DO brassinosteroids ameliorate freezing stress in Cicer arietinum

An experiment was conducted to examine the extent of low-temperature stress during early seed germination and to investigate the mitigating effects of brassinosteroids. Sterilized Cicer arietinum seeds were soaked in distilled water for 24 h then placed in three sets of cotton-lined petri dishes. These three sets of seeds were exposed to different temperatures: 25°C (control), 0°C and -10°C. Another experiment was conducted using the same set of conditions but included a 24 h soaking step in 28-homobrassinolide (HBL) under controlled conditions. The seedlings were evaluated after 72 h. The results clearly indicated that seed germination, the activities of nitrate reductase and carbonic anhydrase, the accumulated levels of proline and protein decreased in response to lowtemperature stress. HBL partially ameliorated the stress at 0°C but failed to overcome the -10°C stress. Based on our observations, it could be concluded that brassinosteroids could partially overcome the stress generated by 0°C during the seed germination stage but could not overcome the stress generated by -10°C.