苹果幼苗部分根系水分胁迫对光合作用主要参数的影响

以1年生苹果组培苗为试材,用改良的Hoagland营养液加20%PEG-6000进行半根渗透胁迫(HS)处理,与仅加营养液的正常水分条件的对照(CK)和加20%PEG-6000进行全根胁迫处理(TS)进行比较,研究了根系不均匀供水条件下植株的叶片水势和光合作用主要参数的反应特点。结果表明,HS与CK之间叶片的日出前水势不存在显著差异,且显著高于TS,但日水势变化动态在大部分情况下HS显著低于CK;和CK相比较,HS处理的叶片气孔导度、蒸腾速率和净光合效率显著降低,但在处理的早期显著高于TS。HS还导致叶片温度较对照显著增高。另外,试验体系中HS处理部分根系处于水分胁迫状态,而另外的根系处于良好的水分供应条件下,可用于模拟定位灌溉和分根区交替灌溉根系不均匀供水条件,对于开展相关果树生理反应及生长发育调控机制的研究提供了良好的试验体系。

Influence of partial root water stress on leaf photosynthetic rate and other related parameters in micro-propagated apple plants

For the purpose of studying the properties of leaf water potential and photosynthesis of plant under unhomogeneous root water supply, half or whole root system of one-year-old micro-propagated apple plants were subjected to water stress by regulating the osmotic potential of the solution using polyethylene glycol (PEG-6000, 20% W/V). No significant difference of predawn leaf water potential was found between half root stress (HS) and control (CK) while predawn leaf water tential from both HS and CK was significantly higher than total root stress treatment (TS). However, diurnal leaf water potential of HS was lower than CK at most time of the day. Moreover, leaf net photosynthesis, stomatal conductance and transpiration rate of HS declined when compared with CK, but higher than TS in the first 7 days, and no difference between HS and TS thereafter. Furthermore, HS resulted in higher leaf temperature than CK. Because some roots of HS were subjected to drought stress while others were under adequate water supply, root water supply status of HS was similar to that of both localized irrigation and partial root drying irrigation under field condition. Thus, the system used in this experiment can be applied to simulate field condition of unhomogeneous root water supply to study the physiological reaction and mechanism related to the development regulation in fruit trees.