Study on the dynamics of kiwifruit tree biomass and calcium accumulation in the growth cycle

【Objective】 The research is to study the dynamics of calcium nutrient in kiwifruit tree,in order to provide a theoretical foundation for high quality kiwifruit tree and timely and proper fertilization of kiwifruit.【Method】 A field experiment was carried out on 10-year-old Actinidia deliciosa,Qinmei kiwifruit trees in growing seasons in Shaanxi Province,China.Biomass,calcium content and accumulation in different organs were studied in this paper.【Result】 The results showed that biomass increment of roots,stems,leaves and fruits was 2.21,7.06,2.73 and 8.21 t/hm2,total plant increased 20.21 t/hm2 in one year.Biomass of plant vegetated slowly from March 28 to May 18,and developed more quickly from May 18 to September 8,and dropped rapidly after fruit harvest and defoliation.Calcium content order in organs was leavesrootsstemsfruits.Calcium content of fruit was high in spring and dropped slowly after July.Calcium content in xylem changed less,but fluctuated in cortex.Calcium content in cortex of stems was 13.21-27.54 g/kg,in xylem of stems 1.12-2.14 g/kg,in cortex of roots between 19.03 g/kg and 25.00 g/kg,and in xylem of roots 6.35-7.55 g/kg.The study showed that trees could produce 50 kg fruits by absorbing calcium 378.85 kg/hm2.The calcium accumulation rose perpendicularly from March 28 to November 6,from 106.97 kg/hm2 to 255.21 kg/hm2,then dropped to 195.89 kg/hm2 in January 11(tree dormancy).【Conclusion】 Calcium content in leaves is the highest and in fruits the lowest,as calcium is difficult to transport from leaves to fruits.Fruits calcium content is higher in the earlier stage of growth and declines in the later stage of growth,so to increase the calcium content of ripe fruit,calcium should be fertilized directly on fruits in the later growth stage.