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ARE CHLOROPHYLL FLUORESCENCE AND PHOTOSYNTHETIC CAPACITY POTENTIAL PHYSIOLOGICAL DETERMINANTS OF DROUGHT TOLERANCE IN MAIZE (ZEA MAYS L.)

MUHAMMAD ASHRAF^1*, SHAMYLA NAWAZISH¹ AND HABIB-UR-REHMAN ATHAR²

Abstract: In order to assess as to whether traits related to plant photosynthetic capacity such as chlorophyll fluorescence and net CO₂ assimilation rate could be used as indicators for drought tolerance in maize, 5 synthetic and 2 hybrids were subjected to PEG-induced water stress for 3 weeks. Although the growth of all maize cultivars was significantly reduced by PEG-induced water stress, they differed significantly in producing shoot biomass under water stress conditions. However, cv. Sahiwal-2002 was higher in growth under water stress conditions. The photosynthetic capacity (A) of all maize cultivars was also reduced under water deficit conditions. Since, there was a positive correlation between biomass production and net CO₂ assimilation rate so photosynthetic capacity could be used as a potential selection criterion for drought tolerance in maize. In contrast no such relationship of drought tolerance of the cultivars with photosystem-II efficiency measured as Fv/Fm. Thus, it did not prove to be a viable criterion for drought tolerance in maize.

¹Department of Botany, University of Agriculture, Faisalabad, Pakistan

²Institute of Pure and Applied Biology, Bahauudin Zakariya University, Multan, Pakistan