关键词: 白羊草, 种子萌发, NaCl胁迫, 外源抗坏血酸引发, 种子活力

Abstract: [Objective] To investigate the effects of exogenous ascorbate （AsA） priming on the seed germination of Bothriochloa ischaemum under NaCl stress.[Methods] Seeds of B. ischaemum were used as experimental materials. Priming treatments were conducted using AsA solutions at concentrations of 0.1, 0.2, 0.3, 0.4, and 0.5 mmol/L for durations of 0 （CK, a blank control without priming under direct salt stress）, 3, 6, 9, and 12 h. Germination tests were subsequently performed in a NaCl solution with an Na⁺ concentration of 30 mmol/L. Seed germination percentage, germination index, mean germination time, seedling vigor index, radicle length, and plumule length were measured and analyzed. [Results] Under fixed treatment durations, the comparison of different AsA concentrations at the same time revealed that the germination percentage, germination index, seedling vigor index, radicle length, and plumule length of B. ischaemum seeds exhibited a continuous downward trend as AsA concentration increased; at a priming concentration of 0.1 mmol/L, both seed germination percentage and seedling vigor index were higher than those of other concentration groups at the same time; mean germination time was significantly （P<0.05） lower only in the 3 h treatment group at 0.2 mmol/L AsA compared to other concentration groups, with no significant differences （P>0.05） observed among other groups. Under fixed treatment concentrations, the comparison among different priming durations at the same concentration showed that at an AsA concentration of 0.1 mmol/L, the germination percentage and seedling vigor index were significantly （P<0.05） higher than those of CK after 9-12 h of priming, while radicle and plumule lengths were significantly （P<0.05） higher than those of CK after 12 h of priming; no significant differences （P>0.05） were found in mean germination time across these groups; at AsA concentrations of 0.2 and 0.3 mmol/L, the germination percentage, germination index, and seedling vigor index showed a trend of initially decreasing and then increasing; at AsA concentrations of 0.4 and 0.5 mmol/L, the seedling vigor index was significantly （P<0.05） lower than those of CK as priming time extended, and differences in germination percentage, mean germination time, radicle length, and plumule length were not significant （P>0.05）. Membership function analysis indicated that the comprehensive evaluation values of B. ischaemum seeds ranked among the highest at an AsA concentration of 0.1 mmol/L, identifying it as the optimal concentration for priming against NaCl stress; at this concentration, 12 h of priming ranked first in comprehensive evaluation. [Conclusion] Under NaCl stress with an Na⁺ concentration of 30 mmol/L, priming with 0.1 mmol/L AsA solution for 12 h is most favorable for the seed germination of B. ischaemum.

Key words: Bothriochloa ischaemum, seed germination, NaCl stress, exogenous ascorbate priming, seed vigor