被子植物适应内蒙古和新疆北部降水分配模式的气孔调控类型、气孔行为及水分利用策略

Angiosperm species widely spread in arid areas in the world. However, whether angiosperm species, as gymnosperm species, have different stomatal regulation and behavior to adapt to different precipitation allocation patterns still need to be looked at in concert. Inner Mongolia have low precipitation (less than 350 mm in most areas), but with more than 70 % of the total annual precipitation occurring during the May–October growing season. Xinjiang Province have an annual precipitation of less than 250 mm, but similar precipitation throughout the year, and the accumulation of thick snow in winter results in high soil water availability in spring after the snow melts. However, this is followed by severe summer and autumn drought. This project will use angiosperm species from arid areas of Inner Mongolian Autonomous Region and north Xinjiang Province as materials to investigate whether an increase in ABA or a decrease in leaf water potential regulate stomatal closure under drought stress, to separate the interacting effects of ABA and water tension on stomatal closure to reveal the types of stomatal regulation, and to investigate the water use strategies of angiosperms species in the Inner Mongolian Autonomous Region and Xinjiang Province. The project proposal will not only aid in revealing stomatal behavior differentiation of angiosperm species, but also providing a deep insight into water use strategies of angiosperm species to adapt to different precipitation allocation pattern in the Inner Mongolian Autonomous Region and north Xinjiang Province.

被子植物广泛分布于旱生生境中，其是否与裸子植物类似，具有分化的气孔调控类型，形成不同的气孔行为和水分利用策略，从而适应旱生生境中不同的降水分配模式，有待揭示。我国内蒙古和新疆北部多为旱生生境，内蒙古降水集中于夏秋，分配不均，植物频遭干旱胁迫；新疆北部降水季节分配基本均匀，春季融雪充分保障植物需水，夏秋植物持遇干旱胁迫。本项目拟以两地分布的被子植物为研究对象，以干旱胁迫和复水为研究手段，揭示被子植物适应内蒙古和新疆北部降水分配模式的气孔调控类型，基于气孔调控类型形成的气孔行为和水分利用策略。旨在深入认识被子植物适应两类降水分配模式的水分利用策略分异基础，完善进化过程中维管束植物抗旱性形成的理论体系。

我国北方地区降水少，生态环境极度脆弱。该地区分布的植物在维持当地生态平衡发挥着重要的作用。深入认识植物化学计量学特征，叶结构功能，气孔行为和水力适应机制对指导当地植被恢复具有重要意义。本项目研究发现：(1)和湿润地区相比，干旱生境分布的锦鸡儿属植物叶水导安全性强，有效性高，二者之间显著正相关；干旱生境分布种叶较高的水导安全性取决于其较高的外木质部水导安全性，外木质部水导安全性又取决于较低的叶膨压消失点；叶较高的水导有效性取决于其较高的叶脉密度、叶容和木质部面积与叶面积之比。但较高的水力供给并没有显著提升叶的光合速率，植物光合供水能力增强。(2)和湿润地区相比，干旱生境分布的柠条锦鸡儿具有叶毛，能够高效利用凌晨的露水，有效缓解干旱胁迫，水势、叶水分传导速率、气孔导度和光合速率沿土壤相对含水量下降缓慢下降，叶失去50%水分传导速率对应的土壤含水量显著降低。(3)我国北方从东向西随着经度递减，年均降水量(MAP)线性下降，年均温度(MAT)变化不大，植物叶碳(C)含量随MAP递减线性下降，氮和磷(N、P)含量线性上升，但C、N、P含量与MAT均不具有线性关系，说明叶C、N、P化学计量特征受MAP的影响。(4)我国北方从东向西随降水递减，植物叶面积和比叶面积线性下降，细脉密度、气孔密度和气孔指数线性增加，气孔长度和远轴比率线性下降；随年均温度递增，细脉密度、气孔密度和气孔指数均线性增加，但气孔长度线性下降；认为降水和温度共同影响了叶性状特征。(5)干旱复水后，内蒙古分布的、具有变水特性的锦鸡儿属植物气孔开放快于新疆北部分布的、具有等水特性的植物锦鸡儿属植物，认为乙烯是限制气孔开放快慢的主要因素。