Published online by Cambridge University Press: 27 March 2009
By growing peas in water cultures with carefully regulated amounts of manganese, the effects of a deficiency of this element have been studied.
Complete absence of manganese produces a mottling of the younger leaves and death of the growing tip as previously reported. The plant does not reach the flowering stage.
Small amounts of manganese, insufficient for normal requirements, enable increased growth and seed formation. The seeds show marsh spot lesions, the severity of the lesions being greater at the lower manganese concentrations.
Normal growth and sound seed are produced when sufficient manganese is present in the nutrient solution.
Marsh spot results from a partial deficiency of manganese, the amount available to the plant being sufficient for its normal vegetative requirements but not for healthy seed production.