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Olga Dichala, Ioannis Therios, Magdalene Koukourikou-Petridou, and Aristotelis Papadopoulos

A field experiment was conducted in a pomegranate (Punica granatum L.) orchard of the well-known cultivars Wonderful and Acco, located in the farm of Aristotle University. The trees were sprayed, every 15 days from flowering (April) to fruit maturation (September), with solutions containing 0, 25, 50, 100 μm Ni, and 100 μm Ni + 100 μm B prepared with Ni(NO3)2·6H2O and boric acid. Leaves and fully ripe fruits were initially sorted into cracked and uncracked ones, then further separated into peel and seeds, sampled, and analyzed. Nickel sprays were effective in controlling fruit splitting as well as Ca and Mg concentration of fruit peels. The correlation between cracking level and Ni concentration in solution was linear and negative. Cracking percentage with 50 μm Ni was lower in ‘Wonderful’, whereas no difference was recorded between the cultivars in the remaining treatments. Leaves had the smallest Ni concentration compared with fruit peel and seeds. Calcium concentration of pomegranate peels was higher than that of control peel at 50 μm Ni in ‘Wonderful’. Concerning ‘Acco’, the treatments 25 μm Ni, 50 μm Ni, and 100 μm Ni + 100 μm B reduced Ca concentration, compared with control. ‘Wonderful’ fruit peel contained more phenolics than ‘Acco’. The treatments 25, 50, and 100 μm Ni increased significantly the flavonoid concentration of fruit peels. The antioxidant capacity ferric-reducing antioxidant potential (FRAP) was linearly increased with Ni concentration in solution in ‘Wonderful’, whereas in ‘Acco’ it decreased at 25 and 50 μm Ni. Our data indicates that improving Ni nutrition of pomegranate can potentially reduce crop loss due to cracking and modified phenol and flavonoid concentration and FRAP value of fruit peel.

Open access

Rachel Leisso, Bridgid Jarrett, and Zachariah Miller

Haskap (Lonicera caerulea), also known as honeyberry, is a relatively new fruit crop in North America. To date, most academic activity and research in North America involving haskap has focused on cultivar development and health benefits, with relatively few field experiments providing information to guide field planning and harvest management for the recently released cultivars. In 2020, we documented preharvest fruit drop (PHFD) rates for 15 haskap cultivars planted in a randomized block design at our research center in western Montana with the aim of preliminarily determining whether certain cultivars may be prone to this phenomenon. Additionally, we evaluated two plant growth regulators (PGRs) to reduce PHFD in two cultivars previously observed to have high rates of PHFD. Results suggest cultivar-specific variations in PHFD near berry maturation. Because haskap harvest indices are not well-defined and may be cultivar-specific, we share our 1-year study results as preliminary information and as a call for further research. Cultivars Aurora, Boreal Blizzard, Borealis, Indigo Gem, Kapu, and Tana all had PHFD rates less than 12% of yield, where yield is the weight of berries lost to PHFD plus marketable yield and marketable yield is fruit remaining on the shrub at harvest. Cultivars Chito, Kawai, and Taka had the highest rates of PHFD, although marketable yields were still relatively high, especially for Kawai. We note that ease of fruit detachment is an important consideration in mechanical harvest, and this characteristic could be advantageous if managed appropriately. The PGRs evaluated (1-napthaleneacetic acid and aminoethoxyvinylglycine) did not influence PHFD rates; however, our study was limited by the sample size and by the lack of information regarding haskap abscission physiology. In summary, the haskap cultivars evaluated exhibited variable PHFD rates in the year of the study, and further research is needed to understand haskap fruit maturation, harvest indices, and abscission.

