Effects of Cultivar and Plant Spacing on the Seasonal Water Requirements of Highbush Blueberry

Abstract

<jats:p>Plant water requirements were investigated in three northern highbush blueberry (<jats:italic>Vaccinium corymbosum</jats:italic> L.) cultivars, Duke, Bluecrop, and Elliott, grown either at a high-density spacing of 0.45 m apart within rows or a more traditional spacing of 1.2 m. Spacing between rows was 3.0 m. As is typical for the species, each cultivar was shallow-rooted with most roots located less than 0.4 m deep, and each was sensitive to soil water deficits with plant water potentials declining as low as −1.6 MPa within 5 to 7 days without rain or irrigation. Compared with traditional spacing, planting at high density significantly reduced dry weight and yield of individual plants but significantly increased total dry weight and yield per hectare. High-density planting also significantly increased total canopy cover and water use per hectare. However, although canopy cover (often considered a factor in water use) increased up to 246%, water use never increased more than 10%. Because of more canopy cover at high density, less water penetrated the canopy during rain or irrigation (by overhead sprinklers), reducing both soil water availability and plant water potential in each cultivar and potentially reducing water use. Among cultivars, water use was highest in ‘Duke’, which used 5 to 10 mm·d<jats:sup>−1</jats:sup>, and lowest in ‘Elliott’, which used 3 to 5 mm·d<jats:sup>−1</jats:sup>. Peak water use in each cultivar was during fruit development, but water use after harvest declined sharply. Longer irrigation sets (i.e., longer run times) or alternative irrigation methods (e.g., drip) may be required when growing blueberry at high density, especially in cultivars with dense canopies such as ‘Elliott’.</jats:p>

Number of drip laterals and irrigation frequency on yield and exportable fruit size of highbush blueberry grown in a sandy soil

“…Total fruit production was also higher in 2009-2010 than in 2008-2009 (Table 2), but in each year it ranged within average production in commercial orchards as well as production reported in other research (Holzapfel et al, 2004;Bryla and Strik, 2007;Bryla et al, 2009). Considering that the pruning was done with the same crew each season and following a standard procedure, and on the basis of previous results, it is possible to infer that the increase in production during the second season can be attributed to the increase in water supply between one season and the next, caused by higher precipitation during the 2009-2010 season.…”

“…Soil water content was also lower at depths of 0.3-0.4 m and 0.6 m, when plants were irrigated with four or six laterals per row four days per week, than with the other treatments. However, soil water content varied, on average, between field capacity and permanent wilting point at depths of 0.1-0.4 m, where most blueberry roots are concentrated (Bryla and Strik, 2007). Similar behavior in soil water content was observed for the treatments in 2009-2010 (data not shown).…”

“…Over-irrigation decreases the amount of oxygen available for plants in the root zone, diminishing root growth and nutrient absorption (Bryla et al, 2011). In addition, Bryla and Strik (2007) determined that 'Duke', 'Bluecrop', and 'Elliot' blueberry root density is greater in the first 0.25 m of depth in plants spaced both 0.45 m and 1.2 m apart within the row, which allows us to infer that the root zone is where water should be applied. The results indicated above may have resulted from improved distribution of the water applied to the root zone.…”

“…Irrigation is critical to highbush blueberry because plants are shallow-rooted and fruit production is reduced by even moderate levels of water stress (Bryla and Strik, 2007;Mingeau et al, 2001). Most blueberry orchards in Chile, which currently comprise over 8000 ha, are irrigated by microjet or drip.…”

Fluorescence phenotyping in blueberry breeding for genotype selection under drought conditions, with or without heat stress

“…Blueberries have a fine, fibrous root system without root hairs (Eck, 1988;Eck and Childers, 1966). Hairless roots are concentrated (almost 80%) in the first 30 cm of soil (Bryla and Strik, 2007), which means that any water deficiency will rapidly impact on the plant which is likely to quickly show signs of hydric stress. The symptoms of such stress appear after a week or more, by which time the damage is irreversible.…”