Abstract: The greenhouse heating was one of the main methods to enhance the growth environment of crop in winter. The energy-saving solar greenhouse was selected. The temporal and spatial variations of temperature in the solar greenhouse and the heating effects under the extreme weather condition and different outdoor temperatures were discussed by a heating experiment with an electric warm-air machine. The economic investment was also analyzed. The results show that the temperature in the greenhouse rises significantly and is distributed uniformly in the whole greenhouse after the heating by the electric warm-air machine. The average temperature in the heating greenhouse is 4.23 ℃ higher than in the control greenhouse, and the average minimum temperature in the heating greenhouse increases significantly. The average temperate  in the heating greenhouse is 4.24 ℃ higher than in the control greenhouse under the low temperature weather condition, while it is 4.48 ℃ higher  under the spare sunlight weather condition. The heating effect by the electric warm-air machine for the greenhouse is best when the outdoor temperature is -12 ~-4 ℃. The analysis of economic investment with the different heating methods suggests that the warm-air machine is an economic heating measure for its small investment, low energy consumption and high economic benefit.

Key words: Solar greenhouse, Warm-air machine, Heating effect, Economic benefit