Open access

B. Schaffer, J. A. Barden, and J. M. Williams

Abstract

In an initial experiment, ‘Tribute’ (day-neutral) and ‘Allstar’ (June bearing) strawberry [Fragaria × ananassa (Duch.)] plants were grouped into fruiting, partially deblossomed, and deblossomed treatments. Net photosynthesis (Pn), dark respiration (Rd), and stomatal conductance for CO2 (gs) were measured at 14-day intervals during the 1st fruiting cycle of both cultivars and at 7-day intervals during the 2nd fruiting cycle of ‘Tribute’. Pn of recently expanded leaves of fruiting plants was greater than that of deblossomed plants only during the 2nd week of the first fruiting cycle and the 2nd and 3rd weeks of the 2nd fruiting cycle. There were no differences in Rd or gs among treatments. At the end of the fruiting cycles, leaves, crowns, and roots of deblossomed plants of both cultivars had greater dry weights than those of fruiting plants. At the end of the first fruiting cycle, roots of deblossomed ‘Tribute’ had a higher percentage of total nonstructural carbohydrates (TNSC) than roots of fruiting plants. In Expt. 2, ‘Tribute’ plants were grouped into fruiting and deblossomed treatments. At 7-day intervals throughout the fruiting cycle, Pn, specific leaf weight (SLW), and chlorophyll content were determined for a leaf that was fully expanded at bloom (old leaf) and for the most recently expanded leaf (young leaf) of each plant. Pn of the young leaf was greater for fruiting plants than deblossomed plants only during weeks 5 and 6 of the fruiting cycle, and no treatment effect was observed for old leaf Pn. During fruit maturation, SLW was higher for deblossomed plants than fruiting plants for both leaf ages. Deblossomed plants had a higher leaf chlorophyll content than fruiting plants during the 1st, 2nd, and 4th weeks of the fruiting cycle.

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Matthew W. Fidelibus, Stephen J. Vasquez, and S. Kaan Kurtural

California table grape (Vitis vinifera) growers cover the canopies of late-season varieties with plastic (polyethylene) covers to shield the fruit from rain. Green- or white-colored covers are commonly used, but there is lack of information whether either cover might be preferable based on canopy microclimate or fruit quality. In late September, ‘Redglobe’ (in 2011) and ‘Autumn King’ (in 2012) table grapevines were covered with green or white plastic, or left uncovered, and canopy microclimate, fungal and bacterial rot incidence, and fruit yield and quality at harvest, and after postharvest storage, were evaluated. Green covers were more transparent and less reflective than white covers, and daily maximum temperature difference in the top center of the canopies of grapevine with green covers was consistently >5 °C than that of grapevine subjected to other treatments, but covers had little effect on temperatures in the fruit zones, which were not enveloped by covers. Effects on relative humidity (RH) depended on location within the canopy and time of day; RH peaked in early morning and was at a minimum in late afternoon. All cover treatments had relatively similar peak RH in south-facing fruit zones and the top center of the canopy. However, in the north-facing fruit zone, vines with green covers had higher RH at night than vines subjected to other treatments. Both covers consistently reduced evaporative potential in the top center of the canopy, but not in fruit zones. Treatment effects on condensation beneath the covers were inconsistent, possibly due to differences in canopy size, variety, or season, but south-facing cover surfaces generally had less condensation than the top or north-facing surfaces. About 0.5 inch of rain fell on 5 Oct. 2011, but no rain occurred during the 2012 experiment. In 2011, green covers delayed fruit maturation slightly, but not in 2012. Covers did not affect vineyard rot incidence, the number of boxes of fruit harvested, or postharvest fruit quality in 2011, but fruit from covered grapevine had less postharvest rot in 2012 than fruit from noncovered grapevines, even though a measurable rain event occurred in 2011 but not in 2012. In conclusion, our results suggest that white covers may be preferable to green since green covers were associated with higher temperatures in both seasons and higher RH in the ‘Autumn King’ trial of 2012, but otherwise performed similarly.

