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- Author or Editor: James M. Spiers x
Bud development in ‘Tifblue’ rabbiteye blueberry (Vaccinium ashei Reade) was reduced with increasing levels of soil-applied paclobutrazol (PB). Flowering was delayed from 10 to 15 days on plants receiving ≥3 g a.i. PB. This effect still existed 2 years after treatment. Rates of ≤2 g per plant did not influence leaf area. Floral or vegetative bud development, photosynthesis, transpiration, or fruit size when measured 1 year after treatment, but fruit yields were inversely correlated to PB levels. Two years after application, ≤2 g rates had not influenced total plant growth. Stems arising from mature canes were reduced by ≥ 0.5 g PB, but length of juvenile canes was increased by rates up to 2 g PB. Paclobutrazol applications had no influence on leaf content of N, P, Ca, Mg, Fe, or Cu. Only the highest level resulted in increased leaf levels of K and Zn, but Mn leaf content was increased by all levels of PB. In general, rates of soil-applied PB which reduced vegetative growth also reduced fruit yield. Chemical name used: β [(4-chlorophenyl)methyl]-α-(1,1 dimethylethyl)-1H-1,2,4-triazole-l-ethanol (paclobutrazol).
A sand culture study arranged in a 3 × 3 factorial was used to determine the influence of Al and Mn levels on leaf nutrient content and plant growth of `Tifblue' rabbiteye blueberry (Vaccinium ashei Reade). Aluminum fertilization increased leaf Al content but did not affect plant vigor, leaf dry weight, or chlorosis. Manganese fertilization resulted in increased Mn in the leaves and a decrease in all growth parameters measured. The Al × Mn interactions were significant for Mn concentration in the leaves and vigor ratings. At the highest Mn fertilization rate, increasing Al fertilization had a synergistic influence on leaf Mn. Plant vigor at the highest Mn rate was lowest when no Al fertilizer was added. Increasing Al fertilization resulted in better plant vigor in plants grown with a high rate of Mn fertilization.
In a sand culture study, increasing N fertilizer levels (NH4–N) had no effect on stem number or leaf concentrations of K, Mg, or Zn in ‘Tifblue’ rabbiteye blueberry (Vaccinium ashei Reade). Leaf N concentration increased when N fertilizer was raised from 25 to 50 mg/liter N. Additional N fertilizer up to 100 mg N/liter did not raise percent N in leaves, but increased P and decreased Ca. Increased K levels raised leaf concentration of K but not those of other elements. High levels of Na resulted in increased N in leaves and reduced plant growth. Significant interactions indicate synergistic and/or antagonistic influences of fertilizer treatments on elemental leaf concentrations of N, P, and B.
Plant yield, height, and vigor were increased and chlorosis symptoms were decreased by irrigation and/or mulching of rabbiteye blueberry (Vaccinium ashei Reade). Plant growth ratings were highest in plants receiving both irrigation and mulching. Height, vigor, and survivability of irrigated plants were about twice that of nonirrigated plants. Incorporated organic matter increased height and vigor for nonirrigated and nonmulched plants. Organic matter types and levels resulted in little difference in irrigated plant growth. Incorporated organic matter, mulching, and irrigation all improved the soil moisture condition and enhanced the growth of rabbiteye blueberries.
Five muscadine grape (Vitis rotundifolia) cultivars (`Carlos', `Doreen', `Magnolia', `Pineapple' and `Summit') were grown in sand-peat-pine bark (1:1:1) medium and fertilized with a complete marco- and micronutrient solution plus added Na. Plant growth plus mineral uptake in 4 plant parts (leaves, terminal stems, basal stems and roots) were measured. Top growth (leaves plus stems) was highest in `Pineapple' and lowest in `Doreen'. Root growth was higher in `Carlos' and `Doreen' and lowest in `Magnolia'. Plant part X cultivar interactions were significant for elemental Ca, Mg, Na, Fe, Zn, Cu, and Mn. Iron tended to be concentrated in the roots and leaves. Leaves and upper stems contained more K than the lower stems and roots and K concentrations were higher in `Carlos' and `Magnolia' than the other cultivars. Sodium content tended to be higher in the leaves than in the other plant parts. Little differences were present in Na uptake by the 5 cultivars.
