【作者】 王磊；

【导师】 傅松玲； 肖斌；

【作者基本信息】 安徽农业大学 ， 林业硕士（专业学位）， 2020， 硕士

【摘要】 为科学扩大薄壳山核桃栽培范围,筛选适宜安徽不同气候类型的薄壳山核桃品种,本研究以我国主要引种的薄壳山核桃品种的茎、叶为试验材料,研究其显微结构与水力性状的关系,旨在评价其抗旱性及适宜栽植立地。通过对不同薄壳山核桃品种的茎、叶组织进行石蜡包埋并切片,使用光学显微镜和摄像机拍摄其茎、叶的显微特征。对比叶肉结构特征,包括上表皮厚度、栅栏组织厚度、海绵组织厚度、下表皮厚度等叶肉组织指标,比较其栅海比、叶片组织结构紧实度和叶片组织疏松度等指标;并通过气孔直径、气孔密度、叶脉密度等指标;对比木质部结构特征,包括导管直径、导管密度、导管内径跨度等指标,并计算导管壁加固系数,探索导致不同薄壳山核桃品种在自然状态下导水损失率差异的原因,弄清薄壳山核桃抗旱性机理,为薄壳山核桃的推广提供科学依据。主要研究结果如下。(1)2019年安徽省内平均连续78天无降雨旱情期间,3个薄壳山核桃品种的自然导水损失率比较结果表明:‘波尼’和‘威斯顿’的栓塞程度为23.3%和22.2%,显著低于(P<0.05)‘马罕’的32.9%,表现了原产于降雨量较少地区的‘波尼’和‘威斯顿’的抗旱性表现更强的特性。(2)叶片厚度、栅栏组织、栅海比、栅栏比等指标比较结果均为‘波尼’>‘威斯顿’>‘马罕’,表明‘波尼’和‘威斯顿’对水分的调控和抗蒸腾的能力要强于‘马罕’,在逆境中的适应性也强于‘马罕’。(3)上表皮厚度、下表皮厚度为‘威斯顿’>‘波尼’>‘马罕’,海绵组织厚度和海绵比为‘马罕’>‘威斯顿’>‘波尼’,‘波尼’和‘威斯顿’的叶片厚度更厚,叶片保护组织更发达,对叶片的调控能力更强,更有利于适应干旱的生境。(4)气孔直径为‘马罕’>‘威斯顿’>‘波尼’,气孔密度为‘波尼’>‘威斯顿’>‘马罕’,叶脉密度为‘波尼’>‘威斯顿’>‘马罕’,‘波尼’和‘威斯顿’拥有更加发达的叶脉系统和更加小而密的气孔特征,这也意味着两者较‘马罕’抗旱性更强,在干旱中维持生理功能的能力更强。从叶片性状层面而言,‘波尼’的抗旱性最好,其次是‘威斯顿’,‘马罕’最差,这与干旱胁迫下薄壳山核桃的栓塞程度是一致的。(5)‘马罕’的木质部导管直径显著大于‘波尼’和‘威斯顿’,这意味着‘马罕’在干旱胁迫下产生栓塞的几率更大,不利于植物在旱境下生存;‘马罕’的导管密度显著低于‘波尼’和‘威斯顿’,因此其有效导水面积最小,这也就导致了它的边材导水率最低的现象。(6)‘马罕’的导管壁加固系数最小而导管内径跨度最大,这均表示其抵御栓塞发生的概率较大,与其在实际旱境中的表现一致。从木质部解剖层面而言,‘波尼’的抗旱性最好,其次是‘威斯顿’,‘马罕’最差,这与叶片性状一致。(7)原产于干旱生境下的‘波尼’和‘威斯顿’在受到同等强度的干旱胁迫后,通过缩短新梢长度、增粗新梢直径的方式主动适应干旱环境,同时两者的茎、叶干物质含量均显著高于‘马罕’,不仅表现出较强的抗旱能力,也表现出受胁迫后更佳的恢复能力。(8)综合品种的茎、叶解剖和水力学特征得知,供试品种抗旱性能力排序为‘波尼’>‘威斯顿’>‘马罕’,原产于干旱生境下的‘波尼’和‘威斯顿’的耐旱性优于原产于富水生境下的‘马罕’,这给薄壳山核桃引进品种的选择提供科学依据。更多还原

