| Juglans is one of the most important species for economic use in China.36hybrid combinations were formulated in this study by NCII design using hybrids (J. sigillata×J. regia) Yunlin A7as female parents and4superior trees of J. sigillata from Sichuan as male parents. The seeds were planted at the seed breeding center which was located at Jintang in2005. The walnut characters were studied, including fruit diameter, shell thickness, fruit weight, kernel percent, yield and precocity. The inheritance of walnut hybrid progeny were known by the genetic parameters such as combining ability, heritability and correlation coefficient. The best hybrid combination was chosen according to the breeding aim from36combinations. The main study results were as follows.(1) The result showed that there were significant differences or extreme significant differences among36hybrid combinations in6characters. Abundant genetic variation was existed. The CV of6characters (fruit diameter, shell thickness, fruit weight, kernel percent, yield and precocity) were8.24%,28.40%,24.01%,20.86%,59.76%and34.07%, respectively.(2) According to the genetic parameters of6characters, a similar inheritance were existed between fruit diameter, shell thickness and kernel percent. For the three characters,the broad heritability (h2B) were more than70%, the narrow heritability (h2N) were less than15%, the specific combining ability contribution rate (Vs) were much greater than general combining ability contribution rate (Vg) and the male general combining ability contribution rate (Vg2) were greater than female general combining ability contribution rate (Vg1).Fruit weight and precocity had a similar inheritance:the h2B were more than75%, the h2N were less than15%, the Vs were far more than the Vg, the Vg1were less than the Vg2. A big difference of inheritance were existed between yield and other characters. The h2B was only22.25%(the minimum of all), the h2N was17.33%(the maximum of all), the Vg were greater than Vs, Vg1were greater than Vg2. (3) According to the2-tailed correlation analysis of36hybrid combinations, the fruit diameter was significantly correlated with the fruit weight, the shell thickness was significant negative correlated with the kernel percent.(4) According to the analysis of effective value of combining ability, F2and F8were the ideal female parents, both advantages and disadvantages were existed in all4female parents. Female parents could be chosen by breeding objectives and characters of female parents. The Vg of5characters were calculated positive in combination F7×M1and the Vg of shell thickness, yield and precocity were the highest of all. There were positive effects in the Vg of yield and precocity in combination F7X Ml and F8X M2. Base on the analysis of effective value of total combining ability, positive effects were existed in most of the characters in combination F7X M1, F8×M2, F2×M3, F8×M3, F2×M4, F9×M4. Parents could be chosen by average character values of hybrid combinations and the TCA values for certain breeding objectives.(5) Comprehensive analysis showed that F2X M4and F9X M4were superior combinations. The fruit diameter, shell thickness, fruit weight, kernel percent, yield and precocity of combination F2×M4were3.610mm,0.058mm,11.4038g,69.27%,125.6224g/m2,4.67, respectively. The fruit diameter, shell thickness, fruit weight, kernel percent, yield and precocity of combination F9×M4were3.430mm,0.064mm,10.0020g,68.58%,158.2844g/m2,4.67, respectively. The filial generation average of fruit diameter, shell thickness, fruit weight, kernel percent, yield and precocity in this experiment were3.368mm,0.090mm,9.8435g,57.99%,75.9962g/m2,3.33, respectively. The two combinations were significant better than filial generation average in6characters with higher TCA values. The influence of heritance were greater than environment in offspring characters, so that superior characters could be conserved... |
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