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Early ripening [earlier than 1 Aug during fruit harvest time (FHT)], large fruit weight (FW; >1000 g), high sugar content [>17% soluble solids content (SSC)], and low acidity in fruit juice (<0.7%) are important breeding targets of pineapple for table fresh fruit use in Japan. We investigated the efficiency of primary selection based on the four fruit traits using 129 first-fruiting F1 offspring population of ‘Yugafu’ × ‘Yonekura’ without replicates. Separately, environmental variances were estimated by an analysis of variance using evaluation data from 50 or 49 offspring in three replicates and two-year repeats. The phenotypic distribution in the 129 F1 population approached a normal distribution (P > 0.05). The genotypic distribution was obtained as a normal distribution with the population mean as the mean and genotypic variance obtained by subtracting the environmental variance from the phenotypic variance. The target genotypes were estimated at 14.4%, 58.7%, 5.0%, and 50.0% of the F1 population for FHT, FW, SSC, and acidity, respectively. Critical phenotypic values were established as the upper (FHT and acidity) and lower (FW and SSC) limits of the critical genotypic values at the 95% probability level. The phenotypic selection was made based on the critical phenotypic value, resulting in 45.0%, 88.4%, 27.1%, and 79.1% of the offspring selected for FHT, FW, SSC, and acidity, respectively, and 12.4% simultaneously for all four fruit traits. The results showed that the phenotypic primary selection reduced the population size to 12.4%, avoiding the discarding of target genotypes with a low risk. If breeders intend to further reduce the population size, then increasing the number of traits subject to primary selection would be effective.

Open Access

This work assessed the alleviating effects of bacteria (Bacillus subtilis) and phosphorus as environmentally friendly materials on the cultivation of pepper plants in polluted soil with lead (Pb) in forms of PbSO4, and Pb(NO3)2 at rates of 0, 1000, 2000 and 3000 µg Pb/g soil. Pot experiments were conducted to study the growth parameters, some physiological factors, biochemical constituents, and yield attributes, as well as the tolerance index (TI), translocation factor (TF), bioconcentration factor (BCF), and health effects [daily intake of heavy metals (DIM), health risk index (HRI), and carcinogenic risk (CR)]. Increasing the Pb concentration of all Pb salt used in soil severely affected the plant vegetative growth parameters. In comparison with other Pb salt forms, Pb(NO3)2 salt had a strong inhibitory impact. Additionally, the photosynthetic pigments in leaves were negatively impacted by all Pb salt forms. The application of Pb in all salt forms led to changes in the leaf water deficit (LWD), osmotic pressure, and membrane integrity and decreased the total water content, relative water content (RWC), transpiration rate, and leaf succulence. Pollution with Pb salts considerably decreased the yield constituents and various chemical properties of pepper, more so in the presence of Pb nitrate than in the presence of Pb sulfate type. A comparison of the concentration of Pb presence of Pb nitrate was greatly increased than the Pb sulfate in the whole plants. The safe limit of 0.3 mg/kg was exceeded by the Pb concentration in pepper fruits (6.3 and 4.3 mg/kg) cultivated in Pb-contaminated soil [with Pb(NO3)2 and PbSO4, respectively]. Additionally, Pb sulfate had a greater detrimental effect on Pb uptake in several plant organs than other Pb salt forms. The TI of pepper plants treated with salt types was >60% with PbSO4 (75.6%), whereas it was <60% with Pb(NO3)2 (35.2%). The BCF values of pepper plants in the polluted Pb soils varied from 0.10 to 0.41, indicating a moderate accumulator plant. At every level of Pb contamination with all Pb salt types, the sequence of Pb TF values was as follows: roots (TFr) > shoots (TFsh) > fruits (TFf), with TF values < 1. When compared with TFr and TFsh, TFs for shoot to fruits (TFf) had the lowest values (range, 0.07–0.22). The DIM, HRI, and CR values of pepper plants revealed that the Pb of fruit of stressed pepper plants is within safe limits. In addition to reducing the detrimental effects of intolerable Pb levels (2000 and 3000 µg Pb/g soil) on the majority of the aforementioned characters, adding Bacillus bacteria as a bio-agent and phosphorus as a chemo-agent to Pb-polluted soils also stimulated growth, increased yield, controlled plant water relations, protected photosynthetic pigments, and sharply decreased the Pb accumulation in plant organs. The Bacillus bacteria application resulted in some superior characteristics, such as root length, leaf number, leaf length, leaf area, leaf area index, fresh biomass, dry biomass, photosynthetic pigments, quantity yield attributes, reduction Pb accumulation in all plant organs, TI, TFr, TFf, BCF, in health effects trials, whereas phosphorus application improved plant height, leaf width, RWC, LWD, osmotic pressure, total soluble solids, acidity, total carbohydrates, total protein, and TFsh.

