SEED MANGANESE AFFECTS THE EARLY GROWTH OF LUPINS IN MANGANESE-DEFICIENT CONDITIONS

Poor crop establishment and split seed associated with manganese (Mn) deficiency are major problems in the production of narrow-leafed lupins (Lupinus angustifolius L.) in Western Australia. A survey of Western Australian seed producers indicated that Mn concentrations in lupin seeds ranged from 8 to 62 mg kg(-1), with the majority of the seed containing less than 20 mg kg(-1). We studied seedling growth of lupins (cultivars Gungurru and Danja) in nutrient solution, from seed with Mn concentrations ranging from 8 (Seed(8)) to 223 (Seed(223)) mg kg(-1). Without added Mn, the final weight of plants grown from Seed(8) was 39% for shoots and 30% for roots, compared to maximum growth (Seed(62)). With adequate external Mn supply, there was no effect of seed Mn on growth of plants grown from undamaged seedlings. Shoot weight of Gungurru lupins 42 days after imbibing increased with increasing seed Mn concentration up to about 55 mg kg(-1) when grown without added Mn. Growth of Danja plants increased similarly with increasing seed Mn concentration.