德国鸢尾6个品种的耐寒性比较

 以6个不同花色的德国鸢尾（Iris germanica）品种为试材，通过田间鉴定与测定冬季自然降温过程中叶片相对电导率，结合Logistic方程计算各品种的半致死温度（LT₅₀），评价其在自然降温过程中的耐寒性，并测定叶片中游离脯氨酸、丙二醛和可溶性蛋白的含量。结果表明：自然低温期6个品种寒害指数范围为1.20 ~ 3.65，半致死温度（LT₅₀）范围为﹣13.81 ~﹣5.73 ℃。耐寒性强的品种为‘Cherry Falls’和‘Bedtime Story’，其次为‘Brown Lasso’和‘Black Swan’，耐寒性弱的为‘China Dragon’和‘Caligula’。在自然降温过程中，6个德国鸢尾品种的低温半致死温度均随温度的下降而降低，下降幅度为1.46 ~ 6.51℃不等，并且叶片相对电导率随温度降低呈“S”型上升，丙二醛、脯氨酸和可溶性蛋白含量均呈现先上升后下降的趋势。

Comparison of Cold Tolerance Within 6 Cultivars of Iris germanica

The relative electric conductivity（REC）and field inspection were determined in leaves of six cultivars of Iris germanica during the natural winter along with dropping temperature. The logistic equation was constructed based on the relationship between REC and temperature，then the semi-lethal temperature was determined. Malondialdehyde（MDA）contents，soluble protein contents and free proline contents were analyzed. The results showed that the index of chilling injury was intervenient 1.20 and 3.65，and the range of semi-lethal temperature（LT₅₀）was from–13.81 ℃ to–5.73 ℃. ‘Cherry Falls’ and‘Bedtime Story’had high cold tolerance. ‘Brown Lasso’and‘Black Swan’had medium cold tolerance. ‘China Dragon’and‘Caligula’had poor cold tolerance. The LT₅₀ decreased with the drop in temperature， the decrease of LT₅₀ was cultivar dependent. The decrease of LT₅₀ varied from 1.46 ℃ to 6.51 ℃. The REC of the all cultivars increased following an S-curve as the temperature dropped. The contents of soluble protein，free proline and MDA increased firstly，then decreased.