Holm oak is an important evergreen tree species in the Mediterranean environment and plays a crucial role in reforestation and ornamental plant production. However, few data are available on nitrogen nutrition of containerised nursery plants. Two greenhouse experiments were carried out to investigate the effect of i) different fertilizer sources and ii) increasing N levels on N uptake, N use efficiency and N partitioning in Holm oak plants. Seven commercial fertilizers were chosen among traditional, organic, organic-mineral, coated and stabilized categories and were supplied at the rate of 1 g N plant-1 which was found to give optimal results in other species under similar growing conditions. Four increasing N levels were compared: 0, 0.5, 1 and 2 g N plant-1. Experiments were carried out simultaneously and lasted 177 days. Relative recovery and agronomic efficiency significantly decreased from 41.5% to 16.1% and from 22.9 to 8 g g-1, respectively, with the increase in N rate. Optimal N demand was met with a total supply of 1 g plant-1. A lower rate (0.5 g) reduced mainly leaf biomass and leaf area development; a further increase (2 g) gave higher N uptakes (+17%) but not significantly higher biomass. Among fertilizer sources, the best results were achieved with the coated products while the traditional (ammonium sulfate), the organic and the organic-mineral fertilizers were less efficient. Plant growth was more affected by different fertilizer sources compared to N uptake, and this caused a wide variation of physiological efficiency values (from 20.7 to 85.8 g g-1). Biomass partitioning was highly responsive to N availability. N fertilization significantly reduced root/shoot ratio. Moderate N stress conditions influenced more leaf growth than leaf N concentration. Under the same N supply, different release times affected mainly biomass partitioning between stem and root tissues.
|Autori:||Stellacci, A.M.;Cristiano, G.;Rubino, P.;De Lucia, B.;Cazzato, E.|
|Data di pubblicazione:||2013|
|Titolo:||Nitrogen uptake, nitrogen partitioning and N-use efficiency of container-grown Holm oak (Quercus ilex L.) under different nitrogen levels and fertilizer sources|
|Rivista:||JOURNAL OF FOOD, AGRICULTURE & ENVIRONMENT|
|Appare nelle tipologie:||1.1 Articolo in rivista|