不同品种小麦叶片对拔节期低温的生理响应及抗寒性评价

以黄淮海麦区参加区试的24个小麦品种为材料,分析了拔节期低温胁迫对其叶片相对电导率、可溶性糖含量、可溶性蛋白含量、游离脯氨酸含量、丙二醛(MDA)含量以及超氧化物歧化酶(SOD)和过氧化物酶(POD)活性的影响。结果表明,低温胁迫后,叶片相对电导率、可溶性糖含量、脯氨酸含量、MDA含量、SOD活性和POD活性均高于对照(P0.01),而可溶性蛋白含量低于对照(P0.01)。小麦叶片各指标存在极显著的品种间差异(P0.01)。以叶片各指标的相对值作为抗寒性指标,采用隶属函数法和极极点排序法计算参试品种的平均隶属度值为0.19—0.63,综合排序值为1.66—4.08。通过K-means聚类,将24个小麦品种聚为5类。其中良星619、丰德存麦1号、B07-4056、石H083-363、山农055843和良星99等6个品种抗寒性最强,宿553、陕农509、A-9、中原6号、徐麦4036、舜麦1718和石麦19等7个品种抗寒性强,尧麦16、C-44、山农05-066、冀麦585和石B05-7388等5个品种抗寒性中等,偃展4110、B-33、B05-6507和石4185等4个品种抗寒性弱,石06-6136和石优20这2个品种抗寒性最弱。相关分析表明,平均隶属度值和综合排序值与相对可溶性糖含量、相对脯氨酸含量、相对POD活性呈正相关(P0.05),与相对MDA含量呈负相关(P0.05)。叶片可溶性糖含量、游离脯氨酸含量、POD活性及MDA含量可以作为拔节期小麦抗寒性的鉴定评价指标。

Evaluation of cold resistance of different wheat varieties based on physiological responses of leaves to low temperature at the jointing stage

Cold injury is one of the main problems in winter wheat production in the Huanghuaihai wheat region. Winter wheat grows rapidly at the jointing stage, and becomes sensitive to the drops in temperatures that frequently occur in spring. Low temperature during the jointing stage restricts the growth of winter wheat and directly affects grain yield. Therefore, correctly evaluating and improving the cold resistance of wheat varieties is very important for grain security. In this study, we evaluated the cold tolerance of 24 wheat varieties grown in the Huanghuaihai region. The wheat plants were grown in pots outdoors, and they were moved into an artificial climate chamber and subjected to a cold treatment at the jointing stage. After the cold treatment, we measured seven physiological indices in leaves; relative electrical conductivity, soluble sugars content, soluble protein content, free proline content, malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, and peroxidase (POD) activity. The results showed that the soluble protein content was lower in low-temperature-treated plants than in the control plants (P < 0.01), while the other six indices showed higher values in the low-temperature-treated plants than in the control plants (P < 0.01). Analysis of variance showed that the values of these seven physiological indices differed significantly among varieties both in low-temperature-treated and control plants (P < 0.01). Compared with control plants, the low-temperature-treated plants showed a greater range of relative conductivity, soluble sugars content, soluble proline content, MDA content, and POD activity, but lower range of soluble protein content and SOD activity. The relative character value, that is, the proportion of the measured value in low-temperature-treated plants to that in control plants, eliminated the genetic background difference. For each wheat variety, we used the relative character values to calculate the average subordinative function value by the subordinative function method, and we calculated the comprehensive score by the polar ordination method. The average subordinative function values ranged from 0.19 to 0.63 and the comprehensive scores from 1.66 to 4.08. Among the 24 cultivars, Liangxing 619 showed the highest value and score, while Shiyou 20 showed the lowest. Using K-means clustering analysis, the 24 winter wheat cultivars were divided into five groups according to cold resistance; strong, high, medium, low, and weak. The strong cold resistance group contained six varieties; Lingxing 619, Fengdecunmai No.1, B07-4056, Shi H083-363, Shannong 055843, and Lingxing 99. The high cold resistance group contained seven varieties; Su 553, Shannong 509, A-9, Zhongyuan No.6, Xumai 4036, Shunmai 1718, and Shimai 19. The medium cold resistance group consisted of five varieties; Yaomai 16, C-44, Shannong 05-066, Jimai 585, and Shi B05-7388. The low cold resistance group contained Yanzhan 4110, B-33, B05-6507, and Shi 4185. Two varieties, Shiyou 20 and Shi 06-6136, were in the weak cold resistance group. Correlation analyses showed that the average subordinative function value and comprehensive score were significantly positively correlated with soluble sugars content and relative proline content (P < 0.01), and with relative POD activity (P < 0.05). The average subordinative function value and comprehensive score were significantly negatively correlated with relative MDA content (P < 0.05). In conclusion, the soluble sugars content, free proline content, POD activity, and MDA content in leaves at the jointing stage can serve as cold-resistance indices. Wheat varieties with higher soluble sugars content, free proline content, and POD activity, but lower MDA content in leaves showed stronger cold resistance. Among the 24 varieties, Liangxing 619 showed the strongest cold resistance at the jointing stage, while Shiyou 20 showed the weakest.