Detailed Introduction to the Latest Appearance Characteristics of Ma Walnut
Ma walnut belongs to the walnut family, Juglans genus, a deciduous tree, with a hard, wrinkled, yellowish-brown endocarp. The fruit is collected around White Dew, the outer skin of the fruit is retted, the endocarp is rinsed and dried, and cleaned up, and it is what people call “walnut”. Actually this is just one way of saying it; according to archaeological findings, walnuts appeared as early as the Neolithic period or even earlier, which proves that our country is one of the places of origin of walnuts.
The Ma walnut tree is generally 30-35 m tall, with silver-gray bark. The leaflets are 7-11 in number, entire or with shallow serrations, and the underside of the leaf blade has short downy hairs. The flowering period is 4-5 months, unisexual, monoecious; the male flower inflorescence is usually 20-25 cm, and the female flower inflorescence is terminal, with 2-5 small flowers clustered. The fruiting period is October; the fruit is nearly spherical, 3-5 cm in diameter, with a protruding tip. The exocarp is fleshy, grayish-green, with brown spots. The endocarp is hard, wrinkled, and yellowish-brown. The inner septum is well developed and bony, making the kernel difficult to extract.
Ma walnut is a warmth-loving tree species. The suitable temperature range and frost-free period for its growth are an annual average temperature of 9-16 degrees, an extreme minimum temperature of minus 25 to -2 degrees, an extreme maximum temperature below 38 degrees, and a frost period of less than 150 days. It is light-loving; after entering the fruiting stage it needs even more sufficient light conditions, and the annual sunshine hours must be above 2000 hours to ensure normal growth and development. If below 1000 hours, both the shell and kernel develop poorly. In cultivation, light exposure must be considered in site selection, planting density, cultivation methods, and pruning.
The extensive root system and tree body of Ma walnut first require a deep soil layer (greater than 1 m) to ensure good growth and development. It tolerates dry air, but is relatively sensitive to soil moisture conditions. Soil that is too dry or too wet is unfavorable for the growth and fruiting of walnuts, so mountain walnut orchards need soil and water conservation engineering measures, while flat land needs to solve drainage problems, and the groundwater level should be below 2 m from the surface.
Ma walnut prefers loose soil and good drainage. It grows poorly on soil with too high a groundwater level and on heavy clay soil, but grows best on slightly alkaline soil containing calcium. Its suitable soil pH range is 6-8, and the soil salt content should preferably be below 0.25%; if slightly exceeded, it will affect growth and fruiting, and too high a salt content leads to death. It prefers fertilizer.
The production areas of Ma walnut are mainly distributed in parts of the mountainous areas of Hebei, Tianjin, Shanxi, and Beijing. The varieties are divided into Lion Head, Young Master's Cap, Official's Cap, Lantern, Chicken Heart, Tiger Head, and others. It can be made into handicrafts. With long-term handling and playing, the color and luster of Ma walnut become like agate and fine jade, and it is of high value. Through the carving of folk artisans, various animal and figure images and patterns are carved on the walnut to make nut carvings.