Effect of ammonium/nitrate ratio on growth of southern highbush blueberry in soil with different pH levels
Taking 1-year-old cutting seedlings of superior strain A47 of cultivar‘Southmoon’ of southern highbush blueberry ( Vaccinium corymbosum hybrids) as experiment materials, effects of applying NH4+-N and NO3--N in soil with pH 4. 5 and pH 6. 0 according to molar ratio of 100:0, 75:25, 50:50, 25:75 and 0:100 on dry weights of root, stem and leaf, stem base diameter and height of cutting seedling were studied by pot experiment method. The results show that in soil with pH 4. 5, there is no significant difference in dry weights of root, stem and leaf of seedling among five fertilization treatment groups ( P>0. 05), and also, there is no significant difference in stem base diameter and height of seedling among most treatment groups. In soil with pH 6. 0, dry weights of root, stem and leaf of seedling in treatment group with molar ratio of NH4+-N to NO3--N of 100:0 are significantly higher than those in other groups ( P<0 . 05 ) , while there is no significant difference among other groups; stem base diameter increases with rising of NH4+-N proportion, in which that in treatment group with molar ratio of NH4+-N to NO3--N of 100:0 is significantly higher than that in other groups;and there is no significant difference in height of seedling among most treatment groups. Comparing to soil with pH 4. 5, in soil with pH 6. 0, dry weights of root, stem and leaf in all fertilization treatment groups reduce significantly;except treatment group with molar ratio of NH4+-N to NO3--N of 100:0, stem base diameter of other treatment groups reduces significantly;and except treatment groups with molar ratio of NH4+-N to NO3--N of 50:50 and 0:100, height of other treatment groups reduces significantly. The comprehensive analysis result indicates that there generally is no obvious difference in effect of either applying ammonium fertilizer or applying nitrate fertilizer in soil with pH 4 . 5 on growth of superior strain A47 , but in soil with pH 6 . 0 , applying ammonium fertilizer is beneficial to growth of superior strain A47 . And superior strain A47 is suitable to be cultivated in soil with pH 4 . 5 .
southern highbush blueberry ( Vaccinium corymbosum hybrids)soil pH valueNH4+-NNO3--Ngrowth index
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