Open Access

East African diploid cooking bananas, commonly called Mchare, are a staple crop for millions of subsistence farmers in Tanzania, particularly in the Pangani region in northern Tanzania. Several pathogens constrain Mchare production significantly and threaten food security. Sources of resistance to these pathogens have been identified; however, partial male and female sterility impedes successful resistance introgression, complicating the breeding process. Mchare cultivars are also the only known surviving representatives of a diploid banana subgroup that contributed unreduced gametes to many of the most widely grown and successful triploid dessert bananas (‘Cavendish’, ‘Gros-Michel’, ‘Silk’, and ‘Prata’). As such, they represent an essential intermediate step in the conventional improvement of bananas worldwide. We assess the amount and viability of pollen among Mchare and wild genotypes to identify the most fertile Mchare cultivars that can be used in conventional banana improvement. Pollen was collected from 14 banana genotypes for quantification and viability testing over 7 months, and the optimal time for pollen collection was determined to be 0800 HR. Significant variation among banana genotypes in terms of both overall pollen production and percentage of pollen viability was observed. The wild-type bananas ‘Calcutta 4’ [International Musa Germplasm Transit Center (ITC) 0249] and ‘Borneo’ (ITC0253) had the greatest overall pollen production (> 31,000 pollen grains/anther) and viability (∼74%), whereas ‘Ijihu Inkundu’ (ITC1460; Mchare genotype) was the least productive (almost completely sterile), with an average pollen production of a few hundred grains per anther and a viability of 7%. There were significant differences among months in terms of pollen viability, with the greatest average viability observed in May, April, and February (> 51%), and the lowest average pollen viability in July (41%). Significant differences were observed among the Mchare genotypes, with ‘Huti-White’, ‘Huti green bell’ (ITC1559), and ‘Mchare Laini’ consistently producing more substantial amounts of total pollen and an overall more significant proportion of viable pollen. This information is vital to improve Mchare bananas and the global breeding of dessert bananas. The choice of Mchare banana used in improvement programs could affect fertility and the likelihood of breeding success.

Open Access

Specialty eggplants (Solanum melongena L.), cultivars with fruit shapes, sizes, and colors different from the typical teardrop-shaped, dark purple eggplant fruit, are an underproduced vegetable commodity in the southeastern United States. Seven cultivars representing seven different fruit types were grown in Charleston, SC, USA, in Spring and Fall 2018 and 2019 to assess cultivar productivity and net return. Despite year-to-year variability, Hansel (Chinese type), Millionaire (Japanese type), and Gretel (white fruit) generally had greater weights of both marketable (US Fancy and No. 1 fruit) and edible (US Fancy, No. 1 and No. 2) fruit than Fairy Tale (Sicilian type) and Patio Baby (Indian type), whereas the globe-fruited cultivars Black Beauty (heirloom) and Rosa Bianca (Italian type), had intermediate yields. Yields of plants after ratooning in the fall were lower than in the spring before ratooning. Prices per carton paid by local food hubs for US Fancy, No. 1, and No. 2 fruit were two to three times greater than wholesale terminal market prices. Nevertheless, fruit weights were a greater determinant of net returns than prices were. Growers in the southeastern coastal plain can maximize net returns from specialty eggplant crops by choosing cultivars that produce high fruit weights.

