Response of some species of Aeschynomene to application of phosphorus in Eastern Highlands Province, Papua New Guinea

Abstract

A glasshouse experiment was conducted at Menifo Sheep Research Centre (1,405 masl) for a period of 28 weeks commencing in July 1996 to determine the responses of two cultivars of Aeschynomene americana, cv. Lee and cv. Glen, and two other species, A. vilosa (CPI 93621) and A. brasilliana (CPI 92519) to application of phosphorus. Both fertiliser treatments and genotypic differences had an effect on leaf dry-matter yield. Application of phosphorus significantly improved (P<0.01) the relative leaf dry matter yield by 32-47% and A. villosa (S3) produced a significantly higher (P<0.05) leaf dry-matter yield. There was no effect of phosphorus on stem dry-matter yield but between genotypes, A. americana, cv. Lee and A. villosa had significantly higher (P<0.05) stem dry-matter yield. Phosphorus had a significant effect (P<0.05) on root growth. Phosphorus also significantly improved (P<0.05) relative dry-matter yield in all genotypes by 40.52%. Leaf/stem and shoot/root ratios were not sensitive to application of phosphorus. A. brasilliana had a significantly high (P<0.05) leaf/stem ratio compared to A. americana, cv. Lee, cv. Glen and A. villosa. Conversely A. villosa had a significantly higher (P<0.001) shoot/root ratio followed by A. americana, cv. Lee while difference between A. americana cv. Glen and A. brasilliana was small. In terms of forage quality, A. brasilliana was more efficient on these soils. This study showed that phosphorous efficient species are valuable in reducing fertiliser requirements and can improve the returns obtained from application of moderate fertiliser.