Seasonal variations in some water relations and biochemical attributes of two genetically diverse maize cultivars

Abstract

Greenhouse (GH) effect has emerged as a major factor in changing cropping patterns and limiting crop yields. This study was conducted to determine the comparative growth and photosynthetic responses of selected heat-resistant (cv. Sadaf) and heat-susceptible (cv. Agatti-2002) cultivars of maize to simulate GH conditions during spring and autumn at seedling, silking, and grain filling stages in 2007. Fifteen day old plants were shifted to plexiglass-fitted canopies to create GH conditions and data were recorded at each growth stage. The results revealed that seasons, GH conditions, and cultivars had large effects on water relations and biochemical attributes. Simulated GH conditions increased the canopy temperature 4–7 °C in spring and 3–5 °C in autumn, but increased relative humidity by 2–3 % in spring and 5–9 % in autumn. Changes in temperature conditions inside the canopy and seasons greatly affected the leaf water, osmotic, and turgor potentials in both cultivars. Temperature variations in both seasons enhanced the production of reactive oxygen species which was evident by increased synthesis of hydrogen peroxide (H2O2), malondialdehyde contents, and increased permeability to ion leakage in both cultivars. Greater free proline accumulation in the tolerant cultivar was marked as a reliable indicator of tolerance to high temperature stress in maize. In addition, Sadaf cultivar was found to be more tolerant than cv. Agatti-2002 in terms of having lower levels of H2O2, MDA contents, and relative membrane permeability.