Lin Jixiang, Hua Xiaoyu, Peng Xiaoyuan, Dong Bolin, Yan Xiufeng
Alkali Soil Natural Environmental Science Center, Northeast Forestry University/Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, Ministry of Education, Harbin, China.
Department of Plant Pathology, North Carolina State University, Raleigh, NC, United States.
Front Plant Sci. 2018 Oct 9;9:1458. doi: 10.3389/fpls.2018.01458. eCollection 2018.
Ryegrass is considered a useful grass species for forage production and turf purposes. Annual ryegrass ( Lam.) and perennial ryegrass ( L.)are two species of ryegrass with similar genomes. So far, little information exists concerning their physiological response to salt-alkali stress during germination stage, especially under different temperature regimes. Seeds of ryegrass were germinated at four alternating temperatures (10-20, 15-25, 20-30, and 25-35°C) with salinity (NaCl) and alkalinity (NaCO, high pH) stresses. Results showed that optimal germination for both species under stress conditions occurred at higher temperatures (20-30°C for annual ryegrass; 20-30°C and 25-35°C for perennial ryegrass). Germination percentage and germination rate were both inhibited by increasing salinity or alkalinity, particularly higher alkalinities under any temperature. The inhibitory effects of the high salinity on germination were greater at 10-20°C for both species. However, seeds were subjected to more stress at 25-35°C under alkali stress even though the concentration was very low. In addition, both high and low temperatures lead to a markedly decrease in seed germination under alkali stress for perennial ryegrass. Recovery percentage of both species were highest at 400 mM salinity and 25 mM alkalinity under any temperature, especially 10-20°C, and 25-35°C also resulted in lower recovery percentages under both stresses for ryegrass. Moreover, annual ryegrass had a much higher recovery percentage than perennial ryegrass under such stress conditions. These results suggest that salinity stress and alkalinity stress are greatly different, and the salt-alkaline tolerance of ryegrass seeds is greatly affected by the interactions of temperature and salinity-alkalinity.
黑麦草被认为是一种用于饲料生产和草坪用途的有用草种。一年生黑麦草（Lolium multiflorum Lam.）和多年生黑麦草（Lolium perenne L.）是基因组相似的两种黑麦草。到目前为止，关于它们在萌发阶段对盐碱胁迫的生理响应，特别是在不同温度条件下的生理响应，信息较少。黑麦草种子在四种交替温度（10 - 20、15 - 25、20 - 30和25 - 35°C）下进行盐度（NaCl）和碱度（Na₂CO₃，高pH值）胁迫处理。结果表明，在胁迫条件下，两种黑麦草的最佳萌发均发生在较高温度下（一年生黑麦草为20 - 30°C；多年生黑麦草为20 - 30°C和25 - 35°C）。发芽率和发芽速率均受到盐度或碱度增加的抑制，特别是在任何温度下较高的碱度。高盐度对萌发的抑制作用在两种黑麦草的10 - 20°C时更大。然而，即使浓度很低，种子在25 - 35°C的碱胁迫下也会受到更大的胁迫。此外，对于多年生黑麦草，高温和低温都会导致碱胁迫下种子萌发显著下降。在任何温度下，两种黑麦草在盐度400 mM和碱度25 mM时的恢复率最高，特别是在10 - 20°C时，25 - 35°C在两种胁迫下也导致黑麦草的恢复率较低。此外，在这种胁迫条件下一年生黑麦草的恢复率比多年生黑麦草高得多。这些结果表明盐胁迫和碱胁迫有很大差异，黑麦草种子的耐盐碱能力受温度与盐碱度相互作用的显著影响。
