Photos by Muhammad Nadeem and M.A. Shahid
Four University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) horticulture researchers recently wrote an update in the Cold Hardy Citrus Connection about optimizing citrus nitrogen applications in North Florida. The authors are Muhammad A. Shahid, Davie Kadyampakeni, Shahid Iqbal and Muhammad Nadeem.
The following edited excerpts explain the research project and provide conclusions:
THE RESEARCH
The need for nitrogen optimization in satsuma mandarin cultivation in North Florida is critical due to the region’s unique challenges, such as freeze risk, pests and climate change. Proper nitrogen management is essential for enhancing tree health, maximizing fruit quality and ensuring the economic sustainability of the growing cold-hardy citrus industry, but site-specific and research-based guidelines are currently lacking.
This project aims to fill that gap by identifying the optimal nitrogen application rates and timing for high plant growth and fruit quality. The Florida Department of Agriculture and Consumer Services is providing the funding to support the research.
Four rates (50, 100, 150 and 200 pounds of nitrogen per acre) along with three different timing strategies as seven splits (February–August), five splits (March, May, July, August, September) and three splits (March, June and August) are being evaluated in satsumas.
CONCLUSIONS
While nitrogen application rates and timings did not significantly affect leaf and soil nutrient content or fruit yield across treatments during initial years, they did influence fruit-quality attributes, particularly fruit weight and total soluble solids (TSS). The lack of immediate response to varying nitrogen rates in the early years highlights the importance of multi-year data to accurately establish nitrogen management recommendations for perennial plants like satsuma mandarins.
Preliminary findings suggest that applying 200 pounds per acre of nitrogen in five splits leads to the best fruit weight and TSS development, with the ideal harvest window for satsumas occurring from late October to early November, even though color development may not be fully achieved by that time. However, multi-year data collection on leaves, soil, fruit quality and yield is needed to refine nitrogen management strategies to balance both fruit maturity and marketability.
Source: UF/IFAS
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