Study On Heredity And Variation Of The Main Characteristics Among Ziziphus Jujuba Mill.cv Dongzao Seedlings And Cold Hardiness Among Chinese Jujube Seedlings

Seedling-selection is a new kind of attempt in jujube breeding. A different extent of variation in the traits such as the trunk, leaf, needle, nutrition and disease-resistance among two-year-old Dongzao seedlings provide the possibility in selection. More strong in tree vigor, beautiful outside candidates will be found in future cultivation as well as the compact, disease-resistance, needle free and fast-fruiting ones. There are 12 compact candidates and 6 "willow-like" ones have been found at present.Based on the effect of freezing injury on the electrolyte leakage of cell membrane, conductance was used in measuring the cold hardiness of Dongzao and Linyilizao cultivars, two and three years old Dongzao seedlings, and 17 different three-year-old female populations. Aim of the research is to enrich the theory of cold hardiness on Chinese jujube and select the most cold hardiness female cultivars and single candidate for cold hardiness heredity research on jujube. The results are as follows:1 Different storage time affect the electrolyte leakage of the branches, so the treatments must be done within 7 days.2 The REL of the branches rise as the treatment-temperature decline. Cold hardiness of the first and the second branches of Dongzao and Linyilizao before winter(beginning of the November)are -33.51℃, -31.72℃, -32.73℃, -31.14℃ respectively, while the trait of the first branches of Dongzao and Linyilizao before germination time(middle of March) change to -20.39℃ and-19.28℃ respectively.3 Cold hardiness changes with growth time, it is the strongest in winter (end of December), followed with the one before winter (beginning of the November) and the one before germination time (middle of March) is the weakest.4 The relative REL change present a normal distribution among two-year-old Dongzao seedlings at different time and different treatment-temperature, which show that cold hardiness of the seedlings is a multi-gene controlled quantitative characteristics.5 Different jujube branches possess different cold hardiness at the same time; they are three-year-old Dongzao seedlings, two -year-old Dongzao seedlings, female cultivars Dongzao and male cultivars Linyilizao respectively. Among the 18 female populations, the strongest one of cold hardiness is Sanbianse, and then followed with Jiaochengtiansuanzao, Popozao,Wukuzhakexiaozao, Guangyangdazao, Mianzao, Ziyuanzao, Zunyitianzao,Jianzao, Yucituanzao, gingxuyuanzao, Yuanquzao, Suzao, Lichengxiaozao, Jiuyueqing, Zhenhulu, Jixinzao and Dongzao.6 There are several single cold hardiness candidates among the different female population; all of them are the seedlings of Jiaochengtiansuanzao, Wukuzhakexiaozao, Popozao, Sanbianse, Guangyangdazao and Mianzao, which could become the effective material hi jujube cold hardiness breeding or new cold hardiness cultivars.7 Diameter of the trunk, diameter of the xylem and the ratio of epidermis with periderm have a significant positive relationship with the relative REL change, while the ratio of periderm with the diameter of the trunk has a significant negative relationship with the relative REL change.