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  • Author or Editor: J.M. Spiers x
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Abstract

Calcium fertilization resulted in leaf Ca concentrations in ‘Tifblue’ rabbiteye blueberries (Vaccinium ashei Reade) equivalent to those reported for low bush and highbush blueberries but did not change plant vigor or yield. Ammonium sulfate was superior to sodium nitrate as a N source, producing higher fruit yield, plant vigor, and leaf macronutrient content.

Open Access
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A field study was conducted to evaluate individual and collective influences of three soil moisture-supplementing practices (irrigation, incorporated peatmoss, and mulching) on root system development in `Gulfcoast' southern highbush blueberries. Root growth was least in plants not mulched and greatest in plants receiving all three supplements. 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 and in root growth concentrated in the upper 15 cm of soil. Other practices (peatmoss > irrigation) tended to concentrate the root system near the crown area and resulted (peatmoss = irrigation) in greater root depth. Soil moisture appeared to be the major factor influencing root distribution.

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The Southern Horticultural Laboratory evolved from the USDA Small Fruit Research Station located at Poplarville, MS. A short history of the research facility and present horticultural research directions will be discussed. Emphases will be on past and present cooperative regional research efforts in horticultural crops.

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Fruit growth and development of 6 rabbiteye blueberry (Vaccinium ashei Reade) cultivars were measured from bloom date through harvest season. Fruit development was characterized by 3 divisions of growth: an early period of accelerated size increase, a second period with lesser increase in fruit size, and a third period with a greatly accelerated increase in fruit size which continued until fruit was mature. Fruit size in all cultivars was largest at the first harvest and smallest at the last harvest. Cultivar differences were evident in fruit size, fruit development, titratable acidity, and percent soluble solids.

Open Access
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Abstract

In sand culture studies, oxidized N (NO3-N) sources increased Ca and Mg and decreased Fe and Mn leaf concentrations in ‘Cheyenne’ blackberry (Rubus spp. L.). Leaf concentrations of K increased, and P, Mg, and Ca decreased with increased K fertilization. High Ca fertilization increased Ca in the leaves but did not affect leaf concentration of other elements measured. Increasing Mg fertilization decreased N and increased Mg leaf concentrations. After two growing seasons, high Mg and Ca fertilization increased, whereas high K decreased plant growth. Significant interactions indicated synergistic and/or antagonistic influences of K and Mg fertilization treatments on the Ca elemental leaf concentrations.

Open Access
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Abstract

‘Tifblue’ rabbiteye blueberry (Vaccinium ashei Reade) plants were subjected to constant and intermittent artificial chilling (7°C) and natural chilling. Insufficient artificial and natural chilling hours affected vegetative-bud break less than floral break. Plants flowered normally only after receiving 500 or more hours constant or intermittent artificial chilling. A high temperature of 23 ± 3°C when alternated with low temperature slowed, but did not nullify, the low temperature effect. A high temperature (18°C) did not nullify low temperature effects. A close association is evident between artificial constant chilling and natural chill-unit data on floral- or vegetative-bud break. Chill-unit models have potential use in predicting completion of the rest period in rabbiteye blueberry.

Open Access
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Abstract

Floral and vegetative buds of ‘Tifblue’ and ‘Woodard’ rabbiteye blueberries (Vaccinium ashei Reade) in various stages of development were exposed to cold under controlled conditions. The temperature required to damage a floral bud was inversely related to the stage of the bud; closed floral buds survived −15°C, but open buds were killed by −1°. Floral buds exposed to but undamaged by cold developed as rapidly as buds with no exposure to cold. Cold hardiness of vegetative buds was similar to that of floral buds.

Open Access
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Abstract

Leaf contents of N, P, Ca, Mg, Mn, and Fe were highest in plants fertilized with (NH4)2SO4 in a sand culture study conducted with 2-year-old ‘Tifblue’ rabbiteye blueberry (Vaccinium ashei Reade) plants. Nitrogen sources caused no differences in leaf uptake of Al, Zn, B, Cu, and K. Amounts of applied S and Na and leaf content of these elements were positively correlated. Leaf mineral content was not influenced by pH levels from 3.5 to 7.5. Shoot length and number of flower buds were not affected by pH, but both were highest for plants fertilized with (NH4)2SO4.

Open Access
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Abstract

Rabbiteye blueberries (Vaccinium ashei Reade) were fertilized with various sources and rates of nutrients over a 4-year period. There were no positive differences in plant growth responses to fertilizer source or rate. At the 80 g/plant rate, plants fertilized with Ca(NO3)2 were chlorotic and lower in plant height and vigor than control (no fertilizer) plants. Plants treated with 160 g of either 13N-6P-11K fast release, (NH4)2SO4, or Ca(NO3)2 fertilizer were shorter than control plants. Plants fertilized with cottonseed meal, 14N-6P-12K slow release, and NH4NO3 did not differ from control plants, regardless of application rate. Fruit yield was highest at the 40 g/plant rate regardless of fertilizer source.

Open Access
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Abstract

Authentic abscisic acid (ABA) and dormant tung (Aleurites fordii Hemsl.) bud-scale extract had similar Rf values in the 4 solvents tested. Corresponding inhibition of lettuce-seed germination and equal retention times of methylated derivatives on gas-liquid chromatograms also indicated the similarity of the isolated inhibitor to ABA.

Open Access