Effects Of Root Restriction On Growth And Development Of Blueberry

Blueberry(Ericaceae, Vaccinium L.) was known as cowberry and blue berries. Blueberry has high medical and economic value. Researches of root restriction on grape, apple, orange, cherry, wax apple, mango and persimmon have been reported. Almost all the studies have affirmed the root restriction to control the vegetative growth, promote flowering and improve fruit quality has good effect. Study of root restriction on blueberry was few reported. Study the blueberry varieties "Northland" as the research material compare the effect of root restriction under the different restricted depth and width to elect the most appropriate limited degree of blueberry, and to study the effect of root restriction on crown, leaf, root, reproductive growth and soil ecology of blueberry. The main results are as follows:(1) The most appropriate restricted root depth and width of blueberry root restriction is 30 cm and 40 cm.(2) Root restriction can significantly promote the growth of plant height first year, but inhibit the plant height the third year. The plant height was shorter 9.7cm than the control. East-West and North-South crown diameter were significantly lower than the control, respectively, compared with the control of small 7.2 cm and 7.4 cm. The total numbers of branches of root restriction were 23.14% higher than the control, 3.60% increase in the proportion of short branches than control. New shoots length of root restriction is 19.1 cm, 19.7 percent lower than the control.(3) Leaf area of root restriction blueberry is reduced, only 82.96% of leaf area of the control. The proportion of dry matter of root cultivation leaf decreased, 90.26% for the control. Blueberry of root restriction leaf chla content was 91.26% of the control. The chlb was 76.71% of the control. The total chlorophyⅡ was 84.70% of the control. Chla was significantly less than the control, chlb and total chlorophyⅡ content was significantly lower than the control. Pn, Gs, Tr and Ls of root restriction blueberry leaf were lower than the control.(4) Root restriction affect vertical distribution, moved on root distribution. The distribution is more concentrated than the control, especially in the distribution of grade Ⅳ roots. Ⅳlevel roots of control mainly were in 0~20 cm, while root restriction were in 10~20 cm; Root restriction affected the root level of the distribution, mainly the distribution of Ⅲ and Ⅳclass roots, so that the twostage roots mainly in the 10~20 cm, which is the roots of the control group two levels a more uniform distribution of 0~30 cm. Root restriction affected the root system composition, a significant increase in the proportion of grade Ⅲ and Ⅳroots, which were increased by 2.64% and 4.13% than the control. The total biomass of root restriction was significantly lower than the control. The dry weight is 96.75% of the control. Root restriction significantly improved the plant shoot ratio, an increase of 0.39 compared with the control.(5) The proportion of bud grafting and the number of flower buds significantly improved by 14.4% and 37.9% respectively higher than the control. Root restriction significantly increased single fruit weight and soluble solid content, which are 1.23 times and 1.53 times of the control. Root restriction significantly reduced the organic content of blueberry fruit, which is 92.57% of the control. fruit diameter, longitudinal diameter, fruit shape index and p H value of root restriction cultivated blueberry were no significant difference with the control.(6) On the sixth day of irrigation, soil moisture of root restriction is 43.70%, 11.33% higher than the control. Different soil temperature of root restriction was in the same trends with the control. Upper soil influenced by the temperature, the lower the soil temperature is stable. New shoots growth period of blueberry, soil temperature of root restriction with soil depth 5cm, 10 cm and 20 cm were significantly lower than the control. Soil temperature of root restriction with soil depth 15 cm and 25 cm had no significant difference. New shoots growth period, the minimum temperature and maximum soil temperature of root restriction is always less than the control. At blueberry leaf fall period, soil temperature at 15 cm soil depth limit root significantly higher than the control. Root restriction treatment various soil p H were less than the controls’. At 10 cm, 15 cm and 20 cm soil layer, p H values were 0.63, 0.65 and 0.55 p H lower than controls. The difference was significant.