空心莲子草在稻田生态系统中的生长特性及对水稻生长发育的影响

为了解空心莲子草在正常耕作稻田中的入侵能力与水稻对该草的抵抗能力,本文通过在秧苗移栽后的稻田中移植少量空心莲子草繁殖体,人工模拟空心莲子草入侵稻田的方法,研究了该草在稻田中的入侵生长繁殖特性及其对水稻生长发育的影响。结果显示:在人工移入空心莲子草后的第一个水稻生长季内,空心莲子草长势较弱,其植株克隆数与直立茎秆数从水稻分蘖前期至成熟期均无显著变化,仅株高增长极显著,但茎秆纤细柔软,部分茎秆顶端弱化,叶片弱小卷曲,出芽量很低或几乎没有新芽生长。空心莲子草对水稻分蘖、有效分蘖与株高等参数均无显著影响。空心莲子草在田埂上与稻田边缘的生长主要表现为该草的覆盖度、直立茎秆数与株高的显著增加,难以向稻田中扩散生长。研究结果表明,空心莲子草在耕作稻田中不能形成严重入侵态势。建议保持稻田于耕作状态,可有效防止空心莲子草的入侵。

Growth characteristics of alligator weed (Alternanthera philoxeroides) inrice ecosystems and effects on rice growth and development

To understand the invading capability of alligator weed (Alternanthera philoxeroide) in cultivated rice fields and rice resistance to A. philoxeroide invasion, the growth characteristics of A. philoxeroide and effects on rice development at early invasion were studied. A paddy field invasion simulation was conducted through transplanting propagators of A. philoxeroide into cultivated rice fields after seedling transplant. The results showed that A. philoxeroide growth weakened in the first cultivation season of rice after field transplanting. The numbers of clones and erect caulis of A. philoxeroide decreased slightly from early tillering to late tillering and also increased slightly from late tillering to mature stage of rice (all insignificant). Although weed height increased significantly, weed stem grew small and soft with weak tops growth. A. philoxeroide weed leaves were generally small, weak and curly and produced few new buds in rice fields. No significant effects were noted regarding rice growth parameters such as number of tillers, effective tillering per cluster and plant height when only few A. philoxeroides propagators were transplanted into rice fields. A. philoxeroide near rice field margins and in rice field levees hardly grew or spread into main rice fields. Although only weed clone number, erect caulis and plant height increased significantly, weed vegetation cover grew thick. These findings suggested that both cultivated lands and rice fields controlled growth and reproduction of A. philoxeroides. It was also proposed to keep rice fields under cultivation to prevent weed invasion.