Articles
BULB TISSUE COLD-TOLERANCE SENSITIVITY DIFFERENCES IN LILIUM LONGIFLORUM ‘NELLIE WHITE’ AND L. FORMOSANUM
Article number
1002_14
Pages
123 – 129
Language
English
Abstract
As part of a breeding objective for selection and development of winter-hardy (USDA Z3-4), seed-propagated interspecific lily hybrids, this research focuses on the identification of cold-sensitive levels of lily bulb tissue(s). The objective of this experiment was to test two cold-sensitive Lilium spp. for tissue sensitivity to and damage by freezing temperatures.
Bulbs of L. longiflorum Nellie White and a L. formosanum hybrid population were acclimated at 2°C for 1,000 hours.
In a separate experiment, Nellie White bulbs were also acclimated at 2°C for 2,000 h.
Cold tolerance was assessed using laboratory freezing tests at 0, -2, -6, -8, -10, -12°C with varying ramp time periods and a 2 hour soak time in a programmable freezer.
Lethal temperatures at which 50% kill occurred (LT50) of all bulb tissues (basal plate, roots, mother scales, daughter scales, meristem, pre-formed leaves), reduction and quantitative regrowth data (leaf, root numbers; shoot length) were determined for dissected bulbs tissue(s) after freezing.
Significant changes in the interaction of genotype × temperature were detected.
The LT50=-6°C for all structures of Nellie White bulbs (both 1,000 and 2,000 h) and roots of L. formosanum whereas an LT50=-8°C was found for L. formosanum mother and daughter scales, leaves, meristems, and basal plates.
Cooling for 1,000 h resulted in significant regrowth differences for leaf number and shoot length of Nellie White between -6 and -8°C. However, after 2,000 hours cooling the number of leaves and shoot length differed significantly between -2 and -6°C for Nellie White. TTC tests did not correspond to laboratory freezing LT50s and had insufficient or variable amounts that were difficult to detect.
As a result, laboratory freezing and regrowth tests provide more substantive data for use in determining cold tolerance in geophytic Lilium.
Bulbs of L. longiflorum Nellie White and a L. formosanum hybrid population were acclimated at 2°C for 1,000 hours.
In a separate experiment, Nellie White bulbs were also acclimated at 2°C for 2,000 h.
Cold tolerance was assessed using laboratory freezing tests at 0, -2, -6, -8, -10, -12°C with varying ramp time periods and a 2 hour soak time in a programmable freezer.
Lethal temperatures at which 50% kill occurred (LT50) of all bulb tissues (basal plate, roots, mother scales, daughter scales, meristem, pre-formed leaves), reduction and quantitative regrowth data (leaf, root numbers; shoot length) were determined for dissected bulbs tissue(s) after freezing.
Significant changes in the interaction of genotype × temperature were detected.
The LT50=-6°C for all structures of Nellie White bulbs (both 1,000 and 2,000 h) and roots of L. formosanum whereas an LT50=-8°C was found for L. formosanum mother and daughter scales, leaves, meristems, and basal plates.
Cooling for 1,000 h resulted in significant regrowth differences for leaf number and shoot length of Nellie White between -6 and -8°C. However, after 2,000 hours cooling the number of leaves and shoot length differed significantly between -2 and -6°C for Nellie White. TTC tests did not correspond to laboratory freezing LT50s and had insufficient or variable amounts that were difficult to detect.
As a result, laboratory freezing and regrowth tests provide more substantive data for use in determining cold tolerance in geophytic Lilium.
Authors
Fang Du, N.O. Anderson, Yiping Xia
Keywords
bulb tissue, freezing injury, Lilium
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