NO对酸铝胁迫下香樟根系形态及叶绿素荧光特性研究

Effects of Exogenous NO on Root Morphology and Chlorophyll Fluorescence Characteristics of Cinnamomum camphora Seedlings under Acid-Aluminum Stresses

以盆栽香樟幼苗为试验材料,探究酸铝胁迫下施加外源NO[硝普钠(SNP)作为供体]对香樟幼苗根系形态以及叶绿素荧光特性的影响。结果表明:1)在不施加外源NO的情况下,随着铝浓度的增加香樟幼苗地上部分生物量、初始荧光(F_o)、最大荧光产量(F_m)、可变荧光(F_v)、最大光化学量子产量(F_v/F_m)均呈现不断降低的趋势;而根系的生物量、根总长、根尖数则呈现不断升高的趋势,且普遍低于对照(CK)。2)在铝浓度一定的情况下,随着SNP浓度的增加,香樟根系的各形态指标以及叶绿素荧光各参数值均呈现先升高后降低的趋势,地上生物量指标以及叶绿素荧光的4个指标参数均在SNP=0.1 mmol·L^(-1)时达到最大值,而根系的各形态指标则在SNP=0.05mmol·L^(-1)时达到最大值,并且均显著(P<0.05)高于CK。3)在没有酸铝胁迫的情况下,施加少量的SNP可以促进香樟幼苗根系的生长,当浓度超过0.1mmol·L^(-1)时表现出抑制作用。4)结合香樟幼苗的生长指标进行苗木质量指数(QI)分析,可知在铝浓度和SNP浓度梯度分别为0.2mmol·L^(-1)及0.05mmol·L^(-1)下最有利于香樟幼苗的生长。综上所述,酸铝胁迫对于香樟幼苗地上部分生物量以及叶绿素荧光的特性所表现的抑制作用显著高于根系形态的各指标,香樟幼苗不同部位的耐铝性表现出了一定的差异性。SNP的加入对酸铝胁迫下的香樟幼苗起到了一定的缓解作用,并且浓度在0.05~0.1mmol·L^(-1)之间缓解作用最大。

In this paper, potted seedlings of Cinnamomum camphora was used as research materials to explore exogenous NO （sodium nitroprusside （SNP） as the donor） effects on seedling root morphology indexes and chlorophyll fluorescence parameters under different acid-aluminum levels. The results showed that 1） in the absence of exogenous nitric oxide, the seedling aerial part biomass, initial fluorescence （Fo）, maximum fluorescence yield （Fm）,variable fluorescence （Fv）,and maximal chemical quantum yield （Fv/Fm） showed a decreasing trend with Al concentration. The root biomass,root length,root number showed a rising trend and were generally lower than those of the control. 2） Within a range of aluminum concentration, the root morphological indexes and chlorophyll fluorescence parameters first increased and then decreased with SNP concentration. The ground biomass index and four indexes of chlorophyll fluorescence parameters reached maximum value when the SNP concentration was 0.1 mmol·L^-1, while the morphological index of the root reached maximum value when SNP=0.05 mmol·L^-1, significantly （P〈0.05） higher than those of the control. 3） In the absence of acid aluminum stress, the application of small amounts of SNP could promote seedling growth. More than 0.1 mmol ·L^-1 concentration showed inhibitory effect. 4） Combining seedling growth indexes,seedling quality index （QI） analysis showed it was the most favorable for seedling growth when the aluminum concentration was 0.2 mmol ·L^-1 and SNP concentration was 0.05mmol·L^-1 . In summary, the inhibitory effects of acid aluminum stress on the biomass of aerial part and chlorophyll fluorescence characteristics were significantly stronger than those of root morphological inde xes. Different part of C. camphora seedlings demonstrated some differences in aluminum resistance. The ap plication of SNP relieved acid-aluminum stress,and the best concentration was 0.05-0.1 mmol·L^-1.