Abstract: This study focused on the effects of different spacings of Paulownia elongata on energy balance and yield of intercropped wheat in paulownia-wheat intercropping field. Results showed that the net radiation (Rn) and its components were reduced in the intercropped wheat field compared to the control plots. However, the proportion of sensible heat flux(H) to Rn decreased while those of the latent heat flux(LE) and soil heat flux (G) increased. At the same time, water relative deficit in the intercropped plots decreased.Effects of paulownia trees on these parameters depended on its density, growth stage, the modified energy balance was favorable to wheat growth during jointing, heading and flowering stages in all paulownia spacings. However, the reduced Rn in denser paulownia spacings caused less favorable effect on wheat growth during grain filling and mature stages. The yield of intercropped wheat was found to vary with paulownia density and with the wheat plants' relative distance from the paulownia tree rows. Paulownia did not affect wheat yield in spacings larger than 5×20m but caused a decrease in spacings of less than 5×20m at the 7th intercropping year.

Key words: Paulownia-wheat intercropping, Energy balance, Water use, Wheat yield