Optimal nitrogen fertilizer application rates for second-generation cranberry hybrids

Nitrogen (N) is the most important element in cranberry (Vaccinium marcrocarpon Ait.) production due to its impact on both vegetative growth and fruiting.
However, N is also naturally deficient in acidic peatland soils, which require N fertilizer additions for commercial production of cranberry.
Nitrogen fertilizer rates have been previously determined for native cultivars and first-generation hybrids, but field data to support N fertilizer recommendations for second-generation hybrids are lacking.
To fill this gap, we conducted a replicated field experiment to develop N rate response curves for native, first- and second-generation hybrids, and to evaluate the effect on yield and fruit rot as influenced by N fertilizer rate on native and hybrid cultivars.
We tested the most common type of native cultivar ‘Howes’, first-generation hybrid ‘Stevens’, and second-generation hybrids ‘Crimson Queen’, ‘Demoranville’ and ‘Mullica Queen’ cultivars planted in Massachusetts cranberry bogs.
Our results showed that fruit yield was highest at the N fertilizer application rate of 112 kg N ha^-1 for second-generation hybrids, 84 kg N ha^-1 for first-generation hybrids, and up to 56 kg N ha^-1 for native cultivars.
Vegetative biomass increased linearly with N rate regardless of cultivar.
Nitrogen fertilizer rates greater than 112 kg N ha^-1 resulted in overly vigorous vegetative growth that diminished fruit production.
Fruit rot generally increased with N fertilizer application rate, with up to 40% fruit rot observed in ‘Crimson Queen’ at the highest N fertilizer rate of 224 kg N ha^-1. The results would suggest that for optimal fruit yield, N fertilizer recommendations for first-generation hybrids are inadequate for second-generation hybrids.

XII International Vaccinium Symposium

P. Jeranyama, G. Mupambi, C. Kennedy

cranberry, Vaccinium macrocarpon Ait., fertilizer nitrogen, fruit rot

https://doi.org/10.17660/ActaHortic.2023.1357.2