干旱胁迫对‘吉美’海棠生理特性的影响

Effects of Drought Stress on Physiological Characteristics of Malus ‘Jimei’

以‘吉美’海棠(Malus‘Jimei’)嫁接苗为试材,采用盆栽试验法,设置对照(CK)、轻度干旱(SD)、中度干旱(MD)和重度干旱(HD)胁迫4个处理组,研究了不同干旱胁迫条件下‘吉美’海棠植株的生理特性规律,以期为‘吉美’海棠的适应性推广提供参考依据。结果表明:随着土壤相对含水量的降低及干旱胁迫时间的延长,‘吉美’海棠的叶片水势及相对含水量(RWC)逐渐降低;光合系统被破坏,气孔关闭,气孔导度(Gs)、蒸腾速率(Tr)及净光合速率(Pn)降低,胞间CO2浓度(Ci)则呈上升趋势,其中,引起Pn下降的原因为非气孔因素;最大光化学效率(Fv/Fm)、实际光能转化率(ΦPSⅡ)和光化学淬灭系数(qP)值下降,PSⅡ遭到破坏;保护酶超氧化物歧化酶(SOD)和过氧化物酶(POD)活性在处理初期略有上升但随着土壤相对含水量的降低及处理时间的增加,均出现了下降并失去了保护酶功能。‘吉美’海棠具有一定的抗旱能力,能适应土壤相对含水量范围在55%~65%的环境;在‘吉美’海棠适宜的光照和温度条件下允许短期轻度干旱胁迫和较短期的中度干旱胁迫,当土壤相对含水量低于45%时应及时补充水分,从而避免持续的重度干旱胁迫所带来的影响,必要时提供人工灌溉措施。

The grafted seedlings of Malus ‘Jimei’ were used as experimental materials,and four treatment groups including control(CK),slight drought(SD),moderate drought(MD) and heavy drought(HD) were carried out in the pot experiment.The physiological characteristics of Malus ‘Jimei’ plants under different drought stress conditions were studied,in order to provide reference for the adaptive promotion of Malus ‘Jimei’.The results showed that with the decrease of soil relative water content and the extension of drought stress time,the leaf water potential and relative water content(RWC) of Malus ‘Jimei’ decreased gradually.Stomatal conductance(Gs),transpiration rate(Tr) and net photosynthetic rate(Pn) decreased with the destruction of photosynthetic system,stomatal closure,and intercellular CO2 concentration(Ci) increased.Among them,non-stomatal factors caused the decrease of Pn.Maximal photochemical efficiency(Fv/Fm),the actual light energy conversion(ΦPSⅡ) and light chemical quenching coefficient(qP) values fell,the PSⅡ destruction;The activity of protective enzymes SOD and POD increased slightly in the early stage of treatment,but decreased with the decrease of soil relative water content and the increase of treatment time,and the protective enzyme function was lost.In conclusion,Malus ‘Jimei’ had certain drought-resistant ability and could adapt to the environment with soil relative water content ranging from 55%-65%.Short term slight drought stress and short term moderate drought stress were allowed under the suitable light and temperature conditions of Malus ‘Jimei’.When the relative soil water content was less than 45%,water should be replenishment in time to avoid the impact of continuous severe drought stress.Artificial irrigation measures should be provided when necessary.