Modelling net photosynthetic rate of field-grown cocksfoot leaves to account for regrowth duration

• Autores: Peri, Pablo Luis; Moot, Derrick; McNeil, David L.; Lucas, R.J.
• Año de publicación: 2003
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: New Zealand Journal of Agricultural Research 46(2): 105-115 (2003)
• Materia: Photosynthesis; Chlorophylls; Modelling; Morphology; Nitrogen; Regrowth; Stomatal Conductance; Temperature; Water Stress; Fotosíntesis; Clorofila; Dactylis glomerata; Modelización; Morfología; Nitrógeno; Rebrote; Conductancia Estomática; Temperatura; Estrés Hídrico
• Institución: Instituto Nacional de Tecnología Agropecuaria

Maximum light-saturated photosynthetic rate (Pmax) of field-grown cocksfoot (Dactylis glomerata L.) leaves was measured in a temperate, sub-humid environment (Canterbury, New Zealand). The aim was to derive an individual function for P max of newly expanded leaves against regrowth duration when other environmental factors were nonlimiting. The decrease in Pmax with regrowth duration was described by a quadratic function. From 20 to 25 days regrowth, Pmax per unit of leaf was constant and maximal (27.4 µmol CO2 m–2 s–1). It then decreased by 0.42 µmol CO2 m–2 s–1 per day of regrowth. The decline in Pmax was attributed to (i) differences in chronological age of the youngest expanded leaf as shown by changes in tiller morphology over time, and (ii) shading within the canopy during leaf expansion. These factors affected Pmax by decreasing the leaf nitrogen and chlorophyll content, and stomatal conductance. The function for regrowth duration was an additional factor included in a multiplicative model to predict Pmax with different levels of temperature, nitrogen, and water status, expressed as pre-dawn leaf water potential (ylp). The only interaction detected was when water stress increased (ylp < –1.2 bar) and leaves had grown for 40–60 days. In this limited situation, stomatal closure at 40–60 days was greater than expected from the non-limiting condition. The inclusion of this function into a simple multiplicative model enabled 80% of the variation in P max for individual cocksfoot leaves to be explained by their temperature, nitrogen, water, and regrowth status. These functions could then be used to develop a canopy photosynthesis model for the prediction of cocksfoot pasture production.
EEA Santa Cruz
Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina
Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral (UNPA). Santa Cruz; Argentina
Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina
Fil: Moot, Derrick. Lincoln University. Faculty of Agriculture an Life Science. Canterbury; Nueva Zelanda
Fil: McNeil, David L. Lincoln University. Faculty of Agriculture an Life Science. Canterbury; Nueva Zelanda
Fil: Lucas, R. J. Lincoln University. Faculty of Agriculture and Life Science; Nueva Zelanda