Abstract:

In order to investigate the mitigative effect of prohexadione-calcium (Pro-Ca) on soybean (Glycine max) root growth under saline-alkali stress, soybean variety Hefeng 50 (salt-tolerant) and Kenfeng 16 (salt-sensitive) were employed as the experimental material to study the effects of foliar spraying 100 mg·L^-1 Pro-Ca on root growth characteristics of soybean, metabolism of reactive oxygen species, antioxidant enzyme activity, and osmotic regulation substances content under saline-alkali stress. The results showed that spraying exogenous Pro-Ca could alleviate the inhibition on root growth of Hefeng 50 and Kenfeng 16 under saline-alkali stress, and the root length, root fresh weight, and root dry weight were increased by 11.2% and 23.6%, 3.2% and 19.8%, 38.0% and 37.6%, respectively. Exogenous application of Pro-Ca up-regulated the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), increased the levels of ascorbate (AsA) and glutathione (GSH), inhibited {\mathrm{O}}_2^{\frac{-}{·}} and H₂O₂ accumulation, and reduced malondialdehyde (MDA) content and electrolyte leakage (EL) in soybean roots under saline-alkali stress. Furthermore, the application of Pro-Ca promoted the accumulation of osmotic regulation substances in which the contents of soluble sugar, soluble protein, and proline in soybean roots of Hefeng 50 and Kenfeng 16 were increased by 10%~7.75% and 6.22%~28.03%, 6.61% ~17.79% and 3.79%~10.37%, 19.1%~31.9% and 6.9%~27.8%, respectively. The principal component analysis indicated that Pro-Ca treatment had a good regulation effect on the roots of salt-tolerant variety Hefeng 50 and salt-sensitive variety Kenfeng 16. These findings showed that exogenous application of Pro-Ca enhanced saline-alkali stress tolerance in soybean roots by enhancing the activities of antioxidant enzymes, osmotic regulation potential and reducing membrane lipid peroxidation. This study preliminarily elucidated the physiological and biochemical mechanism of Pro-Ca in alleviating saline-alkali stress injury in soybean roots, which provides a theoretical basis for further revealing its mechanism at the molecular level.

Key words: soybean roots, prohexadione-calcium(Pro-Ca), saline-alkali stress, physiological characteristics, principal component analysis

摘要：

为探讨调环酸钙(Pro-Ca)对盐碱胁迫下大豆(Glycine max)根系生长的缓解作用,以大豆品种合丰50(耐盐)和垦丰16(盐敏感)为试验材料,研究叶面喷施100 mg·L^-1 Pro-Ca对盐碱胁迫下大豆根系生长特性、活性氧代谢、抗氧化酶活性和渗透调节物质含量的影响。结果表明,外源喷施Pro-Ca均能不同程度缓解盐碱胁迫对合丰50和垦丰16根系生长的抑制,两品种根长、根鲜重和根干重分别增加了11.2%和23.6%、3.2%和19.8%、38.0%和37.6%;上调了盐碱胁迫下大豆根系超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性以及抗坏血酸(AsA)和谷胱甘肽(GSH)水平;抑制了 {\mathrm{O}}_2^{\frac{-}{·}} 和H₂O₂积累,降低了丙二醛(MDA)含量和电解质渗漏率(EL);促进了渗透调节物质积累,合丰50和垦丰16大豆根系的可溶性糖、可溶性蛋白和脯氨酸含量分别增加了5.1%~7.8%和6.2%~28.0%、6.6%~17.8%和3.8%~10.3%、19.1%~31.9%和6.9%~27.8%。主成分分析表明外源喷施Pro-Ca对耐盐品种合丰50 和盐敏感品种垦丰16根系均具有较好的调控效果。综上所述,外源喷施Pro-Ca可通过增强根系抗氧酶活性、渗透调节能力以及降低膜脂过氧化来增强大豆根系的耐盐碱能力。本研究初步阐明了Pro-Ca缓解大豆根系盐碱胁迫伤害的生理生化机制,为进一步从分子水平揭示其作用机制提供了理论依据。

关键词: 大豆根系, 调环酸钙(Pro-Ca), 盐碱胁迫, 生理特性, 主成分分析