Tolerances of lupin species and genotypes to acid soil and coal mine spoil

Abstract

Twenty‐five genotypes of white lupin (Lupinus alhus L.), 20 of yellow lupin (Lupinus luteus L.) and 20 of narrow leafed lupin (Lupinus angustifolius L.) were grown in greenhouse pots of an acid, Al‐toxic Tatum subsoil (clayey, mixed, thermic Hapludult) and a coal mine spoil with and without lime treatments. On the Tatum subsoil at pH 4.7 [72% aluminum (Al) saturation], entries of all three species grew well and showed little response to lime at pH 5.9. Kiev mutant, a white lupin, was green at pH 4.7 and 5.9, but several other white lupin entries showed a mottled chlorosis at both pH levels. Yellow and narrow leafed entries were green at pH 4.7 and 5.9. On the Tatum subsoil at pH 4.3, white lupins showed a range of chlorosis, with PI 316279 and PI 316276 being most resistant and Chilton least resistant. All yellow entries were chlorotic at pH 4.3. Liming the Tatum subsoil to pH 7.3 reduced or prevented chlorosis, but had little effect on vegetative growth. Based on relative shoot dry weight (wt at pH 4.3/wt at pH 7.3 × 100), yellow lupins (despite susceptibility to chlorosis) appeared somewhat more tolerant to the Tatum subsoil at pH 4.3 than white or narrow leafed entries. By this criterion, PI 316276 was most tolerant and PI 289161 least tolerant to the acid soil. At pH 4.1 on the Tatum subsoil, the white lupin PI 251559 was green, but other white entries showed necrosis and distortion of young leaves. Yellow lupin genotypes were green at pH 4.1. Liming to pH 5.5 prevented chlorosis and generally increased growth. At pH 4.0 on mine spoil, two white lupins (Kiev mutant and PI 287241) were green and vigorous, but two yellow entries (PI 289168 and PI 414208) were chlorotic. Two narrow leafed entries (SN LL‐87 and Yorrel) were more resistant to chlorosis than those of yellow lupin. Liming the mine spoil to pH 5.5 prevented chlorosis. Preliminary evidence indicated that susceptibility of yellow lupins to chlorosis on acid mine spoil was due to the interference in iron (Fe) metabolism by other mineral elements [Al, manganese (Mn), calcium (Ca), phosphorus (P), zinc (Zn), copper (Cu), and nickel (Ni)] and not to reduced Fe uptake.