Data/hora: 16/06/2024 07:59:24

Biblioteca(s): | Epagri-Sede.
Data corrente: | 21/06/2011
Data da última atualização: | 29/06/2011
Autoria: | LEMAIRE, G.; OOSTEROM, E. V.; SHEEHY, J.; JEUFFROY, M. H.; MASSIGNAM, A. M.; ROSSATO, L.
Afiliação: | Epagri
Título: | Is crop N demand more closely related to dry matter accumulation or leaf area expansion during vegetative growth?
Ano de publicação: | 2007
Fonte/Imprenta: | Field Crops Research, Amsterdam, v. 100, n. 1, p. 91-106, 2007.
Idioma: | Inglês
Notas: | ISSN, 0378-4290
Conteúdo: | The critical crop nitrogen uptake is defined as the minimum nitrogen uptake necessary to achieve maximum biomass accumulation (W). Across a range of crops, the critical N uptake is related to W by a power function with a coefficient less than unity that suggests crop N uptake is co-regulated by both soil N supply and biomass accumulation. However, crop N demand is also often linearly related to the expansion of the leaf area index (LAI) during the vegetative growth period. This suggests that crop N demand could be also linked with LAI extension. In this paper, we develop theory to combine these two concepts within a common framework. The aim of this paper is to determine whether generic relationships between N uptake, biomass accumulation, and LAI expansion could be identified that would be robust across both species and environment types. To that end, we used the framework to analyze data on a range of species, including C3 and C4 ones and mono- and di-cotyledonous crops. All crops were grown in either temperate or tropical and subtropical environments without limitations on N supply. The relationship between N uptake and biomass was more robust, across environment types, than the relationship of LAI with biomass. In general, C3 species had a higher N uptake per unit biomass than C4 species, whereas dicotyledonous species tended to have higher LAI per unit biomass than monocotyledonous ones. Species differences in N uptake per unit biomass were partly associated with differences in LAI and N-partitioning. Consequently the critical leaf-N uptake per unit LAI (specific leaf nitrogen, SLN) was relatively constant across species at 1.8?2.0 g m&#8722;2, a value that was close to published data on the critical SLN of new leaves at the top of the canopy. Our results indicate that critical N uptake curves as a function of biomass accumulation may provide a robust platform for simulating N uptake of a species. However, if crop simulation models are to capture the genotypic and environmental control of crop N dynamics in a physiologically functional manner, plant growth has to be considered as the sum of a metabolic (e.g. leaves) and a structural (e.g. stems) compartment, each with its own demand for metabolic and structural N.
Palavras-Chave: | Biomass accumulation; Critical N-uptake; LAI; Leaf Area Ratio; N-demand; Specific Leaf Nitrogen.
Categoria do assunto: | --
Registro original: | Epagri-Sede (Epagri-Sede)
Exemplares: | Epagri-Sede - (80515-1) - UPC - AP - -- - SEP 1611/06 -  - 2011.01611 - DIS