【Abstract】 In order to expanding the planting area and selecting suitable varieties of pecan in Anhui,the paper tested the drought resistant index about the stem and leaf of mainly introduced pecan varieties in China.The author studied the relationship between the micro structure with hydraulic properties.The stem and leaf tissues of different thin shell pecans were embedded in paraffin and sliced,and the microscopic features of the stem and leaf were photographed using an optical microscope and a camera.Comparison of mesophyll structural characteristics,including mesophyll tissue indexes such as upper epidermis thickness,palisade tissue thickness,sponge tissue thickness,lower epidermis thickness.Compare the indicators such as the ratio of palisade tissue to spongy tissue,the ratio of palisade tissue to leaf thickness and the ratio of spongy tissue to leaf thickness;and pass the indexes such as the stoma diameter,stoma density,and vein density.Compare the structural characteristics of the xylem,including the diameter of the pipe,the density of the pipe,the span of the inner diameter of the pipe.,and calculate the reinforcement coefficient of the pipe wall to explore the causes of the difference in the water loss rate of different pecan varieties in the natural state,and to understand the mechanism of pecan drought resistance.The promotion of pecans provides a scientific basis.The main results were as follows:(1)This study was carried out during the drought in Anhui province to determine the percentage loss of conductivity(or embolism degree)of three varieties on pecans in 2019.The results showed that the embolism degree of‘Pawnee’(P)and‘Western’(W)were 23.3%and 22.2%,which were significantly lower than that of‘Mahan’(M)(P<0.05)which were32.9%.It shows that P and W are more drought-resistant in areas with less rainfall.(2)The sequence of the leaf thickness,palisade tissue thickness,the ratio of palisade tissue to spongy tissue and the ratio of spongy tissue to leaf thickness were all showed that:P>W>M,which showed that P and W were significantly stronger than M in ability of water regulation and transpiration resistance.Their adaptability in adversity was also stronger than M.(3)Upper epidermis thickness,lower epidermis thickness these data are W>P>M,sponge tissue thickness and the ratio of spongy tissue to leaf thickness those data are all M>W>P,P and W the leaf thickness is thicker,the leaf protection tissue is more developed,so their ability to regulation ability and the adaption of drought habitat is more stronger.(4)The order of stoma diameter is M>W>P,the order of stoma density is P>W>M,the order of leaf veins density is P>W>M.As a result,P and W have a more developed leaf vein system and‘smaller and densier’s stoma characteristics,which also means they are more resistant to drought than M and are better able to maintain plant function in adversity.In terms of leaf traits,P had the best drought resistance,followed by W and M,which was consistent with the actual embolization degree of pecan under drought stress.(5)The vessel diameter in xylem of M is significantly larger than that of P and W, which means that M has a greater probability of embolization under drought stress,which is not conducive to the survival of plants in dry conditions.The catheter density of M is significantly lower than that of P and W,so its effective water conduction area is the smallest,which leads to its sapwood water conductivity is the lowest phenomenon.(6)M has the smallest(t/b)~2 and the largest conduit wall span(b),which indicates that it has a high probability of resisting embolism,which is consistent with its performance in the actual dry environment.From the perspective of xylem anatomy,P had the best drought resistance,followed by W and M,which was consistent with leaf characters.(7)P and W(which are native to arid habitats)were actively adapted to the arid environment by shortening the length of the new shoots and increasing the diameter of the new shoots after being subjected to the same intensity of drought stress.The dry matter content of the leaves is significantly higher than that of M,which not only shows strong drought resistance,but also shows better recovery ability under stress.(8)The stem and leaf anatomy and hydraulic characteristics of the comprehensive varieties are known,and the drought resistance of the tested varieties is ranked as P>W>M.The drought tolerance of W is better than that of M native to rich water habitats,which provides a scientific basis for the selection of thin-shell hickory varieties.更多还原