不同干旱胁迫强度下的类芦生长权衡研究

Growth trade-offs in Neyraudia reynaudiana in response to different levels of drought stress

权衡关系是植物生活史过程中的重要生存策略,植物生长过程的权衡关系对于理解植物在不同生境下的生存策略具有重要意义。本研究以水土保持先锋草本植物类芦(Neyraudia reynaudiana)为研究对象,采用盆栽法对类芦进行不同干旱程度的胁迫处理,分析不同胁迫处理下的生长差异和物质分配特征,探讨干旱胁迫下类芦的生长权衡。结果表明:1)不同干旱胁迫下株高间差异不显著(P>0.05);叶片数仅干旱胁迫中期,中度、重度与供水充足间差异显著(P<0.05);分蘖数仅干旱后期,重度与轻度和供水充足间差异显著(P<0.05)。在干旱胁迫条件下,株丛高生长与分蘖、高生长与叶片数之间存在生长权衡,在中、轻度干旱胁迫初期(30 d)趋向高生长,胁迫时间延长则趋向分蘖生长;重度干旱胁迫初期趋向分蘖,随着胁迫时间延长,株高减小,分蘖数和叶片数增加。2)类芦体内的水分、干物质的分配存在显著负相关关系,随着干旱胁迫的加剧,类芦叶、茎、根和全株的干物质比率均逐渐增加,含水率逐渐下降。随着干旱胁迫程度增加,水分、干物质和总生物量在叶上的分配逐渐减少,在茎上的分配逐渐增加,根系干物质的分配比例逐渐增加。3)类芦株高与分蘖的生长和资源配置存在“此消彼长”的权衡关系,干旱逆境下,类芦通过增加分蘖的投资来提高其抵御干旱的能力和存活几率,反映了干旱胁迫下类芦的生长策略和投资权衡机制。

The trade-off relationship is an important survival strategy in the plant’s life cycle.This relationship is important in plant growth processes because it helps us to understand the survival strategies in different habitats.In this study,the pioneer plant for soil and water conservation,Neyradia reynaudiana,was subjected to different drought stress treatments using the potting method.The growth differences and material distribution characteristics under different stress treatments were analyzed to explore the growth trade-off of N.reynaudiana under drought stress.The results showed that 1)there was no significant difference in the average plant height under different drought conditions.There was a significant difference(P<0.05)in the number of leaves between moderate/severe drought stress,and adequate water supply was available only in the middle stage(60 d).A significant difference(P<0.05)was observed in the number of tillers between severe and mild drought stress and adequate water supply only in the late stage(90 d).There were growth trade-offs between plant height growth and tiller,as well as tall growth and number of leaves,under drought stress conditions.In the initial stage of moderate and mild drought stress(30 days),plants tended to grow tall,and at longer stress times,they tended to grow tillers;in the initial stage of severe drought stress,they also tended to grow tillers.With long stress times,the plant height decreased and the number of tillers and leaves increased.2)A significant negative correlation was observed between the distribution of water and dry matter in N.reynaudiana.With increasing drought stress,the dry matter ratio of the leaves,stems,roots,and the whole plant gradually increased,and the water content gradually decreased.As drought stress increased,the distribution of water,dry matter,and total biomass in the leaves gradually decreased,whereas that in the stems gradually increased.The proportion of dry matter distributed by the root system gradually increased.3)Under different drought conditions,there was a trade-off relationship(as one decreases,the other increases)between plant height and tiller growth in terms of resource allocation.Drought resistance and survival probability were improved by increasing the investment in tillers,which reflects the growth strategy and investment trade-off mechanism of N.reynaudiana under drought stress.