1. Brouwer, R. and Kleinendorst, A. 1965 Effect of root excision on growth phenomena in perennial ryegrass. Meded. Jaarboek I.B.S.280, 11–20.
2. Hansen, G. K. and Jensen, C. R. 1977 Growth and maintenance respiration in whole plants, tops and roots ofLolium multiflorum. Physiol. Plant39, 155–164.
3. Lundegardh, H. 1949 Quantitative relations between respiration and salt absorption. Ann. Roy. agric. Coll. Sweden16, 372–403.
4. Penning de Vries, F. W. T. 1974 Substrate utilization and respiration in relation to growth and maintenance in higher plants. Neth. J. agric. Sci.22, 40–44.
5. Veen, B. W. 1977 The uptake of potassium, nitrate, water and oxygen by a maize root system in relation to its size. J. exp. Bot.28, 1389–1398.