Horticultural Factors Research Articles

Is calcium deficiency the real cause of bitter pit? A review.

Bitter pit is a disorder affecting the appearance of apples. Susceptibility is genetically controlled by both the cultivar and rootstock, with both environmental and horticultural factors affecting its severity and proportional incidence. Symptoms appear more frequently at the calyx end of the fruit and consist of circular necrotic spots, which take on a "corky" appearance visible through the peel. Bitter pit may develop before harvest, or after harvest, reducing the proportions of marketable fruit. In this review, current knowledge of the factors associated with the occurrence of bitter pit in apples is summarized and discussed along with their interactions with Ca uptake and distribution to fruit. This disorder has been previously linked with localized Ca deficiencies in fruit during its development. However, these relationships are not always clear. Even with over a century of research, the precise mechanisms involved in its development are still not fully understood. Additional factors also contribute to bitter pit development, like imbalances of mineral nutrients, low concentration of auxins, high concentration of gibberellins, changes in xylem functionality, or physiological responses to abiotic stress. Bitter pit remains a complex disorder with multiple factors contributing to its development including changes at whole plant and cellular scales. Apple growers must carefully navigate these complex interactions between genetics, environment, and management decisions to minimize bitter pit in susceptible cultivars. Accordingly, management of plant nutrition, fruit crop load, and tree vigor still stands as the most important contribution to reducing bitter pit development. Even so, there will be situations where the occurrence of bitter pit will be inevitable due to cultivar and/or abiotic stress conditions.

Variability Among Forecast Models for the Apple Sooty Blotch/Flyspeck Disease Complex.

Several disease forecast models have been developed to guide treatment of the sooty blotch and flyspeck (SBFS) disease complex of apple. Generally, these empirical models are based on the accumulation of hours of leaf wetness (leaf wetness duration [LWD]) from a biofix at or near the phenological growth stage petal fall, when apple flower petals senesce and drop. The models recommend timing of the initial fungicide application targeting SBFS. However, there are significant differences among SBFS forecast models in terms of biofix and the length of LWD thresholds. A comparison of models using a single input data set generated recommendations for the first SBFS fungicide application that differed by up to 5 weeks. In an attempt to improve consistency among models, potential sources for differences were examined. Leaf wetness (LW) is a particularly variable parameter among models, depending on whether on-site or remote weather data were used, the types of sensors and their placement for on-site monitors, and the models used to estimate LW remotely. When SBFS models are applied in the field, recommended treatment thresholds do not always match the method of data acquisition, leading to potential failures. Horticultural factors, such as tree size, canopy density, and cultivar, and orchard site factors such as the distance to potential inoculum sources can impact risk of SBFS and should also be considered in forecast models. The number of fungal species identified as contributors to the SBFS disease complex has expanded tremendously in recent years. A lack of understanding of key epidemiological factors for different fungi in the complex, and which fungi represent the most challenging management problems, are obvious issues in the development of improved SBFS models. If SBFS forecast models are to be adopted, researchers will need to address these issues.

İSTANBUL FLORASININ DOĞAL VE KÜLTÜREL İZLERİ

Istanbul is the largest metropolis of Turkey, as well as its main economic capital, and core of industrial and finan­cial development center. Beyond the great historical and cultural values it possess, especially because of its unique location as a transition zone between the Mediterranean and Euro-Siberian, the diverse landscape character­istics of Istanbul also effect the diversity of its plant species and richness. The city has shown high potentials for biological diversity and native habitats, due to its location on the transition point of different climatic regimes between Middle Europe and Mediterranean regions. This study investigates natural and cultural processes effecting the floral composition of Istanbul's city-scape and nature-scape by overlapping the different dimensions of this complex metapolis. These include historical and social dimensions as well as ecologic, functional, aesthetic and horticultural factors affecting the plant species composition in and around urban environment. The study consists of three parts: (1) explanation of the general ecological characteristics affecting natural and cultural vegetation, (2) human influences on the flora of Istanbul: thresh­olds in the historical process, and (3) different green landscape characteristics in urban landscape.

Effect of Black Raspberry (Rubus occidentalis L.) Extract Variation Conditioned by Cultivar, Production Site, and Fruit Maturity Stage on Colon Cancer Cell Proliferation

Black raspberries have been shown to inhibit multiple stages of oral, esophageal, and colon cancer. The objective of this study was to evaluate how black raspberry extract variability conditioned by horticultural factors affected the antiproliferative activity of 75 black raspberry extracts using an in vitro colon cancer cell model. HT-29 cells grown in 96-well plates were treated with freeze-dried extracts at 0.6 and 1.2 mg of extract/mL of medium. Percent cell growth inhibition for each concentration of the extracts was determined using the sulforhodamine B assay. All extracts significantly inhibited the growth of HT-29 colon cancer cells in a dose-dependent manner. Cell proliferation was significantly influenced by cultivar, production site, and stage of maturity. The lack of correlation between growth inhibition and extract total phenolic and total monomeric anthocyanin assays suggested horticultural parameters influence bioactivity in a complex manner.

