Plant growth, metabolism and adaptation in relation to stress conditions: XVII. Influence of different water treatments on stomatal apparatus, pigments and photosynthetic capacity in Vicia faba

Water stress induction by six different levels of water ranging from very dry to very waterlogged was found to decrease the number of stomata per unit area as well as the area of stomatal opening, except for wet treatment which appeared to increase these parameters of stomatal apparatus. Leaf pigment content was found to change variably in response to the different water treatments. These changes were found also to depend on the stage of growth of the plants and on whether the measurements were made before or after irrigation. Conflicting changes in the photoreduction of 2,6-dichlorophenol indophenol, taken as a measure of photosystem II activity, were obtained in response to the different water treatments both before and after watering. Furthermore, marked reduction in 14CO2-fixation was, in general, maintained under the different levels of water supply, in relation to the control. Calculating the ratios of soluble: insoluble photosynthates enabled us to deduce that the rate of transformation of the former into photosynthates was inhibited.