Breeding Of High Quality Cultivar With Different Mature Period Of Citrus Reticulate And Study On New Techniques Of Cultivation

Citrus occupies very important position in both international and local market. It is widely cultivated in the southern areas of China.At the present time, the simplex variety structure and the centralized mature period resulted in unsalable of some citrus fruit, quality problem has become the key factor which cumbers the development of citrus industry. Therefore, we must pay more attention to the improvement of quality and commercial capability of citrus fruit in our country. In this paper, four aspects of investigation and experiment were analysed and the main results were as follows:(1) General investigation of newly choosen cultivarsBased on the cultivars introduced or breeded recently which behaved well, an investigation was carried out in Xiangshan, Linhai, Huangyan and Liandu etc. The primary results were as follows:"Dafen"and "Rinanyihao" which belong to wase satsuma mandarin both behaved well,and the good characters were steady. Especially, "Dafen" began to reduce TA at the last ten-day of September and became savory ,on the whole,it's one of the main cultivars which will be extended in future; "Nanxiang" is a serotinous cultivar ,it belongs to Citrus reticulate Blanco,it has the character of middle growth potential,high yield, high quality, infirm-frost resistance, middle drought resistance etc.; "Dongjiangbendizao" is a seedless mutation of Citrus reticulata Blanco cv. Succosa , as a new excellent cultivar, it had the behavior of strong fruit set capacity, full-bodied flavor,seedless (0.6 grains per fruit) and rareripe. In addition,the corresponding cultivation techniques of each cultivar are provided in this study.(2) Molecular identification of seedless variation of Citrus succosa Hort. ex Tanaka by AFLP techniqueGenetic variabilities of the seedless mutants were analysed by AFLP technique. By using 72 pairs of primers,9 specific bands between ordinary cultivar and seedless mutants were detected,and they can be considered as the primary seedless AFLP maker.The sequencing of these specific bands and their Blast analysis showed: band SL1 is homologic with a putative auxin efflux carrier protein gene (identity 78%), band SL2 is homologic with a retrotransposon gene (identity 87%), band SL4 is homologic with the gene encoding chloroplast,the other specific bands can only be considered as AFLP makers.(3) Investigation of new cultivation techniques:Cultivation techniques with high efficiency and quality will be beneficial to improve the fruit quality. Some new techniques of cultivation were summarized by the investigation of different producing area: The study of protected cultrue in Zhejiang Province was the pioneer in China The effect of improving quality of delayed harvest and forcing culture is prominent,and so is the economic benefit. Puffiness of delayed harvest is the main problem; Mulching planting including mulched with plastic film and sod culture was in application in some area, it had distinct advantage in improving quality and reducing cost; Biological control of mites can remarkably improve the natural control capacity of ecosystem, Simultaneously,it make citrus fruit more safer, but it's easily affected by entironment condition, especially the climate,so there's limit in application sometimes; Planting technique with organic nutrient solution which regulates sugar-acid ratio was not carried out successfully now ,it can increase TSS, but the effect of reducing TA was not good,the technique should be optimized. Full ripe harvest was the fist in China,and it's comparatively successful,this technique can improve the quality remarkably, however, puffiness was the main problem that should be solved as soon as possible.(4) Experimental study on storage effect of three citrus cultivar:Improving the storage effect of citrus fruit is also an important measure to improve quality. In this part, citrus fruit of three cultivars were taken in the experiment with different storage temperature. Based on the results,the respective optimal temperature of "Nanxiang", "Buzhihuo", "Laihujia" were 4℃,8℃,6℃; the storage capability at the optimal temperature of each cultivar were as follows: "Buzhihuo" was the first-class, "Laihujia" was inferior ,and "Nanxiang" was the last.