Horticultural factors regulating effectiveness of GA3 inhibiting flowering in peaches and nectarines (Prunus persica L. Batsch)

The application of gibberellic acid during the flower bud induction period significantly reduced flowering in peaches and nectarines. The magnitude of the response significantly depended on the total amount of active material applied per tree. Results show, for cultivars tested, a higher sensitivity of peach to GA3 in comparison with nectarine. Concentrations of 0.5 or 1.0 g tree−1 of gibberellic acid reduce flowering by about 50% in both, peaches and nectarines, respectively, and it gives rise to a reduction of costs of hand thinning by 50%, approximately, without affecting the yield. Fruit colour advanced, total soluble solids concentration increased and fruit firmness increased as a consequence of treatments. The effect was higher in the basal part of the shoots and reduced from the base to the apical part.

"The Boys Will Have to Fight the Battles without Me": The Making of Sam Davis, "Boy Hero of the Confederacy"

On recent Confederate Memorial Day at the Tennessee State Capitol, the General Joseph E. Johnston Camp No. 28, Sons of Confederate Veterans (SCV), performed pathetic little ceremony under the portico of the antebellum building. A small band of die-hards, their numbers were more than doubled by curious tourists, conscripted children, and an entertainment troupe called the Dixie Picks. A history professor from local community college began proceedings with an angry and passionate recitation of Father Abram Joseph Ryan's poem the battle flag. Turning southwards, the speaker pointed the statue of the Confederate martyr Sam Davis, erected on Capitol grounds in 1909, and proclaimed that the story of the boy was a living reminder of the valor of your flesh and blood. Executed by the Union army in 1863 for scouting behind enemy lines, Sam Davis had become folk hero by the end of the nineteenth century; almost Christ-like in his representation of duty, bravery, and honor, he embodied the South's idealized image of itself during the crisis of the 1860s. The martyr's honor, however, was besieged at the turn of the twenty-first century by those who wished associate the memory of his matchless glory with the shame of slavery. Within fifteen feet of the Confederate statue, the speaker's friends had thrown tarpaulin over simple monument erected in 1999 by the Black Caucus of Tennessee state legislators the victims of the Middle Passage who died en route slavery in the Americas. The dedication of this simple granite block, set beside Scarlet Oak sapling, had infuriated members of the SCV who called the monument's proximate placement the Davis statue a foolish little sophomoric prank. In testy exchange of opinions in the press, spokesperson for the Black Caucus claimed no intent to disrespect Confederate soldier or have it overshadow him in any way and said that that the location for the monument slavery's victims was determined by horticultural factors alone. Nonetheless, on Confederate Memorial Day the monument was covered erase any suggestion that slavery was part of the secessionists' cause. (1) Once defiant public celebration for southern whites, Confederate Memorial Day has never been moment for ambivalent thinking about southern identity and the meaning of the Civil War. The days when governors eulogized the Confederate cause, and the most prominent citizens jockeyed for position on the speaker's podium, are long gone. But though the crowds no longer come, time has not diluted the moral imperative--the passionate certitude--of Confederate symbolism, which, like Corinthian columns, continues dominate the temple of the South's historical imagination. As readers of Southern Cultures are well aware, however, the white South's public commemoration of the Civil War era tells highly selective, carefully orchestrated, and incomplete story of the service, suffering, and sacrifice of Americans during the terrible crisis of the 1860s. In recent years, scholars of the American Civil War era--taking cue from historians of the First World War and the Holocaust--have moved into the study of historical memory both explore how we have come know what we think happened during the 1860s and reconceptualize the questions we ask about one of the most critical events in U.S. history. In southern context, the move into memory studies seems especially appropriate because so many popular assumptions and sources about the war and its aftermath continue be stained with resilient dye of sentimentalism, white supremacy, and martial nostalgia. (2) The commemorative history of Sam Davis is case study in collective memory making as part of the reconstruction of white southern identity during the late nineteenth and early twentieth centuries; these memories and identities, moreover, are sustained and perpetuated today by many white southerners. There is puzzling lack of ambiguity in the commemoration of Davis. …

Effects of Postharvest Storage and UV-C Irradiation on the Phenolic Content and Antioxidant Capacity of Cranberries

