干旱和复水条件下黄瓜幼苗生长和生理生化的响应

Growth and physiological-biochemical responses of Cucumis sativus L. seedlings under drought and re-watering conditions

【目的】分析黄瓜幼苗在干旱胁迫和复水条件下的生长和生理生化响应,阐明在有限水分亏缺下复水产生补偿效应的可能性和补偿强度,为黄瓜的抗旱栽培及水分高效利用提供理论依据。【方法】以金瓜王F1黄瓜幼苗为试验材料,采用温室盆栽试验,测定干旱对照、干旱、极旱、极旱复水对照和极旱复水处理下黄瓜幼苗的生长指标及生理生化指标,分析不同处理间各指标的差异。【结果】不同程度干旱胁迫均降低了黄瓜幼苗的叶面积、株高、茎粗、主根长及地上部生物量,与极旱处理相比,极旱复水处理各生长指标增幅达8.3%~366.7%,但显著低于极旱复水对照(P<0.05,下同);随着干旱程度的加剧,黄瓜幼苗叶片的相对水含量、光合速率、蒸腾速率、气孔导度、胞间CO2浓度和叶绿素含量等生理指标逐渐降低,极旱复水处理使得光合速率、蒸腾速率和气孔导度恢复到极旱复水对照水平;干旱胁迫使黄瓜幼苗叶片的丙二醛(MDA)和脯氨酸(Pro)含量、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性及抗坏血酸(AsA)和谷胱甘肽(GSH)含量均显著升高,极旱复水处理则将这些生化指标降至极旱复水对照水平,在一定程度上缓解干旱胁迫带来的伤害。【结论】干旱后及时复水能缓解前期干旱胁迫对黄瓜幼苗生长发育的负面影响,具有一定的补偿效应,但其补偿强度不足以弥补前期干旱胁迫对黄瓜幼苗生长发育的阻碍,对植物的补偿效应具有局限性。

【Objective】The growth and physiological-biochemical responses of Cucumis sativus L.(cucumber)seedlings to drought stress and re-watering after drought stress were analyzed,and the compensation possibility and intensity of re-watering were clarified,which could provide theoretical basis for drought resistant cultivation and high water use efficiency of cucumber seedlings.【Method】The C.sativus Jinguawang F1 seedlings were applied with drought control,drought,extreme drought,control for re-watering after extreme drought and re-watering after extreme drought treatments in a pot greenhouse experiment.The growth and physiological-biochemical indexes were determined.The differences of these growth and physiological-biochemical indexes among different treatments were analyzed.【Result】The results showed that drought stress reduced leaf area,plant height,stem diameter,main root length and aboveground biomass of cucumber seedlings.Re-watering after extreme drought increased these growth indexes by 8.3%-366.7%,but they were still significantly lower than those in the control treatment for re-watering after extreme drought(P<0.05,the same below).As the increase of drought stress intensity,the physiological indexes,such as relative water content,photosynthesis rate,transpiration rate,stomatal conductance,intercellular CO2 concentration and chlorophyll content in leaves of cucumber seedling gradually decreased.Re-watering after extreme drought could restore the photosynthesis rate,transpiration rate and stomatal conductance to the levels in the control treatment for re-watering after extreme drought.Drought stress significantly increased the contents of malondialdehyde(MDA),proline(Pro),ascorbic acid(AsA)and glutathione(GSH),and the activities of superoxide dismutase(SOD)and peroxidase(POD)in leaves of cucumber seedlings.Re-watering after extreme drought decreased those biochemical indexes to the levels in the control treatment for re-watering after extreme drought,which could relieve the damage caused by drought stress to some extents.【Conclusion】Timely re-watering after drought stress can alleviate the negative effects of early drought stress on the growth and development of cucumber seedlings,and has a certain compensation effect on plant growth.However,the compensation intensity is not enough to make up for the obstacles of early drought stress on cucumber seedling growth,as its compensation effect on plant growth is limited.