汉中主栽柑橘品种对低温胁迫的生理响应

以陕西汉中地区3种主栽柑橘泛亚特早、兴津、日南1号为试材,对离体叶片进行-5℃低温处理3 h、6 h、9 h、12 h后分析与耐寒性相关的生理响应,并通过主成分分析法评价各个测定指标的贡献率。结果显示:随着低温胁迫的持续,3种柑橘离体叶片相对电导率(REC)均呈现逐渐升高趋势,出现显著性升高的先后顺序依次为泛亚特早、兴津、日南1号;3种柑橘叶片中MDA和H2O2含量均呈逐渐增加的趋势,兴津和日南1号叶片中O2·—含量均呈先升高后降低的趋势,而泛亚特早则处于持续升高趋势,处理末期(12 h)各品种MDA、H2O2和O2·—含量高低次序表现为泛亚特早兴津日南1号。随着低温胁迫的持续,3种叶片脯氨酸含量变化表现出先升高后降低的趋势,可溶性糖含量则表现出逐渐升高的趋势,与泛亚特早和兴津相比,日南1号渗透调节物质含量升高的时间更早、幅度更大。随着低温胁迫持续,泛亚特早和兴津叶片中的保护酶SOD、CAT、POD和APX活性均表现出先升高后降低的明显趋势,而日南1号叶片中的SOD和APX活性则几乎呈现出持续升高的趋势,CAT和POD活性均表现出先升高后又降低趋势。隶属函数法综合抗寒性评价表明,3种柑橘抗寒能力大小依次为日南1号最强,兴津次之,泛亚特早最弱。REC和脯氨酸含量综合指标的累积贡献率为97.186%,具有较强的代表性,可作为柑橘抗寒性分析的重要指标。在低温胁迫持续胁迫过程中,日南1号离体叶片渗透调节能力和抗氧化酶活性更强,细胞膜受到的过氧化伤害较小,从而表现出较强抗寒能力。

Research on Physiological Response to Low Temperature Stress of Citrus reticulata Cultivars in Hanzhong

Three cultivars of Citrus reticulata ( Fanyatezao, Okitsu, Nidinaul ) planted in Hanzhong of Shaanxi province were used as experimental materials, and their detached leaves were treated at -5 ℃for 3 h,6 h,9 h or 12 h to analyze the physiological responses of Citrus reticulata under low temperature stress. Meanwhile the method of measure parameter and their contribution rate were analyzed using prin-cipal components analysis. The results showed that: the relative electric conductivity of detached leaf all increased gradually in three varieties of Citrus reticulata with the extension of treatment time. The appear-ance order of an obvious increase in three varieties of Citrus reticulata was Fanyatezao>Okitsu>Nichinan 1. The contents of MDA and H2 O2 both showed a gradual upward trend in three varieties of Citrus reticulata. The level ofO2—· increased first and then decreased in leaves in Okitsu and Nichinan 1, while it always showed a upward trend in Fanyatezao. The contents of MDA, O2—· and H2 O2 all showed an order of Fan-yatezao>Okitsu>Nichinan 1 in 3 varieties of Citrus reticulata at the end of treatment time. The changes of proline content exhibited an decrease after the first increase and the contents of soluble sugar increased gradually in three varieties of Citrus reticulata. Compared with the Fanyatezao and Okitsu,the content of osmoregualtion substance elevated levels earlier and more sharply. The activities of SOD,CAT,POD and APX generally increased first and then decreased in Fanyatezao and Okitsu leaves with the extension of treatment time. However, the activities of SOD and APX increased in all the time in Nichinan 1 leaves. Meanwhile CAT and POD activities displayed a decline trend after an initial increase in Nichinan 1 leav-es. The three Citrus reticulata cultivars cold resistance order ( Nichinan 1 >Okitsu >Fanyatezao ) was identified by the average degree of membership hardiness. The results showed that the cumulative contri-bution of REC and proline composite indicator was 97 . 186% and had strong representation as citrus cold analysis of key indicators. The above results indicated that Nichinan 1 had a higher cold resistance than Okitsu and Fanyatezao, because its stronger abilities of osmoregulation and antioxidant activities as well as its littler damages comparing with Okitsu and Fanyatezao under longer low temperature stress.