<正>对引种到山东省济南市长清区、兖州市兴隆庄镇、临沂市罗庄区3个试验地的石楠（Photinia serrulata）、椤 木石楠（p. dayidsoniae）、红罗宾（P. ×fraseri‘Red Robin’）、鲁宾斯（P. glabra Var. Roberts）、金红（P. XfF（1gri Jin Hong）5种植物进行越冬期闻植物外部形态冻害观察，并运用电导法进行抗寒能力的测定。结果表明，采用室内模拟自然界低温胁迫处理测试叶片的相对电导率。计算得出的各树种半致死温度（LT50）能定量地反映这些树种本身的抗寒能力高低，并且与越冬适应性观察结果基本相一致。济南市长清区和兖州市兴隆庄镇两试验地备树种抗寒力从强到弱依次为：鲁宾斯、红罗宾、金红、石楠、椤木石楠；而临沂市罗庄区试验地各树种抗寒力从强到弱依次为：红罗宾、鲁宾斯、金红、石楠、椤木石楠。

The effects of exogenous hormones KT and IAA in the derooted seedlings of Cucumis sativus L. on polyamines in vitro and the formation of female flowers were studied in this paper. It was found that the induction rate of female flower in derooted seedlings cultured on MS mixed with 3.0 mg/L KT and O. 01 mg/L IAA accounted for 28%, whereas the control was 0. It was observed that during the formation of female flower, the content of endogenous Spd and the ratio of Spd to Put in derooted seedlings apparently exceeded those in the control. It revealed that high levels of Spd and the ratio of Spd to Put in derooted seedlings could promote the formation of female flowers. No significant difference existed in the endogenous Spin between treatment of 3.0 mg/L KT+0. 01 mg/L IAA and control, except for the induction rate of female flowers. It indicated that Spin had no direct effects on the formation of female flowers. The levels of DAP in derooted seedlings cultured on MS mixed with 3.0 mg/L KT and 0.01 mg/L IAA were apparently lower than that in control. It was seen that exogenous hormones could promote the formation of female flowers in derooted seedlings by reducing the catabolism of polyamine. However, the levels of Cad in derooted seedlings cultured under the same condition mentioned above were higher than that in control and its emergence was prior to control. It showed that Cad was a kind of material produced from physiological metabolism during formation of female flowers instead of the effect factors.