results showed that adding TSP to the soil had a negative impact on the development of leaves and runners, whereas the berry yield in 2008 was unaffected by the soil treatment ( Fig. 4A–C ). The year after, however, also strawberry yield was lower for the
Marianne Andresen and Nina Cedergreen
D.R. Chrz, N.O. Maness and I. Wahem
Seven different quality attributes were assessed during the early, middle and late phases of harvest for years 1990-1992: marketable berry yield, berry weight, berry firmness, berry color (tri stimulus chromameter “a” value), percent soluble solids, percent titratable acidity (percent cinic acid) and the ratio between soluble solids and titratable acidity. Marketable berry yield was influenced by harvest year, harvest season and cultivar. Berry weight varied substantially between cultivars and between seasons. Berry color remained stable through the harvest seasons with slight differences in color between cultivars. Berry firmness differences were generally associated with cultivar and varied little through the harvest seasons. Berry flavor (indicated by the ratio between soluble solids and acidity) tended to remain stable through the harvest seasons with considerable differences between cultivars. Work was supported by USDA grant 90-34150-5022 and the Oklahoma Agricultural Experiment Station.
N.O. Maness, D.R. Chrz, K. Striegler, I Wahem and T.G. McCollum
Fresh strawberries are highly perishable commodities, and berry quality at harvest delimits their potential shelf life. We are conducting harvest quality evaluations for seven commercially available cultivars. Seven different fruit characteristics were chosen to assess cultivar performance during the early, middle and late phases of the picking season: marketable berry yield, berry weight, berry firmness, berry color (“a” value), percept soluble solids, titratable acidity (percent citric acid) and the ratio between soluble solids and titratable acidity. Marketable berry yield, berry weight and berry firmness varied substantially between cultivars. A few differences were observed between cultivars for berry color. Berry flavor, as evidenced by the ratio between soluble solids and acidity, was also apparently different between cultivars with three of the seven cultivars consistently exhibiting higher ratios. The relationship of each measured parameter to quality will be discussed.
Nicole E. Burkhard, Derek H. Lynch and David C. Percival
Within-row weed management of highbush blueberry (Vaccinium corymbosum L.) is reliant upon herbicide applications. However, in organic production, herbicides are typically not permitted and alternative methods must be used. The impact of thick (25-cm) mulch applications on weed pressure in an organic production system was initiated at a commercial operation in Nova Scotia, Canada, during 2005. A split-plot experimental design was used with five blocks (replications), six treatments, and five plants per split plot (cv. Duke). The whole-plot factor consisted of mulch/fertility treatments and included: i) control (no amendment); ii) ammonium sulphate fertilizer (30 kg·ha-1 N); iii) pelletized poultry manure (60 kg·ha-1 N); iv) pine needles (80 t·ha-1); v) horse manure and sawdust compost (550 t·ha-1); and vi) seafood waste compost (360 t·ha-1). The split-plot factor consisted of level of hand weeding (–/+). Weed control was assessed by sampling percent ground cover and weed shoot biomass in three 0.25-m2 quadrats in nonweeded subplots. Blueberry leaf N content, plant canopy volume, and berry yield (fresh weight and number) were recorded. The manure/sawdust compost and pine needle treatments had the lowest weed biomass and percent ground cover values, thereby providing the best weed control. Weed shoot biomass, blueberry leaf N, plant canopy volume, and berry yield were greatest in the seafood waste compost treatment. Results from this preliminary study indicate the potential of using these groundcover treatments to improve organic cultural management practices.
Xurong Tang and Peter M.A. Tigerstedt
Eight characters relating to flowering and maturity, berry yield, and winter hardiness were estimated on the basis of intersubspecific or interprovenance hybrids to determine heterosis, heritability, and genetic and phenotypic correlations in sea buckthorn (Hippophae rhamnoides L.). Two provenances of ssp. rhamnoides, one of Finnish (Fin) and one of Danish (Dan) origin, were dominant to ssp. sinensis and Russian derived provenances (ssp. turkestanica) for most characters related to flowering or maturity. This tendency for dominance or overdominance also extended to berry yield and winter hardiness, except for hybrids between Finnish origins and Siberian (ssp. mongolica) origins. The start of maturity (Ms) and half maturity (Mh) showed the highest heritabilities (h2 = 0.88 and 0.81, respectively). The hybrids were matroclinal, suggesting that Ms and Mh may be sex-linked or cytoplasmically inherited characters. Winter hardiness was the trait with the lowest heritability (h2 = 0.02), suggesting that the climate at the testing site was not severe enough to differentiate variation among half sibs or full sibs derived from Fin x Dan, which on average proved hardier than the native parental provenance Fin. Full maturity (Mf) showed a moderate heritability but was stable across 2 years (rB = 1). High genetic correlations among Mf, Ms, and Mh (rG = 0.94, 0.96, and 1.00, respectively) suggest that these characters were controlled by the same genes. Yield showed a negative genetic correlation with all characters pertaining to flowering and maturity, indicating that selection for early flowering or early maturity should result in a gain in yield.
