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  • Author or Editor: Ali Sarkhosh x
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The rootstock is an essential element for orchard management, influencing scion growth, nutrient concentration, and fruit quality. Seasonal variations in leaf nutrients of ‘UFSun’ grafted on five different rootstocks (‘Flordaguard’, ‘Barton’, ‘MP-29’, ‘P-22’, and ‘Okinawa’) were investigated during the 2017–18 growing season in Citra, FL. There was no significant variation in the macronutrient concentrations (N, P, K, Mg, Ca, and S) among different rootstocks; however, ‘UFSun’ on ‘Okinawa’ and ‘Flordaguard’ showed greater concentrations of Ca, K, and Mg concentration than other rootstocks. In contrast, ‘Flordaguard’ showed less potential to accumulate P as compared with other rootstocks. The Ca concentration was lowest in ‘MP-29’ and ‘Barton’ in April and June. The concentration of macronutrients (N, P, K, Mg, Ca, and S) in leaves was greater in April and October than in December and June. With respect to rootstocks, macronutrients in December and June were the highest in ‘Okinawa’ and the lowest in ‘Barton’. In April, the lowest concentration of macronutrient was recorded in ‘Barton’, whereas the highest concentrations were found in ‘P-22’, ‘Okinawa’, and ‘Flordaguard’. The highest leaf micronutrient concentrations were found in ‘MP-29’ and ‘Barton’, and the lowest in ‘Okinawa’ and ‘Flordaguard’ in June and October. For all rootstocks, concentrations of micronutrients increased between leaf growth in April and senescence in October. The micronutrient concentrations of leaves decreased during December. The widest dynamic changes during the vegetative cycle were found on ‘P-22’. Seasonal trends were more consistent for micronutrients than for macronutrients.

Open Access

The use of paper or nylon bags (fruit bagging) to surround tree fruit during development provides protection from a variety of pest-disease complexes for peach without yield reduction and different-colored bags have the potential to improve fruit quality based on findings from other crops. An experiment was conducted in 2019 at two locations in central Florida on peach [Prunus persica (L.) Batch] ‘TropicBeauty’ and ‘UFSun’ to analyze the impact of a commercially available white paper fruit bag combined with a photoselective insert. The insert reduced the amount of light outside the spectrum range of interest for blue (400–500 nm), green (500–600 nm), or red (>600 nm) wavebands, or decreased fluence rate with a neutral density black (>725 nm) insert. Relative to ambient, temperature inside all bagging treatments during the daytime hours was increased by 5.1 °C. During the same time, relative humidity was reduced by 10.1%, but calculations revealed that the water vapor pressure was elevated only for treatments that had a plastic colored (blue, green, or red) insert. An orthogonal contrast revealed that the elevated water vapor around the fruit in a colored bag increased the concentration of chlorophyll at harvest but had no effect on other quality parameters. Compared with unbagged fruit, red-bagged fruit were 1.8 times firmer and green-bagged fruit and had a lower peel chroma. White-bagged (without photoselective insert) fruit had similar nutrient concentrations for the peel, flesh, and pit when compared with unbagged fruit. When bags remained on the fruit until harvest, anthocyanin concentration in unbagged fruit peel was double the amount in white bags and 6-fold more than the bags with color inserts. Different-colored bagging treatments did not influence insect attraction or fruit quality parameters, such as fruit size, diameter, difference of absorbance (DA) index, total soluble solids (TSS), titratable acidity (TA), pH, peel lightness, peel hue, flesh lightness, flesh hue, or flesh chroma. Relative to full sun, the colored bag treatments allowed between 3.7% (black) and 17.4% (red) of the photosynthetically active radiation (PAR). Additional research is needed to determine if an increase in fluence rate at specific spectral wavelengths can affect the quality for peach grown in bags in the field.

Open Access

Muscadine grape is a perennial crop that is highly responsive to local environmental factors and viticulture practices. Biochar is a promising soil amendment used to improve soil water and nutrient retention and promote plant growth. The present study aimed to assess the effects of different pinewood biochar rates on nutrient status and vegetative parameters of muscadine grape cv. Alachua grown on a nutrient-poor sandy soil, Ultisols (97.2% sand, 2.4% silt, and 0.4% clay), and mixed with five different rates (0%, 5%, 10%, 15%, and 20%) of biochar based on weight. Variations in soil moisture, temperature, and leaf greenness value [soil plant analysis development (SPAD) reading], net photosynthesis rate, and plant root and shoot dry weights were measured. In addition, the nutrient status of the soil, plant root, and shoot were determined. The results indicated that the higher rate of biochar could significantly (P < 0.05) improve soil moisture. Biochar can also decrease soil temperature, although there were no significant differences among treatments. Regarding the nutrient status, the biochar amendment increased the nutrient content of phosphorus (P), potassium (K), magnesium (Mg), and calcium (Ca), as well as the soil organic matter content and cation exchange capacity. Higher nutrient contents in soil lead to increased P and Mg in both aboveground and belowground muscadine plant tissues and decreased nitrogen (N), iron (Fe), and copper (Cu) in the root part. There were no significant differences observed in SPAD values, net photosynthesis, or dry weights of the root and shoot. This study demonstrates that the addition of biochar may enhance the soil water and nutrient status as well as improve plant P and Mg uptake; however, it showed no significant differences in the physiological performance of muscadine grape plants.

Open Access

Fruit bagging is an acceptable cultural practice for organic production that provides a physical barrier to protect fruit. It can reduce pest and pathogen injury for a variety of fruit crops, but quality attributes have been inconsistent for peach [Prunus persica (L.) Batsch] and other bagged fruit. A 2-year experiment on a U.S. Department of Agriculture (USDA) organic-certified peach orchard in central Florida was conducted to analyze the effects of a commercially available paper bag designed for fruit protection and cardinal quadrant (north, south, east, and west sides) of the tree canopy on low-chill peach ‘TropicBeauty’ fruit quality. Protective bags appeared to delay fruit maturity. Flesh firmness and chlorophyll concentration of bagged fruit were 31% and 27% greater than unbagged fruit, respectively. Bagged fruit were protected as demonstrated with a reduction in mechanical injury by 95%, fruit fly injury by 450%, and scab-like lesions by 810%. Bagging reduced fruit brown rot (Monilinia fructicola) at harvest and 7 days after harvest; unbagged fruit were 2 and 3.5 times more likely to have rot at harvest and 7 days after harvest, respectively. Fruit bags did not affect yield, fruit size, total soluble solids, titratable acidity, pH, peel lightness, peel hue angle, or flesh color. Overall, canopy cardinal quadrant location had minimal effect on fruit quality or fruit injury. These results demonstrate that bagging peach fruit protects against various pests and diseases but has minimal effects on fruit quality. Broad adoption of this technology is highly dependent on available labor, market demands, and profitability but may be suitable for producers using direct-to-consumer market channels.

Open Access