Response of wheat growth and CO2assimilation to altering root-zone temperature

摘要

Wheat plants (Triticum aestivumL. var. Chisholm) grown at an air temperature of 23 deg;C and a root-zone temperature of 3 deg;C exhibited a significant reduction in shoot and root dry weight and leaf area compared with plants grown at a root-zone temperature of 23 deg;C. This reduction was correlated with a significantly lower CO2assimilation rate that was associated with lower leaf conductance, lower internal CO2concentration, and more negative water potential. Low CO2assimilation rate was also associated with high starch and total soluble sugar levels in the shoot, less translocation of photosynthate, and possibly less sink demand. Leaf chlorophyll concentration was not affected by altering the root-zone temperature, whereas water use efficiency of plants grown at a root-zone temperature of 3 deg;C was as much as 1.5 times higher as those grown at 23 deg;C.Key words: carbohydrate, chlorophyll, photosynthate partitioning, leaf conductance, water potential, water use efficiency.