Prospects for more phosphorus efficient subterranean clover

Rebecca E. Haling1, Lawrie K. Brown2, Adam Stefanski1, Daniel R. Kidd3, Megan H. Ryan3, Graeme A. Sandral4, Phillip G.H. Nichols3,5, Timothy S. George2, Hans Lambers3, Richard J. Simpson1

1 CSIRO Agriculture, GPO Box 1700, Acton, ACT, 2601. rebecca.haling@csiro.au

2 The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK.

3 The University of Western Australia, School of Plant Biology & Institute of Agriculture, Crawley, WA, 6009.

4 Department of Primary Industries, Wagga Wagga Agricultural Institute, Pine Gully Road, Wagga Wagga, NSW, 2650.

5 Department of Agriculture and Food Western Australia, 3 Baron-Hay Court, South Perth, WA, 6151.

Abstract

Subterranean clover has a requirement for relatively high soil P fertility to achieve high yields. However, some other pasture legumes can yield as well as subterranean clover with less applied P as a consequence of having roots that can explore soil more effectively. The aim of this work was: (i) to determine whether there is variation in yield among cultivars of subterranean clover when grown in low-P soil, and (ii) to determine the root morphology traits underpinning this variation. Thirty cultivars of subterranean clover were grown at an intermediate and high level of soil P availability in a pot experiment. The cultivars had similar shoot yields in the high-P soil, but varied two-fold in shoot yield at the intermediate level of P supply. In a further experiment, the root morphology acclimation of five of these cultivars was assessed in response to seven rates of soil P availability. Cultivars that had a combination of high root length density and high specific root length were able to maintain higher soil exploration at lower concentrations of available P. They acquired more P from low-P soil and yielded better than the cultivars with roots poorer at nutrient foraging. The results indicate that there is significant intra-specific variation in P-acquisition efficiency among subterranean clover cultivars and this is potentially useful for improving pasture yields in marginally P-deficient soils.

Host

The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

Photo Credits

David Marland Photography david_marland@hotmail.com Southern Farming Systems Agriculture Victoria

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