【作者】 周小玲；

【导师】 田大伦；

【作者基本信息】 中南林业科技大学 ， 生态学， 2007， 博士

【摘要】 当前,由于人类活动造成大气CO2浓度升高,全球气候变暖,水资源紧缺等一系列的环境问题,开展植物生理生态学机理研究在全球生态学、生物多样性保育、退化生态系统的恢复与重建、生态系统的可持续发展等方面发挥着十分重要的作用。探讨四川桤木的生理生态学机理不仅有助于了解桤木的光合能力,植物水分生态特征、植物耗水的主要特征及其对环境因子变化的响应,填补研究的空白,而且可为四川桤木优良品种的早期选育、引种栽培、推广应用提供决策参考。四川桤木(Alnus cremastogyne Burkill)属桦木科(Betulaceae)桤木属,为中国特有种,是国产桤木属11个种中最重要的1个种,现已成为长江流域平原水网地区防护林、丘陵山区水土保持林和短周期工业用材林基地建设中的重要造林树种,栽培面积已达267万公顷。对四川桤木不同品系苗木(H1、H12、J5、J10)生理生态机理的研究将有助于揭示不同桤木品系苗木间生理生态机理的差异性及其与早期生长量的关系,特别是当前大气C02浓度升高,全球气候变暖,水资源紧缺等一系列的环境问题背景下,探讨桤木生理生态机理更有助于了解其对环境变化的响应。本研究的主要研究结果如下：4个四川桤木品系苗木苗木上、下部叶的Pn都有明显的日变化和季节变化。同一品系苗木在不同的生长季节或不同品系苗木苗木在相同的生长季节,Pn日变化有单峰曲线型和双峰曲线型,即使是同一种曲线型,但出现峰值的时间也不完全相同,Pn的大小也不同。在相同生长季,Pn日变化曲线上的同一时刻,H12、J10品系苗木上部叶的Pn均高于H1、J5品系苗木上部叶的Pn。4个四川桤木品系苗木上、下部叶Pn月均值均呈现为双峰曲线季节性变化规律。H12、J10品系苗木上、下部叶的Pn月均值均分别高于H1、J5的上、下部叶的Pn月均值,即H12、J10品系苗木具有较高的光合能力。4个品系苗木上、下部叶,不同月份间及品系间的Pn差异均达极显著(p<0.0001)。以5%显著水平划级,J10、H12品系苗木为第一级,J5和H1品系苗木为第二级。4个四川桤木品系苗木上、下部叶的Tr都有明显的日变化和季节变化。4个品系苗木上、下部叶的Tr日变化趋势基本一致,有单峰与双峰两种类型,而下部叶以单峰型变化曲线为主,属轻蒸腾午休型植物,且其Tr最大值超过5mmol·m-2·s-1,表明桤木属轻蒸腾耗水型植物,对水分要求较高。4个品系苗木上、下部叶的Tr月均值均呈现为双峰型的季节变化规律。H12、J10品系苗木上、下部叶Tr的最高值与月均值均高于H1、J5品系苗木相应上、下部叶Tr的最高值与月均值。4个品系苗木上、下部叶Tr差异极显著(p<0.0001)。月份之间、品系苗木之间Tr差异极显著(p<0.0001),品系之间的平均Tr(mmol·m-2s-1)从高到低的排序为：H12(1.8770)>J10(1.8675)>J5(1.3003)>H1(1.2970)。在不同生长季节同一品系苗木或在相同生长季节不同品系苗木的WUE的日变化表现出不完全相同的变化规律。4个品系苗木上、下部叶的WUE月均值呈现出“W”型的季节变化规律。H1、H12、J5、J10品系苗木的WUE月平均值变化范围分别在-1.111～6.01,1.24～4.265,-0.404～5.80,-1.383～5.546之间,按WUE全年最高值的大小排序为：H1>J5>J10>H12。4个品系苗木上、下部位之间,不同品系苗木之间的WUE差异均不显著(p>0.05),而各月份之间的WUE存在极显著的差异性(p=0.0001)。在PARO-1500μmol·m-2·s-1之内,4个四川桤木品系苗木上、下部叶Pn随着PAR的增强而升高,当PAR超过1500μmol·m-2·s-1时,Pn基本维持恒定值,PAR再继续增加时,Pn不再增加,甚至下降。4个四川桤木品系苗木的表观量子效率变化范围在0.0303～0.0495mol·mol-1之间。H1、H12、J5、J10品系苗木LCP (μmol·m-2·s-1变化范围分别为7.36～34.69、16.3～37.9、3.16～31.95、11.48～50.61之间,H1、H12、J5、J10品系苗木LSP (μmol·m-2·s-1)变化范围分别为1204.72～1458.45、1374.42～1434.96、1224.95～1424.16、1216.69～1530.61之间,4个四川桤木品系苗木具有较低的LCP和较高的LSP,利用弱光能力强且能有效地利用全日照的强光,能适应多种光照环境。4个四川桤木品系苗木上、下部叶的Ci均随着PAR的增强而呈下降趋势,且上、下部叶Ci的变化趋势与最大值相差不大,不同品系苗木Ci对PAR的响应程度略有不同,但差别不是很大。上、下部叶的Cond随着PAR的增强而呈上升趋势,但随着PAR的增强,Cond增幅逐渐变小,不同品系苗木Cond对PAR增强的响应也不同。上、下部叶的Tr随着PAR的增强均呈上升趋势,两者呈明显正相关关系,上部叶Tr与PAR的相关系数R2≥0.6893。J10、H12品系苗木的Tr随着PAR的增强增加幅度、平均值基本上高于J5和H1品系苗木。PAR在0～500μmol·m-2·s-1范围内,上、下部叶的WUE随着PAR的增强而快速增高,当PAR接近或超过500μmol·m-2·s-1时,WUE缓慢增高或达到最大值。当PAR超过1000μmol·m-2·s-1时,WUE普遍都有所下降。CO2浓度在0～800μmol·mol-1范围内,4个四川桤木品系苗木上、下部叶的Pn随着CO2浓度升高而增大,当C02浓度达到800～2000μmol·mol-1之间,Pn逐渐趋于稳定,Pn达到最大值。上、下部叶的Tr随着CO2浓度的增高均呈下降趋势,但变化幅度不大。品系间Tr随着C02浓度增高的变化幅度也不同,H1、H12、J10和J5品系苗木分别为0.76、0.55、1.10和0.6mmol·m-2·s-1。在低C02浓度范围内,WUE随着CO2浓度的增加而上升,C02浓度从400μmol·mol-1上升到800μmol·mol-1,4个四川桤木品系苗木的WUE提高了25.92%以上,最高可达209.22%。上、下部叶的Ci随外界C02浓度的升高而增大,且4个四川桤木品系苗木的Ci与外界C02浓度呈线性正相关,品系之间的差异不大(p>0.05)。Cond随着CO2浓度的增加呈下降趋势,不同品系苗木呈现出不同的变化形式：逐渐下降、先升后降、升降交替地逐渐下降等。叶面饱和蒸汽压亏缺(Vp)随C02浓度的升高呈微弱的上升趋势。影响桤木上、下部位叶,整株苗木Pn的生理生态因子有所不同,且不同品系间也有所差异。Cond, Ci、PARi、Vpdl是影响上、下部叶及整株苗木Pn的主要生理生态因子,不同部位、不同品系略有不同。且均与Cond, PARi呈正相关。影响上、下部位叶,整株苗木叶片Tr的生理生态因子有所不同,且不同品系苗木间也有所差异。其中Cond, Vpdl、Tleaf, PARi对4个品系苗木上部叶的Tr影响最大；Cond, Tair, PARi、Vpdl对下部叶的Tr影响最大；Cond, Tair, RHR对4个品系苗木整株苗木Tr的影响最大,尤其以Cond影响最为显著。影响上、下部位叶,整株苗木WUE生理生态因子有所不同,且不同品系间也有所差异。Ci、Tair, CO2R, RHR, Vpdl、Tleaf, Cond是上部叶WUE日变化的主要影响因子,其中,Ci、Cond, Vpdl、CO2R对上部叶WUE影响较大；Ci、PARi、Vpdl、CO2R对下部叶WUE影响较大；Ci、Cond是整株苗木WUE的主要影响因子。Ci对桤木的WUE影响最大,且呈显著负相关。4个四川桤木品系苗木叶片叶绿素含量从高到低排序为：J5(43.31%)>H1(42.63%)>H12(42.62%)>J10(38.74%),品系苗木间叶绿素含量存在极显著的差异(p≤0.0001)。叶绿素含量与净光合速率、苗高、生长量呈显著的正相关关系(p≤0.05)。叶面积、苗高、生物量大小排序均为：H12>J10>J5>H1,不同品系苗木间叶面积不存在显著差异,苗高存在显著差异(p≤0.05),干生物量存在极显著差异(p≤0.0001)。当净光合速率与苗高、干生物量到达显著正相关(p≤0.05)时,同一桤木树种不同品系苗木内净光合速率对个体生长量和高度的增长的贡献率分别可达80.56%和48.48%。更多还原

