|STRIK, BERNADINE - Oregon State University|
|BANADOS, PILAR - Pontifical Catholic University|
|RIGHETTI, T - University Of Guam|
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/13/2012
Publication Date: 7/1/2012
Citation: Bryla, D.R., Strik, B.C., Banados, P., Righetti, T.L. 2012. Response of highbush blueberry to nitrogen fertilizer during field establishment. II. Plant nutrient requirements in relation to nitrogen fertilizer supply. HortScience. 47(7):917-926.
Interpretive Summary: Nutrient requirements were determined in young highbush blueberry plants. The plants were fertilized with various levels of nitrogen (N) fertilizer each year and excavated and destructively sampled for complete nutrient analysis at key stages of development. Leaf concentration of most nutrients were within or above the range considered normal for blueberry, although leaf N needed for growth was below normal in plants without fertilizer while leaf Boron (B) needed for good fruit development was below normal when the recommended amount of N fertilizer was applied. Plants fertilized with 50 kg per hectare or 56 pounds per acre of N were largest, producing more dry matter than other treatments. Most dry matter accumulated in new shoots, leaves, and roots both years, as well as in fruit at harvest; plant nutrients generally followed the same pattern. Total nutrient requirements are reported. This is the first study to generate a comprehensive nutrient accumulation data set from planting to fruit harvest for establishing highbush blueberries. The information was used to determine nutrient requirements of the young plants, a useful tool for developing efficient fertilizer management practices during the critical stage of field establishment.
Technical Abstract: A study was done to determine the macro- and micronutrient requirements in young northern highbush blueberries. The plants were fertilized with 0, 50, or 100 kg/ha N each year and excavated and sampled periodically for complete nutrient analysis. Leaf concentration of several nutrients including N, P, Ca, S, and Mn increased with N fertilizer application while leaf B concentration decreased. In most cases, the concentration of nutrients was within or above the range considered normal for blueberry. Plants fertilized with 50 kg/ha N were largest, producing 22-32% more dry matter than other treatments the first season and 78- 90% more the second season. Most dry matter accumulated in new shoots, leaves, and roots both years, as well as in fruit the second year. New shoot and leaf dry matter was much higher each year with either amount of N fertilizer, whereas root dry matter was only higher at harvest and only when 50 kg/ha N was applied. Application of 50 kg/ha N also increased dry matter of woody stems by fruit harvest, but neither 50 nor 100 kg/ha N had a significant effect on crown, flower, or fruit dry matter. Depending on treatment, plants lost 16-29% of total biomass during leaf senescence, 3-16% during winter pruning, and 13- 32% at harvest. Most nutrients in the plant followed the same patterns of accumulation and loss as dry matter. However, unlike dry matter, Mg, Fe, and Zn in new shoots and leaves was similar among treatments the first year, and N and S in woody stems was higher whether 50 or 100 kg/ha N was applied. Likewise, N, P, S, and Zn in the crown were higher at times with N fertilizer while K and Ca were sometimes lower. Plants fertilized with 50 kg/ha N were the most productive in terms of growth and required 34.8 kg/ha N, 2.3 kg/ha P, 12.5 kg/ha K, 8.4 kg/ha Ca, 3.8 kg/ha Mg, 5.9 kg/ha S, 295 g/ha Fe, 40 g/ha B, 23 g/ha Cu, 1273 g/ha Mn, and 65 g/ha Zn. Of the total amount of fertilizer applied, only 21, 3, and 9% of N, P, and K, respectively, were used by plants during establishment.