Pattern of plant relations and carbon dioxide exchange rates in contrasting genotypes of Brassica juncea under water deficit conditions

Resistant cultivars RH-8812 and RH-30 of oil seed Brassica juncea developed a significantly lower osmotic potential (ψ) after 8 days of water stress at the seed initiation stage than the susceptible cv. Blaze. This contributed towards better osmotic adjustment, lesser inhibition of photosynthesis and higher water use efficiency of the resistant cultivars. Unlike RH-8812 and RH-30, the decline in rate of photosynthesis in cv. Blaze was much more profound than the rate of transpiration. Thus one of the reasons for poor performance of cv. Blaze under moisture deficiency could be a more extensive stress induced damage to the photosynthetic apparatus of this genotype.