【Abstract】 At present, it is important to study plant eco-physiological mechanism for global ecology, bio-diversity conservation, restoration and reconstruction of graded eco-system and the sustainable development of eco-system due to a series of environmental problems, such as the CO2 concentration elevation, global climate warming and water resource shortage. Exploring the eco-physiological mechanism of Alnus cremastogyne Burk would not only make for understanding its photosynthetic ability, water ecological characteristic, and its response to changing environmental factors, also provide decision-making reference for early breeding, introduction, cultivation and commerical appliance.Alnus cremastogyne Burk, belonging to the genera Alnus in Betulaceae, and being a native species and one of the most important species among the total 11 species in. Alnus in China, has been used as one of the most important forestation tree species for sheltbelt, soil and water conservation forest and short-rotation industrial forest in Yangtze River Valley, whose commercial area has reached 2.67×107hm2. Study on the eco-physiological characteristics of different varieties of A. cremastogyne Burk would help people to understand its eco-physiological mechanism and their relation to growth volume at the early stage, especially under the current background of rising atmospheric CO2, globe climate warming, and the shortage of water resources. Exploring its eco-physiological mechanism would furthermore help us to understand its response to environmental changes. The major results are shown as follows:The diurnal and seasonal variation of net photosynthetic rate (Pn) between the upper and lower crown of four varieties of A. cremastogyne Burk showed obvious difference. The diurnal variation of Pn of the same variety showed two different types of curves, namely, the single or double-peak curve at different growing season, and different varieties did so at the same growing season. Even if they showed the same curve type, the peak value of Pn appeared at different time, and their size were different too. At the same growing season, the value of Pn of H12, J10 were higher than that of H1 and J5 at any time in the upper crown during the diurnal courses. While the seasonal variation of the mean monthly Pn values of these four varieties in the upper and lower crown, respectively, revealed a double-peak curve, H12 and J10 were higher than H1 and J5, i.e., H12 and J10 had a stronger photosynthetic ability. Highly significant difference of Pn was observed between the upper and lower crown or different month, or different varieties (p< 0.001), respectively. If ranked on the 5% significance level, J10 and H12 belonged to the first level, and J5 and H1 the second level.The remarkable difference of diurnal and seasonal variation of transpiration rate (Tr) of these four varieties were observed between the upper and lower crown. The diurnal variation of Tr was generally identical with a single-peak curve or double-peak one. The leaves at the lower crown mainly showed a single peak curve, belonging to the weak-transpiratory midday-depression plant, and the maximum of Tr exceeded 5 mmol·m-2·s-1. This indicated that A. cremastogyne Burk is a weak-transpiratory and strongly water-consumptive plant, needing adequate water. The mean monthly Tr values of these four varieties all displayed the same seasonal changing tendency with double-peak