Articles
Applying nitrate in addition to ammonium nitrogen fertilizer increases flowering and fruit production in ‘Ventura’ southern highbush blueberry
Article number
1440_66
Pages
483 – 488
Language
English
Abstract
In Peru, many growers are using fertilizers containing both the ammonium (NH4) and nitrate-(NO3) forms of nitrogen (N) to fertigate highbush blueberry (Vaccinium sp.). While the plants lack sufficient nitrate reductase activity to utilize NO3, these growers are using it because they feel that NO3 helps with synergistic absorption of cations, such as potassium (K), which is essential for enzyme activation, protein synthesis, photosynthesis, osmoregulation, and transport of sugars from leaves to fruit.
Since there is little evidence for this in the literature, we conducted a study to examine the effects of using a mix of NH4 and NO3 in ‘Ventura’ southern highbush blueberry.
The study was located at a commercial farm in the District of Chancay, Province of Huaral, Lima.
Treatments were initiated in March 2023 and included nutrient solutions containing phosphorus (P), K and N from either 100% NH4 or a mix of 70% NH4 and 30% NO3. To stimulate fruit bud development and bloom, the formula was changed in May 2023 to solutions with more K and a mix of 30% NH4 and 70% NO3 in the latter treatment.
This second formula was applied until the end of July, at which point, the formula was changed to solutions with a high proportion of N and K for fruit growth and 50% NH4 and 50% NO3 in the mixed N treatment.
During the first year of harvest, the mix of NH4 and NO3 accelerated fruit ripening by several weeks and increased yield and berry size relative to fertilizing with NH4 only.
It also increased the concentration of magnesium (Mg) in the leaves but had no effect on their concentrations of N (NH4, NO3, or total), K, or calcium (Ca). Thus, partial substitution of NH4 by NO3 appears to be an effective means of increasing production in ‘Ventura’ blueberry.
Since there is little evidence for this in the literature, we conducted a study to examine the effects of using a mix of NH4 and NO3 in ‘Ventura’ southern highbush blueberry.
The study was located at a commercial farm in the District of Chancay, Province of Huaral, Lima.
Treatments were initiated in March 2023 and included nutrient solutions containing phosphorus (P), K and N from either 100% NH4 or a mix of 70% NH4 and 30% NO3. To stimulate fruit bud development and bloom, the formula was changed in May 2023 to solutions with more K and a mix of 30% NH4 and 70% NO3 in the latter treatment.
This second formula was applied until the end of July, at which point, the formula was changed to solutions with a high proportion of N and K for fruit growth and 50% NH4 and 50% NO3 in the mixed N treatment.
During the first year of harvest, the mix of NH4 and NO3 accelerated fruit ripening by several weeks and increased yield and berry size relative to fertilizing with NH4 only.
It also increased the concentration of magnesium (Mg) in the leaves but had no effect on their concentrations of N (NH4, NO3, or total), K, or calcium (Ca). Thus, partial substitution of NH4 by NO3 appears to be an effective means of increasing production in ‘Ventura’ blueberry.
Publication
Authors
M.A. Valdivia-Huaman, D.P. Leon-Chang, D.R. Bryla
Keywords
fruit quality, mineral nutrition, shoot development, Vaccinium sp., yield
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