influence of the aqueous extract of mustard on seed germination and early seedling growth of continuous cropping cowpea.The results showed that the high concentration mustard extract had a strong inhibitory effect on seed germination and radicle growth,while low concentrations had a significant effect on seed radicle growth and seedling growth.The comprehensive index of cowpea seedlings treated with 10 g·L-1 extract solution was the best.Watering continuous cowpea cropping soil with aqueous extract of mustard increased soil pH and soil enzyme activity and decreased soil electrical conductivity.The plant height,stem diameter,dry weight,fresh weight,strong seedling index,and root length,root surface area,root volume,root tip number and other growth indexes of cowpea seedlings could be increased to varying degrees.The the aqueous extract of mustard treatment could also promote the outbreak of hydrogen peroxide(H2O2)in seedling leaves,and promote the activity of SOD,CAT,POD,GR and DHAR. |
