Influence of belowground nitrogen stocks on light interception and conversion of Miscanthus x giganteus
Résumé
In perennial crops, post-wintering reserves play a key role on regrowth rate and productivity of the crops. The present study aimed at assessing the impact of Miscanthus x giganteus management (harvest date and nitrogen fertilisation) on the subsequent regrowth of the crop via their effects on the nitrogen stocks of belowground organs. The crop growth analysis was conducted by studying radiation use efficiency of the crop and kinetics of leaf area index expansion. Data showed that decreasing nitrogen stocks via early harvest of the crop and no fertilisation had a negative effect on subsequent regrowth. A linear relationship was observed between the leaf area index and the aboveground nitrogen accumulation in the crop, similarly to other crops. The growth rate of the leaf area index depended on the belowground nitrogen stocks before regrowth. A linear relationship followed by a plateau was found between the aerial radiation use efficiency of M. giganteus and the belowground nitrogen stocks before regrowth, as observed in other perennial crops. Finally, it appeared that low nitrogen availability affects more resource conversion than resource capture of M. giganteus. (C) 2013 Elsevier B.V. All rights reserved.