| Walnut (Juglans regia L) is the world's most important oil nuts and woody tree species, which is belonging to the genus Juglans. Walnut is widely distributed and cultivated in China. There are rich walnut resources including common walnut and wild resources in some main areas of our country. It is vital to develop walnut varieties which can simultaneously produce nuts and woody, for meeting the needs of domestic and foreign markets.In this study, germplasm resources of Qinglin-walnut collected from Shandong province were systematically evaluated in change of nutrient content,correlations and genetic diversity aiming at offering scientific basis for choosing the moderate nut and improved cultivarsselection and culturing of walnut. The main results are as following:1. The results showed that the morphological diversity of Qinglin-walnut germplasm resources was high among walnut germplasm. The nut shape among 42 walnut germplasm resources was mainly square round or round, shell texture was mainly pocky. The floodwalls and diaphragm were membranaceous ordegradation, shell suture line was narrow and bulged, The average thickness of nut horizontal diameter were 3.46 cm,and nut vertical diameter were 3.24 cm, the nut side drive were 3.31 cm, single nut weight were 13.37 g, single kernel weight were 5.68 g,kernel percentage were 42.61%, shell thickness were 1.97 mm. The variance analysis indicated that there were significant variation within strains (P<0.01).2. The results of the morphological diversity of Qinglin-walnut nutrients showed as following: In 100g walnut kernel the average protein content was 12.98 g, ranging from 10.93～17.17 g, the average fat was 68.31 g, ranging from 64.18～73.81 g, the average soluble sugar was 3.87g, ranging from 2.23～7.67 g, the average water was 4.11 g, ranging from 1.31～5.76 g. The variance analysis indicated that there were significant variation within strains (P<0.01) among protein, fat and soluble sugar.3. Significant linear correlation was found between the nuts side diameter and nuts vertical diameter of Qinglin-walnut (R2=0.796). The three side diameter and nut vertical diameter were all significantly correlated with the nut single weight. So, choosing the equation (y=-16.439+0.710x1+0.182x2) of the nut side diameter and the nut weight was more accurate to predict the nut single weight.4. The eight main economic characters of Qinglin-walnut strains were analyzed using principal component analysis and synthetic indexes analysis. The expression for the index function(m1~m4:the principal component scores for each strain value): comprehensive index for nuts d1=0.3751m1+0.2248m2, comprehensive index of oil d2=0.3751m1+0.2248m2+0.1568m3, processing of comprehensive evaluation index d3=0.2248m2+0.1086m4.These expression for index function provided theoretical base for selection of excellent Qinglin-walnut strains and their utilization.5. The genetic diversity and systematic relationship among the half-sib family of Qinglin-walnut were studied using SSR (Simple Sequence Repeat) technique.Clustering results show that Qinglin-walnut had a close genetic distance with the ordinary walnuts and the boundaries were not obvious, has significant differences with Juglans mandshrica and J.nigra. There were significant variation and rich genetic diversity among the half-sib family of Qinglin-walnut.
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