Effects of zinc fertilization on the dynamics accumulation and distribution of dry matter and zinc in apple trees

A sand culture experiment was conducted to study the dynamic accumulation and distribution of dry matter and zinc in organs of apple trees under three zinc application levels, Zn 0.013, 0.254 and 5.07 mg/L. The results show that the growth and nutrient uptakes of apple trees are affected under both the deficiency and excess of Zn supplies. There are little effects on the accumulation and distribution of dry matter and nutrient under different zinc levels at the early growth stage, and the nutrients in roots and stems are utilized by branches and leaves for quickly growth. With the plant growth, the first peak of new roots turns up, the dry matter is accumulated quickly under different treatments, while the growth of roots is constrained by the deficiency and excess zinc supplies, and the zinc contents in each organs are significantly increased except branches and the order is Zn3 > Zn2 > Zn1. The dry matter accumulation is constrained by the deficiency and excess zinc supplies at the later growth stage, and zinc toxicity is happened under the excess zinc supply. The accumulation of zinc is increased quickly under the moderate and excess zinc supplies, however, the roots are increased under the deficiency treatment, and the distribution rate in root is significantly higher than that under the moderate and excess zinc supplies. These results indicates that at the later growth stage, the plant growth is constrained by the deficiency and excess zinc supplies; distribution rate of zinc in roots is higher than that in shoots under the lower zinc treatment, while the content of zinc in shoots is higher than that in roots under the moderate and excess zinc treatments.