Photosynthetic, physiological and biochemical events associated with polyethylene glycol-mediated osmotic stress tolerance in taro ( Colocasia esculenta L. Schott)

Six genotypes of taro (Colocasia esculenta L. Schott) were evaluated under in vitro and in vivo polyethylene glycol (PEG–6000)-mediated osmotic stress conditions. A significant variation in growth response was observed among the taro genotypes under in vitro-induced stress conditions. In vivo results indicated a significant effect of osmotic stress on photosynthetic parameters, such as net photosynthetic rate, transpiration rate, stomatal conductance, stomatal resistance, internal CO2 concentration, carboxylation efficiency, and transpiration efficiency on the tested genotypes at the tuberization stage. Lesser variations in photosynthesis and higher accumulation of proline, phenols, and antioxidative enzymes, namely, superoxide dismutase and guaiacol peroxidase, were associated with yield maintenance under osmotic stress conditions. The genotypes DP–89, IGCOL–4, and Ramhipur showed a higher degree of tolerance towards osmotic stress with a minimum variation in the studied parameters. These genotypes could be lines of interest for intensification of breeding strategies to develop drought-tolerant plants.