Dynamics of mineral elements in leaf and fruit of Actinidia chinensis and correlation analysis

Abstract: 【Objective】China is the country of origin of the kiwifruit and also is one of the major kiwifruit production countries. Shanxi,Sichuan and Henan province are the major production areas in China. In recent years, Jiangsu province has begun the work of kiwifruit introduction and cultivation. Mineral nutrition provides the substance basis for growth and development, yield formation and quality improvement of fruit tree. To provide the theoretical basis for balanced fertilization and for high-quality and high-yield cultivation, the research on the dynamics of mineral elements, fruit expanding law and their correlation in kiwifruit was carried out in Jiangsu hilly areas.【Methods】‘Hongyang'kiwifruit(Actinidia chinensis) in different growth period was used as experiment material, which grew in Zhenjiang Institute of Agricultural Sciences in Jiangsu hilly areas. Twenty leaves and fruits were collected from three vines between May 12 to October 12, and the fruit sample was taken on October 12. The samples were washed with tap-water,0.1% detergent solution, tap-water and deionized water respectively, and putted in thermostat at 105 ℃for 30 minutes and 90 ℃ for overnight. Unlike the leaf sample, the fruits were sliced before drying in thermostat. Then, the dry samples were grinded into powder and kept in the shade. The contents of element P,K, Ca, Mg, Fe, Mn, Cu, Zn and B in leaf and fruit were measured with nitric acid, hydrochloric acid and perchloric acid cooking naphthalene-ICP method, and the contents of element N were measured with sulfuric acid, hydrogen peroxide boiled-naphthalene's colorimetric method. The fruit expanding law was investigated by measuring the longitudinal diameter and transverse diameter of fruit using vernier caliper,and thirty fruits were measured every half a month from May 22 to September 19.【Results】During‘Hongyang'kiwifruit growth period, the contents of elements Ca, P, Mg, Zn, Mn, B and Cu were up trend in leaf, and down trend in fruit; the contents of element N and Fe showed a wavy change, but showed down trend as a whole; the dynamic change of the content of element K was small in leaf and fruit. Only the content of element K in leaf was lower than in fruit, the contents of element N, Ca, Mg, Zn, Mn, B, Cu and Fe were higher in leaf than in fruit, and element P was higher in fruit from May to July but higher in leaf from July to October. The macroelement content in leaf was N > Ca > K > Mg > P, and K > N > Ca > P > Mg in fruit; the content of Fe and Zn was much higher than that of element B, Cu and Mn in leaf and fruit. It should be noted that the element Zn in leaf increased sharply from July to August and reached the maximum in September, which might related with flower bud differentiation. May and June were the rapid fruit expanding period of‘Hongyang'kiwifruit, then the fruit expanded stably and slowly until fruit maturation period. During the fruit expanding period, the change trend of longitudinal diameter and transverse diameter of fruit was very similar. The correlation analysis between element in leaf indicated that there was significant negative correlation relationship between element Cu, P and Zn as well as Zn and Fe at 0.05 level, and significant positive correlation relationship between element Mn and Ca, Zn and Mg as well as Fe and N. Significant positive correlation relationship in fruit was universal, for example, between element P,Ca, Mg, B, Cu and Mn, but element Fe had no correlation with other elements, and element K only had significant positive correlation relationship with element Zn. There was significant negative correlation relationship between elements in leaf and in fruit, for example, element Ca had significant negative correlation relationship with element Mg, Cu, Mn and itself, and element Mg also existed the same relationship with element B, Cu, Mn and itself. In addition, correlation analysis between fruit expanding and mineral elements indicated that fruit expanding had significant negative correlation relationship with element N,P, Ca, Mg, B, Cu and Mn in fruit and element Mg and Zn in leaf, and had significant positive correlation relationship with element N in leaf.【Conclusion】This study suggested that the demand amount of elements for kiwifruit at different developmental stages was different. The element Zn increased from July to September, which would benefit the flower bud differentiation of kiwifruit.. Significant positive and negative correlation relationship between elements indicated that synergism and antagonism between mineral elements were universal. Fruit expanding was also related with the content of mineral element in leaf and fruit. The dynamic demand of mineral element in kiwifruit development phase in Jiangsu hilly area, the synergism and antagonism between elements and correlation between fruit expanding and elements in leaf and fruit would give instruction for the fertilization in kiwifruit orchard.