Studies On Identification Of Cold Resistance And Evaluation Of Utilization In Intergeneric Hybrids And Excellent Varieties Of Longan Germplasms

Longan(Dimocarpus longan Lour.) and Litchi(Litchi chinensis Sonn.) are both famous evergreen fruit trees in tropical and subtropical regions of South Asia. In order to study the cold resistance of longan Germplasms, 73 accessions including intergeneric hybrids between longan and litchi, intraspecific hybrids of longan, and cultivars of longan,were as materials. Evaluate the cold resistance of all accessions and selected germplasm resources with strong cold resistance. The main results were list as follows:1. The intergeneric backcross breeding were carried out, which obtained 93 hybrid seedlings from ‘Zaozi No.1'× ‘Wuheli' cross combinations(ZZW population). Most of them were planted in the field and grown well.2. According to the cold resistance identification of 51 real intergeneric hybrids between longan and litchi and their parents. The results showed that trend of the trait presented normal distribution and continuous variation on the whole. ‘ZZW124' ? ‘ZZW26' ?‘ZZW35'?‘ZZW33' showed excellent cold resistance. The LT50 of the four hybrids all below-4?. ZZW64 showed the highest LT50 of 0.64?.3. The chlorophyll fluorescence parameters were significantly decreased during winter, and a significantly negative correlation at the 0.01 level was found between the change rate of Fv/Fm and LT50, the correlation coefficient was 0.952**.4. A significantly positive correlation at the 0.05 level in 51 accessions of ZZW population was found between LT50, cold injury index during winter and damage rate of leaves during the strongest cold wave in 2016, and the correlation coefficient was 0.965**, 0.954**.5. Based on the DUS testing guide of longan and litchi, sellected 14 biological characteristics to observe the 51 accessions of ZZW population. The research showed that there was obviously difference between F1 and their parents in leaf characteristics,especially F1 have larger area of leaflet, more pairs of leaflet and stronger growth.6. According to the cold resistance identification and fruit quality evaluation of 4 excellent varieties of ‘Fengliduo' × ‘Dawuyuan' F1 population, two excellent varieties with the trait of extremely late ripening, large fruit, high quality were selected: ‘FD265'(LT50=-4.25 ?),‘FD105'(LT50=-4.00?). They showed excellent cold resistance and fruit quality, which provided a scientific basis for north cultivation and production application.7. According to the cold resistance identification of 7 intergeneric hybrids between longan and litchi, which had entered blooming and fruit period, their LT50 varied from-5.83? to0.98? indicated wide segregation. ‘Zaozi No.1', ‘Shizi No.19', ‘Shizi No.33' had stronger cold resistance with LT50 about-5.83 ?,-4.41 ?,-4.01 ?. The result indicated that innovation of cold resistance germplasm had considerable feasibility by intergeneric hybrids between longan and litchi.