Commensalism in an agroecosystem: hydraulic redistribution by deep-rooted legumes improves survival of a droughted shallow-rooted legume companion

Authors

  • Jiayin Pang,

    Corresponding author
    • School of Plant Biology, The University of Western Australia, Crawley, WA, Australia
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  • Yanmei Wang,

    1. The Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, The Chinese Academy of Sciences, Shijiazhuang, China
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  • Hans Lambers,

    1. School of Plant Biology, The University of Western Australia, Crawley, WA, Australia
    2. The UWA Institute of Agriculture, The University of Western Australia, Crawley, WA, Australia
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  • Hans Lambers,

    1. School of Plant Biology, The University of Western Australia, Crawley, WA, Australia
    2. The UWA Institute of Agriculture, The University of Western Australia, Crawley, WA, Australia
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  • Mark Tibbett,

    1. School of Earth and Environment, The University of Western Australia, Crawley, WA, Australia
    2. National Soil Resources Institute, Department of Environmental Science and Technology, School of Applied Sciences, Cranfield University, Cranfield, UK
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  • Kadambot H. M. Siddique,

    1. The UWA Institute of Agriculture, The University of Western Australia, Crawley, WA, Australia
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  • Megan H. Ryan

    1. School of Plant Biology, The University of Western Australia, Crawley, WA, Australia
    2. The UWA Institute of Agriculture, The University of Western Australia, Crawley, WA, Australia
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Correspondence

Corresponding author,

e-mail: Jiayin.Pang@csiro.au

Abstract

We investigated commensalism of water use among annual shallow-rooted and perennial deep-rooted pasture legumes by examining the effect of hydraulic lift by Cullen pallidum (N.T.Burb.) J.W.Grimes and Medicago sativa on growth, survival and nutrient uptake of Trifolium subterraneum L. A vertically split-root design allowed separate control of soil water in top and bottom soil. Thirty-five days after watering ceased in the top tube, but soil remained at field capacity in the bottom tube, an increase in shallow soil water content by hydraulic lift was 5.6 and 5.9 g kg−1 soil overnight for C. pallidum and M. sativa, respectively. Trifolium subterraneum in this treatment maintained higher leaf water potentials (with M. sativa) or exhibited a slower decline (with C. pallidum) than without companion perennial plants; and shoot biomass of T. subterraneum was 56% (with C. pallidum) and 67% (with M. sativa) of that when both top and bottom tubes were at field capacity. Uptake of rubidium (a potassium analog) and phosphorus by T. subterraneum was not facilitated by hydraulic lift. Interestingly, phosphorus content was threefold greater, and shoot biomass 1.5–3.3-fold greater when T. subterraneum was interplanted with C. pallidum compared with M. sativa, although dry weight of C. pallidum was much greater than that of M. sativa. This study showed that interplanting with deep-rooted perennial legumes has benefited the survival of T. subterraneum.

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