Articles
EVALUATION OF FREEZING HARDINESS OF ORNAMENTAL GEOPHYTES
Article number
886_12
Pages
105 – 112
Language
English
Abstract
Information of freezing hardiness of plants is important for landscape planting.
Eleven species of ornamental geophytes were planted in pots and were cooled at a constant rate for various periods, and their freezing hardiness was evaluated by calculating the median lethal dose temperature (LT50). We also measured the initiation temperature of the low temperature exotherm (IET) of bulbs of geophytes and discuss the possibility of IET as a rapid method to estimate freezing tolerance.
In the experiment in January, Agapanthus africanus, Babiana stricta, Canna Butter Cup, Freesia Elegance and Narcissus tazetta were freezing sensitive at LT50 >-3°C and Allium chinense and Muscari armeniacum were resistant with LT50 <-9°C. Liatris spicata was a species markedly resistant to freezing, because all plants survived even when its tubers were at -12°C. The freezing hardiness of Crocus sativus, Lycoris albiflora and Oxialis purpurea were intermediate.
The LT50 of Muscari, Lycoris and Liatris decreased by acclimatization from October to December and that of Agapanthus, Canna and Narcissus did not.
In a different thermal analysis of 25 geophytes, the initiation of exotherm (IET) was detected by freezing bare bulbs, corms, tubers or rhizomes from 5°C at a rate of -1.6°C h-1. The IETs varied among the species tested but the relationship between the IET and anatomical characteristics or mass of the plants was unclear.
Because the correlation between LT50 and IET was not significant, we conclude that IET is not a useful indicator of freezing hardiness of geophytes.
Eleven species of ornamental geophytes were planted in pots and were cooled at a constant rate for various periods, and their freezing hardiness was evaluated by calculating the median lethal dose temperature (LT50). We also measured the initiation temperature of the low temperature exotherm (IET) of bulbs of geophytes and discuss the possibility of IET as a rapid method to estimate freezing tolerance.
In the experiment in January, Agapanthus africanus, Babiana stricta, Canna Butter Cup, Freesia Elegance and Narcissus tazetta were freezing sensitive at LT50 >-3°C and Allium chinense and Muscari armeniacum were resistant with LT50 <-9°C. Liatris spicata was a species markedly resistant to freezing, because all plants survived even when its tubers were at -12°C. The freezing hardiness of Crocus sativus, Lycoris albiflora and Oxialis purpurea were intermediate.
The LT50 of Muscari, Lycoris and Liatris decreased by acclimatization from October to December and that of Agapanthus, Canna and Narcissus did not.
In a different thermal analysis of 25 geophytes, the initiation of exotherm (IET) was detected by freezing bare bulbs, corms, tubers or rhizomes from 5°C at a rate of -1.6°C h-1. The IETs varied among the species tested but the relationship between the IET and anatomical characteristics or mass of the plants was unclear.
Because the correlation between LT50 and IET was not significant, we conclude that IET is not a useful indicator of freezing hardiness of geophytes.
Authors
K. Inamoto, K. Matsubara, M. Doi, H. Imanishi
Keywords
exotherm, median lethal temperature
Online Articles (60)