干旱对扁穗牛鞭草生长、营养及生理指标的影响

西南地区干旱频繁，当地的主栽牧草扁穗牛鞭草经常遭受干旱危害。试验设置正常供水，轻度、中度和重度干旱4种处理，盆栽试验研究了干旱对牛鞭草生长、营养和生理指标的影响。结果表明:中度和重度干旱显著抑制地上部生长，生物量减少20%～34%，但对地下部无显著影响，致使根冠比提高，有益于增强抗旱性。干旱条件下，氮、磷、钾吸收量显著减少，可能与根系活力降低有关。干旱降低了地上部的养分积累量，但对地下部养分积累量无显著影响，说明干旱改变了植株体内的养分分布。值得注意的是，干旱显著提高了根系含钾量，最高增加了36%，这有益于提高根细胞渗透压，增强水分吸收能力。此外，干旱不同程度地降低了叶片相对含水量、叶绿素含量和根系活力，可能是造成光合速率降低、养分吸收减少、生物量降低的原因之一。在其它生长和生理指标未发生显著变化的情况下，脯氨酸含量增加了约1.7倍。可以认为脯氨酸的积累可视为植物对干旱，尤其是轻度干旱产生的一种保护性生化反应。

Effects of water stress on growth,nutrition and physiological indices of Hemarthria compressa

As one of artificial pasture in Southwest China,Hemarthria compressa often suffers from drought due to frequently occurred dry spells.A green house pot experiment was carried out to study the effects of drought on the growth,nutrition and physiological indices of Hemarthria compressa under light,middle and serious water stresses.The control was established with normal water supply.The results indicate that the aboveground growth is inhibited and the biomass is reduced by 20%-34% under the middle and serious...