【作者】 肖婷婷；

【导师】 吕金印；

【作者基本信息】 西北农林科技大学 ， 植物学， 2010， 硕士

【摘要】 我国是世界上13个贫水国之一,水分亏缺严重影响了我国的粮食产量的提高和粮食安全。本研究通过水培和盆栽试验,利用石蜡显微切片等方法,研究了水分亏缺对不同基因型小麦形态、生理特性以及结构发育的影响。主要获得以下研究结果:1.水分亏缺条件下,小麦幼苗叶面积减小,叶片水势和RWC降低。随着渗透胁迫加剧,小麦幼苗叶片中抗氧化酶活性受到抑制,脂过氧化产物MDA含量增加,随着水分胁迫的加重,SOD、CAT活性降低越迅速,MDA含量迅速上升,从而导致根系活力、叶片和根中可溶性蛋白含量下降。2.小麦生育后期水分亏缺下,株高减小,叶面积下降,地上部分生物量减少,叶片、叶鞘、茎器官对籽粒的同化物贡献率减小,同化物在穗部非籽粒器官中大量滞留。水分亏缺下,水分敏感品种“西农979”和抗旱品种“普冰143”粒重分别下降13.74%和12.10%;颖壳、内外稃及穗轴的生物量,西农979分别增加了10.37%、15.77%、5.15%,普冰143分别增加了36.94%、13.29%、36.36%,普冰143的转运率较大。正常水分条件下离体旗叶的保水力大于水分亏缺条件下离体旗叶的保水力,两品种间差异不显著。3.小麦旗叶和穗部各器官花后10d,可溶性糖含量呈先增后减,花后10d达到峰值,但穗轴中的可溶性糖含量减少较缓。两种水分条件下,旗叶和穗部中蔗糖含量在花后5d下降剧烈,降幅分别是65.48%~86.25%(旗叶)、33.62~63.44%(颖壳)、56.90~75.25%(内外稃),且水分亏缺条件下旗叶及穗部非籽粒组分中蔗糖含量相对增加。西农979和普冰143籽粒中淀粉含量比正常水分条件下分别低56.09%和5.96%。4.在正常供水及水分亏缺下,西农979和普冰143两个小麦品种开花期靠近穗轴节片处新形成的维管束呈扇形分布,远离穗轴节片处呈椭圆形及其他形状分布。穗轴节片处新增加的维管束与原有维管束之间的细胞倍增,形成厚壁组织;随着穗的发育,原穗轴中的部分维管束与穗轴节片处新形成的维管束延伸至颖壳和小穗轴,尔后向上分支延伸至第1朵小花的外稃、浆片、内稃及后续各小花。5.水分亏缺下由穗基部到顶部穗轴中大、小维管束数目、横截面积等维管参数下降幅度较大,可能是同化物在非籽粒器官颖壳和穗轴中滞留的原因之一。水分亏缺下两个小麦品种穗粒重下降,非籽粒器官生物量明显增加,旱地品种普冰143表现更为突出。更多还原

【Abstract】 China is one of 13 major water-poor countries, there is always seasonal water shortages in the Loess Plateau in western China, and in recent years there also was severe drought in south of China. The effects of water deficit have seriously affected China’s food production and food security. The objective of this study was to determine the defects of water deficit on the morphological, physiological characteristics of wheat(Triticum aestivum L.) and the vascular bundle system of the wheat ear. Pubing143 and Xinong979 was examined on material grown in pots under water deficit from jointing stage. The contribution to total yield of grain in various organs and the vascular system in the rachis were observed by using physical activity measurement and microscopy paraffin sections. The results in this study are as follows:1. Water deficit will not affect the overall growth of wheat seedlings, but it can change the value of root to shoot; reduce the area of wheat seedling’leaves, lower water potential of leaves and the relative of water content. The chlorophyll content of wheat seedling’leaves will not reduce under moderate water deficit conditions. The MDA content in wheat seedlings first increases and then decreases, as the activities of antioxidant enzymes increase in wheat seedlings. With the strength of osmotic stress increased, it is beyond the antioxidant enzyme defense system’s scavenging capacity of wheat seedlings, the value of MDA content increased.2. Under the water deficit condition, the growth of wheat plants was inhibited, stem height decreased, leaf area of wheat was decreased, the over ground biomass was decreased. After flowering stage, the contribution of carbon assimilation in flag leaf, leaf sheath and stem transporting to grain was increasing. However, it is difference between Pubing143 and Xinong979. In filling stage, the flag leaf in vitro which is under adequate moisture conditions is larger than which is under the water deficit.3. Material transferring rate increased with the increasing of sucrose content in vegetative organs; the accumulation of carbon assimilation in grain increased as the sucrose content in vegetative organs with and physical functioning with the increase rate. After flowering 10 to15 days, the carbohydrates stored in the vegetative organs begin to decompose, then the decomposition products was deliveryed to the ear, the soluble carbohydrate content decreased. Under water deficit conditions, the amount of sucrose and starch increased in non-grain composition of ear.4. The number of central and peripheral bundles declined acropetally along the length of the rachis. A significant difference appeared in the rate of declining between the basal spikelet to central and the central to terminal spikelet. While under water-deficit condition, the levels of declining increased significantly. However, little influence on the number of vascular which prolonged and developed to spikelet was showed. On the contrary, the diameter of the large vessel and the area of the vascular which are in the first three floret of each middle spikelet were affected largely by water deficit. Water deficit affects the allocation and transportation of carbon assimilate by affecting the vascular structure significantly under water deficit, which induces a large number of carbon assimilates remaining in wheat ear.更多还原