Selection And Evaluation On Crack-Resistant Jujube Germplasm

Jujube (Ziziphus jujube Mill), as one of the important economic trees, is a special fruit tree native to China. Shanxi Province is one of the origins and main producing areas of jujube. Yet in production, fruit crack exsits as a rather important problem which results in large economic losses. Many researchers and jujube growers have carried out a lot of research and practice. Yet because of the unclear crack mechanism, there is still no effective prevention, agent or technique lightening fruit crack.Through investigation on natural fruit crack at the National Jujube Germplasm Repository in the Pomology Institute, Shanxi Academy of Agricultural Sciences, a group of crack-resistant germplasms were selected. Then the crack-resistant property of some easily-cracking and crack-resistant germplasms were evaluated, so as to further make clear relationship among fruit-crack and adverse weather conditions, content of water, sugar, Ca, Fe, Zn, K and Na, and anatomic structure. And then, crack-resistant germplasms were selected and directly applied to production, as well as being used as breeding materials. The main results are as follows.1. Through3-year continuous research using combination of field investigation on fruit crack and test of water inducing crack, it was made clear that the best period for evaluating fruit crack in the field was after a rain during the crisp-maturing period, and that for test of water inducing crack was48hours after being immersed in water.2. Based on crack-resistant evaluation on236germplasms,55germplasms strongly resistant to fruit crack were selected.3. Through observation on pericarp cell structure of17jujube varieties, it was found out that significantly negative correlation existed between fruit crack rate and the thickness of cuticle and pericarp.4. Based on analysis on content of sugar, water and7mineral nutrients including K, Na, Ca, Mg, Cu, Zn and Mn of16varieties in different growing periods, it was found out that there was no significant correlation between fruit crack rate and content of sugar, water and the7minetal nutrients.