遮阴和藜竞争对黄顶菊光合荧光和生长特性的影响

为了防控黄顶菊进一步在国内蔓延,明确黄顶菊的生长机制迫在眉睫.本研究设不同遮阴程度(0、50%和80%)和种植方式(黄顶菊单种、藜单种、两者混种)共9个处理,研究遮阴和种植方式对两种植物出苗率、光合荧光和生长特性的影响.结果表明: 适度遮阴有利于黄顶菊出苗,但是出苗不整齐,这是造成黄顶菊入侵性强的一个重要因素.随着光照强度的增强,两种植物净光合速率(P_n)、光化学猝灭(q_P)、PSⅡ电子传递速率(ETR)、实际量子产量(Y)、非光化学猝灭(q_N)、水分利用效率(WUE)、茎生物量比(SMR)、冠宽(CW)和干物质积累量(DM)都增加,而比叶面积(SLA)降低;黄顶菊叶生物量比(LMR)显著增加,而藜不显著;黄顶菊DM增幅比藜的增幅高.80%遮阴下,藜P_n和DM都高于黄顶菊.自然光下,黄顶菊P_n、q_N、WUE和相对竞争强度(RCI)最高,混种黄顶菊CW、DM和混种藜P_n、Y显著低于相应的单种处理.黄顶菊的光饱和点(LSP)和光补偿点(LCP)均比藜高.因此,黄顶菊耐阴能力比藜弱,两种植物都是通过增加SLA和降低LMR来适应弱光;黄顶菊适应强光的能力大于藜,自然光下混种黄顶菊通过增加SMR和降低CW来提高竞争力.

Effects of shade and competition of Chenopodium album on photosynthesis,fluorescence and growth characteristics of Flaveria bidentis.

It is necessary to elucidate its growth mechanism in order to prevent and control the further spread of Flaveria bidentis, an invasive plant in China. The effects of shading (shading rate of 0, 50% and 80%, respectively) and planting pattern (single cropping of F. bidentis, single cropping of Chenopodium album and their intercropping) on germination rate, fluorescence characteristics and growth characteristics of the two plants were investigated. The results showed that moderate shading contributed to emergence rate, but emergence rate of F. bidentis was not uniform, which was one of important factors as a stronger invader. With the increasing light intensity, net photosynthetic rate (P_n), photochemical quenching (q_P), electron transport rate of PSⅡ(ETR), quantum yield of PSⅡ(Y), non photochemical quenching (q_N), water use efficiency (WUE), shoot biomass rate (SMR), crown width (CW) and dry biomass (DM) increased, specific leaf area (SLA) decreased, LMR of F. bidentis significantly increased, LMR of C. album changed insignificantly, and the increment of DM of F. bidentis was higher than that of C. album. In 80% shade treatment, P_n and DM of F. bidentis were lower than those of C. album. In natural light treatment, P_n, q_N, WUE and relative competitive index (RCI) were the highest, CW and DM of intercropped F. bidentis and P_n, Y of C. album were significantly lower than that of the respective single treatment. F. bidentis had higher light saturation point (LSP) and light compensation point (LCP). In conclusion, the shade tolerant ability of F. bidentis was weaker than that of C. album, but it was reversed in natural light treatment. The two plants adapted to the weak light in 80% shade treatment by
increasing SLA and decreasing LMR. F. bidentis improved competition under natural light by increasing SMR and decreasing CW.