Influence of changes in manganese and magnesium supply on some aspects of wheat physiology

Abstract

Wheat (Triticum aestivum L.) cv. UP 2003 was grown in refined sand at three levels of manganese, 0.02 (deficient), 10 (adequate), and 200 (high) μM, each at three levels of magnesium, 0.02 (deficient), 2 (adequate), and 4 (excess) mM. In wheat magnesium deficiency aggravated the effects of low manganese supply namely decreases in dry weight, seed yield, chlorophyll content, Hill reaction activity, contents of DNA and RNA, and activities of ATPase and DNAse. On the other hand, the decrease in the activity of RNAse and increase in that of peroxidase were less pronounced in the combined deficiencies of manganese and magnesium than in manganese deficiency. Excess Mg accentuated the visible symptoms of Mn deficiency. Excess Mg also alleviated the effects of high manganese level by increasing the biomass, contents of chlorophyll, DNA, and RNA, Hill reaction activity, and activities of peroxidase and DNAse and by decreasing further leaf Mn content. It appeared that manganese could not replace the role of magnesium in RuBP carboxylase activity.