The influence of temperature on the accumulation and distribution of manganese in two cultivars of soybean (Glycine max [L.] Merr.)

Abstract

Accumulation and distribution of manganese in soybeans (Glycine max [L.] Merr. cvv. Lee and Bragg) grown over a range of manganese concentrations from 0 to 275 8m in solution culture were studied at four day-night temperatures ranging from 20-15¦C to 33-28¦C in growth cabinets. High levels of solution manganese (275 8m ) produced symptoms of manganese toxicity and reduced yields of both varieties with the symptoms and yield reductions being more severe on Bragg than Lee. Increasing the day-night temperatures from 20-15¦C to 33-28¦C increased the ability of both cultivars to tolerate high concentrations of manganese in solution but there was no indication of any effect of temperature on the differential tolerance of the two cultivars. At high managanese concentrations in solution, high temperatures increased the rate of absorption by roots and total plant uptake of manganese, but there was no effect on the concentration of manganese in the plant tops. Total leaf concentration increased markedly while stem concentration were reduced at high temperatures. Young leaves contained lower concentrations of manganese than older leaves at all temperatures. While the concentration of manganese in the youngest expanding leaf decreased slightly as temperatures were raised from 20-15¦C to 28-25¦C, there was no significant difference in concentrations at 20-15¦C and 33-28¦C. These results suggest that the increased tolerance of soybeans to high manganese supply was not due to growth dilution in young tissues.