Abstract: This paper studied the photosynthetic characteristics of four hybrid hazel fine breeds (Nos. 1-4) in Xinjiang under field conditions in summer. The light saturation point (LSP) of Nos. 1-4 varied from 1195.27 to 1620.63 μmol·m^-2·s^-1, light compensation point (LCP) varied from 34.03 to 87.80 μmol·m^-2·s^-1, CO₂ saturation point (CSP) varied from 1188.50 to 1617.05 μmol·mol^-1, and CO₂ compensation point (CCP) varied from 65.88 to 99.15 μmol·mol^-1. The No. 1 and No. 4 showed the characteristics of low photosynthetic rate (P_n) and low transpiration (T_r), the No. 2 showed lower LCP and higher LSP, indicating a wider scope of light energy utilization and higher photosynthetic potential, while the No. 3 possessed the highest LCP and LSP, higher CSP and CE, but lower CCP, showing the higher photosynthetic capacity (P_max, 31.55 μmol·m^-2·s^-1) than the others (24.63-25.45 μmol·m^-2·s^-1). As compared with that at normal temperature (25 ℃), the P_n of the No. 1 was more affected by high temperature (40 ℃), while the G_s of the No. 3 was lesser affected than that of the others.

Key words: chemical fertilizer, straw returning, organic and inorganic fertilizer, weed, wheat field.