Effect of shading on growth and protective enzymes activities of north highbush blueberry

ObjectiveThe effects of shading on growth and protective enzymes of north highbush blueberry were ana-lysed, in order to provide references for promoting flower bud formation and improving yield. MethodSpartan, Jersey and Berkeley used as testing materials were shaded with commercially available sunshade net of 70%(light transmittance of 30%), with natural sunlight as control(CK). Then the characteristics of 1-year-old shoots were determined, including length and diameter, flower-bud number per shoot, longitudinal diameter and horizontal diameter of flower-bud and per-oxidase(POD), catalase(CAT), polyphenol oxidase(PPO) and ascorbic acid oxidase(ASP) activity. ResultUnder shad-ing conditions of 30 days, the longitudinal diameters of Spartan, Jersey and Berkeley were 14.73%, 25.42% and 33.20%thicker than those of control, respectively, their horizontal diameters were 38.34%, 37.72%and 44.94%thicker than those of control, respectively, their POD activities were increased by 53.23%, 43.02%and 44.88%, respectively, their PPO ac-tivities were increased by 64.00%, 33.33% and 116.22% compared with those of control, respectively, so their POD and PPO activities were extremely significantly higher than those of control(P<0.01, the same below). The flower-bud numbers per shoot for Spartan and Berkeley were 26.77%and 42.13%higher than those of control, respectively, with extremely sig-nificant differences. And the flower-bud number per shoot and CAT activity for Jersey were increased by 23.60% and 22.94%compared with those of control, with significant differences (P<0.05, the same below), the ASP activity for Berkeley were increased by 33.33%compared with those of control, with significant difference. There were non-significant differences in the one-year-old shoot length and diameter of three blueberry varieties (P>0.05). ConclusionWhen cultivating north highbush blueberry in greenhouse at Liaodong peninsul, using 70%shade net in late September for 30 days can effectively improve quantity and quality of flower-buds.