外源6-BA对干旱胁迫下苹果砧木M26的生理效应

Physiological effect of exogenous 6-BA on apple rootstock M26 under drought stress

【目的】探究6-苄氨基腺嘌呤(6-BA)对干旱胁迫下苹果砧木M26生理特性的影响。【方法】以树龄2 a的苹果砧木M26为试验材料,采用盆栽控水法,设置正常水分(CK)、干旱胁迫(T_(1))、干旱胁迫+25 mg/L 6-BA(T_(2))、干旱胁迫+50 mg/L 6-BA(T_(3))、干旱胁迫+75 mg/L 6-BA(T4)、干旱胁迫+100 mg/L 6-BA(T5)6个处理。测定各处理的叶绿素含量、光合荧光、抗氧化酶活性、相对电导率(REC)和渗透胁迫物质含量。【结果】随着干旱时间的延长,丙二醛(MDA)含量、脯氨酸(Pro)含量、相对电导率(REC)、胞间CO_(2)(Ci)均呈上升趋势;叶绿素a(Chl a)、叶绿素b(Chl b)、叶绿素a+b(Chl a+b)、叶绿素a/b(Chl a/b)、气孔导度(Gs)、净光合速率(Pn)、蒸腾速率(Tr)、过氧化氢酶(CAT)活性和荧光参数F0、Fm、Fv/Fm持续下降;过氧化物酶(POD)活性、超氧化物歧化酶(SOD)活性和可溶性糖(SS)含量呈先升后降的趋势。喷施6-BA后各指标的变幅均减小了,其中T3(50 mg/L 6-BA)处理下MDA、Pro、REC、Ci升幅最小,均显著低于其他处理组,但显著高于CK;CAT、Pn、Tr降幅最小,均显著大于其他处理组,但显著低于CK。主成分分析结果显示,外源6-BA对干旱胁迫下苹果砧木M26缓解能力依次为:T_(3)>T_(4)>T_(2)>T_(1)>T_(5)。【结论】50 mg/L 6-BA处理能更好改善干旱胁迫下M26的光合能力,提高抗氧化酶活性,增加生物膜的稳定性,达到缓解干旱胁迫的目的。

【Objective】The study was conducted to explore the effect of 6-benzylaminoadenine(6-BA)on the physiological characteristics of apple rootstocks under drought stress.【Method】Two year old apple rootstock M26 was used as experimental material,which was treated with different water stress by the pot water control method,i.e.,normal water(CK),drought stress(T_(1)),drought stress+25 mg/L 6-BA(T_(2)),drought stress+50 mg/L 6-BA(T_(3)),drought stress+75 mg/L 6-BA(T_(4))and drought stress+100 mg/L 6-BA(T_(5)).For each treatment,the Chlorophyll content,chlorophyll fluorescence,antioxidant enzyme activity,relative conductivity and osmoregulation substance content were determined at different periods.【Result】With the drought days extended,the contents of malondialdehyde(MDA),proline(Pro),relative conductivity(REC)and intercellular CO2(Ci)increased,but Chlorophyll a(Chl a),chlorophyll b(Chl b),chlorophyll a+b(Chl a+b),chlorophyll a/b(Chl a/b),stomatal conductance(Gs),net photosynthetic rate(Pn),transpiration rate(Tr),catalase(CAT)activity and fluorescence parameters F_(0),F_(m) and F_(v)/F_(m) decreased continuously,whereas peroxidase(POD)activity,superoxide dismutase(SOD)activity and soluble sugar(SS)content increased first and then decreased.After spraying 6-BA,the variation amplitude of each index decreased.The increase of MDA,Pro,REC and Ci in T_(3)(50 mg/L 6-BA)treatment was the smallest,which was significantly lower than that in other treatment groups and significantly higher than CK,CAT,Pn and Tr decreased the least,which were significantly higher than other treatment groups and significantly lower than CK.Through comprehensive analysis,the mitigation ability of exogenous 6-BA on M26 of apple pootstock under drought stress was T_(3)>T_(4)>T_(2)>T_(1)>T_(5).【Conclusion】The treatment with 50 mg/L 6-BA could improve the photosynthetic capacity of M26,increase the activity of antioxidant enzymes and the stability of biofilm under drought stress,and whereby alleviate drought stress.