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The production of cherry tomato (Solanum lycopersicum var. cerasiforme) is negatively affected by harsh environmental conditions such as extremely high and low temperatures, wind and hail damage, and pest and disease infestation. These factors delay maturity and cause uneven ripening, fruit abrasion, and blemishes, which consequently result in poor fruit quality and reduced shelf life. Preharvest bagging is an environmentally friendly alternative technique for enhancement of fruit quality and hence alleviates the stated problems. The study evaluated the physico-chemical quality of ‘Tinker’ and ‘Roma VF’ cherry tomato as influenced by preharvest bagging (transparent and blue plastics) during 8 days of shelf life at ambient conditions. Five clusters of fruit per plant per cultivar with a diameter of 1.5 to 2.0 cm were bagged after 16 days of fruit set and harvested at the green maturity stage, 12 days after preharvest bagging for the assessment of postharvest quality. Preharvest bagging effectively accelerated fruit maturity and ripening as indicated by enhanced fruit size, uniform color development, high pH, dry matter (DM) content, soluble solid content (SSC), and low titratable acidity (TA) during shelf life. Bagged fruit had higher loss of firmness and weight mainly due to ripening and showed very slight incidence of diseases during shelf life of 8 days. Unbagged cherry tomato had delayed maturity and ripening; small-sized fruit; uneven color development; low pH, SSC, and DM; and high TA. Although unbagged cherry tomato had lower firmness and weight loss due to delayed ripening, fruit showed moderate to severe incidence of tomato bacterial canker disease (Clavibacter michiganensis subsp. michiganensis) during shelf life. These results indicated that preharvest bagging accelerated fruit maturity and ripening, improved physico-chemical quality, and reduced disease infestation on cherry tomato during shelf life.
The effect of supplemental lighting on strawberry growth and anthracnose disease response of three strawberry (Fragaria ×ananassa) cultivars was evaluated in two greenhouse trials, and the effect on strawberry anthracnose pathogens (Colletotrichum sp.) was evaluated in the laboratory. The objective of the greenhouse trials was to determine the effect of various intensities of the red and blue light emitting diode (LED) light treatment on strawberry plant vigor, injury, and disease development. In these trials, the duration of supplemental light treatments was split into two 4-hour periods: dawn and dusk. The intensity of the red and blue LED bulbs was set using an adjustable dial at 1 or 3 in trial 1 and at 1, 5, or 10 in trial 2. Illuminance and photosynthetic photon flux densities of the light treatments ranged from lows of 402 lx and 5 μmol⋅m–2⋅s–1 (blue LED 1) to highs of 575 lx and 25 μmol⋅m–2⋅s–1 (red LED 1 + blue LED 3) in trial 1, and from lows of 4213 lx and 81 μmol⋅m–2⋅s–1 (red LED 1) to highs of 7051 lx (red LED 5) and 194 μmol⋅m–2⋅s–1 (red LED 10) in trial 2. Lower light intensities in trial 1 resulted in no significant differences as a result of light treatments in relative chlorophyll content, plant vigor ratings, or disease severity ratings (DSRs). However, plant injury ratings were significantly greater in plants in the wide-spectrum fluorescent (WSF) plus ultraviolet B (UVB) light treatment compared with the other treatments. Under the higher light intensities in trial 2, there were more significant effects among light treatments. Relative chlorophyll content of plants in the WSF + UVB, WSF, and red LED 1 treatments was significantly greater than that of plants in the red LED 10 treatment; however, plants in the red LED 10 treatment had the greatest injury ratings. Detached leaves from plants in the red 5 LED and red 10 LED treatments inoculated with Colletotrichum gloeosporioides received the greatest DSRs, and leaves from plants in the red LED 1 and WSF treatments received the lowest DSRs. In the laboratory, five days of exposure to supplemental lights did not prevent the growth of isolates of three species of Colletotrichum pathogens even though the intensity of the LED lights was set at their highest intensity. However, growth of isolates exposed to the WSF + UVB light treatment was slowed.
