低温胁迫下蓝花楹的耐寒生理机制分析

Mechanism of Chilling Injury in Jacaranda acutifolia Humb. et Bonpl.under Chilling Stress

本试验研究了蓝花楹在15和4℃两种温度条件下,胁迫24 h（平均光强22 500 lx,湿度75%）后,多项生理指标的变化趋势,尝试从生理角度了解蓝花楹在低温逆境环境下的生长发育机制。结果表明：1蓝花楹在15℃条件下,胁迫8~12 d后,各项生理指标保持稳定,说明体内的耐冷调节机制与冷害达到了平衡;而随着低温4℃的持续胁迫,各项生理指标发生剧烈变化,表明4℃低温对蓝花楹的伤害程度远大于蓝花楹自身的修复速度。2 2种低温胁迫下,部分生理指标在3~5 d出现拐点,如净光合速率（Pn）和超氧化物歧化酶（SOD）活性在第3天显著降低,SOD活性和脯氨酸（Pro）含量在第5天明显升高,推测3~5 d可能是蓝花楹体内各系统应答低温胁迫的启动时间。综上所述,蓝花楹可以耐受15℃低温,但对4℃的耐受能力较弱,建议蓝花楹引种地区的纬度尽量不大于29°。

The trends of physiological indicators of Jacaranda acutifolia Humb. et Bonpl. under 15 and 4 ℃ stress control after 24 h（ light intensity 22 500 lx,75 % humidity） were studied in the present experiment to learn the growth mechanism of J. acutifolia at low temperature stress environment from the physiological point. The results showed that：（ i） The physiological indexes could maintain a steady state for8- 12 d under 15 ℃,suggesting that it being balanceable between the seedlings＇ resistance（ cold adjustment mechanism） and chilling injury. In addition,it indicated that J. acutifolia could adapt to the low temperature of 15 ℃. However,J. acutifolia seedlings were intolerant for a long time under 4 ℃,with physiological indexes fluctuated dramatically. So the damage degree to leaves under 4 ℃ was more than the repair speed of J. acutifolia itself.（ ii） Inflection points of some physiological indicators appeared at 3- 5 d,for example,the net photosynthetic rate（ Pn） and superoxide dismutase（ SOD） activity were significantly reduced at 3 d,while,SOD activity and proline（ Pro） content were significantly increased at 5 d under 15 ℃. It was speculated that 3- 5 d may be the start-up time of response system to low temperature stress in J. acutifolia leaves. In summary,J. acutifolia could bear low temperature of 15 ℃,however its tolerance to 4 ℃ stress was weak.We suggest that the latitudes for J. acutifolia＇s distribution do not exceed 29 °.