苗期无瓣海桑与互花米草的营养竞争关系研究

Study on nutrient competition between Sonneratia apetala and Spartina alterniflora seedlings

采用间植分隔法开展了无瓣海桑和互花米草营养竞争关系研究,结果表明竞争作用刺激了无瓣海桑高、径、冠幅、分枝及叶片数的增长,却抑制了叶面积的增加。地上竞争可增加无瓣海桑的地上生物量,但对根冠比影响不大。地下竞争增加了互花米草的地上生物量,降低了其根生物量,此时根冠比最小。地下竞争促进了无瓣海桑的主根生长,抑制了侧根生长,而地上竞争则正相反;随着竞争程度的加深,根活力逐渐降低。地下竞争时互花米草根活力显著下降。无瓣海桑和互花米草在有地上竞争时叶绿素a和b的含量均降低。各竞争处理未对P、K、Ca和Mg元素的含量产生显著影响,但地上竞争显著降低了N元素在无瓣海桑和互花米草根茎叶中的含量。互花米草的竞争强度略高于无瓣海桑,但是地上竞争强度无瓣海桑远远高于互花米草,而二者地下竞争强度相当。

The nutrient competitive relationship between the seedlings of S.apetala and S.alterniflora were studied by the separation-planted method.The results showed that the competition had stimulated the height,diameter,crown width,number of branches,and leaf number of S.apetala,but inhibited its leaf area.The ground competition increased the aboveground biomass of S.apetala,but had little effect on the shoot ratio.The underground competition increased the aboveground biomass of S.alterniflora,but reduced its root biomass,and resulted in a minimum shoot radio.Underground competition promoted the main root growth of S.apetala,and inhibited the lateral root growth,but the ground competition was opposite;with the increased competition,root activity was decreased.The root activity of S.alterniflora was significantly decreased in underground competition.Both of chlorophyll a and b of the two species were reduced in ground competition.Under all competitive conditions,the content of P,K,Ca and Mg had no significant change,but the content of N was significantly reduced in ground competition of the two species.The competitive intensity of S.alterniflora was slightly higher than that of S.apetala,but the ground competition intensity of S.apetala was much higher than that of S.alterniflora,and the underground competition intensity of S.alterniflora and S.apetala had little difference.