Value-added (VA) technologies can help farmers in the specialty crops industry generate new products, increase off-season income sources, expand market access, and improve overall profitability. The United States Department of Agriculture defines VA agricultural products as those that have been changed physically or produced in a manner that enhances their value. Drawing from this definition, we investigated the adoption of VA technologies, such as drying, physical cutting into customer-ready portions, and washing, by specialty crops farmers. The objectives of this study were two-fold. First, we analyzed how market access drives specialty crop farmers to adopt VA technologies. Second, we addressed key identification issues by investigating the potential endogeneity between the adoption of VA technologies (vertical diversification) and the number of crops (horizontal diversification), which have not been addressed in the VA technology adoption literature. Data for this study were from a 2019 Web-based survey of specialty crops farmers in the United States. The results suggest that market access, growers’ networks, and crop diversification are major drivers of VA technology adoption in the specialty crops industry. The results indicate that farmers who adopted VA technologies experienced economic growth relative to their counterparts.
Because the leaf area index (LAI) is an essential parameter for understanding the structure and growth status of plant canopies, nondestructive and continuous estimation methods have been required. Recently, an LAI estimation method using the ratio of near-infrared radiation (NIR; 700–1000 nm) to photosynthetically active radiation (PAR; 400–700 nm) (NIRin/PARin) transmitted through a canopy has been proposed. However, because previous studies on this NIRin/PARin-based LAI estimation method are limited to tall plants (e.g., forest and rice canopies), in this study, we applied this method to a short canopy (i.e., spinach) and investigated its validity. NIRin/PARin and three other traditional indices for indirect LAI estimation—relative PPF density (rPPFD), normalized difference vegetation index (NDVI), and simple ratio (SR)—were measured in 25 canopies with different LAI. NIRin/PARin showed better estimation sensitivity (R 2 = 0.88) to the observed LAI than the other three indices, particularly when LAI was greater than 3 m2·m−2. In addition, the LAI estimated from NIRin/PARin measured at 10-min intervals in the entire growth period could capture an increasing trend in the measured LAI throughout the entire growth stage (mean absolute error = 0.87 m2·m−2). Errors in long-term LAI estimations may be caused by the sensor location and insufficient data due to unsuitable weather conditions for measuring NIRin/PARin. The current study demonstrates the merits and limitations of the NIRin/PARin-based LAI estimation method applied to low height canopies, thereby contributing to its practical use in horticultural crops.
Muscadine grape (Vitis rotundifolia var. rotundifolia) is a rare crop in that it has transitioned from a wild fruiting plant to a domesticated fruit within the past 150 years. Furthermore, this domestication process was carried out by just a few institutions that published copious records of the origin and traits of the first wild selections, goals and methods of the breeding programs, and the pedigrees of releases. We thus have a near complete record of the domestication of this interesting fruit crop. Early breeding efforts made use of fewer than a dozen wild selections, most of which were collected from the coastal plain of North Carolina and South Carolina. This narrow germplasm base has led to increasing levels of inbreeding in the most recent muscadine cultivar releases. To better understand the germplasm base of muscadine, the pedigrees of 54 muscadine cultivars released since 1970 were examined. Only 15 founders (founding clones) were identified that appeared in more than two cultivars, and five of these represent open pollination events that may not indicate the addition of new genetic material. By far the most used founder was ‘Scuppernong’, which appeared in 53 of 54 pedigrees and had an average genetic contribution of 22.8%. The remaining founders varied from 0.9% to 14.8% in their average genetic contribution. Coancestry coefficients between cultivars averaged 0.18, but were often much higher among recent fresh-market releases. Analysis of vine vigor as measured by trunk caliper in seedling progenies suggests that coancestry coefficients greater than 0.23 result in below average seedling vigor. The University of Georgia muscadine breeding program is evaluating multiple wild muscadine accessions to reduce inbreeding and increase the genetic diversity of its germplasm.