镁营养对苦瓜生长发育及生理代谢的影响

采用砂培的方式,以‘翠玉’苦瓜（Momordica charantia）品种为试验材料,研究不同镁素浓度（0、20、40、80、160 mg/L）处理下对苦瓜生长特性（叶片和根系形态、光合色素含量、碳氮代谢、生物量积累）和生理响应（渗透调节、膜伤害和抗氧化）的影响。结果表明：镁浓度为20~80 mg/L时可以降低苦瓜叶片膜伤害,增加叶片中可溶性糖、可溶性蛋白质、光合色素和谷胱甘肽（GSH）含量,增强叶片抗氧化酶活性,包括超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和单脱氢抗坏血酸还原酶（DHAR）,降低叶片丙二醛（MDA）、脯氨酸（Pro）、过氧化氢（H₂O₂）含量和超氧阴离子（O₂^-）的产生速率及细胞膜透性,促进根系活力、光合作用和生物量积累。其中,40 mg/L镁处理对苦瓜的生长发育增效最明显,而缺镁（0 mg/L）和过量镁（160 mg/L）胁迫下,苦瓜叶片产生膜脂过氧化伤害、主根变短、侧根减少,苦瓜地上部和地下部生长均受到明显抑制,缺镁比镁过量的抑制作用更强。综上所述,缺镁和过量镁抑制苦瓜生长,而适量增施镁可有效提高苦瓜的生理活性,增强苦瓜抗逆性,促进苦瓜生长,40 mg/L为苦瓜栽培最适宜施镁浓度。

Effects of Magnesium Nutrition on the Growth and Development of Momordica charantia and Its Physiological Metabolism

A variety ‘Cuiyu’ of Momordica charantia was planted by sand culture and treated with five magnesium concentrations (0, 20, 40, 80, 160 mg/L). The effects of magnesium nutrition on the growth characteristics (leaf and root morphology, photosynthetic pigment content, carbon and nitrogen metabolism, and biomass accumulation) and physiological response (osmoregulation, membrane damage and antioxidation) of M. charantia were investigated. Application of 20-80 mg/L magnesium reduced leaf membrane damage, increased the contents of soluble sugar, soluble protein, photosynthetic pigment and glutathione (GSH), and enhanced the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and monodehydroascorbate reductase (DHAR). But the contents of M. charantia leaf malondialdehyde (MDA), proline (Pro) and hydrogen peroxide (H₂O₂), the production rate of superoxide anion (O₂ ^-), and cell membrane permeability were all reduced, while their root vitality, photosynthesis and biomass accumulation were promoted. Among them, 40 mg/L magnesium treatment had the most obvious synergistic effect on the growth and development of M. charantia. However, under the stresses of magnesium deficiency (0 mg/L) and excess (160 mg/L), the membrane lipid peroxidation damage occurred in the M. charantia, and the main roots were shortened, the lateral roots decreased, the growth of the above ground and underground parts was significantly inhibited, and magnesium deficiency had a stronger inhibitory effect on M. charantia than excessive magnesium. To sum up, the results indicated that magnesium deficiency and excess inhibited the growth of M. charantia. The appropriate application of magnesium could effectively improve the physiological activity, enhance the stress resistance and promote the growth of M. charantia. And 40 mg/L magnesium was the most suitable concentration of magnesium for the cultivation of M. charantia.