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Percentage of fruiting uprights, fruit set, number of fruit per upright, and flower bud formation of `McFarlin' and `Stevens' cranberries (Vaccinium macrocarpon Ait.) were reduced by removal of old leaves, new leaves, or both on the upright. Results varied slightly, based on which leaves were removed, time of removal, cultivar, year, and bog site. Percentage of fruiting uprights, flowers and fruit per upright, and fruit set were higher on uprights with a terminal bud size >1 mm in diameter in September than for those <1 mm in diameter. Effects were cultivar and site dependent. Terminal bud size of `McFarlin' was negatively related to the subtending number of fruit and positively related to leaf fresh weight of the upright.
A late spring frost, -2°C on 10 Mar 1989, destroyed all blossoms on `Delite' rabbiteye blueberries. To determine the effect of hedging as a rejuvenation method, six-year-old `Delite' plants were pruned on 26 April 1989. All branches were removed at 46 cm from ground level. Unpruned control plants were approximately 184 cm tall. On 21 Mar 1990 a frost of -2°C occurred. Two days later bud damage was assessed on three wood types: spring-old (SO), spring growth on old, weak wood; spring-new (SN), spring growth on vigorous 1-year-old shoots; and fall (F), postharvest late summer/fall growth. Buds were identified as to their stage of development. Buds formed on both types of spring wood were further developed than those on fall wood. As flower stage advanced frost damage increased. Blossoms on fall growth were most frost tolerant and SN was more hardy than SO. Subsequent yields will be determined and reported.
Rabbiteye blueberry flower buds are initiated and differentiated on three distinct wood types - spring growth on old weak growth, spring growth on vigorous 1-year-old shoots, or postharvest late summer/fall growth. Flower buds on spring growth are usually formed and visible by July, while buds formed on postharvest growth flushes appear in late summer and early fall. To evaluate the influence of wood type on cold damage, shoots of `Tifblue' and `Delite' were tagged by season of growth. Following a -10°C freeze in Feb. flower buds on shoots from each growth flush were examined for dead ovaries. Flower buds surviving the freeze were evaluated following a -2° late frost in Mar. Influence of wood type on floral bud and fruit development was determined. All fruit were removed from 5 shoots of each wood type on 2 harvest dates corresponding to early and midseason harvests. Floral buds formed on fall growth were more freeze and frost tolerant than those initiated on spring growth at similar stages of bud development. `Tifblue' was more cold tolerant than `Delite'. Floral buds formed on both spring wood types were earlier to develop than buds formed on fall wood. There were no differences in ripening patterns and quality of fruit removed from spring - new and fall wood. Fruit formed on spring - old wood were later maturing and smaller sized for both harvests than spring-new or fall wood. Postharvest pruning to encourage fall growth may be a cultural means of frost avoidance.
Highly variable productivity among Vaccinium macrocarpon (Ait.) Pursh `McFarlin' bogs in Washington has been noted by growers. The fruiting habits of 12 Washington `McFarlin' bogs, ranging from 5.7-28.4 t/ha productivity were characterized. Uprights from each bog were characterized using RAPD markers, and then used in a greenhouse pollination experiment to determine if variation in fruiting and fertility phenotypes could be associated with RAPD profiles. Fifteen RAPD profiles were identified, and genetic heterogeneity was high among the 12 bogs. An association between RAPD profiles and reproduction characteristics was observed. The most frequent (30%) RAPD profile appeared to represent the `true' `McFarlin', since it was abundant in higher-yielding bogs and its profile was identical to `McFarlin' samples from other growing regions. A unique RAPD profile was also identified which exhibited high yield characteristics, but did not appear to be related to `McFarlin'. The Washington `McFarlin' bogs examined are composed of a diverse array of genotypes with variable fruiting phenotypes, indicating the variability in production has a genetic component.
Abstract
When the water content of cherries (Prunus avium L.) was increased by more than 5% of the initial weight following immersion in distilled water, the force to bioyield (FBY) and the maximum slope of a compression curve (slope 2) decreased, and impact-induced surface pitting increased. When water content of cherries was decreased by more than 2% of the initial weight following dehydration, FBY increased and the minimum slope of a compression curve (slope 1) and impact-induced surface pitting decreased. Force to bioyield and slope 1 and 2 increased with an increase in fruit turgor potential (ψp) and a decrease in fruit osmotic potential (ψπ). There was a slight positive correlation between fruit water potential (ψ) and FBY and slope 1. Fruit texture changed diurnally, corresponding to changes in fruit ψ. This diurnal texture change, however, was largely a response to diurnal differences in fruit temperature.
