Does assimilate supply limit leaf expansion in wheat grown in the field under low phosphorus availability?

• Autores: Rodríguez, Daniel; Andrade, Fernando Héctor; Goudriaan, Jan
• Año de publicación: 2000
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Leaf Expansion; Phosphorus; Water-Soluble Carbohydrates; Wheat
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Under conditions of phosphorus deficiency, reductions in plant leaf area have been attributed to both direct effects of phosphorus (P) on the individual leaf expansion rate and a reduced availability of assimilates for leaf growth. Simulation techniques have been used to test the hypothesis of a non-trophic limitation to leaf expansion in wheat grown on P-deficient soils; this study provides further experimental evidence supporting this hypothesis, in a field experiment, we studied the effects of soil P additions (0-200 kg P2O5 ha-1) and assimilate availability (non-shaded and shaded treatments) on the expansion of individual leaves of wheat (Triticum aestivum L. cv. Oasis), light interception and radiation use efficiency. The soil was low in P (5.5 μg P g-1), the crop was drip irrigated and nitrogen was applied at non-limiting rates during the experiment. At 61 days after emergence (DAE), phosphorus deficiency reduced above ground biomass 70 and 61%, leaf area index 73 and 69%, the percent intercepted radiation 63 and 46%, and radiation use efficiency 21 and 31%, in non-shaded and shaded plots, respectively. Leaves of shaded plants had lower %WSC and lower accumulation of structural dry weight than non-shaded ones. In shaded leaves, there was a more important restriction to the accumulation of structural material in high-P than in low-P treatments. This and the fact that leaf expansion rate of individual leaves was negatively related to %WSC led us to conclude that leaf expansion in low P plants is unlikely to be limited by the availability of assimilates.
Fil: Rodríguez, Daniel. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Wageningen Agricultural University. Group of Theoretical Production Ecology. Department of Plant Sciences; Países Bajos
Fil: Andrade, Fernando Héctor. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
Fil: Goudriaan, Jan. Wageningen Agricultural University. Group of Theoretical Production Ecology. Department of Plant Sciences; Países Bajos