| Quinoa(Chenopodium quinoa Willd.)is a species of Chenopodiaceae in Amaranthaceae family with a long history of cultivation and has been widely cultivated all over the world for its rich nutritional value,potential medicinal function,good stress tolerance and high economic value.In recent years,with the deepening of global quinoa research,the successful development of quinoa economic value and the continuous increase of consumers’ demand,the cultivation scale of quinoa industry has been expanding in China.However,due to the limitation of land resources,planting structure and other factors,continuous cropping is often used as the main crop cultivation mode for quinoa.The soil of continuous cropping for many years will have problems such as the increase of diseases and pests,the accumulation of toxic substances and the decrease of microbial abundance,which is not conducive to the growth and yield improvement of quinoa.In the rotation system,reasonable fore crops and diversified cultivation methods can play an important role in improving soil physical,chemical properties and microbial community structure,so as to promote crop growth.Therefore,through two-year field experiments,this study studied the effects of multi-year quinoa stubble,multi-year alfalfa stubble and one-year double season oat stubble on the grain yield,1000 grain weight,plant properties,soil nutrients,soil enzyme activity and soil bacterial community of quinoa,and analyzed the factors of quinoa yield difference between different previous crop treatments,so as to provide a theoretical basis for the selection of high-yield cultivation mode of quinoa.The main conclusions of this experiment are as follows:(1)Different previous crops significantly affected soil nutrient content.Continuous cropping of quinoa reduced the soil p H value and the contents of total nitrogen,nitrate nitrogen and available potassium,increased the contents of soil ammonium nitrogen and available phosphorus to a certain extent,and the effect on the content of soil total organic carbon varies greatly between years.Double season oat stubble increased the soil p H value to a certain extent and significantly reduced the contents of soil total organic carbon,total nitrogen,ammonium nitrogen,nitrate nitrogen,available phosphorus and available potassium.Alfalfa stubble significantly increased the soil p H value and the contents of soil total organic carbon,total nitrogen,ammonium nitrogen,nitrate nitrogen and available potassium,but it will cause the shortage of soil available phosphorus to a certain extent.Therefore,alfalfa stubble is beneficial to improve the soil nutrient content,and double season oat stubble and quinoa continuous cropping will reduce the soil nutrient content to varying degrees.(2)Different previous crops had significant influence on soil enzyme activity.Continuous cropping of quinoa reduced soil α-1,4-glucosidase,β-1,4-glucosidase,β-1,4-xylanase,cellobiohydrolase and acid phosphatase activity,and the effect on the activity of L-leucine aminopeptidase and β-1,4-N-acetylglucosaminidase varies greatly between years.Double season oat stubble significantly reduced the activity of soil α-1,4-glucosidase,β-1,4-glucosidase,β-1,4-xylanase,L-leucine aminopeptidase and acid phosphatase,and the effect on the activity of cellobiohydrolase and β-1,4-N-acetylglucosaminidase varies greatly between years.Alfalfa stubble significantly improved the activity of soil α-1,4-glucosidase,β-1,4-glucosidase,β-1,4-xylanase,cellobiohydrolase,L-leucine aminopeptidase,β-1,4-N-acetylglucosaminidase and acid phosphatase.Therefore,alfalfa stubble is conducive to improve soil enzyme activity,and double season oat stubble and quinoa continuous cropping will reduce soil enzyme activity to varying degrees.(3)Different previous crops will affect α Diversity and community structure of soil bacteria.Compared with continuous cropping of quinoa,alfalfa stubble and double season oat stubble were beneficial to improve the indexes of soil bacteria Chao1 and ACE at the flowering stage of quinoa.In addition,alfalfa stubble was also beneficial to improve the Simpson index and Shannon index of soil bacteria.Different previous crops will significantly affect the relative abundance of some bacteria in the soil.Among them,the relative abundance of Bradyrhizobium and Ensifer involved in nitrogen fixation is the highest in alfalfa stubble.Under the three previous crop treatments,the dominant groups of soil bacteria at the level of phylum are Proteobacteria,Acidobacteria and Bacteroidetes,and the dominant groups at the class level are Gammaproteobacteria,Alphaproteobacteria,Bacteroidia,Deltaproteobacteria and Gemmatimonadetes,but the abundance of these dominant groups is different under different previous treatments.(4)Different previous crops had significant effects on the grain and plant characters of quinoa.Alfalfa stubble has a better effect on improving quinoa grain yield,1000 grain weight,stem diameter and chlorophyll content of quinoa,which is related to alfalfa stubble is conducive to improving nutrient content,enzyme activity and bacterial community structure of soil.Continuous cropping of quinoa is not conducive to the accumulation of soil nutrients and the improvement of soil enzyme activity,but its effect on the yield and growth of quinoa is not significantly different from that of Alfalfa stubble.The grain yield,1000 grain weight and plant characters of quinoa under the treatment of double season oat stubble were significantly lower than those of the other two treatments,which was caused by the decrease of soil nutrient content and soil enzyme activity after oat planting.In summary,quinoa is not suitable for continuous cropping,and the planting mode of rotation can be adopted in quinoa planting,and leguminous crops such as alfalfa crop can be selected in rotation as previous crop to improve the soil ecological environment and improve crop yield.In addition,it is not suitable to set up the cultivation mode of double season in quinoa rotation,because the double season cultivation mode increases the consumption of soil fertility of crops,which leads to the decrease of soil nutrient content and soil enzyme activity,thus resulting in crop yield reduction. |
PDF Full Text Request