【作者】 喻方圆；

【导师】 徐锡增； RobertD.Guy；

【作者基本信息】 南京林业大学 ， 森林资源与环境， 2002， 博士

【摘要】 本研究以杉木、马尾松苗木为主要研究对象,花旗松、北美乔柏和扭叶松为辅助研究对象,研究了在水分和热胁迫下,生长期间苗木的叶绿素荧光、气体交换参数、水分利用效率、糖代谢,生长和生物量等指标的反应,同时研究了剪根、剪叶、失水、冷冻等环境胁迫对起苗到造林期间苗木质量的影响,结果如下:(1)热和水分胁迫对杉木、马尾松和北美乔柏三个树种的叶绿素荧光有显著影响,可用Fv/Fm来预测苗木遭受胁迫的程度。(2)水分胁迫使杉木、马尾松和北美乔柏三个树种的净光合速率显著下降。但热胁迫只影响杉木和北美乔柏的净光合速率,对马尾松的净光合速率影响不大。热和水分胁迫均对马尾松苗木针叶气孔导度有显著影响,但对杉木和北美乔柏苗木针叶的气孔导度只有轻微影响。(3)水分胁迫处理对杉木、马尾松、花旗松和北美乔柏4个树种的稳定碳同位素的组成(δ13C值)均有显著影响,随着水分胁迫程度的加深,4个树种苗木针叶的δ13C 值增大(负值变小),说明其永久水分利用效率更高。热胁迫对杉木和北美乔柏苗木针叶的δ13C 值有显著影响,且在热胁迫下,两树种苗木针叶的δ13C 值减小(负值增大),即永久水分利用效率下降。但热胁迫对马尾松和花旗松苗木的δ13C值没有显著影响。(4)水分胁迫对杉木、马尾松、花旗松、北美乔柏和扭叶松五个树种的苗高增长量和增长百分率均有显著影响,但影响的程度因树种而异。热胁迫对苗木高生长和高生长百分率也有一定影响,但不如水分胁迫的影响大。(5)水分胁迫处理对杉苗的生物量指标影响不大,但热胁迫对杉苗生物量所有三个指标均有显著影响。(6)水分和热胁迫处理对杉木针叶果糖含量的影响显著性不强,但对杉木针叶葡萄糖和蔗糖的含量却有显著影响。随着胁迫程度的加深,杉木针叶的葡萄糖和蔗糖含量提高。水分胁迫处理对马尾松苗木针叶葡萄糖和蔗糖含量的影响显著,而热胁迫则对葡萄糖和果糖含量影响显著。水分和热胁迫处理对马尾松苗木针叶三种可溶性糖含量的影响均呈上升趋势。(7)剪根、剪叶等处理对杉木、马尾松苗木根生长势有显著影响,随着对苗木伤害的加深,苗木根生长势下降。(8)苗木根生长势随着晾晒失水时间的延长显著下降,当晾晒失水时间达到4h,失水率26.09%时,杉木苗新根生长点数量和>1cm 长新根数量分别下降67.51%和63.82%。当晾晒失水时间达到4h,失水率28.83%时,马尾松苗木新根生长点数量和>1cm长新根数量分别下降80.65%和87.63%。不同程度的失水处理对杉木、马尾松苗木的造林成活率有显著影响。杉苗在晾晒2h后成活率仅有40.3%,而当晾晒达7h,造林成活率8.1%。马尾松苗造林成活率在晾晒2h 后成活率为45.0%,晾晒4h后成活率为30.5%,当晾晒7h,苗木造林后全部死亡。(9)根系活力(脱氢酶活性)随晾晒失水时间的延长显著下降。根系脱氢酶活性与苗木水势,根生长势(RGP)和造林成活率的相关关系极为显著。(10)冷冻处理后的苗木针叶浸出液电导率明显高于对照,根系脱氢酶活性明显低于对照。更多还原