David S. Conner and Kathleen Demchak
Strawberry (Fragaria ×ananassa) and caneberries (Rubus sp.) are popular crops that can bring revenue to farms and may improve farm profitability. High and low tunnels can bring a number of benefits to growers, including season extension and improved berry yield and quality, as well as management challenges. Few studies in the literature report directly on grower experiences using tunnels. We report the results of interviews of 10 independent growers who use tunnels to produce strawberries and caneberries. The results echo previous studies finding improved yield and quality, and highlight benefits and challenges around pest, weed, and nutrient management. One novel finding is the role of season extension in creating marketing opportunities. Interviewed growers caution of a learning curve and the need to start on a small scale and grow gradually. Future focus for research should include improved ventilation and mechanization.
Benjamin Mullinix, Gerard Krewer and Paul Sumner
'Climax' and 'Tifblue' blueberry cultivars were harvested, cooled, and later warmed to room temperature for use in individual berry dropping experiments. Surfaces used were concrete, “Softer NoBruze” and “Poron #7R70-Grey.” Berries in the check were not dropped. Three groups of 25 berries were dropped individually from various heights ranging from .5 ft to 7 ft. Initially, berries were cut to determine percent flesh showing bruising. Later, berries were rolled between fingers and assigned a firmness: firm, medium firm, or soft. The first two firmnesses are considered marketable. Fruit tended to bruise more when harvested later in season. More bruising occurred with higher drop heights. More marketable fruit resulted from thicker padding. Repeated dropping increased bruising. “NoBruze” was superior to “Poron” at any thickness. Many berries in the mechanical harvester have to drop over a foot onto a metal surface; padding these surfaces should increase percent of marketable (undamaged) berry yield.
Bernadine C. Strik and Arthur Poole
Timing and severity of pruning in a 30-year-old commercial `McFarlin' cranberry (Vaccinium macrocarpon Ait.) bed were studied. Treatments in 1989 and 1990 consisted of early or late pruning and heavy, moderate, light, or no pruning. Yield component data were collected in Fall 1989 and 1990, just before harvest. Time of pruning did not affect yield components. In 1989, the unpruned and lightly pruned vines had a higher total plant fresh weight, fewer berries, higher berry yield, longer and more fruiting uprights, and fewer nonfruiting uprights (U,) compared with moderately or heavily pruned vines. Average length of UN and anthocyanin content of berries in 1989 were not influenced by pruning. In 1990, the effects of pruning severity were similar to 1989. In 1990, unpruned vines had a lower percent fruit set and berries contained less anthocyanin than pruned vines. Annual pruning with conventional systems in use decreases yield.
Eric J. Hanson and Jorge B. Retamales
`Bluecrop' highbush blueberries (Vaccinium corymbosum L.) received various N fertilizer treatments for 5 years. Treatments were evaluated by measuring berry yields and leaf N levels annually and bush size after 5 years. Nitrogen fertilizers increased yields and leaf N levels compared with nonfertilized controls. Split applications of urea (half applied at budbreak, half at petal fall) resulted in 10% higher yields than the same amount in a single application at budbreak. Urea and two controlled-release fertilizers (CRF) with different dissolution rates (3 to 4 months, 8 to 9 months) resulted in similar yields and leaf N levels when compared at the same rate of N. The dissolution rate of the CRF materials did not affect yields or leaf N levels.
Chuhe Chen, J. Scott Cameron and Stephen F. Klauer
Two sets of field experiments have been set up in Lynden, Wash., to evaluate cold damage to red raspberry `Meeker'. The locations represent newly established crops (fi eld 1) and a field that suffered reoccurring cold damages in recent years (fi eld 2), respectively. Temperature and moisture HOBOs were set up in the check and colddamaged treatments of both of the fields to record the air and soil temperatures and air moisture. The cold-damaged treatments in both fields had significantly higher cane dieback and dead buds. Cold injury significantly reduced berry yield in field 1, but not in field 2, through an steep drop in berry number per cane, mainly due to a significant reduction in lateral number/cane. Cold damage reduced primary lateral number/cane, and increased secondary lateral number/cane in both fields. Secondary laterals were shorter in length and had lower berry number/lateral than the primary ones. It proved that cold damage also delayed initiation and development of secondary laterals, and resulted in more yield loss to the plant. The cold-damaged fruiting cane had lower gas exchange rates, leaf and stomatal conductance, and transpiration rates during fruit development in both fields. It also significantly reduced fluorescence parameters Fo, Fm, Fv, T1/2, and Fq of the cold injury treatment in field 1. On a few cold days this spring, the HOBOs recorded a lower daily low temperature in the cold damaged area than in the check area.