Manganese Nutrition of Lupinus spp. Especially in Relation to Developing Seeds

Patterns of transport and accumulation of manganese were studiedin Lupinus albus L. and Lupinus angustifolius L. in a wide rangeof availability levels in the rooting medium. The recently described‘split seed’ disorder, involving discolouration,splitting, and deformity of seeds, was reproduced in sand cultureusing critically low levels of manganese. The disorder was preventedby maintaining adequate manganese in the medium and its incidencein field and glasshouse was quantitatively related to the managneselevel in seed and fruit phloem sap. The use of phloem sap analysisfor early diagnosis of the disorder is suggested. High levelsof manganese in parent seed is suggested to afford protectionagainst the disorder by improving early vegetative growth ina manganese deficient situation. Direct carry-over of manganesefrom one seed generation to the next was insignificant. Manganese proved to be fully mobile in xylem but only sparinglymobile in phloem from vegetative structures to seed. It wasaccumulated in massive amounts in leaves and fruits when availabilitywas high. Seed manganese content increased 80–100 foldas the level in the rooting medium was increased from 0•1to 500 mg Mn 1^–1. L. albus was superior to L. angustifoliusin accumulating manganese in leaves and pods, and more efficientin translocating the element to its seeds. These differenceswere greatest at low or moderate manganese levels. Xylem intakeby a fruit was small relative to phloem intake when manganeseavailability was low, but became increasingly important as thesupply in the rooting medium was raised.