curves. The maximum and mean monthly values of Tr of H12 and J10 were higher than those of H1 and J5 in the upper and lower crown, respectively. Tr of these four varieties showed a highly significant difference (p<0.0001) at the upper and lower crown, and this was also true of different month or different varieties. The order of Tr mean among different varieties was H12 (1.8770)>J10 (1.8675)>J5 (1.3003)>H1 (1.2970).The changing trend of diurnal variation of water use efficiency (WUE) of the same variety was incompletely similar in different growing seasons, and different varieties did so at the same growing season. The seasonal variation of WUE mean monthly of these four varieties presented the form as "W". The WUE mean monthly of H1, H12, J5, J10 varied from-1.111 to 6.0,1.24 to 4.265,-0.404 to 5.80,-1.383 to 5.546, respectively, and the order of WUE maximum was H1 >J5>J10>H12. WUE of these four varieties between different positions or different varieties had no significant difference (p>0.05). And a highly significant difference between different months was observed (p=0.0001).When photosynthetically active radiation (PAR) ranged 0～1500μmol·m-2·s-1, Pn of these four varieties increased with the increase of PAR in the upper and lower crown. When PAR exceeded 1500μmol·m-2·s-1, Pn kept rather stable. While PAR continued to increase, Pn varied little, and decreased in certain cases. The apparent quanta efficiency of these four varieties varied from 0.0303 mol·mol’1 to 0.0495 mol·mol-1, and the light compensation point (LCP) of H1, H12, J5 and J10 ranged 7.36～34.69,16.3～37.9,3.16～31.95 and 11.48～50.61μmol·m-2·s-1, respectively, while their corresponding light saturation point (LSP) ranged 1204.72～1458.45,1374.42～1434.96,1224.95～1424.16,1216.69～1530.61μmol·m-2·s-1, respectively. These indicated that these four varieties possessed rather lower LCP and higher LSP, having a higher utilization efficiency on weak light and strong light, capable of adapting to a manifold light environment.Ci of these four varieties decreased with the increase of PAR in the upper and lower crown, and the response degree of Ci to PAR of different varieties were slightly different. Cond increased with the increase of PAR, but with the increase of PAR, the amplitude of Cond gradually became weaker, and the response of Cond of different varieties to the increase of PAR were different too. Tr in the upper and lower crown increased with the increase of PAR in the upper and lower crown, and there was a significantly positive correlation between them, with the correlation coefficient being 0.6893 in the upper crown. The increase amplitude, mean values of Tr of J10 and H12 were higher than those of J5 and HI with the increase of PAR. When PAR ranged 0～500μmol·m-2·s’1, WUE in the upper and lower crown rapidly increased with the increase of PAR. While PAR approached or exceeded 500μmol·m-2·s"1, WUE gradually increased, or reached the maximum. When PAR exceeded 1000μmol·m-2·s-1, WUE generally decreased.When the concentration of CO2 ranged 0～800μmol·mol-1, Pn of these four varieties increased with the increase of CO2 concentration in the upper and lower crown. When the CO2 concentration reached between 800 and 2000μmol·mol-1, Pn varied little, even reached the maximum. Tr decreased with the increase of CO2 concentration, but its changing amplitude was rather little. And the changing amplitude of Tr with the increase of CO2 concentration among different varieties were different, For H1, H12, J10 and J5, that