Free access

Monica Ozores-Hampton, Francesco Di Gioia, Shinjiro Sato, Eric Simonne, and Kelly Morgan

Florida had the largest fresh-market tomato (Solanum lycopersicum L.) production in the United States, with a value of $437 million and 13,355 ha harvested in 2014. Despite the development of Best Management Practices (BMPs) and University of Florida/Institute of Food and Agricultural Sciences (UF/IFAS) fertilizer recommendations, tomato growers often use fertilizer rates above the recommended ones, especially when seepage irrigation is used and a longer growing season is foreseen. If a mass balance of N–P–K partitioning could be made in field conditions, a better understanding of nutrition applications could be reached. Therefore, a field study was conducted on seepage-irrigated tomato on a commercial farm in southwest Florida, during the spring and winter season of 2006 to evaluate the nitrogen (N) rate and season effects on tomato plant growth, fruit yield, N, phosphorous (P), and potassium (K) accumulation and use efficiency. The UF/IFAS N-recommended rate (224 kg·ha−1) was compared with a commercial grower (CG) rate (358 kg·ha−1). Both N rates were incorporated at bedding with 61 and 553 kg·ha−1 of P and K, respectively. Fruit yield and plant growth were measured and roots, stems, leaves, and fruit samples were analyzed to determine total N, P, and K content and accumulation in different plant parts. Nutrient recovery (REC) and the partial factor of productivity of applied nutrients (PFP) were calculated for each N rate. In the spring, 120 days after transplanting, plants dry biomass was 11.5% higher (P = 0.01) in the CG N rate than with UF/IFAS N rate, while no significant differences were observed in the winter season. In the spring, N, P, and K accumulation were 250, 56, and 285 kg·ha−1 in plants grown with CG N rate and were significantly lower (23%, 5%, and 23%, respectively) with the UF/IFAS N rate, respectively. In the winter, total N accumulation was 231 kg·ha−1 in plants fertilized at CG N rate and significantly lower (16%) with the UF/IFAS N rate. N rate did not significantly affect P and K accumulation, which were on average 64 and 312 kg·ha−1, respectively. Marketable fruit yield was significantly higher (P = 0.03) with CG N rate than with UF/IFAS N rate (91.1 vs. 81.5 Mg·ha−1), and was significantly higher (P = 0.03) in the spring than in the winter (100.8 vs. 71.8 Mg·ha−1). The NREC was significantly higher (P = 0.01) with the UF/IFAS N rate than with CG N rate and was not significantly affected (P = 0.94) by seasons. The PFPN was significantly higher (P = 0.001) with the UF/IFAS N-rate than with CG N-rate, and was significantly higher (P = 0.04) in the spring than in the winter season. These results suggest that current UF/IFAS N recommendations are more conservative of N and this should lead to reduced leaching potential but, UF/IFAS recommendations must be season specific due to the difference in environmental conditions of fruit maturation in cooler weather of the winter season compared with a warmer environment of the spring season.

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Mingtao Zhu, Jun Yu, Sheng Wu, Meijun Wang, and Guoshun Yang

. Fruit maturation is regulated by the various internal and external factors, such as genetic factors, developmental signals, hormones, light, and temperature ( Klee and Giovannoni, 2011 ; Qin et al., 2012 ; Tian et al., 2013 ). It is important to find

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Junxin Huang, Robert Heyduck, Richard D. Richins, Dawn VanLeeuwen, Mary A. O’Connell, and Shengrui Yao

cultivar trials have been set up at four NMSU agricultural science centers in New Mexico. The objective of this study was to assess the nutrient dynamics during jujube fruit maturation and the differences among cultivars for nutrient characteristics

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at four harvest times during three crop seasons. This variety yielded extra virgin olive oil at all ripening stages studied, but fruit maturation had a major effect in various quality parameters. A loss of antioxidants and decrease of sensory quality

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Eliezer E. Goldschmidt

evolved by citrus fruits have nonetheless a significant physiological role in fruit maturation. This conclusion is in line with a recent review that questions the classic distinction between climacteric and non-climacteric fruits ( Paul et al., 2012

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Shin Hiratsuka, Yuka Yokoyama, Hiroshi Nishimura, Takayuki Miyazaki, and Kazuyoshi Nada

activity was expressed in units (1 unit = 1 μmol NADH oxidation per milligram protein per hour). Determination of sugar and acid content. At fruit maturation (204 DAFB), 15 fruit each were sampled from bagged and unbagged treatments as described previously