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 Lupi nus 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 Austra lia. Fifteen wild L. angustifolius lines, collected on a variety of so ils that ranged in pH from 4.2 to 9.0, were compared with cultivars of L. angustifolius and known alkaline-tolerant (L. cosentinii) and alka line-sensitive (L. luteus) lupin species. Five-week-old seedlings vari ed greatly in chlorosis on the alkaline soil, from almost no chlorosis (as in L. cosentinii cv Erregulla) to severely chlorotic (L. angustif olius line MJS176 from Spain). No lines were chlorotic after acid amel ioration 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 signifi cant correlation between altitude of collection sites and chlorosis sc ores. Chlorosis-sensitive lines were from higher altitudes, had lower root and shoot fresh weight, were lower in Fe, Mn and K and were highe r in Zn, P, and S in new growth than resistant lines. Chlorosis-sensit ive lines also had the largest increases in fresh weight of roots and shoots in response to soil acidification. Genotypes with better root g rowth and therefore lower chlorosis symptoms on alkaline soil did not necessarily have the strongest root growth on acid ameliorated soil. S oil pH at the collection site in the Mediterranean region was not a re liable predictor of chlorosis in L. angustifolius induced by an alkali ne fine-textured soil in Western Australia, although significant varia tion in tolerance to this soil was found within the species.