Estimation of nitrogen uptake dynamics in banana with two simple indicators of biomass
Introduction – Banana cropping systems in the French West Indies are tending towards low nitrogen (N) input cropping systems. This implies efficient N management by monitoring N uptake in the plant to ensure that N resources are sufficient to match with crop N requirements. Biomass drives N uptake in plant, so biomass can be considered as an indicator of N uptake. But determining biomass in banana is tedious and disruptive to the cropping system. Materials and methods – The ability of five relationships to estimate banana biomass at vegetative and reproductive stages was investigated by using only two indicators: basal girth and fruit diameter. Then, these relationships were used to estimate the N uptake of banana plants at different phenological stages during two successive crop cycles. Results and discussion – Basal girth proved a good indicator for i) estimating banana biomass at the vegetative stage (RRMSE=0.29) and ii) fruit number (RRMSE=0.09). The increase in biomass at the reproductive stage resulted from the bunch development, whose biomass was explained by the fruit number and the fruit weight (R²=0.86). Fruit weight is accurately predicted with fruit diameter (RRMSE=0.13). Regression analysis confirmed the allometric relationship between banana biomass and nitrogen content. These relationships allowed a good prediction of nitrogen uptake during two crop cycles (RRMSE=0.14). Conclusion – Use of only two easily measured, non-destructive and inexpensive indicators could be key elements in the management of N fertilization in banana plantations. The relationships developed in this study could be derived and coupled with crop simulation models to investigate consequences of new N fertilization practices on N bioavailability in banana cropping systems.
| Summary: | Introduction – Banana cropping systems in the French West Indies are tending towards low nitrogen (N) input cropping systems. This implies efficient N management by monitoring N uptake in the plant to ensure that N resources are sufficient to match with crop N requirements. Biomass drives N uptake in plant, so biomass can be considered as an indicator of N uptake. But determining biomass in banana is tedious and disruptive to the cropping system. Materials and methods – The ability of five relationships to estimate banana biomass at vegetative and reproductive stages was investigated by using only two indicators: basal girth and fruit diameter. Then, these relationships were used to estimate the N uptake of banana plants at different phenological stages during two successive crop cycles. Results and discussion – Basal girth proved a good indicator for i) estimating banana biomass at the vegetative stage (RRMSE=0.29) and ii) fruit number (RRMSE=0.09). The increase in biomass at the reproductive stage resulted from the bunch development, whose biomass was explained by the fruit number and the fruit weight (R²=0.86). Fruit weight is accurately predicted with fruit diameter (RRMSE=0.13). Regression analysis confirmed the allometric relationship between banana biomass and nitrogen content. These relationships allowed a good prediction of nitrogen uptake during two crop cycles (RRMSE=0.14). Conclusion – Use of only two easily measured, non-destructive and inexpensive indicators could be key elements in the management of N fertilization in banana plantations. The relationships developed in this study could be derived and coupled with crop simulation models to investigate consequences of new N fertilization practices on N bioavailability in banana cropping systems. |
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