Establishment Of Mineral Nutrient Content Standards And Nutritional Diagnosis Of Citrus Leaves In China

This article mainly analyzes the mineral nutrient content of different citrus varieties in the main citrus production areas in 11 Provinces(Cities,Districts)which included Hubei,Hunan,Jiangxi,Guangdong,Guangxi,Fujian,Chongqing,Yunnan,Sichuan,Shanxi,Zhejiang,etc.The appropriate range of mineral element content in the leaves of the three major varieties of mandarin,orange and pomelo;Two nutritional diagnostic methods,DRIS and DOP,were used to diagnose mandarin and orange leaves to determine the order of fertilizer requirements,and to provide scientific basis for rational fertilization,quality improvement and yield increase in citrus orchards.The main conclusions of this research are as follows:(1)It is preliminarily determined that the appropriate values of mineral nutrients of mandarin leaves are: N(2.5-2.9)%,P(0.13-0.17)%,K(1.0-1.4)%,Ca(2.6-3.6)%,Mg(0.24-0.30)%,Fe(75-120)mg/kg,Mn(25-75)mg/kg,Cu(5.0-14.0)mg/kg,Zn(14-22)mg/kg,B(30-80))Mg/kg,the N element is lower than the domestic level,which is basically the same as the Japanese satsuma mandarin,and the Mg and Zn elements are lower than the domestic level.The appropriate values of mineral nutrients of orange leaves are: N(2.5-3.0)%,K(0.13-0.18)%,K(1.0-1.6)%,Ca(2.8-4.2)%,Mg(0.20-0.26)%,Fe(60-130)mg/kg,Mn(30-100)mg/kg,Cu(6-14)mg/kg,Zn(13-20)mg/kg,B(40-80)mg/kg,The levels of Ca and Zn were lower than those in foreign countries,while the levels of Mn were higher.The optimum values of mineral nutrients in grapefruit leaves are: N(2.4-2.7)%,P(0.13-0.16)%,K(1.3-1.7)%,Ca(2.8-3.7)%,Mg(0.32-0.38)%,Fe(60-200)mg/kg,Mn(35-75)mg/kg,Cu(8-20)mg/kg,Zn(25-45)mg/kg,B(35-80)mg/kg,The levels of K,Mg and Zn were lower than those in China,while the levels of Ca and B were higher.(2)There are certain differences in the mineral nutrient content of the leaves of different citrus varieties.Among the mandarin,The contents of P,Ca and B in leaves of satsuma mandarin are higher than those of ponkan,and the contents of Mg and Fe in the leaves are lower than those of ponkan.The content of B and B is lower than that of Newhall navel orange.Among pomelos,the content of Ca,Mg and Mn in the leaves of Shatian pomelo is higher than that of Guanxi pomelo,and the content of Fe,Cu,and B is lower than that of Guanxi pomelo.(3)By comparing the three varieties of mandarin,orange and pomelo,it can befound that the content of K in mandarin leaves is the lowest,the content of Mn in orange leaves is the highest,and the content of Fe,Cu,Zn and B in pomelo leaves is generally high.(4)Through the two nutritional diagnosis methods of DRIS and DOP,the mineral nutrient status of mandarin leaves was analyzed.The diagnosis results of the DRIS method in each main production area are as follows: Hunan,Guangxi,Fujian,Jiangxi,and Chongqing need to strengthen the application of Mg fertilizer,Guangdong and Zhejiang need to strengthen the application of Ca and Mg fertilizers,Chongqing recommends reasonable supplementation of Mn and Cu fertilizers,and Shanxi appropriately strengthens the application of B fertilizers.All provinces and cities need to strengthen the application of Zn fertilizer.The diagnosis results of DOP method are as follows: Hunan,Jiangxi,Yunnan,Chongqing,etc.need to strengthen the application of Mg fertilizer,Guangxi and Fujian need to strengthen the application of Ca and Mg fertilizer,Shaanxi and Hunan can appropriately increase the amount of B fertilizer,and Chongqing should reapply Cu fertilizer.Most areas should pay attention to the application of Zn.(5)Through the two nutritional diagnosis methods of DRIS and DOP,the mineral nutrient status of orange leaves was analyzed.The diagnosis results of the DRIS method in each main producing area are as follows: Hubei,Hunan,Guangxi,Yunnan,Chongqing,Jiangxi and Sichuan all need to strengthen Zn And Mg fertilizer application,Hunan needs to apply N fertilizer appropriately,Chongqing and Sichuan appropriately strengthen the application of B fertilizer,in addition,Chongqing should also pay attention to the application of Mn fertilizer.The diagnosis results of DOP are as follows: Hubei,Hunan,Guangxi,Yunnan,Chongqing,Jiangxi,Sichuan all need to strengthen the application of Zn and Mg fertilizers,Hunan and Chongqing should appropriately strengthen the application of B fertilizer,and Chongqing should also pay attention to the application of Mn fertilizer.(6)For pomelos to further improve the fruit quality,it is suggested to improve the soil,increase the soil p H,pay attention to the supplement of Mg,Zn and other elements,appropriately reduce the amount of B fertilizer,and rationally apply medium micro fertilizer.