Walnut has strong adaptability. Walnuts are widely distributed in China, with 2 1 province (city) planting walnuts. From Mengla County in Yunnan at 2 1 degree 08'32 "north latitude to Lexian County in Xinjiang at 44 degrees 54' north latitude; 75 degrees east longitude 15' from Tashkurgan, Xinjiang to Dandong, Liaoning 124 degrees 2 15'. From Buweike village in Turpan, Xinjiang, about 30 meters above sea level, to Lasi in Tibet, 4200 meters above sea level. It's all planted. Walnut, on the other hand, has strict requirements on suitable conditions, such as large differences, although it can survive, but it has poor growth and fruiting, poor economic benefits and little cultivation significance.

First, walnut planting conditions

(1) temperature

Walnut is a warm-loving tree species, and the suitable temperature range and frost-free period are: annual average temperature 9 degrees-16 degrees, extreme minimum temperature minus 25 degrees-minus 2 degrees, extreme maximum temperature below 38 degrees, and frost-free period 150 days. The cold tolerance of walnut after germination in spring is low. If the temperature drops to -2-4 degrees, the new buds will be frozen stiff. When the temperature drops to-1-2 degrees during the flowering and young fruit period, the yield will be reduced due to freezing. When the temperature exceeds 38 degrees in summer, the fruit is easy to be burned, and the nucleolus can not develop normally or turn black.

(2) Lighting

Walnut is a positive tree species that likes light and is suitable for growing in the sunny place of the north wind. Planting in low mountain areas with an altitude of 300-700 meters has high and stable yield. Walnut needs sufficient light conditions after entering the fruiting period, and the annual sunshine hours should be more than 2000 hours to ensure the normal growth and development of walnut. If it is less than 65,438+0,000 hours, the core-shell and nucleolus will be stunted. In cultivation, light must be considered from the aspects of garden selection, planting density, cultivation method, shaping and pruning.

(3) Soil

Soil is the foundation for the growth and development of all plants. Walnut is suitable for growing on warm sandy soil and black loam with deep soil layer and good drainage, and should be planted on sunny slopes and leeward. It doesn't grow well in the soil with high groundwater level and high viscosity. But it grows best in weak alkaline soil containing calcium. The adaptive range of soil PH value is 6-8, and the soil salt content should be below 0.25%, with 6-7 being the best. A little more will have an impact on the growth results. Too much salt will lead to death. The huge root system and tree body of walnut need deep soil layer (more than one meter) to ensure its good growth and development. Walnut trees like fertilizer, and all kinds of nutrients can be satisfied, so that they can grow and bear fruit normally, otherwise, they will form "small old trees" or wither twigs year after year, and cannot form yield. Fertilize according to the fertilizer requirement of walnut. Generally speaking, increasing soil organic matter content can promote the growth, development and fruiting of walnuts. Walnut trees like calcium and grow well in calcareous soil.

(4) Humidity

Walnut is resistant to dry air, but sensitive to soil moisture. Too dry or too wet soil is not conducive to the growth and fruiting of walnuts. Walnut needs a lot of water during its growth and development, especially during fruit development. When the water is insufficient at seedling stage, the growth almost stops. Under the condition of excessive drought, the growth potential of trees is weak, the leaves are small, the fruits are small, and even a large number of flowers and fruits fall or the leaves wither, thus reducing the production and accumulation of nutrients. This situation is called "physiological drought" and must be watered in time to correct it. Under the condition of poor drainage and long-term water accumulation in the soil, especially when it is polluted, walnuts will lack oxygen, cause root rot and even suffocate the whole root system. Frequent rain in autumn often causes the exocarp to crack early, and the seed slope in the core-shell becomes brown and moldy. Affect the quality of walnuts. Therefore, soil and water conservation engineering measures should be taken in mountain walnut orchard; On the flat land, the drainage problem should be solved. The groundwater level of walnut orchard should be 2 meters below the surface.