【作者】 贺少轩；

【导师】 梁宗锁；

【作者基本信息】 西北农林科技大学 ， 植物学， 2009， 硕士

【摘要】 以采自陕西榆林、杨凌和安塞3个种源酸枣的天然实生幼苗为试验材料,应用盆栽试验,人工控制土壤水分在75%θf、55%θf和40%θf条件下,对其耗水规律、水分生理特征、水分利用效率、渗透调节物质和保护酶活性、光合色素变化情况等进行了研究,并结合不同种源酸枣茎叶的形态解剖结构,对其进行了苗木抗旱性评价。旨在揭示3个种源苗木的耗水特性和抗旱性差异,为黄土高原酸枣林建设提供参考。取得主要结论如下:1.在干旱胁迫下,3个种源酸枣幼苗耗水量表现为:S1>S2>S3。且在3个水分梯度下的耗水量表现为:CK>MD>SD。各个种源酸枣幼苗在不同土壤水分条件下总耗水量均呈现极显著差异。3个种源苗木在不同土壤水分条件下的耗水节律基本相似,总耗水量在各旬、月份的分配比例也基本相同。整个水分处理期的旬耗水曲线为多峰波动曲线,耗水高峰期多集中于7月下旬至9月上旬;月耗水曲线为单峰曲线,最大耗水月出现在8月份。2.随水分胁迫时间的延续,3个种源酸枣叶片的SOD、CAT、APX的活性上下波动协调作用,叶片游离脯氨酸含量在中后期连续积累,可溶性糖也在后期累积加快,这些渗透调节物质与保护酶共同作用,使MDA含量在胁迫的中期和后期均呈下降趋势。3种源苗木在不同的水分条件下叶片相对含水量均保持在较高的水平上,水分饱和亏则相应的维持在较低的水平。种源S3苗木在各个水分条件下叶片均保持了稳定的持水力,种源S1则在重度胁迫下,叶片持水力有所提高,种源S2则在中度胁迫下保持了较高的叶片持水力。种源S1、S2叶片的叶绿素和类胡萝卜素含量变化相似,种源S3在8月份叶绿素a含量较高,而叶绿素b维持在较低的水平,从而保持了较高的叶绿素a/b值,体现出较高的光合活性和抗旱性。3.在中度胁迫下,S1种源能及时的调节有机物质分配,增加根冠比,利用有限的水资源,增强了抗旱性;在SD处理下,种源S3地上部生物量下降最少,地下部生物量也下降最少,种源S1则正好相反,S2则居中,表明重度胁迫下,种源S3更能够有效地分配有机物质,耐受土壤干旱。在同一水分处理下,种源S3苗木水分利用效率均高于其它2个种源,S1种源次之,S2种源水分利用效率最低,即3个种源酸枣苗木在同一土壤水分条件下的水分利用效率排序为S3>S1>S2。4. S3叶片栅栏组织与海绵组织厚度比极显著高于S1、S2叶片,并且S3种源叶片的厚度、上下表皮的厚度和栅栏组织厚度均高于S1、S2,叶片紧密度较大、疏松度最小。而种源S1叶片的栅栏组织和海绵组织厚度比居中,且上下表皮厚度和组织疏松度亦居中。S3茎木质部和韧皮部厚度的比值极显著高于S1、S2茎,并且S3种源茎的髓半径、髓/半径高于S1、S2,韧皮部厚度小,皮层所占比例大。而种源S2茎的木质部和韧皮部厚度的比值居中,且髓部和皮层所占比例亦居中。本文采用主成分分析方法对不同种源苗木的抗旱性进行了综合评价,结果表明3种源抗旱性大小为:S3>S2>S1。更多还原

【Abstract】 The water consumption characteristics and drought-resistance mechanism were studied by pot-culture seedlings in Yangling of China. Three different levels of soil water treatments with 75% (CK), 55% (MD) and 40% (SD) field water capacity were set by artificially controlling the soil moisture. The three provenances of Wild Jujube seedlings were from Yulin, Yangling, and Ansai of Shaanxi, which were named as S1, S2 and S3 respectively. The physiological indexes include water physiological characteristics, water use efficiency, osmotic adjustment substance, principal protective enzyme activity, photosynthetic pigment etc. of three provenances of Wild Jujube seedlings under different soil-water stress. In addition, combined with the anatomical structure difference from stem and leaf of different provenances seedlings, we made a comprehensive evaluation of three provenances, expecting to discover the differences of the water consumption and drought-resistance among them. The results provided reference for construction of Wild Jujube forest in Loess Plateau. The main results are as follows:1. In the water-stress condition, the water consumption of the three provenances showed S1>S2>S3, and for the same provenance under different soil water content, that showed 75%(CK) >55%(MD) >40%(SD). Different soil water content had obviously affected the total water consumption of the three provenances of seedlings. Water consumption rhythm of the three provenances under different soil water content was basically similar, and so was the distribution proportion of total water consumption in every ten or thirty days. The water consumption trend among ten days was multi-peak waving curve, which concentrated on the last ten days in July until the first ten days in September; the water consumption trend among months was single-peak curve with the biggest value of that in August.2. With the extending of water stress, the activity of protective enzymes, such as SOD, CAT, and APX in the leaves of the three provenances were up-down fluctuating, and coordinated interactively. In the meanwhile, the content of osmoregulation substance, such as soluble proline and soluble sugar, accumulated continuously in the later period, which combined action with the protective enzymes above and made the content of MDA down in the middle-later period. The relative water content of the leaves on the three provenances in all treatments was in high level, and the water saturation deficit of leaves was in low level. The water holding ability of S3 leaves was stable after 1h and 12h in vitro, that of S1 was higher in serious stress, and that of S2 was higher in moderate stress. The content changes of chlorophyll and carotenoid of S1, S2 provenances were similar, while the content of chlorophyll a of S3 provenance was in high level, and chlorophyll b was in low level in August, therefore got a high ratio of a/b, which showed higher photosynthetic activity and drought-resistance.3. In moderate stress, S1 provenance could promptly regulate organic matter allocation, increase root-shoot ratio, use limited water resources, and enhance drought-resistance. While in serious stress, the biomass of S3 provenance both decreased least up-down ground, and S1 provenance showed in opposite way, S2 were in central tendency. It indicated that S3 provenance could regulate organic matter allocation more efficiently to adapt soil drought in serious stress. S3 provenance showed higher water use efficiency than S1, S2, so the water use efficiency of three provenances seedlings in the same soil water content showed S3>S1>S24. the ratio of palisade tissue and spongy tissue of S3 leaves was higher extremely significantly than that of S1leaves and S2 leaves, and the thickness of leaves, upper epidermislo and lower epidermis of S3 were higher than those of S1 and S2. In addition, the tissue of S3 leaves was tighter than that of S1 and S2. The ratio of palisade tissue and spongy tissue of S1 leaves, the thickness of upper epidermislo and lower epidermis and leaf looseness were in the middle. The ratio of xylem and phloem of S3 stem was higher extremely significantly than that of S1 stem and S2 stem, and S3 stem had bigger pitch radius, higher ratio of pitch to stem radius, in addition, less phloem thick, and more cortex. Those of S2 stem were in the middle. Main component analysis was used to reveal the inherent mechanism of drought resistance and compare the ability of drought-resistance of different provenances of seedlings. The result is S3>S2>S1.更多还原