| Heat tolerance in lily (Lilium) indicates the ability of resistance and adapt to hightemperature. The aim of the experiment is to study the effect of hot water treatment ofbulbs on heat tolerance of lily plants. Used Asiatic hybrids'Pollyanna'as the experimentalmaterial, the bulbs were dept into hot water at 45℃, for different times of 0, 10, 20, 30, 40and 50 min. After planting, the resistance physiological indices , stomatal aperture, theelectrical impedance spectroscopy parameters and the chlorophyll fluorescence parametersof young plants under heat stress at 38℃were studied.The main results were as follows:1. Heat shock bulbs for 20 min promoted the activity of SOD and the content ofsoluble sugar in the leaves, they were higher than these of the control 65.95%(P<0.01)and 23.75%(P<0.01)respectively; starch content was lower than that of the control26.11%(P<0.01)and the root activity was higher than that of the control 57.11%(P<0.01), but there was no significant difference between relaxation time and control.SOD activity and soluble sugar content reached the peak after 30 min treatment, and therewas no significant difference with 20 min treatment, but the root activity decreased rapidly,and it was lower than that of the control 20.63%. Lily plants can acquire heat toleranceobviously through hot water treatment of bulbs for 20 min which the perimeter of the bulbwas 5—6 cm.2. Synergistic effect of the SOD and photosynthetic pigment were caused by heatshock 30 min, they were higher than these of the control 426.16%(P<0.01), 70.69%(P<0.01)and 79.16%(P<0.01), and the system improved the heat dissipation to avoidthe heat injury. Although the content of soluble sugar and proline in the leaves reached thepeak and the content of super oxide anion, stomata aperture reached its lowest level whenheat shock bulbs for 40 min, the photosynthesis of plant was affected, and lily plants withthe bulbs perimeter of 9—10 cm can acquire heat tolerance obviously through hot watertreatment of bulbs for 30 min.
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