Comparative Study On Integrated Traits Of Different Groups Of Walnut

There are 40 walnuts selected from three different sources (hybrid walnut, introduction walnut, local walnut) in two towns of Shimian County and one town of Hanyuan County in Ya’an, Sichuan province are studied in this paper. These single plants are measured in trees’morphological index, fruits’abdominal diameter, slit diameter, height, dry weight, kernel weight, kernel rate, plumpness, crude fat, crude protein, mineral elements (P, Fe, Ca, K, Cu, Zn, Mn, etc.) as well as vitamin C, etc. By using analysis methods such as analysis of variance, multiple comparisons, the coefficient of variation, principal component analysis and cluster analysis to completely analyze the data, hoping to provide scientific theory for choosing appropriate nuts species and breeding conditions. The results are as follows:(1) Study on the phenotype of walnuts shows that the trees’morphology characteristics and the main coefficient of variation characters do not change much and the weight characters of walnuts are non-significant. Three diameters and the kernel rate of the hybrid walnut are more lager than other walnuts and reach up to 3.615cm and 50.434% while the introduction walnut is in second place and the local walnut comes last. Three diameters of the 40 walnut plants ranges from 2.723 cm to 4.296 cm and those of M2 are the largest. The minimum fruit weight is ZS8 and is as low as 6.597 g. Both of the largest fruit weight and kernel weight are YB, which is up to 24.924 g and 11.567g, which is 3.038 times of the minimum kernel weight (ZS10). The shell thickness ranges from 0.055cm to 0.149 cm, of which the thinnest one is ZS8 while the thickest is YX. The thickness of the thickest one is 2.709 times of the thinnest one. Fruit size is directly related to the economic condition of walnut. The larger ones are M2, YB and JX3, which are mainly the introduction walnuts. On the contrary, the smaller ones are ZS11, ZS10 and SMZ, which are mainly the native walnut. The higher kernel rate ones are SZ8, XL21, SC13S SZF5 and M2, etc. The variance analysis on phenotypic trait of walnut single plant shows a significance at the 5% level and the fruit weight, kernel weight, shell thickness and fullness are relatively high in coefficient of variation. Hybrid walnut phenotypic traits more stable, but volatile mineral elements; native walnut phenotypic traits are also stable; introduce walnut are instability.(2) The results of the nutritional quality of walnut nuts are as follow:the crude fat content is 44.37%～72.48% and crude protein content is 17.04%～29.15%. The contents of Vc and crude protein in hybrid walnut are larger than the other two walnut, but it holds the lowest fat content. The crude fat content of the introduction walnut possesses the highest place while its Vc and crude protein content possesses the lowest. The crude fat, crude protein and Vc content of native walnut are in the middle place. The results of the mineral elements and Vc content shows that K is the most abundant element of walnut and the others are relatively low, especially for Cu. The comparison of the mineral elements in the 40 Sichuan walnuts show that different walnuts selected from different regions have a significant difference in mineral elements. The mineral elements of walnuts from different sources have diversity in a certain degree. Content of P element in exotic walnut is the highest one and is up to 228.69 mg/100g while native walnut is the lowest and hybrid ones are in the middle, but its coefficient of variation is as large as 30.854%. The Ca and K elements of hybrid walnut are highest of all and to 248.562 mg/100g and 371.359 mg/100g, respectively, but native walnut possesses a minimum content. As to Mg Cu, Fe, Mn and Zn element contents, the native walnut is higher than the others while the exotic walnut is lowest and the hybrid walnut is between them. P, K, Mg, Cu and Mn are higher in coefficient of variation than the others, but Zn in introduction walnut is the highest in coefficient of variation. Ca and Fe of native walnut is the largest in variation coefficient.(3) With the principal component analysis, the former 6 principal components provide 78.132% information of the original characters. By building a comprehensive evaluation index, SC13, SZ14, SC12 and so on of varieties hybrid walnut, they have fine integrated traits, quality are very good, is worthy of promotion.(4) Cluster analysis shows that 40 plants can be divided into 4 categories:Class Ⅰ, walnut shell protein with significant thin shell features of only 0.110 cm, which is easy to take kernel and has he highest crude protein that is 23.399%. The main representative plant are SC13,SZ14,SC12,ZS6, YX, SMZ, etc., which are from the three kinds of walnuts. Class Ⅱ, general high quality walnut, with larger shape, average three diameters of 4.189cm, fruit weight for 15.202g, higher crude protein content of 22.42%, but only has JX3, which belongs to native walnut. Class III, high mineral walnut, which is characterized by a high content of mineral elements, of which K elements is the highest (796.687 mg/100g), Ca(243.858 mg/100g), Zn(44.899 mg/100g), which are beneficial to humans, but only has SL2, which belongs to hybrid walnut. Class Ⅳ, giant high-fat walnuts, whose three average diameter is 4.079 cm, fruit weight for 22.338 g, which is as 2 times as the normal walnut quality. It also has a really high fat content (70.305%), higher kernel rate(48.165%), has YB and WM that are introduction walnuts. Genetic diversity among the three groups walnut is rich, the genetic distance is small, the genetic relationship is close; But the genetic distance between groups ranged larger, the genetic background is complex, providing a good foundation for the breeding of fine varieties of walnut.