Abstract:

Growth, photosynthetic characteristics and water parameters of two Poplar clone seedlings were studied comparatively under different water conditions in order to explore their adaptation mechanism to water stress. The results indicated that water stress affected growth and photosynthetic rate of the 2 Poplar clones, and its effect on Populus×xiaozhuanica‘Zhaolin-6’was less than on Populus×euramericana cv.‘N3016’.Photosynthesis of the 2 clones was limited by stomatal factor within 16 days after water stress;and it was limited by non-stomatal factor 16 days after stopping watering and in the recovering period.Respiration rates decreased under water stress conditions,especially that of ‘Zhaolin-6’,which was advantageous to carbon balance. When water stress was imposed ,ψ_s¹⁰⁰,ψ_s⁰ and ROWC⁰ of the two clones decreased,and the difference between ψ_s¹⁰⁰ and ψ_s⁰ increased ,which showed that Poplar could have adaptation reaction to water stress through osmotic adjustment and maintain turgor. And the ability of Populus×xiaozhuanica ‘Zhaolin-6' was stronger than that of P.×euramericana cv.‘N3016’, which indicated that drought tolerance of Populus×xiaozhuanica ‘Zhaolin-6' was greater.

Key words: Poplar clones, Water stress, Growth, Net photosynthetic rate, Pressure-Volume technique, Water parameters