Rhizodeposition and C-partitioning of Lolium perenne in axenic culture affected by nitrogen supply and defoliation

• Published in: Plant and soil Vol. 216; no. 1-2; pp. 155 - 164
• Main Authors: Paterson, E. (Macaulay Land Use Research Inst., Craigiebuckler, Aberdeen (United Kingdom). Plants Group), Sim, A
• Format: Journal Article
• Language: English
• Published: Dordrecht Kluwer Academic Publishers 01.01.1999; Springer; Springer Nature B.V
• Subjects: ABONOS NITROGENADOS; Acid soils; Agricultural soils; Agronomy. Soil science and plant productions; ammonium nitrate; ANATOMIA DE LA PLANTA; ANATOMIE VEGETALE; application rate; Biological and medical sciences; CARBON; CARBONE; CARBONO; DEFOLIACION; DEFOLIATION; Dry matter; dry matter accumulation; ENGRAIS AZOTE; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Grasses; Grasslands; LOLIUM PERENNE; Microcosms; nitrogen; Nitrogen fertilization; NITROGEN FERTILIZERS; Nitrogen, phosphorus, potassium fertilizations; nutrient availability; Nutrient concentrations; Nutrient cycles; nutrient solutions; NUTRIENT TRANSPORT; PLANT ANATOMY; Plant roots; Plants; RACINE; Radiocarbon; RAICES; Rhizodeposition; root exudates; root shoot ratio; root systems; ROOTS; Sand; Soil biochemistry; Soil-plant relationships. Soil fertility. Fertilization. Amendments; TRANSPORT DES SUBSTANCES NUTRITIVES; TRANSPORTE DE NUTRIENTES; Grassland; Productivity; Nitrogen fertilization; Organic matter; Monocotyledones; Axenic culture; Rhizodeposit; Root; Browsing; Bioavailability; Nitrogen; Carbon; Dose activity relation; Carbon cycle; Defoliation; Gramineae; Morphology; Angiospermae; Nutrient; Spermatophyta; Fodder crop; Lolium perenne
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1023/a:1004789407065

This study investigated the effects of N-supply and partial defoliation on C-partitioning, root morphology and soluble rhizodeposition, for Lolium perenne grown in axenic sand culture systems percolated with nutrient solution. Plants were grown for 36 d in nutrient solutions with differing N concentrations (4 mM or 0.02 mM NH₄⁺NO₃⁻), and effects of repeated defoliation to 4 cm were determined. The 'low N' supply reduced (P < 0.05) dry matter accumulation, with proportionately increased partitioning to the root systems. Root morphology was also altered at 'low N', with development of a finer root system, manifest as increased (P < 0.05) specific root length. Concurrent with these effects on growth of L. perenne, 'low N' increased (P < 0.05) exudation of C-compounds from roots on a per g root basis. Defoliation was found to increase exudation (P < 0.05) of soluble compounds for periods of 3-5 d following each cut, at both N-supply rates. The effects of N-supply and defoliation are of importance in understanding the coupling of plant productivity to nutrient cycling in soils with differing N availabilities and for grassland systems which are subject to grazing.