Seed priming with water (hydropriming or HP) has been shown to be beneficial for seed germination and plant growth. However, there is little information on the effects of seed priming with amino acids and casein hydrolysate (CH) compared with HP, particularly in relation to early post-germinative seedling growth under salinity stress. In this study, Italian ryegrass seeds (Lolium multiflorum L.) were primed with 1 mM of each of the 20 protein amino acids and CH (200 mg l−1) before they were germinated in 0, 60 and 90 mM NaCl in Petri dishes for 4 d in darkness. Germination percentage (GP), radicle length (RL) and peroxidase (POD) activity in the root of 4-d-old Italian ryegrass seedlings were investigated. Generally, when the seeds were germinated in 0, 60 and 90 mM NaCl, there was no significant difference in GP of seeds among various priming treatments, except that a higher GP was observed in seeds of HP treatment compared with the non-primed seeds when incubated in 60 mM NaCl. When incubated in 60 and 90 mM NaCl, seedlings from seeds primed with L-methionine or CH exhibited greater RL (greater protection against salinity stress) and higher root POD activity than those from non-primed and hydro-primed seeds. Under salinity stress, there were higher levels of malondialdehyde (MDA) in the root of 4-d-old Italian ryegrass seedlings, a marker of oxidative stress, but seed priming with CH was effective in reducing the salinity-triggered increase in MDA content. These results suggest that priming with L-methionine or CH would be better than HP for the protection of seedling root growth under salinity stress and might be associated with enhanced antioxidative defence against salinity-induced oxidative stress.

中文翻译：

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用 L-蛋氨酸和酪蛋白水解物引发种子后保护意大利黑麦草 (Lolium multiflorum L.) 幼苗免受盐胁迫

用水引发种子（水力引发或 HP）已被证明对种子萌发和植物生长有益。然而，与 HP 相比，关于用氨基酸和酪蛋白水解物 (CH) 进行种子引发的影响的信息很少，特别是与盐胁迫下的早期发芽后幼苗生长有关。在这项研究中，意大利黑麦草种子 (何首乌L.）用 1 mM 的 20 种蛋白质氨基酸和 CH（200 mg l-1) 在培养皿中在 0、60 和 90 mM NaCl 中在黑暗中发芽 4 天之前。研究了 4 d 生意大利黑麦草幼苗根部的发芽率 (GP)、胚根长度 (RL) 和过氧化物酶 (POD) 活性。一般而言，当种子在 0、60 和 90 mM NaCl 中发芽时，不同引发处理的种子 GP 没有显着差异，但 HP 处理种子的 GP 比未引发的种子更高。在 60 mM NaCl 中孵育。当在 60 和 90 mM NaCl 中孵育时，用 L-蛋氨酸或 CH2 引发的种子幼苗表现出比未引发和水引发的种子更大的 RL（对盐胁迫的更大保护）和更高的根 POD 活性。在盐分胁迫下，4 d 龄意大利黑麦草幼苗的根中丙二醛 (MDA) 水平较高，这是氧化应激的标志物，但用 CH 引发的种子可有效降低盐度引发的 MDA 含量增加。这些结果表明，用 L-蛋氨酸或 CH 引发比 HP 在盐胁迫下保护幼苗根系生长的效果更好，并且可能与增强对盐度诱导的氧化应激的抗氧化防御有关。