The Citrus Orchards Soil And Tree Body Nutrient Status And Their Influence To Fruiting, Quality In Guizhou Karst Valleys

The production of citrus fruits was the long-term pillar industry in the karst river valley areas of Guizhou province, but in recent years some questions appearanced. Such as the citrus tree condition to decline ,the leaf lesion, the fruit abnormally, the fruit quality dropt and so on. In order to make clear the citrus orchards soil and tree body nutrient background value in karst river valleys of Guizhou province. And solve these questions which puzzling the local citrus fruits industry development, this topic has researched 101 citrus orchards soil and plants nutrient conditions, and the influence of the nutrient conditions to the citrus fruiting and fruits quality has been researched too.Investigating and Sampling places were collected in Guizhou Beipan Jiang basin, Duliu Jiang basin, Zhangjiang river basin, Wu River basin, Yachi River basin, Red River basin and Chishui River basin. The main results were as follows:Citrus orchards soil pH value was generally high in the karst river valley of Guizhou province, it was disadvantageous to the citrus fruits growth. The organic matter of soil was rich, the majority citrus orchards were in above the optimum range. In the soil massive elements, available N, available K, exchangeable Ca,exchangeable Mg were seriously deficient, especially deficiency of Mg to be most serious, but the available P content generally was all higher.In the soil trace element, available Cu and available Mn content deficient orchard were few, most orchard performance for high or excessive; Available Fe, available Zn and available B were seriously deficient, especially available B completely all were in the deficiency range, also had the majority sample to belong extremely deficient.In the citrus leaves massive elements of Guizhou karst river valley area, Mg content was seriously deficient; Next was K and N contents were deficient also serious; But P, Ca contents were quite rich, generally in above the optimum range .In the citrus leaves trace elements, B was seriously deficient; Next was Mn and Zn contents seriously deficient; Fe content was lightly deficient; Cu content was in above the optimum range.Between the contents of N, K, Ca, Mg, Zn, Mn, B in citrus plants and soil available N, available K, exchangeable Ca, exchangeable Mg, available Zn, available Mn , available B content, Except that citrus plants total B and soil available B were significant positive, others had no correlation.Between the citrus tree body nutrient relations were very complex, Antagonistic and accelerate effect among nutrition elements in citrus leaves were generally. P and K, Ca and Zn, Ca and Mn, Mg and Fe, Mg and B, Zn and Mn were significant positive correlation, K and Ca, P and Ca, P and Zn were significant negative correlation.Citrus (Ponkan mandarin) fruit set percentage and soil available K content and available B content were significant positive correlations; fruit set percentage and leaf Zn and B contents were significant positive correlations, there were no obvious correlations between other nutrient elements. There were significant negative correlations between citrus orchards soil exchangeable Mg content and the citrus abnormal fruits proportion and the total rate of lesion fruits in the karst river valleys of Guizhou Province.There was significant negative correlation between citrus orchards soil available B and the citrus small stiff fruits proportion, and between the abnormal fruits proportion and the total rate of lesion fruits there were very significant negative correlation.There were significant negative correlation between the Mg content in the citrus tree body nutrient and the abnormal fruits proportion and the citrus total rate of lesion fruits. Between the B content and the citrus small stiff fruits proportion and the citrus total rate of lesion fruits there were significant negative correlations. But there was very significant negative correlation between the abnormal fruits proportion and the B content.The findings indicated that, soil pH value higher also was one of the reasons which caused citrus fruit set percentage low and citrus fruits appeared nutritional deficiency disease in the karst river valleys of Guizhou province.Integrating the conclusion, the citrus orchards soil pH value was higher in Guizhou karst river valleys; The available K, exchangeable Mg ,available Fe and available B contents were seriously deficient in the citrus orchards soil, as well as in the citrus tree body nutrient Mg, Zn, B contents seriously deficient to the citrus fruit set percentage and the fruit quality have very tremendous negative influence. These were the important reasons which causing the citrus fruit set percentage low, fruit lesion and the quality dropt. In which, soil pH value was higher; exchangeable Mg content, available Fe content and available B contents were seriously deficient, could be considered as the soil main stress factors which limiting citrus fruits industry development in karst river valley areas of Guizhou province.