Study On Character Of Cold-Resistance Physiology In Three Jujube Cultivars

Jujube is one of valuable tree in our country. It has high medical value and jujube fruit s nutrition is rich. But jujube can live in only a few error of china. The low temperature is one of important reason that limited jujube to live. In this paper dongzao.zanhuangdazao and linyilizao were used to study. Under low temperature and overwintering period the physiological property of dongzao.zanhuang and linyilizao were studied. The main results were as followed:1. Effect of low temperature on physiological indexes : superoxide dismutase(SOD), peroxidase(POD) and malondialdehyde (MDA) content.With the falling of temperature in overwintering period, the activity of cell defense enzymes viz, SOD and POD were gradually increased in the three cultivars. The increase of MDA content fluctuated and was negatively correlated with SOD and POD.Under artificial low temperature (-20 ),the activity of SOD and POD were higher than the activity of SOD and POD under -10 in three cultivars. Under low temperature (-10 ), the changing of cell defense enzymes were slow. The increase of MDA content fluctuated and was not correlated with SOD and POD.With the falling of temperature in overwintering period, the contents of free proline soluble protein, sugar and starch accumulated. The contents of soluble sugar negatively correlated with soluble starch.2. The relative conductivities and leakage of K+ were studied. The results showed that as temperature decreasing, relative conductivities and leakage K+ increased. And significantly negative correlation existed between relative conductivities and leakage of K+.3. Chloroplast fluorescence parameters in the three cultivars were studied in field. With the temperature falling, Chlorophyll a fluorescence induction kinetic curves of jujue leaves were changed obviously., the Fo, Fv, Fv/Fm and Fv/Fo values were decreased. But the photochemical quenching(qP) and the non- photochemical quenching(qN) were increased in different level.Under artificial low temperature, the changing of Fo, Fv, Fv/Fm and Fv/Fo values were different. At the Low temperature ranging of 10~0'C, Fo values was decreased with the temperature in three cultivars. When the temperature reached -5 Fo value increased.. With the increase of stress, Fv value decreased. Fv/Fm and Fv/Fo were all increased at certain low temperature. All Chloroplast fluorescence parameters decreased rapidly at -5 low temperature.4. After treatment at -30 low temperature, the germination rates of three cultivars were all zero. The germination rates at -10 low temperature were higher than CK. That mean -10 low temperature enhanced the germination rates of shoots.5. From the result of comprehensive comparision, it can tell that the ability of cold-resistance was zanhuangdazao>dongzao>linyilizao. Cold-resistance indices, SOD activity, POD activity, MDA content soluble protein, lose water, the non- photochemical quenching(qN) are important in Cold-resistance of jujube.