以‘美登’(‘Blomidon’)、‘北陆’(‘Northland’)、‘蓝丰’(‘Bluecrop’)和‘密斯梯’(‘Misty’)4 个越橘(Vaccinium spp.)品种为研究对象,对经-15 ℃、-20 ℃、-25 ℃、-30 ℃、-35 ℃和-40 ℃低温处理后各品种枝条的相对电导率(REC)、丙二醛(MDA)含量、过氧化物酶(POD)和过氧化氢酶(CAT)活性以及各指标的增长量进行比较; 在此基础上, 建立各品种REC 值与温度的Logistic 方程并获得各品种的低温半致死温度(LT50 ), 初步确定各品种的抗寒性。结果表明:经不同低温处理后,各品种枝条的REC 值以及POD 和CAT 活性总体上极显著(P<0. 01)高于对照(10 ℃),MDA 含量极显著或显著(P<0. 05)高于对照。随处理温度降低,各品种枝条的REC值和MDA 含量逐渐升高,但不同品种间这2 个指标的变幅不同;各品种枝条的POD 和CAT 活性随处理温度降低呈“单峰型冶曲线,但不同品种枝条POD 和CAT 活性的峰值及其达到峰值的处理温度均存在差异,其中,经-25 ℃低温处理后品种‘密斯梯’枝条的POD 和CAT 活性最高,而其余3 个品种的POD 和CAT 活性经-30 ℃低温处理后最高。总体上,品种‘密斯梯’枝条的REC 值和MDA 含量增长量处于较高水平,POD 和CAT 活性增长量处于较低水平;而品种‘美登’枝条的REC 值和MDA 含量增长量则处于较低水平,POD 和CAT 活性增长量处于较高水平。各品种的Logistic 方程拟合度为0. 862 2 ~0. 977 8,且各品种间的拟合度差异均达到极显著或显著水平;REC 值与温度的相关性极显著,其相关系数为0. 928 5 ~0. 988 8;品种‘密斯梯’、‘蓝丰’、‘北陆’和‘美登’的LT50 值分别为-18. 87 ℃、-26. 85 ℃、-27. 52 ℃和-30. 83 ℃。综合分析结果显示:LT50 值、MDA 含量变化量、保护酶活性及其变化量均可作为越橘品种抗寒性的评价指标,据此初步确定供试4 个越橘品种抗寒性由强至弱依次为‘美登’、‘北陆’、‘蓝丰’、‘密斯梯’。

Taking four cultivars of Vaccinium spp., i. e. ‘Blomidon', ‘Northland', ‘Bluecrop' and ‘Misty'as research objects, relative electric conductivity (REC), malondialdehyde (MDA) content, peroxidase (POD) and catalase (CAT) activities and increment of each index in branch of different cultivars were compared after treated by low temperatures of -15 ℃, -20 ℃, -25 ℃, -30 ℃, -35 ℃ and -40 ℃. On the basis, Logistic equation between REC value and temperature of different cultivars was established, their semilethal low temperature (LT50 ) was obtained, and also, cold resistance of different cultivars was preliminarily determined. The results show that after treated by different low temperatures, overall, REC value and POD and CAT activities in branch of different cultivars are significantly or significantly (P <0. 05) higher than that of the control. With decreasing of treatment temperature, REC value and MDA content in branch of different cultivars increase gradually, but change ranges of these two indexes among different cultivars are different. POD and CAT activities in branch of different cultivars appear “single-peak type”curve with decreasing of treatment temperature, but there are differences in peak values of POD and CAT activities in branch of different cultivars and in their treatment temperatures reaching peak value, in which, POD and CAT activities in branch of cultivar ‘Misty' is the highest after treated by low temperature of -25 ℃, while those of other three cultivars is the highest after treated by low temperature of -30 ℃. In general, increments of REC value and MDA content in branch of cultivar ‘Misty' are at high level and those of POD and CAT activities are at low level, while increments of REC value and MDA content in branch of cultivar ‘Blomidon' are at low level and those of POD and CAT activities are at high level. Fitting degree of Logistic equation of different cultivars is 0. 862 2 -0. 977 8, and differences in fitting degree among different cultivars all reach extremely significant and significant level. Correlation between REC value and temperature is extremely significant, their correlation coefficient is 0. 928 5 - 0. 988 8. LT50 value of cultivar ‘ Misty', ‘Bluecrop', ‘Northland' and ‘Blomidon' is -18. 87 ℃, -26. 85 ℃, -27. 52 ℃and -30. 83 ℃, respectively. The comprehensive analysis result indicates that LT50 value, MDA content variation, protective enzyme activity and their variation all can be used as evaluation index for cold resistance of cultivars of Vaccinium spp. Hereby, it is preliminarily determined that cold resistance of four cultivars of Vaccinium spp. tested in order from strong to weak is ‘ Blomidon', ‘ Northland', ‘ Bluecrop ', ‘Misty'.