Greer D H, Robinson L A
Plant Physiology Group, Horticulture and Food Research Institute, Private Bag 11030, Palmerston North, New Zealand.
Tree Physiol. 1995 Jun;15(6):399-404. doi: 10.1093/treephys/15.6.399.
Seedlings of Leptospermum scoparium J.R. et G. Forst (manuka) originating from seed from a low altitude coastal site (Auckland) and from a high altitude inland site (Desert Road) were grown for 96 days in four controlled environments to compare the relationship between growth temperature and frost hardening. Day/night temperature treatments were 12/6, 12/3, 12/0 and 12/-3 degrees C. Frost hardiness was determined at 14-day intervals by exposing whole seedlings to temperatures ranging from -2 to -8 degrees C. Frost damage differed significantly between the two populations: Desert Road seedlings were less affected than Auckland seedlings. At all growth temperatures, the time courses of frost hardiness of both populations followed curvilinear relationships reaching a maximum hardiness at about Day 50, after which the seedlings spontaneously dehardened. The rate of frost hardening increased linearly with decreasing temperature from 6 to 0 degrees C, but thereafter, no further increase occurred with decreasing temperature to -3 degrees C. The frost hardening process was more sensitive to temperature in the Desert Road seedlings than in the Auckland seedlings, and this difference may account for the intraspecific variation in frost hardening capacity of this species. Comparisons with Pinus radiata D. Don and Lolium perenne L. indicated that interspecific variation in frost hardening capacity can also be accounted for by differences in the sensitivity of the hardening process to temperature.
源自低海拔沿海地区（奥克兰）和高海拔内陆地区（沙漠路）种子的帚石楠幼苗，在四种可控环境中生长96天，以比较生长温度与抗冻硬化之间的关系。昼夜温度处理分别为12/6、12/3、12/0和12/-3摄氏度。每隔14天通过将整株幼苗暴露在-2至-8摄氏度的温度下测定抗冻性。两个种群的冻害差异显著：沙漠路的幼苗比奥克兰的幼苗受影响小。在所有生长温度下，两个种群的抗冻性时间进程均呈曲线关系，在大约第50天达到最大抗冻性，此后幼苗自发脱硬。抗冻硬化速率随温度从6摄氏度降至0摄氏度呈线性增加，但此后，温度降至-3摄氏度时不再进一步增加。沙漠路幼苗的抗冻硬化过程比奥克兰幼苗对温度更敏感，这种差异可能解释了该物种抗冻硬化能力的种内变异。与辐射松和多年生黑麦草的比较表明，抗冻硬化能力的种间变异也可由硬化过程对温度的敏感性差异来解释。