Open Access

Cucumber (Cucumis sativus L.) belongs to the cucumber genus of the Cucurbitaceae family, and the selection of cultivars with minimal or no lateral branches can enhance the cultivation management efficiency. The growth of lateral branches is inhibited by strigolactone. To investigate the regulatory mechanism of strigolactone on the lateral branch development in cucumber, the cultivar LZ1 exhibiting multiple lateral branches was selected as the experimental material. The axillae of the plants were infiltrated with 1, 5, and 10 μmol·L−1 germination releaser 24 (GR24) at the four- to five-leaf stage. It was identified that 1 μmol·L−1 GR24 exhibited the most potent inhibitory effect on cucumber lateral branches. Additionally, exogenous strigolactone decreased the auxin content in the apical bud and axillae and increased the auxin content in the stem. This inhibited polar auxin transport in the axillary bud and promoted polar auxin transport in the apical bud. The content of strigolactone in the axilla region of cucumbers was elevated, whereas the synthesis and expression of cytokinin in the same area were reduced. A low concentration of GR24 induced the expression of cucumber branched 1 (csbrc1), whereas a high concentration of GR24 downregulated the expression of cucumber lateral suppressor (cscls) and blind (csblind), which inhibited the growth of cucumber lateral branches.

Open Access

Huanglongbing (HLB), which is associated with the phloem-limited bacteria Candidatus Liberibacter asiaticus (CLas), is a devastating disease that affects citrus trees worldwide. Because of the pervasiveness of the bacteria and psyllid vector, the disease is considered endemic in Florida. Although the effects of CLas on tree growth and physiology have been investigated for decades, most studies compared infected and noninfected trees under greenhouse conditions. This study used newly planted field-grown ‘Valencia’ sweet orange (Citrus sinensis) trees on two different rootstocks to monitor the distribution and accumulation of CLas in aboveground and belowground tissues following natural psyllid colonization and assess tree physiological responses and biomass reductions under HLB-endemic conditions. Trees were transplanted into the field with individual protective covers (IPCs), which are used to exclude psyllids and prevent infection. Openings were cut in the IPCs of half of the trees; to promote infection, these IPCs were temporarily removed during the main vegetative flushing period when psyllid populations were high. All trees that were exposed to psyllids became infected and displayed the symptoms typically associated with HLB. Throughout the study, higher levels of CLas were detected in the leaves compared with those in the fibrous roots. Trees that were not exposed to psyllids remained noninfected and healthy. After 18 months, a subset of trees was excavated to assess biomass differences between infected and noninfected trees. Infected trees had root system reductions of 37% and shoot system reductions of 20%, thereby significantly reducing the belowground-to-aboveground biomass ratio. Fibrous root loss was 49% and more severe than the loss of the rest of the root tissue. This study is the first to demonstrate the full extent of damage caused by CLas infection under natural HLB-endemic conditions. The results confirm previous observations that suggested fibrous root loss as one of the major consequences of infection and colonization with CLas. They also reinforce the benefits of using IPCs to prevent infection of young citrus trees during the first years of growth in the field.

Open Access

Like everything for the past 2 centuries, agriculture has depended increasingly on fossil fuel energy. Pressures to shift to renewable energy and changes in the fossil fuel industry are set to massively alter the energy landscape over the next 30 years. Two near-certainties are increased overall prices and/or decreased stability of energy supplies. The impacts of these upheavals on specialty crop production and consumption are unknowable in detail but the grand lines of what will likely change can be foreseen. This foresight can guide the research, extension, and teaching needed to successfully navigate a future very unlike the recent past. Major variables that will influence outcomes include energy use in fertilizer manufacture, in farm operations, and in haulage to centers of consumption. Taking six increasingly popular fruit and vegetable crops and the top two horticultural production states as examples, here we use simple proxies for the energy requirements (in gigajoules per ton of produce) of fertilizer, farm operations, and truck transport from Florida or California to New York to compare the relative sizes of these requirements. Trucking from California is the largest energy requirement in all cases, and three times larger than from Florida. As these energy requirements themselves are all fairly fixed, but in future will likely rise in price and/or be subject to interruptions and shortages, this pilot study points to two commonsense inferences: First, that fruit and vegetable production and consumption are set to reposition to more local/regional and seasonal patterns due to increasing expenses associated with fuel, and second, that coast-to-coast produce shipment by truck will become increasingly expensive and difficult.

