Comparative performance of Lupinus albus genotypes in response to soil alkalinity

Abstract

Narrow-leafed lupin (Lupinus angustifolius L.) grows poorly on alkaline soils, whereas white lupin (Lupinus albus L.) grows relatively well. This study aimed at examining genotypic variations of white lupins grown in limed acid and alkaline soils in the glasshouse and to test whether the glasshouse findings correlated with those observed in the field.

Twelve white lupin genotypes were tested for their tolerance of limed and alkaline soils in the glasshouse. In limed soils compared with the control soil, genotypic variation in shoot growth ranged from 58 to 80%, root weight from 49 to 72%, and leaf chlorophyll concentration from 47 to 96%. In the alkaline soil, shoot weight ranged from 75 to 110%, root weight from 39 to 63%, and chlorophyll concentration from 58 to 94% of the control. However, iron chlorosis did not negatively correlate with shoot growth of the genotypes on the limed or alkaline soils. The results suggest that iron chlorosis may not be used as a sole indicator for selecting tolerant albus lupins for alkaline soils. Nineteen lines including those used in the glasshouse were compared in the field for their ability to grow on an alkaline clay. Large genotypic variation in early shoot growth was also found; shoot weight on the alkaline soil relative to an acid soil ranged from 38 to 85%. However, growth performance of the white lupin genotypes in response to the alkaline soil did not correlate with those in the glasshouse, indicating that factors other than soil alkalinity might also be important for the growth of albus lupin. Screening techniques to identify tolerant genotypes for alkaline soils need to be further developed.