Research On Pecan Viriaties Breeding In Anhui Agricultural University

This research studied on the23pecan varieties which introduced from United Statesin the year2000. Through more than ten years of cultivation experiment, according to treegrowth indicators, fruiting habits, fruit characteristics and quality of seeds and combiningwith physiological indicators, the author selected five excellent plant and named1st-5thAnhui Agricultural University(AAU1-AAU5) to prepare for the identification of newvarieties initially. This provided available resources for promotion of cultivation of pecanin Anhui. The main results are as follows:1. There were five outstanding of growth performance among the372introductionseedling plants of12-year-old in the Agriculture Demonstration Garden of AnhuiAgricultural University by comparison of the growth indicators, which have an averageheight10.08m, average diameter16.47cm, average crown width5.3×6.2m, and theirsaverage amount of fruit per plant are within touch16.89kg.2. Ten major economic characteristics, including fruit shape coefficient，nut shellthickness, single fruit weight, dried unit weight, single kernel weight, shelling nuts rate,the seed rate, kernel oil ratio, protein, per unit area (kg/m2) fruit production for fivevarieties of pecan were determined by using a principal component analysis based on aspecimen correlation matrix. According to more than94.29%of the cumulative variance,the author identified three main ingredients that can reflect major economic traits of thepecan. They were：fruit shape coefficient，kernel oil ratio，nut shell thickness. Combiningthese available as optimal selection indicatoran and the characteristics of fruit seeds of thefive varieties to choose five excellent individuals and named as AAU1, AAU2, AAU3,AAU4and AAU5initially.3. The curve of diurnal variation of leaf photosynthesis of five excellent individualsshowed two single peaks, which the largest is AAU2. Water use efficiency of fiveexcellent individuals also showed two single peak. Diurnal changes of transpiration rateshowed a single peak curve and the highest occurred at around12:30pm. Studies showAAU4has strong drought resistance, followed by AAU1and AAU5, and finally AAU2and AAU3. AAU1has the stronger shade tolerance and greater range of light adaptationthan other varieties, which is able to adapt to low-light environments. In addition, Furtherstudies have shown that the dominant factor that affect net photosynthetic rate of fivespecies are stomatal conductance, transpiration rate and photosynthetic active radiation,while the influence of the intercellular CO2concentration (Ci) and watershed utilization (Pn/Tr) are less, the correlation was not significant.4. Grafting experiments of five excellent individuals showed that different varietieswith different grafting methods exist differences in graft survival rate.The survival rate oftree bark grafting is higher than the other two methods for AAU3, AAU4and AAU5, sotree bark grafting may be more suitable for these three excellent individuals. While treebark grafting may be more suitable for AAU1, AAU2can adopt tree bark grafting andcut-grafting.