【作者】 秦晓东；

【导师】 吕成群；

【作者基本信息】 广西大学 ， 生态学， 2016， 硕士

【摘要】 泡桐(Paulownia)具有生长快、适应性广、易繁殖等特性,是我国重要的速生用材树种之一。本研究通过设置不同程度水分、遮荫及其交互作用处理,4个水分梯度为：田间最大持水量的75-80%、55-60%、40-45%、25-30%,3个遮荫处理为：无遮荫(100%NS)、一层遮荫(23.6%NS)、二层遮荫(5.7%NS),研究了干旱胁迫和弱光胁迫下,苗期泡桐主要生长指标、生化指标和光合生理指标的差异。研究结果表明：(1)苗期泡桐在受到弱光和干旱双重胁迫时,苗高和地径增长量均显著下降(P<0.05),两者之间存在极显著的相关性(P<0.01)。(2)在一层和二层遮荫条件下,干旱胁迫导致苗期泡桐叶片MDA含量升高,重度干旱与其他水分处理间差异显著(P<0.05)。无遮荫条件下,正常水分和重度干旱时,MDA含量显著高于轻度和中度干旱(P<0.05)。正常水分和重度干旱条件下,遮荫在一定程度上降低了MDA含量,一层遮荫显著低于无遮荫和二层遮荫(P<0.05)。在一定范围内,干旱胁迫导致游离脯氨酸含量升高,重度干旱胁迫则导致游离脯氨酸含量下降。可溶性糖含量随干旱胁迫程度的增强逐渐升高。不同程度的水分处理对可溶性蛋白含量在不同遮荫层下影响效果不同。弱光胁迫导致游离脯氨酸、可溶性糖、可溶性蛋白含量的显著降低(P<0.05)遮荫处理导致苗期泡桐SOD、CAT活性的显著降低,POD活性显著升高(P<0.05)。不同水分处理对SOD、POD、CAT活性影响在不同遮荫层下表现出不同的变化规律。(3)弱光胁迫导致光合色素含量升高,重度干旱则导致光合色素含量显著降低(P<0.05)。净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和胞间CO2 (Ci)之间存在极显著的相关性(P<0.01)。 Pn、Gs、Tr之间呈现正相关,其与Ci呈负相关。干旱胁迫导致净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)日变化曲线在无遮荫和二层遮荫时由单峰型变为双峰型,胞间CO2 (Ci)由“V”型变为“W”型。一层遮荫下,净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)日变化曲线均呈单峰型,胞间CO2 (Ci)均呈“V”型。在无遮荫与一层遮荫下,原初光量子效率(a)、光饱和点(LSP)、最大净光合速率(Pnmax)、呼吸速率(Rd)等指标均随土壤含水量的降低而降低,重度干旱胁迫导致光补偿点(LCP)的显著升高。除原初光量子效率(a)外,遮荫均导致光响应曲线特征参数的下降。(4)相关分析表明,轻中度干旱胁迫导致苗期泡桐生长速度变慢,保护酶活性升高,MDA含量升高,渗透调节物质含量升高,光合作用效率下降。重度干旱胁迫导致苗期泡桐生长停滞,MDA含量进一步升高,游离脯氨酸含量下降,POD、SOD等保护酶活性降低,光合作用效率大幅下降。一层遮荫缓解了干旱胁迫对苗期泡桐造成的不良影响,表现为保护酶活性增强, MDA含量显著降低,光合作用“午休”现象消失。二层遮荫下,苗期泡桐表现出受干旱、弱光双重胁迫的反应,生长速率进一步降低,保护酶活性降低且低于无遮荫,MDA含量升高,及光合作用效率的显著下降。因此,泡桐苗期适当遮荫可以在一定范围内增强苗期泡桐对干旱胁迫的适应性。更多还原

【Abstract】 Paulownia is one of the main Fast-growing timber species with some characteristics of fast-growing, wide adaptability and breeding easily in China. The article analysis the differences of seeding-stage Paulownia’s growth indicators, biochemical indexes and photosynthetic physiological indexes under different levels of light and water. There was 4 levels of water:75-80%,55-60%,40-45%,25-30%, and 3levels of light: No-shading condition (100%NS),a layer of shade(23.6%NS) and two layers of shade(5.7%NS). Results:(1) When seeding-stage Paulownia was under the Low-light and drought stress, the amount of height and basic diameter were decreased significantly. The correlation between them was highly significant.(2) Under a layer and two layers of shading, severe drought stress increased MDA content significantly. Under the no-shading condition, when normal water and severe drought, the MDA content significantly higher than that of mild and moderate drought. Under the normal water and severe drought, shade decreased the MDA content to some content, the MDA content under a layer of shade was lower significantly than that of no-shading and two layers of shade. To some content, drought stress result the free Proline content increased, but severe drought result it decreased significantly. Soluble sugar content was increased with drought stress degree increasing. Different degrees of water treatment result in different effects on soluble protein under different layers of shade condition. Low-light stress result the content of free Proline, soluble sugar and protein decreased significantly. Shading treatment result in the decreasing of SOD, CAT activity significantly and the increasing of POD activity significantly. Different degrees of water treatment result in different effects on SOD, CAT, POD under different layers of shade.(3) Low-light stress result the photosynthetic pigment content increased and the severe drought stress decreased it significantly. It was positively correlated between Pn, Gs and Tr, but they were negatively correlated with Ci. Drought stress result that the curve of diurnal change of Pn, Tr were from single-peak type to double-peak type under no-shading condition and teo layers of shade, Ci diurnal variation curve from "V" to "W". Under a layer of shade condition, the curve of diurnal change of Pn, Tr and Gs were all single-peak type, the curve of diurnal change of Ci were "V" type. Under no-shading and a layer of shade condition, a, LSP, Pnmax and Rd decreased with the decreasing of water degree, but severe drought stress result the LCP decreased significantly. Except a, the other parameters of light response curve were decreasing under shade conditions.(4) Connectively analysis showed that the seeding-stage Paulownia growed slowly, the content of MDA, protective enzymes and osmoticas content rised with it under the light and miderate drought stress. The severe drought stress made it in very low rate of growth, and MDA content was highly increased, protective enzymes activity and osmoticas content was decreased greatly. Drught stress made the photosynthesis efficiency went down. Under a layer of shading condition, the harmful effect from drought stress was remetitent. We could know it by the evidence that the protective enzymes activity went up and the MDA content went down, in addition, the midday depression was disappeared. Under two layers of shading condition, the seeding-stage Paulownia’s growth rate decreased severesly, protective enzymes activity lower than no-shanding condition, MDA content was increased and photosynthesis efficiency significantly reducted.As a result, appratiate shading treatment could increase the resistance of the seeding-stage Paulownia to drought stress.更多还原