Investigation on genetic diversity of Persian walnut and evaluation of promising genotypes.

摘要

In order to investigate genetic diversity of Persian walnut (Juglans regia) and identify promising genotypes, eighty-one different walnut genotype seeds were collected from walnut orchards of Hamadan, Toiserkan, East Azarbaijan, West Azarbaijan, Khorasan, Ghazvin, Semnan (Shahrood), and Fars Provinces (Iran) in 1983 by the Seed and Plant Improvement Research Institute (SPIRI) and were planted in a nursery. After eleven years, in 1994, the morphological characteristics; fruit and kernel of three half-sib family genotypes were evaluated and the results were recorded. According to IBPGRI descriptor, time of leafing, male floribundas, susceptibility to spring cold, kernel colour, fruit shape, shell seal, shell texture and kernel plumpness were ranked and kernel weight, percentage of kernel and thickness of shell were measured. One-way analysis of variance on traits was carried out. This analysis showed that there were significant differences between all half-sib families. Broad sense hereditability (h2bs) were calculated to be over 60% for all the traits except for susceptibility to spring cold and percentage of kernel, which were 45 and 39% respectively. The broad sense hereditability of 71% for time of leafing, 90% for type of flowering, 79% male floribundas, 80% for fruit weight, 72% for kernel weight, 60% for kernel colour, 86% for shell texture, 73% for shape of fruit, 70% for loss of removal of shell and 64% wooden shell texture, 84% for kernel plumpness were calculated. The Spearsman simple correlation coefficients between traits in most cases were significant at 1 or 5%. There was also positive correlation between kernel weight and fruit weight (r=0.837), and also between kernel weight and shell thickness (r=0.299). Furthermore, correlation between leafing time, flowering type, rate of male floribundas, susceptibility to spring cold, kernel colour, fruit shape, rate of loss of removal of shell from kernel, shell texture and kernel plumpness with kernel weight was observed. Furthermore, positive correlation between susceptibility to spring cold (r=0.332), shell thickness (r=0.299), plumpness (r=0.19) and negative correlation coefficient between kernel weight with rate of male floribundas (r=0.203) were established. Then a step-by-step regression analysis was performed in order to find the relation between kernel weight and other traits. For this purpose, only kernel weight and shell thickness were entered into the model. Based on the findings, it is possible to forecast kernel weight from fruit weight and shell thickness in these hybrids. By utilizing matrix main indices, it was possible to satisfy more than 80% of the total variance. By further observation it was found that it is possible to select genotypes that will have superiority over other genotypes in fruit weight, kernel weight, and shell thickness. Finally, by utilizing Cluster Analysis according to Ward Method and Euclidian Spacing, 81 half-sib genotypes were classified in eight groups. The most genetic differences were observed between genotypes 74, 78, 54 and 48 with genotypes 8, 23, 53, 63, 64 and 51 respectively. It is highly expected that by crossing between a.m. groups remarkable heterosis will be obtained..