Recent interest in the human health-promoting properties of fruit phenolics, and especially fruit flavonoids, has stimulated research on how these secondary metabolites may be affected by pre- and postharvest horticultural factors. Resveratrol, although a minor phenolic in many fruit, possesses potent bioactivities, and is therefore of particular interest. To study the effects of postharvest storage and UV-C irradiation on selected phenolic components and antioxidant capacity of cranberry (Vaccinium macrocarpon), fruit of cv. Pilgrim, Stevens, and Bergman, were irradiated with UV-C at levels between 0 and 2.0 KJ·m-2, followed by storage at 9 °C for 7 and 17 d. Total phenolic content did not change during storage. However, resveratrol content was higher and antioxidant capacity (ORAC) was lower at 7 days of storage compared to 17 days. There was no main effect of UV-C on total phenolics, anthocyanins, resveratrol, or ORAC. However, there was an interaction between storage time and UV-C irradiation. Anthocyanin content was lower at 7 days, and higher at 17 days, at UV dosages of 1.0 or 2.0 KJ·m-2. Resveratrol content was higher in UV-C irradiated fruit at 7 days, while at 17 days there was no difference between UV-treated and untreated fruit.

Densely Planted Okra for Destructive Harvest: III. Effects of Nitrogen Nutrition

Research was conducted to develop a cultural system that would permit a destructive mechanical okra [Abelmoschus esculentus (L.) Moench] harvest. Okra grown at a highly dense (HD) plant population of 25 × 23 cm and destructively harvested by machine was compared with control plants spaced at 90 × 23 cm and repeatedly and non-destructively harvested by hand. The control N fertilization regime was 45 kg·ha-1 of N preplant, followed by one or two topdressings, each with 22 kg·ha-1 of N. Treatments applied to HD plots were designed to be multiples of the control N fertilization levels. Preplant fertilizer was added such that the sum of residual soil N plus the added fertilizer would total to 45, 90, or 135 kg·ha-1 of N for the standard, intermediate, and highest rates, respectively. Topdressing rates were 22, 44, or 66 kg·ha-1 of N for standard, intermediate, and highest, respectively. Topdressing was timed to follow a mechanical harvest of the HD plots. Since there was only one mechanical harvest in the two 1995 studies, topdress N treatments did not affect yields from mechanical harvest in that year. Nitrogen treatments had few effects on fruit yield per hectare of HD okra, even when stem N concentrations equaled or exceeded those of control plants. The highest N rate tended to delay fruit production. Increasing N rates did not affect the marketable fruit yield obtained by mechanical harvest of HD plants expressed as a percentage of the total cumulative marketable fruit yield from control plants. Physiological factors appear to be limiting the potential for densely planted okra in a destructive mechanical harvest system rather than horticultural factors such as N nutrition.

Horticultural Factors Affecting Antioxidant Capacity of Blueberries and other Small Fruit

It is now widely held that the antioxidants contained in fruit and vegetables can provide protection against certain human degenerative conditions that are associated with oxygen free radical damage. This view is supported by epidemiological, in vitro, and more recently, in vivo evidence. Phenolics (polyphenolics) contribute substantially to the antioxidant complement of many small fruit species whose ripe fruit are red, purple or blue in color. Fruit containing high levels of phenolic antioxidants would be attractive to health conscious consumers, therefore optimization of production and processing factors affecting small fruit antioxidant capacity is desirable. In many small fruit crops, antioxidant activity [measured as oxygen radical absorbing capacity (ORAC)] is positively correlated with their content of anthocyanins and total phenolics. Genera, species, and genotypes vary with respect to phenolic content. Both annual and geographical factors appear to influence ORAC, although many years of study are needed to distinguish these effects from other biotic and abiotic factors that influence fruit phenolic content. Antioxidant capacity due to phenolics is decreased by food processing practices, such as heat or aeration.

