What walnut germplasm resources are there? An introduction to the main walnut germplasm in China
Walnut, known in China by such aliases as huta, qiangtao and wansuizi, is called Persian walnut, English walnut or European walnut abroad, and is an important nut tree species in the world.
Pictured: walnut
Walnut belongs to the genus Juglans in the family Juglandaceae, of which about 10 or more species have cultivation value. The following 5 species are native to China and serve as the main walnut breeding resources.
1. Common walnut is the most widely cultivated and used tree species in the genus Juglans. It is relatively tolerant of cold and drought but not of wet waterlogging. Its cultivar types are numerous, and the age at which it bears fruit varies from early to late. The nuts are relatively large, the shell is thin, the kernel is plump, and the quality is excellent. It is the main cultivated tree species in the world's major walnut-producing countries, and is also the main distributed tree species in China's northern walnut-producing regions.
2. Iron walnut is a southern type in the genus Juglans, native to the Yunnan, Guizhou and Sichuan regions of China. This species tolerates damp heat but not drought, and has weak cold resistance. Its cultivar types are numerous, and the nut size and shape are highly varied. The quality is excellent, the outer surface of the nut is not smooth, but the kernel is plump.
3. Manchurian walnut is native to Northeast China and the Russian Far East. It is relatively drought-tolerant and extremely cold-resistant, able to withstand low temperatures of -50°C. The nut shell is thick, and the kernel is very difficult to remove from the shell.
4. Hebei walnut is an interspecific hybrid of common walnut and Manchurian walnut, also called ma walnut. It is a tall tree, and the nut is nearly spherical with 8 ridges, a thick shell, and a small edible kernel. It is used as a walnut rootstock; ma walnut developed as a handicraft is called wenwan walnut, and its market prospects have looked promising in the past two years.
5. Black walnut. This species is native to the American continent. It is cold-resistant, drought-resistant, and highly adaptable to adverse environments. Its nuts have high edible value, making it an excellent tree species for both timber and nuts.
In addition, there are other species in the genus Juglans and the genus Carya. Common ones include wild walnut, also called mountain walnut, distributed across most regions of China, with a thick, ridged shell and a small edible kernel, and it can be used as a walnut rootstock. In addition, gray walnut, Jibao walnut, heart-shaped walnut, northern California black walnut, small-fruited walnut, Guozhi walnut, long-fruited walnut and others can also serve as potentially valuable germplasm resources for future walnut production.