Limitations in photosynthesis of sugar beets under water deficit and
rehydration conditions
Abstract
The limiting factors in photosynthesis for many crops under water
deficit and rehydration conditions have been studied, but few studies of
this kind on sugar beet can be found.Our study aimed to analyze the
dynamic changes of mesophyll limitations, stomatal limitations, and
biochemical limitations by examining the influences of water deficit and
rehydration on photosynthetic characteristics, electron transport, and
leaf anatomical structure. According to the analysis on photosynthetic
characteristics, severe deficit irrigation treatment significantly
decreased photosynthesis rate, light saturation point, and CO2
saturation point. After rehydration, there was no difference in
photosynthetic characteristics between the well irrigated sugar beets
and the ones with severe deficit irrigation treatment. The analysis on
leaf anatomical structure found that sugar beets dealt with water
deficit by increasing leaf thickness, and the severe deficit irrigation
treatment significantly decreased the number of chloroplasts without
influencing each one in terms of shape and cross-section area.Therefore,
deficit irrigation treatments cannot significantly influence
photosynthetic assimilation of sugar beets. The analysis of limitations
in photosynthesis showed that the stomatal and biochemical limitations
increased while the mesophyll limitations decreased when sugar beets
were under water deficit; however, the stomatal and biochemical
limitations decreased while the mesophyll limitations increased after
rehydration.