Study On Leaf Chlorosis Causes And Plant Nutritional Diagnosis Of Jujube

Nutritional diagnosis is one of the important means to understand the nutritional status of plants and guide precise fertilization,but so far there is no systematic and comprehensive research on leaf and soil nutrition diagnosis of local winter jujube..To this end,based on the investigation of farmers,this study carried out nutritional diagnosis of winter jujube cultivated in Dali facilities,and used DRIS diagnostic method to comprehensively analyze the nutritional status of jujube leaves,and to explore the correlation between soil physical and chemical properties,leaf nutrient element content and fruit quality.,aiming to clarify the nutrient abundance and deficiency of jujube orchards in this area,to identify the key factors of leaf yellowing of winter jujube,and to explore the correlation between mineral elements and quality.The main research results obtained are as follows:(1)The DRIS diagnostic method was used to diagnose the leaves of winter jujube in the winter jujube production area of Dali County,Shaanxi Province.The suitable ranges of mineral elements were N: 27.938 ～ 46.625 g / kg,P: 1.474 ～ 3.682 g / kg,K:19.377 ～ 31.123 g / kg,Ca: 6.720 ～ 16.744 g / kg,Mg: 1.582 ～ 3.718 g / kg,Mn: 27.098～ 77.016 g / kg,B: 35.550 ～ 90.588 g / kg,Cu: 5.401 ～ 13.547 g / kg,Zn: 21.618 ～55.044 g / kg,Fe: 31.536 ～ 72.104 g / kg.According to DRIS diagnostic index,the order of fertilizer demand of winter jujube is Ca > Mn > Cu > Fe > Zn > Mg > K > N >P > B.therefore,the fertilization of winter jujube in Dali facilities should pay more attention to and supplement the medium amount elements calcium,trace elements manganese,iron and zinc.(2)From the analysis of soil nutrients in the facility-cultivated winter jujube orchards in Dali County,37.6% of the jujube orchards had a soil p H above 8.5,54.5%of the jujube orchards lacked organic matter,and 20.6% of the jujube orchards had a serious lack of available phosphorus content,while the content of available potassium relatively abundant.20.6% of the jujube orchards were seriously deficient in available manganese,21.7% of the jujube orchards were deficient in available iron,34.9% of the jujube orchards were deficient in available zinc,and 40.8% were deficient in available calcium.According to the analysis of the reasons for the yellowing of winter jujube leaves in this area according to the grading standard,it was found that 56.5% of the 62 jujube orchards with yellow leaves were lacking two or more elements at the same time,and jujubes lacking both available iron and available manganese at the same time accounted for 56.5%.The garden accounted for the largest proportion,reaching 19.4%,and the jujube gardens lacking both available calcium and manganese accounted for16.1%,indicating that the yellowing of the leaves of the nutrient-deficient winter jujube was mainly caused by the lack of two and two essential nutrients.(3)The fruit quality of winter jujube cultivated in different facilities was significantly different.The fruit shape index of winter jujube cultivated in warm shed(solar greenhouse)is high and the hardness is the lowest.The content of soluble sugar and soluble solid is higher than that of the other three kinds of facility cultivation.The single fruit weight and yield of winter jujube in steel frame cold shed are the highest.The Vc content of winter jujube cultivated in cold shed(including bamboo,ordinary rain proof and cold shed)is the highest and the fruit hardness is the highest.Based on the comprehensive analysis of the fruit quality of winter jujube,it is concluded that the winter jujube cultivated in greenhouse tastes crisp and sweetest.(4)K,Ca,Mg,B and other mineral elements had significant effects on the quality of jujube.Through the correlation and path analysis between mineral elements and quality indexes in winter jujube fruit,the correlation results showed that K was significantly positively correlated with single fruit quality,Mg was significantly positively correlated with fruit hardness,and Ca was positively correlated with fruit hardness;The results of path analysis showed that K element in fruit was the main factor affecting the single fruit quality,titratable acid and soluble solids of winter jujube,and Ca element was the main factor affecting vitamin C of winter jujube;Coordinating the proportion of mineral elements in the production management of winter jujube can improve the quality and achieve the purpose of high-quality production.To sum up,the DRIS diagnosis results of jujube leaves make up for the gap in nutritional diagnosis of winter jujube plants.Combined with the diagnosis results of soil and leaves,it is found that there is no lack of available copper in soil,and there is a relative lack of copper in leaves.It may be that calcareous soil or excessive phosphorus fertilizer hinder the absorption of copper by winter jujube plants.Except for Cu,the soil diagnosis is basically consistent with the diagnosis results of DRIS.The conclusion provides a scientific basis for rational fertilization of local winter jujube industry.