The impact of early cropping on subsequent yield of highbush blueberry.

摘要

The effect of early cropping (no blossom removal the first two years) and in-row spacing at 0.45 m and 1.2 m were studied in 'Duke', 'Bluecrop', and 'Elliott' blueberries (Vaccinium corymbosum L.) grown on raised beds for 4 years. In a separate study, the effect of early cropping on yield of 'Bluecrop' on "flat ground" was studied for 8 years. No yield was produced on the control plants in the planting year (year 1) and the year after planting (year 2). In 'Bluecrop' grown on flat ground, cumulative yield at 0.45 m was 106% higher than at 1.2 m over the 8 years of the study. Early cropping increased cumulative yield by 17% from years 3 through 8 compared to control plants. In a separate study of 'Bluecrop', 'Duke', and 'Elliott', however, plant growth at the start of year 3 was adversely impacted by early cropping. Early cropping reduced the dry weight of the root system, crown, and one-to three-year-old wood in all cultivars. 'Bluecrop' plants had less total dry weight than those of 'Duke' or 'Elliott'. Roots accounted for 30 to 45% of the total plant dry weight depending on cultivar. Early-cropping reduced root system weight 42% compared to control plants. Early-cropped plants had a lower percentage of fruit buds in 'Bluecrop' and 'Duke' than control plants. Early cropping reduced yield in year 3 by 18% in 'Bluecrop', 26% in 'Duke', and 54% in 'Elliott'. Yield of 'Elliott' in year 4 was still affected by early cropping. Cumulative yield (years 1 through 4) was not affected by early cropping in 'Bluecrop' or 'Duke', whereas in 'Elliott', cumulative yield was lower in early-cropped plants. Plants spaced at 0.45 m produced 62% to 140% more yield than those spaced at 1.2 m. 'Elliott' plants seemed less suited to high density planting due to their large total dry weight and large root system..