Ecological conditions for the growth and development of walnut

   walnut can grow in many areas of China, reflecting that walnut has a strong ability to adapt to natural conditions. However, walnut growth has relatively strict requirements for suitable growth conditions, and thus formed a number of main walnut producing areas. Although it can survive beyond its suitable conditions, it often loses its cultivation significance, such as poor growth, low or no yield, poor nut quality and so on.

The picture shows walnut

   I. Lighting

   walnuts like light. After entering the fruiting period, sufficient light conditions are needed. The annual sunshine hours should be more than 2000 hours in order to ensure the normal growth and development of walnut. If less than 1000 hours, both nucleolus and nucleolus are underdeveloped. Especially in the annual period, sunshine hours and intensity have important effects on walnut growth, flower bud differentiation and flowering and fruiting.

   the annual sunshine of Aksu and Kuqa in Xinjiang early-fruiting walnut producing areas is more than 2700 hours, and the sunshine hours in the growing period (April to September) are more than 1500 hours. The walnut yield here is high, the quality is good, and sufficient light is one of the important factors. Similarly, all the plants at the edge of the walnut orchard showed good growth and more fruit, and the same plant had more fruit on the outer branches than on the inner branches, which was also related to the light conditions. Therefore, the problem of light must be considered in cultivation from the aspects of garden selection, planting density, cultivation mode, shaping and pruning, etc.

   II. Temperature

   walnut belongs to temperature-loving tree species, and most of its natural producing areas are in warmer areas, but different varieties are suitable for different temperatures.

   1. The suitable temperature range and frost-free period for common walnut are annual average temperature 9-16 ℃, extreme minimum temperature-25 ℃, extreme maximum temperature below 38 °C, frost-free period more than 150days. During the dormant period, young walnut trees can suffer frost injury under the condition of-20 ℃. Although adult trees can withstand the low temperature of-30 ℃, but when the temperature is lower than-28 ~-26 ℃, branches, male flower buds and leaf buds are vulnerable to freezing injury. In Yining and Urumqi, Xinjiang, when the extreme minimum temperature reaches-37 ℃, walnuts can not bear fruit and most of them grow in small trees or clumps. After leaf spreading, if the temperature drops to-4 ~-2 ℃, the new shoots can be frozen. In flowering and young fruit stage, when the temperature dropped to-2 °C, the yield was reduced by freezing. In areas where the temperature is too high, such as more than 38-40 ℃, the fruit is vulnerable to sunburn and the nucleolus can not develop.

   2, iron walnut only adapt to subtropical climate conditions, resistant to hot and humid, not resistant to dry and cold. The annual average temperature in the suitable planting area is 12.7-16.9 ℃, the coldest monthly average temperature is 4-10 ℃, and the extremely lowest temperature is-5.8 ℃. It is difficult to overwinter if it is too low. For example, when introduced to the Beijing area, when the seedlings are 3 or 4 years old, if they are not protected against the cold, they can freeze to death even their roots in winter.

   's study on walnut (cultivated species of iron walnut) in Yunnan showed that the average temperature in May was significantly negatively correlated with the yield of pickled walnut, that is, the yield of walnut decreased in the year with high average temperature in May, and there was also a negative correlation between the average temperature in August and walnut yield, because the walnut fruit was easy to burn and fall off under high temperature.