The effect of soil- and foliar-applied manganese in preventing the onset of manganese deficiency in Lupinus angustifolius

The efficacy of the application of manganese, either applied to soil or as foliar sprays at three stages of flower development, in preventing the expression of manganese deficiency (ruptured seed coats ('split seed'); delayed maturity ('regreening'); and poor grain yield) in two cultivars of Lupinus angustifolius (cvv. Marri and Illyarrie) was assessed on sandy soils of the upper South East and Eyre Peninsula regions of South Australia. Six experiments were conducted during 1979 and 1980. A single foliar application of manganese (1.7 kg Mn/ha, in 200 litre water) when the upper-lateral shoots were in mid-flower, prevented the onset of the disorder. Applications of manganese to the soil at sowing at rates of up to 11.1 kg Mn/ha were usually less effective. The appearance of 'split-seed' symptoms in mature grain was a more sensitive indicator of manganese deficiency than was grain yield response to manganese fertilization. The degree to which these symptoms appeared increased markedly when the manganese concentration in intact seed became less than 8-10 ¦g/g dry seed, an observation which is consistent with other studies.