莲雾不同种的低温半致死温度及抗冷适应性

以叶片和成熟枝条为试材,应用电导法测定莲雾在不同低温下细胞膜透性的变化,配合Logistic方程求出低温半致死温度(LT50),评价6个莲雾种在不同降温时期的抗冷性,及同一时期不同部位的抗冷性,并结合露地栽培越冬表现进行验证。结果表明,在自然降温过程中,6个莲雾种的低温半致死温度均随气温的下降而不断降低,但下降幅度因种而异,1.69～2.97℃不等。6个种抗冷性由强到弱排序依次为水蒲桃>本地种>粉红种>紫红种>青色种>印度红。2 a生枝条的抗冷力最强,明显比叶片耐冷。冬季越冬表现与1月半致死温度测定结果基本一致,表明半致死温度可作为莲雾抗冷性评价的一个可靠指标。长时间低温加上霜冻,使露地栽培本地种、粉红种、紫红种的叶片和部分嫩梢受冷害,而印度红、青色种不能越冬成活。

LT50 and cold tolerance adaptability of Syzygiums amarangense during a natural drop in temperature

In order to investigate the semi-lethal temperature(LT50) change for Wax-apple during the natural drop in temperature from autumn to winter,the changes of cell membrane permeability at different low temperature were studied with leaves and mature branches collected from Wax-apple species.The temperature of breakpoint was obtained on the basis of conductivity and Logistic equation.The cold tolerance of 6 Wax-apple species and different parts of Wax-apple were evaluated by LT50.The validity of LT50 in evaluating the cold tolerance of Wax-apple was proved by overwintering performance of open cultivation.The results showed that the LT50 temperature decreased with the drop in temperature,the change of LT50 was species-dependent,the decrease of LT50 varied from 1.69 to 2.97 ℃.The cold tolerance of 6 species decreased in the order of Shui putao,Native species,Pink species,Purplish red species,Cyan species and Ying duhong.The cold hardiness of biennial branch was stronger than that of shoot and leaf.Overwintering performance of open cultivation was overall in consistence with the result of the freezing test,which indicated that LT50 temperature was a credible indicator to evaluate the cold tolerance of Wax-apple.The leaves and a part of shoot of native species,pink species and purplish red species suffered cold,while Ying duhong and Cyan species could not survive under long-time low temperature with obvious frost.