INTERACTION EFFECTS OF SOLUTION PH AND CALCIUM-CONCENTRATION ON LUPIN(LUPINUS-ANGUSTIFOLIUS L) GROWTH

The effects of sand solution calcium (Ca) concentration and pH on the growth of narrow-leafed lupin (Lupinus angustifolius L.) were examined in an attempt to assess the relative importance of these two soil fac tors. Two pH (6.5, 8.5) and three Ca concentration treatments (0.625, 6.25, 16.25 mM) were applied by growing lupin in columns of sand which were flushed regularly with otherwise complete nutrient solutions. Ro ot and shoot weights 63 days after sowing were reduced by both increas ing pH and increasing Ca concentration. The pH x Ca interaction effect on shoot weight suggested increasing Ca played an important role (whi ch was greatest at pH 6.5) in reducing lupin growth. It was unlikely t hat growth was reduced by either disrupted iron (Fe) nutrition or poor nodulation of the lupins.