| Acacia is a tropical and subtropical important timber species, its resistance to low temperature research has important implications for the expansion of its growing range. In this study,11Acacia clones was tested material, the use of artificial climate chamber temperature approaches were studied under four temperature conditions (15℃,10℃,5℃,0℃) for11volumes photosynthetic characteristics Acacia seedlings and clones of physiological and biochemical aspects, in order to reveal the physiological mechanisms Acacia cold, and through analysis of variance, multiple comparisons, principal component analysis and other mathematical tools to identify screening photosynthetic capacity and cold and strong performance asexual Department of Acacia provide the basis for the promotion of culture. The main results are as follows:1. Observed at low temperatures clonal growth phenotype changes that cooling the initial phase, all participants plant leaf shape, leaf color, shoot morphology did not change significantly. When after10℃, the majority of clones with drooping leaves and wilting, as when the temperature drops, most clones mainly as leaf chlorosis, wilting aggravated and start curling; at0℃,clones2-15,2-21,14-5,14-11leaves a slight wilting symptoms before now, but still leaves over the green, while the remaining clones leaf chlorosis obvious and easy to fall.2. After11Acacia clones that were analyzed relative conductivity, low temperature process, the tested material is severely damaged cells, causing electrolyte leakage rate increases, the relative conductivity rise. At5℃treatment, some clones relative conductivity compared to controls, a significant increase, indicating that clones at this temperature, the cells damaged. And then tested clones of semi-lethal temperature analysis, the results showed that some clones between5℃-0℃had already seen a relative conductivity of more than50%in a semi-lethal state. Without the ability of the Department of14-5,14-11,2-15,2-21the cold better than other clones.3. Determination of soluble sugar and soluble protein content11Acacia clones at low temperatures, by analysis of variance showed that the difference was between the clones reached a significant level, and both with decreasing temperature, showing first increased and then decreased. Clones Gold18, SS2, NS and2-15when the temperature dropped to0℃, the body of soluble sugar content than the control, indicating0℃cells severely damaged the plants, the plants were not able to gather more soluble sugars, clones2-21late in cooling the body still contains high soluble sugar, indicating their strong resistance to cold. And at0℃, still higher than the control after all clones tested soluble protein content decreased. Clones2-15in the whole process of soluble proteins in vivo has been on the rise, so the cold better than other clones.4. At low temperatures, SOD, CAT, POD activity after the first rise and fall, which SOD activity in the0℃treatment, cytoprotective enzyme mechanism is affected, resulting in activity clones tested values are lower than in accordance with, clones14-5,14-11,2-15,2-21small decline relative to the control, cold natural ability is strong. CAT activity trends, and at a temperature of0℃, only14-5,14-11’s activity is still higher than the control, and the ability to clone14-11hardy stronger than14-5; POD activity changes,中4, ZJ1, ZJ8, trends ZJ22,14-5,14-11the more apparent.0℃, in addition to the four clones than the control, and the rest were higher than controls. Clones ZJ22at low temperatures, to maintain a higher POD activity;5. When the plant suffered hypothermia persecution, by increasing the body’s SOD, CAT, POD to avoid injury to the cell membrane, and cell protective enzyme activity increased, slowing the increase in MDA content, which is Acacia seedlings to chilling stress arising protective response. In the process of low temperature stress, MDA concentration changes clones tested inconsistent, but substantially increased and then decreased after the last rise. Because of the strong cold MDA content in plants should be low, seen, clones金18, SS2, cold tolerance ZJ22,2-15is higher than other varieties.6. Under low temperature stress Acacia photosynthetic rate (Pn) continued to decline, and stomatal conductance (Gs), transpiration rate (Tr) also decreased, but intercellular concentration (Ci) was slowly rising, indicating that photosynthetic rate the decline was mainly caused by the non-stomatal factors. Clones2-21chilling stress in the whole process can maintain a higher net photosynthetic rate, stomatal conductance and transpiration rate. 7.11Acacia clones chlorophyll fluorescence parameters, initial fluorescence (Fo) With the deepening of stress, an upward trend, PSII maximum optical efficiency (Fv/Fm) then showed a significantly decreased, and this variation in there are differences of Acacia species also. Clones2-15in the low-temperature treatment, the initial value of the smaller increase in fluorescence, indicating that the low temperature to maintain a higher excitation energy efficiency, conducive to the normal operation of the photosynthetic electron transport chain. The plant’s maximum photochemical efficiency (Fv/Fm), clones ZJ1smaller decline, indicating that the low-temperature environments, PS Ⅱ reaction center plant suffered minor injuries, occurred less photoinhibition has better low temperature adaptability.8. For this experiment, all the indicators were measured correlation analysis, the correlation that the relative conductivity and MDA, soluble protein, photosynthetic indicators and Fv/Fm closely, it can be used as indicators of Acacia cold.9.For cold tolerance11Acacia clones comprehensive evaluation of cold tolerance, the use of principal component analysis, to determine the ability of cold varieties,11Acacia clonal resistance to cold in the order of2-21,14-5, ZJ1, NS,2-15,14-11, ZJ8,中4, ZJ22, SS2,金18. |
PDF Full Text Request