A METHOD TO IDENTIFY LUPIN SPECIES TOLERANT OF ALKALINE SOILS

Narrow-leafed lupins (Lupinus angustifolius L.) grow poorly on alkalin e soils. In contrast, L. pilosus Murr. and L. atlanticus Glad. grow we ll on such soils. This study aimed to develop a solution culture metho d to screen lupin species for their ability to grow well on alkaline s oils. Sixteen lupin genotypes from 6 species, including introduced cul tivars and wild types, were grown in high pH solutions with varying co ncentrations of buffers and bicarbonate. Relative taproot elongation, shoot growth and iron chlorosis were compared with iron chlorosis, rel ative shoot growth and seed yield for the same genotypes on an alkalin e soil in the field. The results suggested that root elongation rate a t pH 7 in solution buffered with a mixture of 1 mmol MES/L and 1 mmol TES/L (plus 10 mmol CaCl2/L), and shoot weight at 5 mmol bicarbonate/L at pH 8.7 are good indicators of tolerance to an alkaline soil among the lupin species.