黄土高原降雨梯度对刺槐不同器官内源激素分布格局及生长的影响

Effects of Rainfall Gradients on the Distribution Pattern and Growth of Endogenous Hormones in Different Organs of Robinia pseudoacacia on the Loess Plateau

环境梯度如何影响树木不同器官内源激素分布格局,以及该内源激素格局变化如何影响树木不同器官的异速生长,目前尚不是十分清楚。选择黄土高原地区不同降雨量梯度神木(440.8 mm/a)、绥德(475.4 mm/a)、安塞(505.3 mm/a)和淳化(606.1 mm/a)地区的刺槐林为材料,比较其叶、枝和不同径级根(最细根(0~1 mm)、细根(1~2 mm)、粗根(2~5 mm))内源激素含量及其对器官生长的影响。结果表明:(1)随着降雨量增加,3种器官中玉米素核苷(ZR)、赤霉素(GA 3)含量增加,脱落酸(ABA)含量整体下降;不同径级根系中w(ZR+GA 3+IAA)/w(ABA),w(GA 3)/w(ABA),w(ZR)/w(ABA),w(IAA)/w(ABA)比值增加,但不同器官增幅不一致。淳化地区刺槐叶,枝,最细根,细根和粗根中GA 3含量比神木地区分别高55%,21%,274%,376%和279%。(2)降雨量相对较高的安塞和淳化地区刺槐各器官年均累积量均显著高于降雨量相对较低的绥德和神木地区(p<0.05)。(3)根系促生长类激素(ZR,GA 3和IAA)含量主要受降雨量和土壤全氮(TN)影响。(4)根系生物量与ZR和w(ZR)/w(ABA)呈显著正相关,w(GA 3)/w(ABA)和w(ZR)/w(ABA)比值与枝生物量显著负相关。沿着降雨梯度,降雨量和土壤TN通过增加不同径级根系中ZR,GA 3和IAA含量从而促进刺槐根系的异速生长。

How environmental gradients affect the distribution pattern of endogenous hormones in different organs of trees,and how the changes in endogenous hormone patterns affect the allometric growth of different organs of trees are still not very clear.This study selected different rainfall gradients of Shenmu(440.8 mm/a),Suide(475.4 mm/a),Ansai(505.1 mm/a)and Chunhua(606.1 mm/a)in the Loess Plateau.Robinia pseudoacacia′s leaves,branches and roots of different diameters(the finest root(0~1 mm),fine root(1~2 mm),coarse root(2~5 mm))content and their effect on organ growth were compared.The results showed that:(1)with the increase of rainfall,the contents of zeatin nucleoside(ZR)and gibberellic acid(GA 3)increased,and the content of abscisic acid(ABA)decreased in all organs;the ratio of different diameter roots w(ZR+GA 3+IAA)/w(ABA),w(GA 3)/w(ABA),w(ZR)/w(ABA),w(IAA)/w(ABA)increased,but the growth of different organs was inconsistent;in Chunhua area,the GA 3 contents in the leaves,branches,finest roots,fine roots and coarse roots of the locusts were 55%,21%,274%,376%and 279%higher than those in Shenmu area;(2)the average annual accumulation of the organs of Robinia pseudoacacia in Ansai and Chunhua areas with relatively high rainfall was significantly higher than that in Suide and Shenmu areas with relatively low rainfall(p<0.05);(3)the contents of root growth-promoting hormones(ZR,GA 3 and IAA)are mainly affected by rainfall and soil total nitrogen(TN);(4)there is the significant positive correlation between root biomass and ZR and w(ZR)/w(ABA)content,and w(GA 3)/w(ABA)and w(ZR)/w(ABA)ratios are significantly negatively correlated with shoot biomass.Along the rainfall gradient,rainfall and soil TN promote the allometric growth of the roots of Robinia pseudoacacia by promoting the contents of ZR,GA 3 and IAA in roots of different diameter classes.