Objective dy the nut fruit shape, the composition, the nutrient contents and their variation of Carya cathayensis clone.

Method 11 trait and nutrient indices of C. cathayensis nut fruit from trial forest were analyzed by the methods of variance analysis and multiple comparison based on the national standard of China.

Result The results showed that there was a significant difference in nut length between the fresh fruits and the nuts, and no significant difference was found in the rest indices of C. cathayensis. The kernels of C. cathayensis were rich in fats (52.64%-58.51%), proteins (55.07-65.50 mg·g^-1), soluble sugars (0.26%-0.68%) and mineral elements such as K, Ca, Na, Mg, Zn, Mn, and Fe. 17 kinds of amino acid were identified in the kernels of C. cathayensis. There were extremely significant differences in the contents of amino acids among the clones of C. cathayensis.

Conclusion According to the characteristics of the nut nutrients of C. cathayensis, the directions of breeding and utilizing of C. cathayensis are suggested. Three clones are comprehensively selected as the clones of high yield and high quality; one clone is selected as the clone suitable for edible oil production; and two clones are selected as the clones with high contents of amino acids.