The role of manganese toxicity in crop yellowing on seasonally waterlogged and strongly acidic soils in north-eastern Victoria

Abstract

Concentrations of exchangeable and easily reducible manganese (Mn) were measured monthly for 3 1 months in acidic soils at 6 sites used for cropping in north-eastern Victoria. Manganese concentrations in shoots of wheat (Triticum aestivum), when present, were also measured. Changes in Mn concentrations in the soils and in wheat plants were related to seasonal conditions and to the occurrence of crop yellowing, a chlorotic and stunting disorder which affects cereals grown in the region. Peaks in the concentration of exchangeable Mn occurred either when the soils were waterlogged for a prolonged period or when they were subjected to extreme heating and drying during summer. Shoot concentrations of up to 1200 mg/kg of Mn were measured for plants growing in waterlogged soils. However, in some cases concentrations less than 400 mg/kg, a concentration not considered harmful, were measured in shoots of wheat growing under waterlogged conditions but which still showed symptoms of severe chlorosis and stunting. In the absence of waterlogging, concentrations of Mn in wheat shoots were usually less than 400 mg/kg. The evidence suggests that Mn toxicity is not the primary cause of crop yellowing in north-eastern Victoria, but Mn toxicity, induced by waterlogging, probably contributes to crop yellowing when waterlogging is severe. Soil acidity did not appear to be high enough to cause Mn toxicity in the absence of waterlogging.

Variation of tolerance to manganese toxicity in Australian hexaploid wheat

“…Waterlogging was identified as a cause of increased soil Mn concentrations in northeastern Victoria (Sparrow and Uren, 1987). Similarly in Western Australia, high to toxic concentrations of Mn were observed in shoot tissues of wheat after waterlogging of an acidic soil (Khabaz-Saberi et al, 2006), giving the first indication of a potential Mn toxicity problem.…”

“…After Al, excess in Mn is the most growth-limiting factor in acid soils worldwide (Manyowa and Miller, 1991). High concentrations of Mn in the soil solution also occur in poorly drained and reduced environments (Sparrow and Uren, 1987) associated with waterlogged soils. Some environmental factors (e.g., high temperature; Marsh et al, 1989) can also increase the availability of Mn and consequently affect crop growth.…”

The Waterlogging Tolerance of Wheat Varieties in Western of Turkey

“…Sparrow and Uren [ 26 ] and Wagatsuma et al [ 27 ] stated that soil Mn concentration that could be toxic to plant growth increased in waterlogging. Similarly, mineral Fe coating of epidermal surface of roots increased under waterlogging [ 28 ].…”

OsMTP11 is localised at the Golgi and contributes to Mn tolerance

“…Thus, symptoms of Mn toxicity may lead to losses in agricultural yield. Mn toxicity represents an important problem in tropical, acidic soils, and under conditions which favour a reducing environment, such as water-logged soils with low redox potential 15 .…”