摘要
为探究氮添加对濒危植物东北红豆杉幼苗生长-防御权衡的影响,为该物种的保护工作提供理论依据,本研究以东北红豆杉4年生幼苗为对象,进行了3种氮源(硫酸铵、硝酸铵和硝酸钾)和4个施氮量(30、60、90、120 kg N·hm^(-2)·a^(-1))的氮添加实验。结果表明:(1)东北红豆杉幼苗的苗高增长量、地径增长量和总生物量随施氮量增加显著增加,施氮量超过90 kg N·hm^(-2)·a^(-1)后地径增长量和总生物量开始下降,施氮处理的幼苗根冠比显著低于对照组,但在不同施氮量下无显著差异;(2)净光合速率(Pn)和气孔导度在氮添加处理后显著提高,在施氮量为90 kg N·hm^(-2)·a^(-1)时达峰值,胞间CO_(2)浓度与Pn的变化方向相反,说明氮添加可以缓解植物的非气孔限制;(3)黄酮类化合物含量在施氮后呈现先增高后降低的趋势,施氮量30 kg N·hm^(-2)·a^(-1)为转折点;(4)施氮后,生长指标与光合指标呈显著正相关,类黄酮指数与光合指标呈显著负相关,净同化率、相对生长速率和黄酮类化合物指数变化符合生长-分化平衡假说;(5)硝酸铵处理相对单一态氮处理对幼苗的地上部分生长、气孔导度和花青素合成具有促进作用,硝酸钾处理下类黄酮指数显著提高。总的来说,东北红豆杉幼苗对氮添加的响应与施氮量和氮素类型有关,当氮添加为30~90 kg N·hm^(-2)·a^(-1)时,东北红豆杉幼苗的生长发育和防御水平较优,可作为东北红豆杉迁地保护或野外回归的参考措施。
To clarify the effects of nitrogen addition on the growth-defense trade-off of seedlings of the endangered species Taxus cuspidata and provide a theoretical basis for its protection,an experiment was conducted on 4-year-old seedlings of T.cuspidata using three N types(ammonium sulfate,ammonium nitrate and potassium nitrate)and four addition levels(30,60,90 and 120 kg N·hm^(-2)·a^(-1)).The results showed that:(1)Height increment,basal diameter increment,and total biomass of T.cuspidata seedlings increased significantly with increasing N addition level.When the N addition level exceeded 90 kg N·hm^(-2)·a^(-1),the basal diameter increment and total biomass began to decline.Nitrogen addition significantly reduced the root/shoot ratio of seedlings,but without significant differences among different N addition levels.(2)Net photosynthetic rate(Pn)and stomatal conductance increased significantly after N addition,peaking at 90 kg N·hm^(-2)·a^(-1).The change of intercellular CO_(2)concentration was opposite to the Pn,indicating that N addition could alleviate non-stomatal limitation of plants.(3)Flavonoid content increased firstly and then decreased after N addition,with a threshold of 30 kg N·hm^(-2)·a^(-1).(4)After N addition,there was a positive correlation between growth and photosynthetic indices,and a negative correlation between flavanols and photosynthetic indices.The changes of net assimilation rate,relative growth rate and flavonoid indices were consistent with the predictions from the growth-differentiation balance hypothesis.(5)Compared with the single N form treatment,the addition of ammonium nitrate promoted aboveground growth,stomatal conductance and anthocyanin synthesis of seedlings.The flavonoid index increased significantly under the potassium nitrate treatment.In general,the response of T.cuspidata seedlings to N addition was related to both the amount and type of N addition.When the N addition was in the range of 30-90 kg N·hm^(-2)·a^(-1),the growth and defense level of seedlings were better.The findings can be used as a reference measure for the ex-situ conservation and reintroduction of T.cuspidata.
作者
孟秋实
秦倩倩
刘艳红
MENG Qiu-shi;QIN Qian-qian;LIU Yan-hong(Beijing Key Laboratory of Forest Resources and Eco-system Process,Beijing Forestry University,Beijing 100083,China)
出处
《生态学杂志》
CAS
CSCD
北大核心
2022年第12期2325-2334,共10页
Chinese Journal of Ecology
基金
国家重点研发计划项目(2016YFC0503106)资助。