Usefulness of Apogee® for the PA Apple Industry

Excessive tree vigor is a significant production problem for the PA apple industry. A series of experiments were conducted from 1994 to 1999, which indicated that Apogee® could effectively reduce vegetative shoot growth. Results from 1994 to 1996 have previously been reported (HortScience 31:598, 32:558). In 1997, 16 treatments composed of four rates (0, 63, 125, and 250 ppm) and four timings (22 May; 4, 11, and 24 June) in various combinations, were applied as dilute handgun sprays. These treatments were applied to sixth leaf `York Imperial' apple trees. Ten peripheral shoots, at a height of 2 m, were tagged and measured on 21 May, 9 and 30 June, 16 July, 12 Aug., and on 10 Oct. Shoots treated with 63, 125, or 250 ppm on 22 May followed by 0, 63, or 125 ppm on 4, 11, or 24 June were from 65% to 76% of the length of the controls (25.5 cm). Treated shoots were from 69% to 78% of the length of the controls following sprays with 63 ppm on 22 May followed by 0, 63, or 125 ppm on 4, 11, or 24 June. Shoots treated with 125 ppm on 22 May followed by 0 or 63 ppm on 4, 11, or 24 June were from 69% to 73% of the length of the controls. The later applications (11 and 24 June) of 250 ppm gave no growth control but the 22 May treatment gave a 30% reduction in growth. In 1999, dilute handgun sprays of 125, 125, 83, and 83 ppm were made on 22 May and on 4, 11, and 24 June, respectively. Cultivars treated were `Spartan', `Delicious', `York Imperial', `Gala', and `Mutsu'. The length of 10 peripheral shoots at 2 and 3 m were measured on 28 July and on 12 Aug. All cultivars responded and on 12 Aug. treated terminal shoot lengths ranged from 33% to 55% of the controls. With reduced vegetative tree vigor many horticultural factors will be improved. In addition, the severity of shoot fire blight can be reduced and the control of all pests that prosper on young succulent leaves will be easier, especially apple aphids and obliquebanded leafrollers. Major factors to be considered in developing an efficacious Apogee® program appear to be initial tree vigor, length of growing season, and crop load. An initial application at 1 to 3 inches of terminal growth is probably the most critical factor.

675 Horticultural Factors Affecting Anthocyanin and Phenolic Content and Antioxidant Capacity of Small Fruit

Fruit and vegetable components that possess antioxidant capacity are being actively investigated because of the purported impact of dietary antioxidants on human health. Phenolic components, including anthocyanins, are believed to be major contributors to the antioxidant capacity of many small fruit species. Various horticultural factors have been examined with respect to anthocyanin and phenolic content, and antioxidant capacity of small fruit, especially Vaccinium species. Vaccinium species, and certain other fruits, had a high antioxidant capacity compared to strawberries and raspberries. However, genotypic variation in these characteristics was substantial among wild blueberry clones. Fruit maturity did not influence antioxidant capacity, although phenolic profiles changed dramatically during ripening. Fresh storage of certain ripe fruit at 20 °C led to increased anthocyanin content and increased antioxidant capacity. Certain food processing factors, such as heat and oxygen, decreased the antioxidant capacity of blueberry products.

Apple Storability as Influenced by Tufted Apple Bud Moth Injury, Orchard Fungicide Programs, and Horticultural Factors

As public pressure increases to reduce the use of agricultural chemicals, the effects of lower chemical dosages in the orchard on fruit storability must be determined. Based on both artificial and natural damage, minor tufted apple bud moth (TABM) injury (<10 mm aggregate diameter) did not cause significant loss during controlled-atmosphere (CA) storage. However, damage in excess of 10 mm often caused significant weight loss and decay. Damage occurring closer to harvest caused more loss of quality than earlier damage (i.e., during July and early August). Forty percent of apples damaged 1 week before harvest decayed during storage. Several orchard fungicide spray programs were studied, and in 1993–94, all of the tested programs adequately controlled both fruit blotches and rots, and few storage rots developed. These diseases were light in 1993 due to low rainfall during the summer months. Development of the summer diseases were somewhat higher in 1994, but similar fungicide programs provided adequate control of the complex at harvest. Apples inoculated with P. expansum (punctured with a nail) decayed less when stored in 3% CO2 than in 0% CO2 (at both 1% or 2.4% O2). Decay of `Golden Delicious' caused by P. expansum inoculation increased with later harvest (twice as much decay in fruit harvested 14 Oct. than in fruit harvested 23 Sept.–7 Oct.).

Factors Affecting Performance of Sliding-Needles Gripper During Robotic Transplanting of Seedlings

Transplanting tests with commercially grown seedling plugs were conducted using a Sliding-Needles with Sensor (SNS) gripper operated by a SCARA type robot. A total of 11 plug trays, with 600 cells each, were tested. Many mechanical and horticultural factors were found to affect the percentage of successful transplanting, which were analyzed to understand their influence on the effectiveness of the gripper. The mechanical factors were 1) the angles of gripper needles; 2) plug extraction acceleration; and 3) the sensor sensitivity. The horticultural factors included 1) empty cells on the plug trays; 2) plant species; 3) root connections; 4) adhesion between roots and cell walls; 5) root zone moisture; and 6) the number of seedlings in one cell.

Orchard Systems Research with Deciduous Trees: A Brief Introduction

Abstract An orchard system is the integration of all the horticultural factors involved in establishing and maintaining a planting of fruit trees. These factors include tree density and arrangement, cultivar, root-stock and interstock, tree size and form, pruning and training techniques needed to maintain the desired configuration, mechanical training and harvesting, and support systems. An orchard system is a blueprint for the orchardist to follow throughout the life of a planting.

Testing seedling potato stocks for specific horticultural factors under controlled conditions

Testing seedling potato stocks for specific horticultural factors under controlled conditions