DAR ES SALAAM, Sept. 28 -- A CRATE of fresh vegetables or flowers may begin its journey on a farm in one corner of Eastern Africa, but getting it to a buyer in another country or on the global market involves a chain far more complicated than planting, harvesting and packing.

Behind every shipment are roads and border posts, cold rooms and warehouses, customs systems, quality standards, digital platforms, cargo operators and, increasingly, questions about climate resilience and the environmental cost of moving produce across long distances.

When one link in that chain is weak, the consequences travel back to the farm. Produce can lose value, exporters can face higher costs and smallholder farmers can find themselves further removed from...