水分胁迫对柠条基质栽培黄瓜幼苗生长及光合特性的影响

Effects of water stress on growth and photosynthetic characteristics of cucumber seedlings under substrate culture of Caragana korshinskii

研究水分胁迫对柠条基质栽培黄瓜幼苗光合作用及相关生理指标的影响,为利用新型园艺基质培育优质黄瓜幼苗提供理论参考。采用72穴标准穴盘进行育苗,测定正常供水(CK)、中度水分胁迫(5%PEG-6000,DR-M)和重度水分胁迫(10%PEG-6000,DR-S)处理下黄瓜幼苗的株高、茎粗、根冠比、丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、光合参数、叶绿素荧光参数的变化。结果表明,水分胁迫显著抑制了黄瓜幼苗的生长,处理后第17 d,与CK相比,DR-M处理的株高降低8.30%,DR-S处理的株高降低16.20%,DR-M处理的黄瓜幼苗茎粗增加0.85%,DR-S处理的茎粗下降7.67%。与CK相比,DR-M处理下黄瓜幼苗干物质积累量增加,根冠比下降,叶绿素含量降低,丙二醛含量增加,SOD和POD活性升高,净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、胞间CO_2浓度(C_i)、水分利用效率(WUE)、初始荧光(F_o)、最大荧光(F_m)、可变荧光(F_v)、单位反应中心捕获的用于电子传递的能量(ET_o/RC)均下降。对夏季柠条基质培育黄瓜幼苗而言,中度水分胁迫处理可抑制因温度过高、水分充足引起的徒长,有利于提高抗逆能力,增加干物质积累量,培育优质壮苗。

The effects of water stress on photosynthetic characteristics and related physiological indices of cucumber seedlings under substrate culture of Caragana korshinskii was studied to provide theoretical reference for the cultivation of high quality cucumber seedlings by using new horticultural substrate. 72-well standard plug trays were used for nursery. Changes of plant height, stem diameter, root-shoot ratio, malondialdehyde (MDA) content, superoxide dismutase ( SOD ) activity, peroxidase ( POD ) activity, photosynthetic parameters, and chlorophyll fluorescence parameters of cucumber seedlings were studied under normal water supply (CK), moderate water stress (5% PEG-6000, DR-M) and severe water stress (10% PEG-6000, DR-S) conditions. The results showed that the water stress significantly inhibited the growth of cucumber seedlings. On the 17th day of treatment, the plant height in the treatments of DR-M and DR-S decreased by 8.30% and 16.20% compared with that in CK. Moreover, compared with that in CK, stem diameter in the treatment of DR-M increased by 0.85%, and stem diameter in the treatment of DR-S decreased by 7.67%. Compared with those in the treatment of CK, the accumulation of dry matter in cucumber seedlings increased, the root-shoot ratio decreased, the content of chlorophyll decreased, the content of MDA increased, the activities of SOD and POD increased, the net photosynthetic rate ( P n ), transpiration rate ( T r ), stomatal conductance ( G s ), intercellular CO 2 concentration ( C i ) and water use efficiency ( WUE ), the basic parameters of chlorophyll fluorescence( F o , F m , F v ), captured energy for electron transfer ( ET o /RC ) decreased in the treatment of DR-M. Moderate water stress can inhibit legume growth caused by excessive temperature and sufficient water in the cultivation of cucumber seedlings under substrate culture of Caragana korshinskii in the summer, and it is beneficial to improve resistance to stress, increase dry matter content, and cultivate high-quality and strong seedlings.