WATER USE EFFICIENCY IN PHASEOLUS VULGARIS EXPOSED TO ELEVATED CO₂

Stomatal conductance (g_s) declined significantly as expected in bean plants grown under elevated CO_2-. Similarly a significant decline in transpiration rates (E) occurred in these plants.
Reduced g_s and E led to high net carbon assimilation (A)l E ratio which meant improved water use efficiency (WUE) values for CO₂-enriched bean plants.
Leaf carbon isotope discrimination (Δ) against heavier isotope of carbon (¹³C) has been used increasingly to select for high WUE in C₃ plants. Δ was significantly reduced in plants grown under elevated CO₂. Although Δ was negatively correlated to WUE in both CO₂ treatments, the correlation was steeper and highly negative for CO₂-enriched plants.
These results indicate underlying differences in gas exchange physiology including stomatal responses that directly affect water economy in ambient and elevated CO₂-grown plants.

II International Symposium on Irrigation of Horticultural Crops

J.M. Mjwara, C.E.J. Botha

Carbon isotope discrimination, elevated CO₂, Phaseolus vulgaris, stomatal conductance, transpiration, water use efficiency

https://doi.org/10.17660/ActaHortic.1997.449.61