Effect of Temperature on Germination Behavior of Horsenettle (Solanum carolinense L.) Seeds.

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The temperature range of germination, thermal time and the effects of temperature fluctuation on horsenettle (Solanum carolinense L.) seeds were investigated. Base temperature (Tb) and thermal time (θ) to germination for seeds treated with gibberellin were calculated by Garcia-Huidobro's method. Tb was estimated to be between 14-16°C. Maximum temperature was surmised to be between 45-50°C from a graph. Gompertz function adequately described the relationship between θ and germination fraction (%), but a modification of the equation was needed in some cases. The germination percentage of seeds exposed to diurnal temperature fluctuation with an upper limit of 15-30°C and amplitudes of 5-15°C for 10 or 20 cycles was significantly higher than that of seeds incubated at a constant 30°C. Seeds incubated at lower temperatures needed more cycles to increase the germination percentage, but the maximum percentage obtained with each temperature regime was similar. Horsenettle seeds appeared to respond even to temperature fluctuation below Tb because exposure to 15/10°C for 20 cycles increased the germination percentage.It was suggested that horsenettle seeds whose dormancy can be broken by temperature fluctuation may be released from dormancy by temperature fluctuation below Tb, and then germination may begin with the temperature above 14-16°C under field conditions.
日本雑草学会の論文