混种非洲狗尾草对紫茎泽兰表型特征的影响

紫茎泽兰是我国最具入侵性的外来杂草之一,现已在西南大部分地区造成危害。研究了紫茎泽兰和非洲狗尾草在重度、中度和轻度3个不同入侵程度的土壤和未入侵土壤中单种和混合种植时的表型特征差异。结果表明,混合种植时非洲狗尾草的长势明显强于紫茎泽兰,混种非洲狗尾草可明显降低紫茎泽兰的生长势。混种区的紫茎泽兰株高、节间距、节数、单株叶片数、绿叶率、叶绿素含量和根长均小于单种区,其中株高、节间距和叶绿素含量差异达到显著水平(P0.05);非洲狗尾草对紫茎泽兰生长的抑制作用随其密度的增加而增强,在非洲狗尾草植株数量3倍于紫茎泽兰时抑制效果最大,紫茎泽兰株高只有其单种的1/3,节间距只有单种的1/2,叶绿素含量不足单种的1/2。对不同入侵类型土壤中的替代效果进行比较研究表明,在相同种植比例下,随着入侵程度的增加,非洲狗尾草对紫茎泽兰的抑制作用呈现逐渐减弱的趋势。在紫茎泽兰与非洲狗尾草等比种植时,重度入侵土壤中的紫茎泽兰节间距和单株叶片数与轻度和中度入侵土壤中的紫茎泽兰节间距和单株叶片数差异达显著水平(P0.05),在轻度入侵土壤中开展紫茎泽兰的牧草替代控制效果最为显著。

Effect of Mixed Culture Setaria sphacelata on the Phenotypic Characteristics of Ageratina adenophora

Crofton weed, Ageratina adenophora, is one of the worst invasive weeds in China, has invaded a large areas of southwestern China. To study the competitive effect between Setaria sphacelata and A. adenophora, and to explore the methods of controlling the invasive weed A. adenophora displaced by S. sphacelata, a potted experiment was conducted with monoculture and mixed culture of the above two species in 3 levels of invaded soils (newly, moderate and heavily invaded soil) and non invaded soil. The results showed that there was a obviously mutual antagonism between A. adenophora and S. sphacelata compared with A. adenophora, and the relatively competitive ability of S. sphacelata was higher. Mixed culture of A. adenophora and S. sphacelata heavily decreased the growth of A. adenophora, and the inhibiting effect increased with the increment of the density of S. sphacelata, the optimal inhibiting effect was obtained when the number of S. sphacelata equaled to 3 times of S. sphacelata. The height, node length, node number, leaves per plant, chlorophyll content and root length of A. adenophora planting in the mixed culture were all lower than those in the monoculture, and the difference of node length and plant height were significant(P＜0.05). It will be a promising strategy for replacement control of A. adenophora by using S. sphacelata as a competitor. For the different levels of invaded soil, S. sphacelata planting in newly invaded level soil had more biomass than those planting in moderate and heavily invaded level soil, suggested that the newly invaded soil was easier to be replaced than the other two levels of invaded soil. In the mixed cultures (50%/50%) of A. adenophora and S. sphacelata, node length, node number and leaves per plant of A. adenophora planting in heavily invaded soil were significantly different from those planting in newly and moderate invaded soils (P＜0.05).