ASSOCIATION BETWEEN COLLECTION SITE SOIL-PH AND CHLOROSIS IN LUPINUS-ANGUSTIFOLIUS INDUCED BY A FINE-TEXTURED, ALKALINE SOIL

Collection site soil pH may be a useful predictor of tolerance in Lupinus angustifolius to chlorosis induced by alkaline soils. We examined a range of genotypes from the Mediterranean region for their tolerance of an alkaline sandy clay loam (pH 8.8) from Merredin, Western Australia. Fifteen wild L. angustifolius lines, collected on a variety of soils that ranged in pH from 4.2 to 9.0, were compared with cultivars of L. angustifolius and known alkaline-tolerant (L. cosentinii) and alkaline-sensitive (L. luteus) lupin species. Five-week-old seedlings varied greatly in chlorosis on the alkaline soil, from almost no chlorosis (as in L. cosentinii cv Erregulla) to severely chlorotic (L. angustifolius line MJS176 from Spain). No lines were chlorotic after acid amelioration of the soil. Chlorosis score in wild L. angustifolius was not significantly correlated with soil pH at the collection site and was not associated with a particular soil texture, but there was a significant correlation between altitude of collection sites and chlorosis scores. Chlorosis-sensitive lines were from higher altitudes, had lower root and shoot fresh weight, were lower in Fe, Mn and K and were higher in Zn, P, and S in new growth than resistant lines. Chlorosis-sensitive lines also had the largest increases in fresh weight of roots and shoots in response to soil acidification. Genotypes with better root growth and therefore lower chlorosis symptoms on alkaline soil did not necessarily have the strongest root growth on acid ameliorated soil. Soil pH at the collection site in the Mediterranean region was not a reliable predictor of chlorosis in L. angustifolius induced by an alkaline fine-textured soil in Western Australia, although significant variation in tolerance to this soil was found within the species.