EAR PHOTOSYNTHESIS AND ITS CONTRIBUTION TO GRAIN FILLING UNDER STRESS

MAYDUP, MARIA LUJAN; TAMBUSSI, EDUARDO ALBERTO; GUIAMET, JUAN JOSE; ANTONIETTA, MARIANA

CORRIENTES

Congreso; XXXI Reunion Argentina de Fisiología Vegetal; 2016

Sociedad Argentina de Fisiología Vegetal

Abstrac:The main sources for grain filling in wheat are flag leaf and ear photosynthesis and the redistribution of assimilate stored in the stem. Ears have particularities compared with the rest of green tissues in the plant (v.g. xeromorphism, refixation of respiratory CO2, low water potentials and osmotic adjustment) which, in part, may explain why photosynthesis is less affected in the ear than in the flag leaf under water stress. While it is accepted that grain yield is usually limited by sink strength, cases of source limitations have been reported in modern germplasm. We have reported that the relative contribution of ear photosynthesis increases under reduced source conditions (drought, defoliation), and across genetic improvement (which implies a reduction in source-sink ratio). Some of the ear photosynthetic characteristics are known but not fully mechanistically understood, nor has been studied its variability among cultivars. We are currently analyzing the role of the awns on ear thermal balance, and also, possible mechanisms relating to CO2 refixation in the ear. The potential source of assimilates related to ear photosynthesis may be relevant for optimizing resource use efficiency under adverse scenarios (pathogens, water stress, heat stress).