Effect of Mounding Height and Mulching Material On Growth and Fruiting of 'duke' Highbush Blueberry Plants

Two experiments were conducted with highbush 'Duke' blueberry plants in Korea to determine the effect of (1) mounding or soil covering and (2) mulching on growth and fruiting. For experiment 1, two-year old trees were transplanted in the field and then mounded with the same field soil at 5, 10, 15 or 20 cm in height, and finally mulched with 15 cm of pine bark (PB). For experiment 2, the two-year old trees transplanted were mulched with either bark, black non-woven fabric (BNWF), black shading screen (BSS) or black PE film (BPEF). The results of the experiment 1 showed that, when determined 3 years after planting, the cumulative number of suckers produced was about 112% higher in the trees receiving 15 cm mounding compared to 5 cm mounding, with 20 cm mounding being less effective than 15 cm. Root to shoot ratio was highest in 15 cm, followed by 20 cm. The number of flower clusters and total yield per tree was 128 and 94% higher in 15 and 20 cm mounding treatments than 5cm mounding, respectively. Mean fruit weight, TSS, acidity and firmness were unaffected by the mounding height. The results of the experiment 2 showed that soil temperature was highest in BPEF while the other mulching treatments had similar temperatures. Soil water content was maintained the highest in BPEF, followed by BNWF, PB and BSS. Determined two years after planting, tree growth was best in BPEF while lowest in BSS. The number of fruit set was similar among PB, BNWF and BPEF, which was significantly higher than BSS. Mean fruit weight and fruit quality were not significantly affected. Yield was similarly higher in PB and BNWF than BPEF and BSS, with BSS showing the lowest yield. Some freezing injury was observed from the current year’s shoots of the trees mulched with BPEF where growth termination was delayed.