Adequate magnesium nutrition mitigates adverse effects of heat and high light stress on maize and wheat
Mengütay, Melis (2014) Adequate magnesium nutrition mitigates adverse effects of heat and high light stress on maize and wheat. [Thesis]
Heat stress and excess light intensity are growing concerns in crop production because of global warming. In many cropping systems these stresses often occur simultaneously with other environmental stress factors such as mineral nutrient deficiencies. This study aimed to investigate the role of adequate magnesium (Mg) nutrition in mitigating the detrimental effects of heat and high light stress on wheat (Triticum aestivum) and maize (Zea mays). Visual leaf symptoms of Mg deficiency were aggravated in wheat and maize when exposed to heat or high light stress. Magnesium deficiency markedly reduced soluble carbohydrate concentrations in young leaves; but resulted in substantial increase in source leaves, indicating reduced transportation of carbohytrates from older (source) leaves into younger (sink) leaves. Magnesium deficiency also increased activities of antioxidative enzymes, especially when combined with heat and high light stress. The highest activities of superoxide dismutase (up to 80% above the control), glutathione reductase (up to 250% above the control) and ascorbate peroxidase (up to 300% above the control) were measured when Mg-deficient plants were subjected to heat or high light stress, suggesting stimulated formation of reactive oxygen species (ROS) in Mg deficient leaves under heat or high light stress. These results indicate that Mg deficiency increases susceptibility of wheat and maize plants to heat or high light stress, probably by increasing oxidative cellular damage caused by ROS. Ensuring a sufficiently high Mg supply for crop plants through Mg fertilization is a critical factor for minimizing heat or high light-related cellular damage in leaves and losses in crop production.
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