Abstract
The resistance of sweet cherries to compression damage as measured by the fruit firmness variables, [force to bioyield (FBY), slope of a compression curve, and maximum and residual forces of a compression-relaxation curve] decreased linearly with increasing fruit temperture. The incidence of impact-induced surface pitting decreased linearly as fruit temperature increased. The rate of decrease in impact damage per degree increase in fruit temperature was a function of the cultivar, contact surface, and drop height.
Abstract
Limbs of ‘Bing’ cherries (Prunus avium L.) were shaded with neutral density shade structures to reduce light levels to 10–15% full sun. Three placement times were used: a) petal fall to pit hardening (PF-PH), b) pit hardening to harvest (PH-H), and c) petal fall to harvest (PF-H). Shaded limbs had reduced fruit set, and fruit color and soluble solids were less in comparison to fruit from unshaded limbs. Fruit from shaded limbs were smaller than unshaded for the first 2 harvests, but for the last 2 harvest dates, fruit shaded from PF-PH or PF-H were larger. The time to reach dark red maturity was delayed 5 days by shading from PF-PH or PH-H and 12 days by shading from PF-H. When compared at equal color maturities, fruit from unshaded limbs were firmer than those from shaded limbs. In a study using natural shade, the relationship of fruit color and soluble solids to the percentage of full sun (FS) was logarithmic, with both variables dramatically reduced at light levels below 10–15% FS. Neither fruit weight nor firmness were related to the percentage of FS.
Abstract
Sweet cherry (Prunus avium L.) flower and pistil weight at anthesis decreased at late bloom times. Fruit from early-opening flowers remained larger through harvest and developed higher soluble solids and color than fruit from flowers than opened later. Time of anthesis was delayed and fruit color and soluble solids decreased linearly as flower or fruit location progressed basipetally on one- and 2-year-old wood.
Blueberry reducers in Texas must often irrigate with sodic water. Excess Na+ leads to reduced growth, necrosis, and plant mortality. Ca2+ is known to ameliorate such detrimental effects in many crops, but little is known about the response of rabbiteye blueberry. To elucidate the influence of Ca2+ on the uptake and translocation of Na+, plants were subjected to NaCl in hydroponics solutions (10, 25, 50 and 100 mM NaCl) and the uptake of Na+ was traced over a 24h period using 22Na+ Additionally, for each treatment, half the plants were supplied with 10 mM Ca2+. Plants were then transferred to identical, but unlabeled, solution, then harvested at intervals up to 28 days following cessation of labelling.
Preliminary results indicate that plants subjected to 25 mM Na+ and 0 mM Ca2+ showed less ability to exclude Na+ from the roots, and accumulated more Na+ in roots, stems, an leaves than did plants supplied with 25 mM Na+ and 10 mM Ca2+. Leaf tissue accumulated more Na per gram fresh weight than did any other part of the plant, regardless of Ca2+ treatment.
Results from the remaining treatments, root 22Na+ efflux data, and total tissue Na+ and Ca2+ concentrations will also be reported.
Abstract
‘Tifblue’ rabbiteye blueberry (Vaccinium ashei Reade) plants were grown for 3 years under a sodic irrigation regimen. Mulched and non-mulched plants were irrigated by one of three methods: one drip emitter at the base of the plant, two drip emitters on either side of the plant, or low-volume spray emitter (LVSE). There was a mulch × irrigation treatment interaction. Mulch increased the growth of drip-irrigated plants but not LVSE-irrigated plants. Salt-induced leaf chlorosis and necrosis was only evident on plants with no mulch and irrigated with two emitters. Under mulched soil, K, Na, Mg, Cl, electrical conductivity (ECe), and Na adsorption ratio (SAR) levels were several times lower and uniform throughout the soil profile compared to the non-mulched treatments. Maximum root-zone salinity was 3.7 dS·m−1 for two emitters without mulch and a minimum of 0.5 dS·m−1 for one emitter with mulch.