Calcium chloride priming increases chilling tolerance in Salvia miltiorrhiza Bunge

Lu Gao1 and Min Yan1*
Chilling stress inhibits germination and early seedling growth of Salvia miltiorrhiza Bunge. The present study was carried out to investigatethe effects of osmopriming with CaCl2 on the germination and early seedling growth of S. miltiorrhiza under chilling stress (10 °C). Seeds were soaked in different concentrations of CaCl2 solutions (0, 50, 100, and 150 mM) at 20 °Cfor 24 h in darkness, rinsed, and air-dried. The effects of seed priming were evaluated on germination and survival during subsequent exposure to chilling stress(10 °C) for 14 d. An unprimed control treatment was sown under optimal temperatures (25 °C). Results indicated that germination percentage, germination potential, and seedling vigor index of unprimed seeds decreased from 69.2%, 12.4, and 0.092 to 28%, 3.6, and 0.022, respectively, when subjected to chilling stress. Higher malondialdehyde (MDA) content and lower chlorophyll contents (including total chlorophyll, chlorophyll a, and chlorophyll b) were detected in S. miltiorrhiza seedlings. Osmopriming with 100 and 150 mM CaCl2 effectively lessened the negative effects of chilling stress. Germination percentage, germination potential, and seedling vigor index of primed seeds reached 42% and 48%, 6.36 and 8.78, and 0.037 and 0.047, respectively. Meanwhile, CaCl2 priming significantly triggered superoxide dismutase, peroxidase, and catalase antioxidant enzyme activity, enhanced the accumulation of osmoregulation substances (soluble protein, accumulation sugars, and proline), increased the photosynthetic pigment content (total chlorophyll, chlorophyll a, chlorophyll b, and carotenoids), and decreased the MDA content. The most effective concentration of CaCl2 priming was 150 mM.
Keywords: Calcium chloride, chilling stress, Salvia miltiorrhiza, seed priming.
1Qingdao Agricultural University, College of Agronomy, 266109 Qingdao, China.*Corresponding author (yanmin75@163.com).