Reduction in radiation use efficiency of cotton (Gossypium hirsutum L.) under repeated transient waterlogging in the field

Yield loss in cotton has been quantitatively related to the duration of waterlogging. However, the processes which contribute to the yield reduction over the term of a growing season are not well understood. Two field experiments were conducted in a semi-arid environment at Narrabri in northern New South Wales, Australia (30° S 150° E), on a gray-clay soil (vertosol) with a low drainage rate. Irrigation was scheduled according to industry practice. A waterlogged treatment was imposed by extending the duration of application of furrow irrigation. Waterlogging reduced radiation use efficiency (RUE), but RUE calculated for short time periods during crop growth could not be related directly to soil O2 status. A single transient waterlogging event had a long term impact on the performance of the cotton crop: RUE did not recover from a single large waterlogging event early in crop development and remained low for the rest of the season. The response of lamina net photosynthesis (Pn) to repeated waterlogging suggested some degree of acclimation. The long term suppression of RUE was in contrast to the relatively short duration for which Pn of the youngest fully expanded leaf was affected. To be able to scale from the impact on Pn to the impact on RUE will require the changes in specific leaf nitrogen, light and Pn to be measured at various heights within the canopy during the period of hypoxia and subsequent recovery.

► Waterlogging reduced radiation use efficiency (RUE) of cotton but RUE calculated for short periods during growth could not be related directly to soil O2 status.
► A single prolonged waterlogging event early in growth had an impact on RUE almost as large as a number of shorter events, even though the total period of oxygen stress was less.
► The response of net photosynthesis (Pn) of the youngest fully expanded leaf (YFEL) to repeated waterlogging suggested some degree of acclimation.