不同生态型喜旱莲子草对干旱的生理生态反应

Ecophysiologcal Responses to Soil Drought in Two Contrasting Alternanthera philoxeroides Ecotypes

研究了两种生态型(水生型和旱生型)喜旱莲子草对土壤干旱的生理生态响应。结果显示,干旱显著降低了两种生态型喜旱莲子草的株高、节长、叶长、叶宽、总叶面积、比叶面积、生物量和相对生长速率,但对茎直径没有明显影响。水生型植株在株高、节长、茎粗、叶长、叶宽和总叶面积等生长参数上都显著大于旱生型植株。而干旱对水生型植株的总叶面积、生物量和相对生长速率的影响更大。就生物量分配模式而言,在干旱条件下,两种生态型植株都表现出将更多的生物量分配到根和茎,较少分配到叶。尽管干旱对水生型植株叶片的相对含水量、叶绿体色素有一定负面影响,但两种生态型植株都能维持较高的相对含水量和叶绿体色素的含量。相比较而言,旱生型比水生型喜旱莲子草具备更强的抗旱能力。

A potted experiment was conducted to compare ecophysiological responses to soil drought in two contrasting Alter-nanthera philoxeroides （Mart.）Griseb ecotypes （i.e xeric ecotype and aquatic ecotype）.Drought significantly reduced plant height, internode length, leaf length, leaf width, total leaf area, specific leaf area, total biomass and relative growth rate, but had little effect on stem diameter in both ecotypes.Plant height, internonde length, stem diameter, leaf length, leaf width and total leaf area in aquatic ecotype were significantly higher than those in xeric ecotype across soil water content.However, the interaction of drought×ecotype indicated that drought decreased much more total leaf area, biomass and rela-tive growth rate in aquatic ecotype than those in xeric ecotype.Under drought condition, two kinds of ecotype could distributed more biomass to root and stem, less to leaf compared with well water treatment.Although drought decreased leaf relative water content and leaf pigments especially in aquatic ecotype, these two physiological parameters could be sustained a relative high level even under sever drought in the two kinds of ecotypes.Based on these results, authors suggested that both aquatic ecotype and xeric ecotype of A.philoxeroides could survive sever drought by increasing leaf thickness, reducing leaf size, changing biomass allocation as well as sustaining high leaf reality water content and leaf pigments.Furthermore , the xeric ecotype had higher drought resistance than aquatic ecotype.