Nutrients needed for the growth and development of walnut fruit trees

The growth and development of    fruit trees need two kinds of nutrients: one is organic nutrients, including amino acids, proteins, sugars and phospholipids, which account for 90% ~ 95% of the total dry matter, all of which are synthesized directly or indirectly by photosynthesis, which shows that photosynthesis is the basis of fruit yield formation. The other is inorganic nutrients, that is, mineral nutrients, which are mainly absorbed by roots from the soil, accounting for 5% to 10% of the total dry matter of trees. These two kinds of nutrients depend on each other and transform each other, which play a very important role in the growth and development of fruit trees.

The essential mineral elements for    fruit trees include nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), boron (B), zinc (Zn), copper (Cu), manganese (Mn), molybdenum (Mo), chlorine (C1) and so on. The demand for iron, manganese, copper, zinc and boron is small, and the content level in the plant is often expressed as a few parts per million, which is called "trace elements". Although the demand of fruit trees for various mineral elements varies greatly, each element has its own role and is indispensable. Otherwise, it will affect the growth and development of fruit trees and show corresponding symptoms. In addition, there are synergistic or antagonistic effects among the elements. Synergism means that the existence of one element can promote the root system to absorb another or more elements, that is, the effect of the combined application of the two elements will be better. Antagonism means that the excess of one element will inhibit the root system's absorption of another or more elements. Therefore, when applying fertilizer to fruit trees, we should pay attention to the proportion of various nutrient elements, and improper application will also affect the effect of fertilization. In the annual cycle of growth and development of walnut trees, it can be divided into two different nutrition stages: the use of storage nutrients and the use of synthetic nutrients.

The first stage of    is the nutrition stage based on the storage nutrition of trees. In the early stage of growth and development of walnut trees, such as sprouting, branching, leaf spreading, flowering and fruit setting, young fruit development, flower bud differentiation, root growth and other growth and development processes are completed by the storage nutrients of the tree. If the storage nutrients are sufficient, the sprouting is early, the leaves spread evenly, the new shoots grow rapidly, the fruit setting rate is high, and the quality of flower bud differentiation is high. At the same time, when the storage nutrients are sufficient, the nutrient conversion period begins and ends early, which can lay the foundation for high yield and high quality. As the nutrition source of the growth and development of walnut trees in spring is mainly the nutrition accumulated in the autumn of the previous year, strengthening autumn management and improving the level of storage nutrition is the basic guarantee to achieve high yield and high quality.

The second stage of    is the nutrition stage which mainly uses the synthetic nutrients of the current year. With the end of the rapid growth period of the spring shoot of walnut, the storage nutrients of the tree were exhausted, while the leaf area generated in that year increased rapidly and the photocontract products gradually increased. The tree began to change from the stage of using storage nutrients to the stage of using assimilation nutrients in the same year. In this stage, the level of tree nutrition is closely related to the growth rate of walnut leaf area, leaf size and photosynthetic intensity. Therefore, scientific fertilization and improving the nutritional status of trees are important technical ways to achieve high yield and high quality of walnut.