【Abstract】 Effects of water and heat stress treatments on Chlorophyll fluorescence (Fv/Fm),Gas exchange, Carbon isotope composition; Sugar contents ,seedling height and biomass of Chinese fir, Masson pine, Douglas fir ,western redcedar and lodgepole pine seedlings were measured during a three cycle stress period in spring 2001 at The University of British Columbia. And the effects of shoot pruning, root cutting, exposure to sunny field as well as freezing treatments on root growth potential, seedling survival rate, electrolyte conductivity and activity of dehydrogenase of 1-0 Chinese fir and Masson pine bareroot seedlings before planting were also conducted in spring 2000 at Nanjing Forestry University. The results were shown as follow: (1)Fv/Fm ratios of Chinese fir, Masson pine and western redcedar had different responses to water stress treatments. The Fv/Fm ratio of western redcedar decreased dramatically after water stress treatments while that of Chinese fir had only a slight reduction and that of Masson pine had no significant change. The experiment also showed that the Fv/Fm ratio of all three species differs significantly under heat stress treatments. Concerning three different water and heat stress cycles, it was found that the Fv/Fm ratios of Chinese fir and Masson pine measured at the end of each water and heat stress cycle was not significantly different. However, the Fv/Fm ratio of Western redcedar was diminished significantly in response to an increase of stress time. (2)After 36 days water stress treatments, the net photosynthesis of all three species including Chinese fir, Masson pine and Western rededar decreased significantly. But heat stress only affects the net photosynthesis of Chinese fir and Western redcedar. It was only be observed that the needle conductance to water vapor of Masson pine was significantly affected by both water and heat stress treatment. The needle conductance to water vapor of other species has just a slight change after water and heat stress treatment. Therefore, instantaneous water use efficiency, which was expressed as the ratio of A/ gwv, has no significant difference except for masson pine. (3)Different levels of water stress treatments in Chinese fir only slightly influenced seedling biomass. There is no significant difference in root dry weight under different level of water stress treatment. The biomass of Chinese fir, however, was dramatically affected under heat stress treatment. All four biomass indexes have significant difference under different levels of heat stress treatments. Masson pine, another subtropical tree species, showed significant difference in all biomass indexes under both water and heat stress treatment except for root/shoot ratio (dry weight) under heat stress treatments. Douglas fir showed that its four biomass indexes were significantly effected by heat stress treatment but not by water stress treatments. The western redcedar also showed that the heat stress influenced its biomass much stronger than water stress did. Lodgepole pine, had the similar trend to tolerate heat and water stress treatment as redcedar and Douglas fir. All its biomass indexes had no significant different under water stress treatments but there are differences observed under heat stress treatments. (4)There are significant differences in carbon isotope composition(δ(13)~C) among four species including Chinese fir, Masson pine, Douglas fir and Western redcedar under water stress treatments. Along with the prolong of water stress, the value of carbon isotope composition(δ13C) of all four species increased. This means that the Water Use Efficiency (WUE) will be improved under water stress treatments. Heat stress treatment had also significant effects on carbon isotope composition(δ13C) of Chinese fir and western redcedar. But the differences of carbon isotope composition(δ13C) did not be observed under heat stress in Masson pine and Douglas fir. (5)There is no significant difference of Fructose in Chinese fir needles under water and heat stress treatment. But it was observed that there are significant differences of Sucrose and Glucose in Chinese fir needles under water and heat stress and the value of Sucrose and Glucose was found to increase under water and heat stress. Water stress had significant effects on Sucrose and Glucose contents in Masson pine needles while heat stress had significant effects on Fructose and Glucose contents in Masson pine needles. And It was shown that All three sugars were found to increase under water and heat stress in Masson pine. (6)Both shoot pruning and root cutting treatments have a significant effects on root growth potential of Chinese fir and Masson pine , but the changing extent of root growth potential is different between two species. The results also showed that root growth potential of both species will decreased rapidly after exposure only a few hours to sunny field. We also carried out a correlation analysis between seedling morphological indexes and root growth potential and the results told us that most of morphological indexes of both species have significant relationship with root growth potential. Finally, The relationship analysis between seedling density and root growth potential showed no regular relationship between them. (7)Needle Electrolyte conductivity of Chinese fir and Masson pine has a big increase after freezing treatment and there are no significant differences of needle electrolyte conductivity between two species. The fine root activities of dehydrogenase of both Chinese fir and Masson pine are significantly correlated with the intensity of freezing and desiccation. We suggested that both electrolyte conductivity and activity of dehydrogenase could be used as quick indicators of Chinese fir and Masson pine bare-root seedling quality. (8) Root growth potential and field survival decreased along with prolonging duration of exposure. to sunny field. –1.60Mpa and –1.70Mpa are suggested critical values of Chinese fir and Masson pine respectively for successful reforestation.更多还原