红树植物白骨壤叶片凋落物浸提液对桐花树胚轴萌发与幼苗生长的化感作用

Allelopathic effects of leaf litter leachates from Avicennia marina on hypocotyl germination and growth of Aegiceras corniculatum

白骨壤与桐花树是我国南方潮间带红树林中2种常见的本土优势种红树植物。本研究以桐花树为实验材料,研究不同浓度白骨壤叶片凋落物浸提液(0、2、10、20和50 g·L^(-1))处理对其胚轴萌发与幼苗生长的化感作用。结果表明:随着白骨壤叶片凋落物浸提液处理浓度的升高,桐花树幼苗的细根数、营养根数与茎长逐渐降低,且桐花树胚轴的生根和发芽时间会逐渐变长;桐花树胚轴发芽率、幼苗叶干重与根冠比在2 g·L^(-1)浸提液处理时显著增加,而在10、20和50 g·L^(-1)浸提液处理下表现为下降的趋势。50 g·L^(-1)浓度的浸提液处理明显降低桐花树胚轴的生根率、幼苗的细根长、营养根长、叶片数、根干重与茎干重,而2、10和20 g·L^(-1)浓度的浸提液处理对桐花树上述生理指标的抑制作用均不明显。与胚轴萌发相比,桐花树幼苗生长对白骨壤叶片凋落物浸提液的化感响应更为敏感。

Avicennia marina and Aegiceras corniculatum are two indigenous and common mangrove species dominantly distributing in intertidal mangrove of southern China.In this research,the allelopathic effects of different concentrations of leaf litter leachates(0,2,10,20,and 50 g·L^(-1))from A.marina on the hypocotyl germination and seedling growth of A.corniculatum were studied.The results were as followed:with the increase concentrations of A.marina leaf litter leachate treatments,the numbers of fine and nutritive roots and stem longth in A.corniculatum decreased gradually and the germination time of roots and stems became longer steadily.However,another trend was found that hypocotyl germination rate and seedling leaf biomass and rootshoot ratio enhanced significantly under 2 g·L^(-1)concentration of A.marina leaf litter leachate treatment but decreased when the concentrations increased to 10,20,and 50 g·L^(-1).The hypocotyl rooting rate,fine/nutritive root lengths,leaf number,and root/stem biomasses of A.corniculatum decreased gradually under 50 g·L^(-1)concentration of A.marina leaf litter leachate treatment,while there were no obvious allelopathic effects on the above physiological properties of A.corniculatum subjected to 2,10,and 20 g·L^(-1)concentrations of A.marina leaf litter leachate treatments.For A.corniculatum,the seedling growth elicited a more sensitive allelopathic response to leaf litter leachates from A.marina compared to its hypocotyl germination.