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

Abstract

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-temperaturetreated plants than in the control plants( P0.01),while the other six indices showed higher values in the low-temperature-treated plants than in the control plants( P0.01).Analysis of variance showed that the values of these seven physiological indices differed significantly among varieties both in low-temperature-treated and control plants( P0.01).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,Shunmai1718,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.