The effect of leaf water potential on the carbon-dioxide uptake rate during different growth stages of wheat (Triticum aestivum L.)

Abstract

The effect of water stress on the CO₂ uptake rate was measured at three different growth stages of wheat grown in Mitscherlich pots in a glasshouse experiment. Stress was induced by withholding water until the leaf water potential reached −2 000 kPa and −3 000 kPa, while control plants were irrigated continuously. Although stress inhibited the CO₂ uptake rate of the entire plant, low stress levels briefly stimulated this process during the differentiation of the spikelet. Recovery of the CO₂ uptake rate deteriorated with increased stress and at later growth stages, and no recovery was evident on alleviating severe stress during seed-filling. The CO₂ uptake rate per unit living leaf area generally decreased under stress, while the recovery after severe stress was considerably lower than after moderate stress. During seed-filling there was no recovery whatsoever of the CO₂ uptake rate per unit leaf area after the alleviation of severe stress.