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- Author or Editor: James M. Spiers x
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.
The effects of varying rates of a complete fertilizer and irrigation on the growth and fruit yields of `Tifblue' rabbiteye blueberries (Vaccinium ashei Reade) established 3 years before treatment initiation were determined in a field study. Increased rates of irrigation resulted in increased plant growth and fruit yields. Five- and 6-year-old plants were more responsive to increasing irrigation rates than older plants. Irrigation water efficacy was greatest at lower rates and progressively less at higher rates of irrigation. Five- and 6-year-old plants fertilized with the lowest rate (14N–4P–7K; 150 g/plant) grew and yielded less than those fertilized with higher rates. Older plants did not respond to fertilization rates higher than 150 g/plant. Yearly rates of fertilization above 300 g/plant did not influence plant growth or fruit yields. Fertilization and irrigation responses were independent.
In a field study, `Gulfcoast' southern highbush blueberry plants were subjected to irrigation [7.5 L (low) or 30 L per week (high)], mulching (none or 15 cm depth), row height (level or raised 15 cm), and soil-incorporated peatmoss (none or 15 L in each planting hole) treatments, in a factorial arrangement, at establishment. Plants were grown on a well-drained fine sandy loam soil that contained <1.0% organic matter. Plant volume and fruit yield were greater with mulching, high irrigation, incorporated peatmoss, and level beds. Plants grown with the combination of mulching, level beds, incorporated peatmoss, and high irrigation levels yielded 2.4 kg per plant or approximately eight times as much as plants grown without mulch, with raised beds, without peatmoss, and with the low rate of irrigation. Of the four establishment practices evaluated, mulching had the greatest influence on plant growth and fruiting.
Abstract
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).
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.
Abstract
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.
Abstract
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.
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.
A greenhouse study was conducted to evaluate the influence of substrate temperatures (16, 27, and 38C) on root and shoot growth of six blueberry (Vaccinium spp.) clones (three clones each of two types). Between types, southern highbush (primarily V. corymbosum L.) produced more roots and total growth than rabbiteye (V. ashei Reade). Comparing clones, `Gulfcoast' (southern highbush) was the most vigorous and `Tifblue' (rabbiteye) the least vigorous. Each clone had a negative linear response to substrate temperatures in all growth characteristics. Root and shoot growth was best at 16C. This study indicates that both rabbiteye and southern highbush blueberries would respond favorably to cultural practices that lower soil temperatures during the summer growing season.
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.