was 0.76,0.55、1.10 and 0.6mmol·m-2·s-1, respectively. Within low CO2 concentration, WUE increased with the increase of CO2 concentration. When CO2 concentration increased from 400μmol·mol-1 to 800μmol·mol-1, WUE of these four varieties increased by 25.92%, and the maximum more than 209.22%. Ci in upper and lower crown increased with the increase of CO2 concentration, and linear positive correlation between them were observed, and the difference among these varieties varied little (p >0.05). Cond decreased with the increase of CO2 concentration, and showed manifold changing type:gradually decrease, first increase and late decrease, or significantly fluctuate, etc. Vapor pressure deficit at the leaf surface (Vpdl) slightly increase with the increase of CO2 concentration.The eco-physilogical factors affecting Pn in upper, lower crown or whole plant were different, and as far as different varieties were concerned, it did so. the major factors affecting Pn in upper crown were Cond, Ci, PARi, Tleaf and Vpdl, while a little difference were observed among different varieties. The major factors affecting the lower crown were Cond, Ci, PARi, Tleaf, Tair, Vpdl and CO2R, and rather great difference were observed among different varieties. The major factors affecting whole plant were Cond, Ci, PARi, Tair and Vpdl, and there were positive correlation among Pn, Cond and PARi.The eco-physiological factors affecting Tr in upper, lower crown or whole plant were different, and among different varieties, the mainly affecting factors were different too. The main factors affecting the diurnal variation of Tr were Cond, Tair, Tleaf, Vpdl, PARi, H2OR and RHR, and among these factors, the influence of Cond, Vpdl, Tleaf and PARi were greater than that of others. The influence of Cond, Tair, PARi and Vpdl on Tr in lower crown were rather greater, and Cond, Tair, RHR on the whole plant were the greatest, especially, the influence of Cond was the most remarkable.The eco-physiological factors affecting WUE of the upper, lower or whole plant were different, and different varieties did so. The major factors affecting the diurnal variation of WUE in upper crown were Ci, Tair, CO2R, RHR,Vpdl,Tleaf and Cond, and among these factors, the affect of Ci、Cond, Vpdl、CO2R were greater than that of other factors. The major factors affecting WUE in lower crown were Ci, Tair, H2OR, RHR, Vpdl, CO2R, PARi, and among these factors, the affect of Ci、PARi、Vpdl、CO2R were greater than that of others. The major factors affecting WUE of the whole plant were Cond, Ci, Vpdl, CO2R, Tair, Tleaf, RHR, Tair and PARi, and among these factors, the affect of Ci、Cond were greater than that of others. In conclusion, Ci was the most important affecting factor on WUE, and there were significantly negative correlation between Ci and WUE. The order of Chi content of these four varieties was J5 (43.31)>H1 (42.63)>H12 (42.62) >J10 (38.74), and Chi content among different varieties had highly significant difference (p≤0.0001). Significant positive correlation were observed between Chi content and Pn, or seedling height, growth volume (p≤0.05). The order of leaf area, seedling height and biomass all was H12>J10>J5>H1, and leaf area among different varieties had significant difference (p≤0.05), seedling height and biomass did so. Pn had a terribly significantly positive coefficient with seedling height and biomass (p≤0.05), The accumulated contribution rate of Pn to individual growth volume reached 80.56%, to individual height 48.48%.更多还原