Influence of perlite in peat- and coir-based media on vegetative growth and mineral nutrition of highbush blueberry

Authors: KINGSTON, PATRICK - Oregon State University; Scagel, Carolyn; Bryla, David; STRIK, BERNADINE - Oregon State University

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2020
Publication Date: 5/1/2020
Citation: Kingston, P.H., Scagel, C.F., Bryla, D.R., Strik, B.C. 2020. Influence of perlite in peat- and coir-based media on vegetative growth and mineral nutrition of highbush blueberry. HortScience. 55(5):658-663. https://doi.org/10.21273/HORTSCI14640-19.
DOI: https://doi.org/10.21273/HORTSCI14640-19

Interpretive Summary: Peat and coir are commonly used for long-term soilless media production of highbush blueberry (Vaccinium sp.). Unfortunately, these substrates decompose and settle over time and eventually restrict the root volume. The purpose of the present study was to evaluate the benefit of adding perlite to the media. Perlite is an inert substrate often added to soilless media to improve draining and stability. Northern (V. corymbosum L. ‘Liberty’) and southern highbush blueberry (interspecific hybrid of V. corymbosum L. and V. darrowii Camp. ‘Jewel’) were grown for 3 months in media mixtures containing 0% to 30% perlite, by volume, and either 1:0, 2:1, 1:2, or 0:1 ratios of peat and coir. Increasing perlite in the media decreased growth in ‘Jewel’ and dry weight of ‘Liberty’ was greatest in media with = 10% perlite. The response of the plants to perlite did not appear to be function of pH or nutrition and was most likely related to water relations of the media and more peat than coir. Growth‘Liberty’ was greatest in media containing more peat than coir and the growth response to peat and coir, may have been due to nutrition. These findings suggest that peat may be useful for improving blueberry growth and nutrition in soilless media, while use of perlite in the mix should be limited.

Technical Abstract: Peat and coir are commonly used for long-term soilless media production of highbush blueberry (Vaccinium sp.). Unfortunately, these substrates decompose and settle over time and eventually restrict the root volume. The purpose of the present study was to evaluate the benefit of adding perlite to the media. Perlite is an inert substrate often added to soilless media to improve draining and stability. Northern (V. corymbosum L. ‘Liberty’) and southern highbush blueberry (interspecific hybrid of V. corymbosum L. and V. darrowii Camp. ‘Jewel’) were grown for 3 months in media mixtures containing 0% to 30% perlite, by volume, and either 1:0, 2:1, 1:2, or 0:1 ratios of peat and coir. Plants were fertigated daily with a nutrient solution, and drainage was targeted at 25% of the total volume of solution applied. At 95 d after transplanting, increasing perlite in the media decreased total dry weight in ‘Jewel’ and dry weight of ‘Liberty’ was greatest in media with = 10% perlite and more peat than coir. The response of the plants to perlite did not appear to be function of pH or nutrition and was most likely related to water relations of the media. Response to peat and coir, on the other hand, may have been due to nutrition. In both cultivars, more peat in the media improved uptake of N, P, Mg, and S and decreased uptake of K, B, Zn, and Na. Coir, on the other hand, contained higher concentrations of Na and Cl than peat, and blueberry is sensitive to these ions, particularly Na. These findings suggest that peat may be useful for improving blueberry growth and nutrition in soilless media, while use of perlite in the mix should be limited. Our results indicate that media composition can influence growth and nutrition of young blueberry plants and suggest that long-term plant growth in substrate production requires that selection of media components consider differences among cultivars and that fertilizer management be tailored for whether peat or coir is used in the media.