The effects of varying potassium and sodium fertilization levels on 'Shawnee' blackberry (Rubrus, subgenus Eubatus, spp.) plant growth and leaf elemental content were studied in sand culture experiments. Increasing K fertilizer levels linearly increased K, but decreased Mg and Zn in the leaves. Concentrations of Na, Ca, Cu. Fe, and Mn were not significantly influenced by K fertilization. Plants contained six times more Na with high than with low Na fertilization. Na fertilization did not significantly affect leaf K, Ca, Mg, Fe, Cu or Zn, but leaf Mn was linearly reduced by increasing Na fertilization. Leaf K and Na were directly influenced by the amounts of supplied K and Na. 'Shawnee' blackberries readily take up Na but exhibit some salt tolerance at low to moderate Na fertilization levels. At high Na levels, they appear to lack a mechanism to reduce Na uptake, which results in reduced plant growth.
In a 1989 field study, `Gulfcoast' southern highbush blueberry plants were subjected to irrigation [8 liters per week (low) and 30 liters per week (high)], mulching (none and 15 cm height), row height (level and raised 10-15 cm), and soil incorporated peat (none and 15 liters in each planting hole) treatments at establishment. Plants were grown on a well-drained fine sandy loam soil that contained < 1.0% organic matter. Plant volume was increased by either mulching, high irrigation, incorporated peat moss or level beds. Fruit yields were not significantly affected by irrigation levels but were highest with either mulching, level beds or incorporated peat moss. The bed height X mulching interaction indicated that mulching increased yield more with level beds than with raised beds. Plants grown with the combination of mulching, level beds, incorporated peat moss, and high irrigation levels yielded 1.1 kg per plant or approximately 10 times more than plants grown without mulch, with raised beds, without peat moss, and with the low rates of irrigation. Of the 4 establishment practices evaluated, mulching had the greatest influence on plant growth and fruiting.
In a sand culture study, increasing Na levels increased leaf concentration of Na, Mg, Ca, Mn, and Zn, and reduced leaf K and plant dry weight. Magnesium fertilization did not affect leaf concentration of Ca, K, Mn, Fe, or Zn. High Ca fertilization increased leaf Ca. At high Mg levels, Ca fertilization had a synergistic influence on Mg uptake. Ca and Mg fertilization did not independently influence plant vigor, chlorosis symptoms, or dry weight production of leaves and stems. As levels of Na fertilization increased, plant vigor and leaf production decreased and chlorosis symptoms increased. With low Na fertilization levels, high Mg fertilization reduced leaf production but with high Na fertilization, plants receiving high Mg levels produced twice the weight of leaves as those with low Mg fertilization. High Mg fertilization reduced the detrimental effects of high Na fertilization on plant growth. This effect may be due to the antagonistic influence of Mg fertilization on Na uptake at high Na fertilization levels.
The effect of incorporated sphagnum peatmoss and minimal fertilization on the establishment and subsequent growth of rabbiteye blueberries (Vaccinium ashei Reade) was determined in 4 field studies conducted on typical fine sandy loam, upland mineral soils in south Mississippi. Incorporated peatmoss increased plant vigor, plant height, shoot weight, leaf chlorophyll level, and fruit yield and reduced chlorosis symptoms. First- and second-year plant growth and second-year fruit yields were reduced by either slow-release or fast-release granulated fertilizer. Soluble fertilizers produced less plant damage than granulated fertilizers but no more plant growth than no fertilization. There was a close association between over-fertilization and cholorosis symptoms.
A field study was conducted to evaluate individual and collective influences of 3 soil moisture-supplementing practices (irrigation, incorporated peatmoss, and mulching) on root system development in ‘Tifblue’ rabbiteye blueberries (Vaccinium ashei Reade). Plants that received no water-supplementing treatments died within 3 years. Root growth was least in plants receiving only one of the 3 treatments and greatest in plants receiving all 3. Ranking of individual treatments on root dry weight production was mulch > incorporated peatmoss > irrigation. Mulching resulted in uniform root distribution from the plant crown outward, while peatmoss tended to concentrate the root system near the crown area. Incorporating peatmoss concentrated roots at the 30- to 45-cm depth, while mulching tended to concentrate the roots in the upper 15 cm of soil. In a sandy, well-aerated soil, the major factor influencing root distribution appears to be soil moisture.