滴灌条件下土壤基质势对红豆杉幼苗叶绿素荧光特性和生长的影响

The Effects of Soil Matric Potential on Fluorescence Characteristics of Chlorophyll and Growth of Taxus Chinensis Seedlings under Drip Irrigation

【目的】探索不同土壤基质势对红豆杉幼苗叶绿素荧光特性和植株生长的影响。【方法】以太行红豆杉幼苗盆栽为材料,在滴灌条件下,将滴头正下方20cm深处的土壤基质势设定为-10、-20、-30、-40和-50k Pa 5个下限,每月记录红豆杉幼苗的生长指标,并用PAM-2500型便携式叶绿素荧光仪测定红豆杉幼苗叶片的叶绿素荧光参数。【结果】①春季时,红豆杉幼苗叶片F0、Fm、Fv/Fm和Fv/F0随土壤基质势的降低呈下降趋势,叶片qP、NPQ、ETR和Y(Ⅱ)呈上升趋势,虽然低土壤基质势下的红豆杉幼苗表现出轻微胁迫,但仍有很好地抗性。进入夏季后,红豆杉幼苗叶片F0、Fm、Fv/Fm和Fv/F0无显著差异,q P、ETR和Y(Ⅱ)呈下降趋势,NPQ呈先上升后下降趋势,高土壤基质势有利于提升叶片的光合电子传递速率和PSⅡ反应中心的开放程度,但低土壤基质势的红豆杉幼苗仍具有一定的光保护能力。②-20 kPa处理组的红豆杉幼苗的株高、地径和冠幅于试验后期达到最大值,LAI仅次于-30 kPa处理组,但无显著差异。【结论】红豆杉幼苗具有一定的抗旱能力,将滴头正下方20cm处土壤基质势下限设置在-20 kPa有利于红豆杉幼苗的生长。

【Background】Taxus chinensis is a valuable medicinal herb and the paclitaxel in it can inhibit tumor growth.Clinical tests have shown that it is effective in treating many types of advanced cancers.As such,the demand for paclitaxel has increased over recent years.Wild Taxus chinensis grows slowly and is less competitive in natural environment.Exploitation of the wild types over the past decades has driven it almost to extinction.Domestic cultivation is essential to keep germplasm of Taxus chinensis from extinction,in which irrigation plays an important role.Drip irrigation is a micro-irrigation technology and can control soil moisture by automation.It is not only water use efficient but also improves plant yield and quality.Current research on drip irrigation focused on greenhouse crops and there is a paucity of study on its application in medicinal plants.【Objective】The objective of this paper is to experimentally investigate the effects of soil matric potential controlled by drip irrigation on fluorescence characteristics of chlorophyll and growth of the Taxus chinensis seedlings.【Method】The Tai Hang Taxus chinensis seedlings grown in pots was used as model plant.The matric potential at the depth of 20 cm underneath the drip emitter was kept at-10 kPa(F0),-20 kPa(F1),-30 kPa(F2),-40 kPa(F3)and-50 kPa(F4)respectively by adjusting the dripping rate.During the experiment,growth traits of the plant were recorded and the fluorescence parameters of the chlorophyll were measured monthly using a PAM-2500 Portable Chlorophyll Fluorometer.【Result】①As time elapsed in spring,the F0,Fm,Fv/Fm and Fv/F0 in the seedlings decreased,while qP,NPQ,ETR and Y(II)increased.The seedlings growing under low soil matric potential endured a slight water stress,but they remained resilient.In summer,F0,Fm,Fv/Fm and Fv/F0 did not show significant change,whereas qP,ETR and Y(Ⅱ)monotonically decreased and NPQ increased first followed by a decline.High soil matrix potential benefited photosynthetic electron transfer and opening of the PS(II)reaction center,but the seedling growing in low soil matrix potential still had a certain light protection ability.②Plant height,ground diameter and crown breadth of the seedling peaked at matric potential of-20 kPa at late stage of the experiment.【Conclusion】Taxus chinensis seedlings can withstand water stress to certain extent.Keeping the soil matrix potential at the depth of 20 cm below the emitter at-20 kPa appeared to be optimal to benefit growth of the Taxus chinensis seedlings.