深圳城市公园不同栽植环境对毛棉杜鹃生长的影响

Effects of different planting environments on the growth of Rhododendron moulmainense in Shenzhen urban parks

【目的】研究毛棉杜鹃(Rhododendron moulmainense)在深圳城市公园不同环境下的生长适应性,为其引入城市进行观赏种植提供参考。【方法】选择长势一致的10年生毛棉杜鹃,在深圳市香蜜公园选择了临水、高地、平地3个栽植环境并各为半光照和全光照两个环境,分为6个试验样地进行种植,测定植株开花情况、生长量、叶绿素含量、光响应曲线的变化和光合特性日变化等。【结果】①不同栽植环境对毛棉杜鹃的形态和生长量均有不同程度的影响,临水环境⁃半光照环境中毛棉杜鹃的花芽数量、新梢粗度、新梢体积、新梢数量显著高于(P<0􀆰05)其他试验样地;②平地⁃全光照环境中毛棉杜鹃叶片的叶绿素a(Chla)、叶绿素b(Chlb)、总叶绿素(Chlt)含量显著高于其他试验样地,而平地⁃半光照环境中Chla、Chlb、Chlt含量均出现最低值。高地⁃半光照环境下类胡萝卜素(Car)、叶绿素a与叶绿素b质量比(Chla/Chlb)、总叶绿素与类胡萝卜素质量比(Chlt/Car)显著高于其他样地;③临水⁃半光照和临水⁃全光照环境下毛棉杜鹃的最大净光合速率(Pn,max)、光补偿点(LCP)、光饱和点(LSP)均高于其他试验样地,高地⁃半光照环境中毛棉杜鹃的表观量子效率(AQY)最高,平地⁃半光照的暗呼吸速率(Rd)最高。【结论】土壤含水量较高或排水不畅时会导致毛棉杜鹃叶绿素含量下降,光照强度过高时会导致其株高、花芽数量、新梢数量等降低;反之,环境中光照强度减弱时,对毛棉杜鹃新梢枝条的生长、花芽形成等具有促进作用,表明在城市公园种植毛棉杜鹃时应选择有适当的遮阴和具有一定透水性能的土壤环境。

【Objective】The growth adaptability of Rhododendron moulmainense in different environments in Shenzhen urban parks was studied to provide a reference for its introduction into urban areas as an ornamental tree species.【Method】Ten⁃year⁃old R.moulmainense with the same growth statuses,and three planting environments,including waterfront,highland and flatland,were selected in Shenzhen Xiangmi Park.These trees were planted under two irradiance environments,such as half⁃light and full light,and divided into six experimental plots.The trees flowering rate,growth rate,chlorophyll content,changes of light response curves and diurnal changes of photosynthetic characteristics were determined.【Result】(1)Different planting environments had different effects on the morphology and growth of R.moulmainense.The number of flower buds,thickness of new shoots,volume of new shoots and number of new shoots of R.moulmainense in the waterfront half⁃light plot were significantly higher than those in other test plots(P<0.05).(2)The content of the chlorophyll a(Chla),chlorophyll b(Chlb)and total chlorophyll(Chlt)in the leaves of R.moulmainense on the flatland⁃full light plot were significantly higher than those on other test plots,while the Chla,Chlb and Chlt in the flatland half⁃light plot showed the lowest values.The carotenoid content(Car),Chl a/Chl b(mass ratio,the same below),and Chlt/Car in the highland half⁃light plot were significantly higher than those on other plots.(3)The maximum net photosynthetic rate(Pn,max),light compensation point(LCP),and light saturation point(LSP)of leaves in the waterfront full⁃light plot were higher than those on other test plots,the apparent quantum efficiency(AQY)of highland half⁃light was the highest,and the dark respiration rate(Rd)of leaves in flatland half⁃light was the highest.【Conclusion】The chlorophyll content of R.moulmainense will decrease when the soil water content is high or the drainage is not smooth.The plant height and the number of flower buds and new shoots decreased when the light intensity was too high.On the contrary,the growth of new shoots and the formation of flower buds of R.moulmainense were promoted when the light intensity in the environment was weakened,indicating that the soil environment with appropriate shading and water permeability should be considered when planting R.moulmainense in urban parks.