Open Access

During the past 40 years, the US fresh-cut product market has experienced a consistent increase in demand because consumers prioritize health and convenience. Increased interest in fresh-cut products and ready-to-eat vegetables has led to innovations in breeding, product selection, and packaging. However, despite the increased popularity of bell pepper and chile pepper (Capsicum annuum L.), research of fresh-cut jalapeño pepper is limited. This study was conducted to identify jalapeño cultivars that could be suitable as a raw fresh-cut product and explore measures beyond tissue membrane electrolyte leakage (EL) of processed products that may be useful for the identification of cultivars suitable for fresh-cut applications. A total of 22 fresh-cut parameters were examined across five cultivars of jalapeño peppers and 10 intercrosses of these cultivars, including visual quality based on an image analysis via a computer vision system, package headspace gas composition, tissue membrane EL, and texture. Based on our results, the genotypes were grouped into five clusters using a cluster analysis. Variables including tissue softening (r2 = 0.95), EL (r2 = 0.95), total energy of the mesocarp (r2 = 0.95), and package headspace carbon dioxide (CO2) partial pressure (r2 = 0.94) had strong associations with the cluster. A principal component analysis with biplots further confirmed the results. Cultivars Goliath and Emerald Fire and their hybrids in the first and second clusters showed good quality for fresh-cut applications. The fifth cluster, represented by a single cultivar, Jalapeño M, had the smallest physical size, rapid shelf-life decline, accumulated CO2 partial pressures, increased EL, and rapid tissue softening in comparison with the other genotypes. All jalapeño cultivars except Jalapeño M maintained good quality until day 14 postprocessing, and some maintained good quality until 21 days postprocessing. Hybrid crosses suggested that two of the cultivars evaluated, Goliath and Emerald Fire, were useful as parents when transferring superior fresh-cut quality traits to progeny. Traditionally, the EL level has been used as an index of freshness (or tissue deterioration). Our results showed that other quality analyses, including measurements of tissue softening via an imaging analysis, and physical analyses of tissue firmness can also be used as indices for the freshness of fresh-cut jalapeños. The results suggest that fruit size, wall thickness, and skin toughness might be useful as predictive measures in the field for the selection of jalapeño genotypes with superior fresh-cut quality.

Open Access

Northern highbush blueberry (Vaccinium corymbosum L.) often requires frequent irrigation for commercial production, but irrigation is becoming increasingly challenging for many growers because of warmer and drier weather conditions, increased water regulations, and other water-use limitations. The purpose of this study was to develop improved methods of irrigation to prepare the industry more effectively against future water uncertainties. Treatments were applied for 2 years (2021 and 2022) and included a combination of weather-based or fixed irrigation schedules using continuous or pulse irrigation in a commercial field of ‘Draper’ blueberry in eastern Washington, USA. The soil at the site was a silt loam, and irrigation was applied using two laterals of drip tubing per row. Plants on a fixed schedule were irrigated for 12 to 13 hours per application (set by the grower), whereas those on a weather-based schedule were irrigated according to daily estimates of crop evapotranspiration (downloaded from an automated weather station). In both cases, irrigation was applied every 2 to 4 days as a single, continuous application or in 30- to 50-minute pulses every 2 hours (up to nine times per day) with the same amount of water as the continuous treatment. During the first year of the study, weather-based scheduling maintained greater stem water potentials in the plants and, on average, increased yield by 3.4 t⋅ha–1, berry weight by 0.14 g/berry, berry diameter by 0.4 mm, and fruit bud set by 4.3% when compared with fixed scheduling. Likewise, pulse irrigation maintained greater stem water potentials and, on average, increased berry weight and diameter by 0.10 g and 0.4 mm, respectively, fruit bud set by 3.3%, and canopy cover by 2.4% relative to continuous irrigation. Yield and canopy cover were unaffected by any treatment in the second year, which was likely a result of uncharacteristically cool, wet weather in the spring. However, weather-based scheduling continued to maintain greater stem water potentials and, when combined with pulse irrigation, increased berry weight and diameter by 3.7 g and 1.0 mm, respectively, relative to continuous irrigation on a fixed schedule. Pulse drip irrigation also increased fruit bud set by 5.1% during the second year. These results demonstrate the potential benefits of using weather-based scheduling and pulse drip in northern highbush blueberry, especially when the plants are grown on light-textured soils in hot, dry climates.

Open Access