柑桔不同晚熟品种（系）的抗寒性测试分析

晚熟品种需要挂果通过冬季低温时段,抗（耐）寒性是其重要特性之一。以目前生产上大量推广和新选育的不同晚熟品种（系）及少量中熟对照品种为试材,采用其经过前期自然低温锻炼的1年生春梢叶片,测定离体叶片在人工控制的5个不同低温条件下的相对电导率,建立Logistic回归方程,分析评价抗（耐）寒性。结果发现,参试品种的相对电导率一般随着温度的降低而增加,但变化的幅度在品种间存在明显差异,表明不同品种（系）对低温有不同反应;全部样品的平均半致死温度为-6.55℃;沙田柚和晚白柚的半致死温度最高,分别为-4.4和-5.2℃,可能最不耐寒;江安无核夏橙的半致死温度最低,为-8.5℃,在测试样品中最耐寒。 The on-tree fruits of late-maturing citrus cultivars have to pass through the low temperature period during winter. Therefore, cold-resistance is very important for these varieties. In this study, several late-maturing citrus cultivars or lines were tested for their cold resistance u- sing mid-maturing varieties as control （CK）. Leaf explants from one year old spring shoots were treated under 5 different low temperatures and were measured for their relative electric conductivity following cold treatments. Semi-lethal temperature was estimated by fitting Logistic equations. Leaf relative electric conductivity increased as the temperature decreased, and varied depending on culti- vars. The semi-lethal temperatures were averaged at --6. 55℃. The semi-lethal temperatures of Shatianyou pummelo and Bampeiyu were --4. 4 ℃ and --5.2 ℃, respectively. Jiangan seedless va- lencia sweet orange was considered the most cold-tolerant variety among the tested samples for haw ing the lowest semi-lethal temperature （--8. 5 ℃）.