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Soil phosphorus supply affects nodulation and N:P ratio in 11 perennial legume seedlings

Pang, J., Tibbett, M. ORCID:, Denton, M. D., Lambers, H., Siddique, K. H. M. and Ryan, M. H. (2011) Soil phosphorus supply affects nodulation and N:P ratio in 11 perennial legume seedlings. Crop and Pasture Science, 62 (11). p. 992. ISSN 1836-0947

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To link to this item DOI: 10.1071/CP11229


Developing new perennial pasture legumes for low-P soils is a priority for Australian Mediterranean agro-ecosystems, where soil P availability is naturally low. As legumes tend to require higher P inputs than non-legumes, the ability of these plants to fix N2 under varying soil P levels must be determined. Therefore, the objective of this study was to investigate the influence of soil P supply on plant N status and nodule formation in 11 perennial legumes, including some novel pasture species. We investigated the effect of applying soil P, ranging from 0 to 384 μg P/g dry soil, on plant N status and nodulation in a glasshouse. Without exogenous P supply, shoot N concentration and N : P ratio were higher than at 6 μg P/g soil. Shoot N concentration and N : P ratio then changed little with further increase in P supply. There was a close positive correlation between the number of nodules and shoot P concentration in 7 of the 11 species. Total nodule dry weight and the percentage of plant dry weight that consisted of nodules increased when P supply increased from 6 to 48 μg P/g. Without exogenous P addition, N : P ratios partitioned into a two-group distribution, with species having a N : P ratio of either >70 or <50 g/g. We suggest that plants with a high N : P ratio may take up N from the soil constitutively, while those with a low N : P ratio may regulate their N uptake in relation to internal P concentration. The flexibility of the novel pasture legumes in this study to adjust their leaf N concentrations under different levels of soil P supplements other published evidence of good growth and high P uptake and P-use efficiency under low soil P supply and suggests their potential as pasture plants in low-P soils in Australian Mediterranean agro-ecosystems warrants further attention.

Item Type:Article
Divisions:Life Sciences > School of Agriculture, Policy and Development > Department of Sustainable Land Management > Centre for Agri-environmental Research (CAER)
ID Code:42860
Publisher:CSIRO Publishing

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