M.A. GILBERT1, R.K. JONES2 and P.N. JONES3
1Queensland Department of Primary Industries, Brisbane, Queensland, Australia
2Division of Tropical Crops and Pastures, and
3Biometrics Unit, CSIRO, Brisbane, Queensland, Australia
Seven experiments were used to evaluate nutritional screening techniques in terms of their usefulness for rapidly characterising new plant introductions. Characteristics were the ability to grow and nodulate on different soil types, reaction to waterlogging, the response to phosphorus fertiliser, growth on an acid soil of low calcium and phosphorus status, ability to nodulate and grow at various pH and calcium levels, and the reaction to high manganese, aluminium and salinity. Legumes were Leucaena leucocephala cv. Cunningham, Macroptilium lathyroides cv. Murray, M. atropurpureum cv. Siratro, Centrosema schiedianum cv. Belalto, Stylosanthes guianensis cv. Cook, S. hamata cv. Verano, S. hamata CPI 33205, and S. scabra cvv. Seca and Fitzroy. Plants were grown in soil, sand and solution cultures in a glasshouse at Townsville, north Queensland.
Where it was possible to validate the responses of the test species with findings from previous studies, the screening techniques provided a reasonable assessment of the nutritional value of the legumes. The 9 legumes reacted differently (in terms of growth) on the 3 contrasting soils, failed to nodulate effectively on those soils, but responded differently to waterlogging, phosphorus application and high solution levels of manganese and aluminium. Techniques for assessing the plants under acid, low calcium conditions and salinity did not appear to be successful, possibly because the species were tolerant of those conditions.
Murray, Siratro, Belalto, Verano and Fitzroy grew well on all 3 contrasting soils, but the other legumes reacted differently to soil type with added nitrogen fertiliser. The legumes responded differently to phosphorus application on a red earth soil of low phosphorus status, with Cunningham, S. hamata 33205, Seca and Fitzroy giving relatively low yield responses compared to the other legumes. Under waterlogged conditions, Cunningham, Murray, Verano, Seca and Fitzroy performed better than the others. Reactions to conditions of low pH and low calcium status varied between legumes, and with culture conditions. On the yellow earth, growth was generally poor, with Murray, Belalto and Seca being more tolerant of low soil calcium than the other legumes. In sand culture conditions, Belalto alone responded quite markedly to increasing pH and calcium concentration. Elevated salt concentration (1.2 mM NaCl) did not greatly affect any legumes, but additional manganese reduced yield of Siratro only to 61% and high aluminium markedly reduced yields of all legumes except Fitzroy. Results generally agreed well with previous experience with these legumes under field and glasshouse conditions.