Morphological responses of <i>Zizania latifolia</i> seedlings at different ages to short-term submergence

Abstract

菰（Zizania latifolia）是长江中下游流域常见的挺水植物.为了解菰在野外的扩张和退化机制，本研究通过模拟实验分析了不同时期菰幼苗对短期淹没的形态学响应.实验共选择株高36和70 cm两种幼苗，设计不淹没、50%淹没和100%淹没3个处理.研究结果表明：两组菰幼苗地上部分的形态学响应有一定差异.在100%淹没处理下，36 cm幼苗组株高最低，茎粗和最大叶宽均显著低于其他两个处理；而70 cm幼苗组在不淹没处理下株高最低，茎粗和最大叶宽在50%和100%淹没处理下均无显著差异.两组菰幼苗根系的形态学响应也不一致.36 cm幼苗组，100%淹没处理组的所有6个根系指标均与其他两种处理有显著差异；70 cm幼苗组，不淹没处理组的6个根系指标均与其他两种处理有显著差异.随着淹没深度的增加，两组菰幼苗总生物量和根茎比均逐渐下降；但36 cm幼苗组在100%淹没处理下总生物量和根茎比均显著低于其他两个处理，而70 cm幼苗组在50%和100%淹没处理下却无显著差异.综合以上分析，本研究结果表明随着菰幼苗的生长，其对淹没的形态学响应能力增强.本研究结果对长江中下游湖泊菰的生态调控具有重要意义.;Zizania latifolia is a common emergent macrophyte in the middle and lower reaches of the Yangtze River Basin. In order to understand the expansion and degradation mechanism of Z. latifolia in the field, the morphological responses of Z. latifolia seedlings at different ages to short-term submergence are analyzed by simulation experiments. Two groups of seedlings with respective plant height of 36 and 70 cm were selected in this study. Three submergence treatments (0%, 50%, and 100% submergence) are tested in each group. The results showed that the morphological responses of aboveground part of the two groups of seedlings have certain differences. In treatment of 100% submergence, plant height was the lowest, and the shoot thickness and maximum leaf width were significantly lower than the other two treatments in 36 cm group. However, the plant height was the lowest in 0% submergence treatment, and no significant difference was detected between 50% and 100% submergence treatments in 70 cm group. Moreover, the morphological responses of root in the two groups also showed differences. All the six root parameters showed significant differences between 100% submergence treatment and the other two treatments in 36 cm group, while in the 70 cm group significant differences were found between 0% submergence treatment and the other two treatments. The total biomass and root/shoot ratio of the two groups of seedlings decreased with the increase of submergence depth. However, the two parameters were significantly lower in 100% submergence treatment than the other two treatments in 36 cm group, while no significant difference was found between 50% and 100% submergence treatments in 70 cm group. In conclusion, the morphological responses of Z. latifolia to short-term submergence were increased with the growth of the seedlings, and this had significant implications to the ecological regulation of Z. latifolia in lakes along the middle and lower reaches of the Yangtze River.