Inter - plant competition for resources in maize crops grown under contrasting nitrogen supply and density variability in plant and ear growth
Increased plant population density in irrigated and fertilized maize crops enhances plant-to-plant variability since early vegetative stages, because the most suppressed individuals of the stand intercept less radiation per unit leaf area than the dominant ones [i.e. a size-asymmetric competition fo...
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| Otros Autores: | , |
| Formato: | Artículo |
| Lenguaje: | Inglés |
| Materias: | |
| Acceso en línea: | http://ri.agro.uba.ar/files/intranet/articulo/2011Rossini.pdf LINK AL EDITOR |
| Aporte de: | Registro referencial: Solicitar el recurso aquí |
| Sumario: | Increased plant population density in irrigated and fertilized maize crops enhances plant-to-plant variability since early vegetative stages, because the most suppressed individuals of the stand intercept less radiation per unit leaf area than the dominant ones [i.e. a size-asymmetric competition for light]. Contrarily, a size-symmetric competition has been proposed for the acquisition of soil resources in a plant community [e.g. N capture per unit root length is similar among plants of different size]. Hence, N fertilization effect on the variability of maize plants would depend on the initial plant-to-plant variability or on that promoted by a high plant population density. Two maize hybrids with contrasting tolerance to crowding [tolerant AX820 and intolerant AX877] were cultivated under different combinations of stand densities [6, 9 and 12plantsm-2] and N supplies [0 and 200kgNha-1] without water restrictions. Variability in plant growth rate among plants was computed along the cycle, especially after fertilizer was applied [i.e. the early reproductive period; PGRER] and during the critical period around silking [PGRCP]. Plant-to-plant variability in biomass partitioning to the ear [partition index; PI], ear growth rate during the critical period [EGRCP] and kernel number per plant [KNP] was also established. Reduced N supply increased the coefficient of variation [CV] of PGRER, PGRCP, EGRCP and KNP [0.05 less than P less than 0.10]. The CVs of PGRCP, PI, EGRCP and KNP augmented [0.001 less than P less than 0.10] at the highest stand density. The CVs of PGRER, PGRCP, PI and KNP were larger for hybrid AX877 than for hybrid AX820 [0.001 less than P less than 0.10]. N fertilization smoothed the initial plant-to-plant variability, but the extent of this benefit in a maize crop is genotype dependent; it was much larger in the hybrid tolerant to crowding stress than in the intolerant one. For the latter, the variability held during the critical period around silking and produced a high CV of KNP. |
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| ISSN: | 0378-4290 |