根系温度对苋菜生长及光合特性的影响

气候室中研究了根温对苋菜幼苗生长及光合等生理特性的影响。结果表明,苋菜幼苗生长曲线呈S形, 30d苗龄时生长最快, 40d苗龄时每株干、鲜重分别为0.45g和6.79g。20~25℃根温时40d苗龄苋菜生长最快,高根温对生长的危害大于低根温, 40℃根温苋菜根系生长、代谢受害严重。苋菜净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Cs)和胞间CO2分压(Pi)随根温的变化趋势基本一致, 20~25℃根温时,Cs、Pi、Pn和Tr均高,不良根温影响了Cs,使Tr降低, Pi降低,进而影响到Pn。回归分析表明, Pn与Cs、Pn与Pi、Tr与Cs、Pi与Cs均呈显著正相关。说明Cs下降是不良根温影响Pn的主要原因。

THE EFFECT OF ROOT SYSTEM TEMPERATURE ON GROWTH AND PHOTOSYNTHE TIC CHARATERISTICS IN AMARANTHUS TRICOLOR

The effect of root temperature on growth, photosynthetic and other physiological characteristics of A. tricolor seedlings were studied in phytotron. The result showed that growth curve of A. tricolor seedling presented "S" shape, 30-day-old seedling grew fastest. Dry and fresh weight per a seedling was 0.45g and 6.79g respectively. The harmfulness of superoptimum root temperature to growth was bigger than that of suboptimum root temperature, 40℃ root temperature harmed growth and metabolism of root system of A. tricolor seriously. The variation of net photosynthetic rate (P_n), transpirat ion rate(T_r), stomatal conductance(C_s), and intercellular CO₂ partial pressure (P_i) with root temperature was similar in A. tricolor. C_s, P_i, P_n and T_r were higher at 20~25℃ root temperature. Suboptimum or superoptimum root temperature affected C_s, and caused decreasement of T_r and P_i, then affected P_n. Regressive analysis showed that P_n correlated with C_s and P_i positively, T_r and P_i correlated with C_s positively too. The main cause of the decreasement of P_n at suboptimum and superoptimum root temperature was the decreasement of C_s.