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Horticulturae, Volume 7, Issue 4 (April 2021) – 27 articles

Cover Story (view full-size image): Challenging weather conditions force farmers around the world to find innovative solutions to grow foods that are necessary for their livelihood. In the Central Dry Zone of Myanmar, to face water shortage and low vegetable production, mainly during the dry season, farmers have adopted simplified cropping systems to grow green leafy vegetables. The starting point to ensure final vegetable cultivation success depends primarily on high-quality seedlings. This contribution focuses on two fundamental factors that significantly affect seedlings' growth at the early development stage, substrate and nutrient solution, offering optimal standards to enhance seedlings’ vegetable production in this semi-arid context. View this paper
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14 pages, 4565 KiB  
Article
A Transcriptomic Analysis of Gene Expression in Chieh-Qua in Response to Fusaric Acid Stress
Horticulturae 2021, 7(4), 88; https://doi.org/10.3390/horticulturae7040088 - 19 Apr 2021
Cited by 2 | Viewed by 2224
Abstract
Fusarium wilt results in undesirable effects on the quality and production of chieh-qua (Benincasa hispida Cogn. var. Chieh-qua How). Fusaric acid (FA), a secondary metabolite of biotin produced by pathogens of genus Fusarium, induced resistant responses in chieh-qua; however, the physiological and [...] Read more.
Fusarium wilt results in undesirable effects on the quality and production of chieh-qua (Benincasa hispida Cogn. var. Chieh-qua How). Fusaric acid (FA), a secondary metabolite of biotin produced by pathogens of genus Fusarium, induced resistant responses in chieh-qua; however, the physiological and molecular mechanism(s) of FA resistance remains largely unknown. In our study, ‘A39’ (FA-resistant cultivar) exhibited decreased malondialdehyde (MDA) content and increased superoxide dismutase (SOD) enzyme activity when exposed to FA compared with ‘H5’ (FA-susceptible cultivar). More apoptosis cells existed in ‘H5’ than ‘A39’ after 2 days of FA treatment. RNA-seq results revealed that a total of 2968 and 3931 differentially expressed genes (DEGs) were detected under normal conditions (1562 up-regulated and 1406 down-regulated) and FA treatment (2243 up-regulated and 1688 down-regulated), respectively. Interestingly, DEGs associated with pathogen-related protein and ethylene (ET) biosynthesis and signal pathways were most significantly changed during FA stress. Notably, several crucial genes encoding pathogenesis-related protein (CL4451.Contig2, CL2175.Contig4), peroxidase (Unigene49615 and CL11695.Contig2), and ET-responsive transcription factors (TFs) (CL9320.Contig1, CL9849.Contig3, CL6826.Contig2, CL919. Contig6, and CL518.Contig7) were specifically induced after FA treatment. Collectively, the study provides molecular data for isolating candidate genes involved in FA resistance, especially ET related genes in chieh-qua. Full article
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10 pages, 2188 KiB  
Article
A Quantitative Management of Potassium Supply for Hydroponic Production of Low-Potassium Cherry-Type Tomato Fruit for Chronic Kidney Disease Patients
Horticulturae 2021, 7(4), 87; https://doi.org/10.3390/horticulturae7040087 - 19 Apr 2021
Cited by 3 | Viewed by 2658
Abstract
Chronic kidney disease (CKD) has been a global health problem in recent years. CKD patients often restrict their potassium (K) intake to avoid the high risk of hyperkalemia. In this study, quantitative K management in hydroponics was adopted to produce low K cherry-type [...] Read more.
Chronic kidney disease (CKD) has been a global health problem in recent years. CKD patients often restrict their potassium (K) intake to avoid the high risk of hyperkalemia. In this study, quantitative K management in hydroponics was adopted to produce low K cherry-type tomato (Solanum lycopersicom L.) fruit. The total quantity of K supply per plant during the cultivation was 7.2 g (1 K), 3.6 g (1/2 K), 1.8 g (1/4 K), 0.9 g (1/8 K) and 0.6 g (1/12 K), respectively. The total fruit yield decreased to about 75% at 1/2 K and 58% at 1/12 K compared to 1 K. The fruit K content was lower in 1/4 K, 1/8 K and 1/12 K than in 1 K and 1/2 K, and the fruit from 1/8 K and 1/12 K achieved below 100 mg 100 g−1 FW of K. Total soluble solid content (Brix) was 7–8% in 1 K and 1/4 K but was lower in 1/8 K and 1/12 K. Fruit acid content decreased to 87% in 1/2 K to 70% in 1/4 K and 1/8 K, and to 57% in 1/12 K of 1 K. In conclusion, quantitative K management in hydroponics is expected to produce low K tomato fruit. Fruit K content of approximately 100 mg.100 g−1 FW was achieved when the quantity of K supply was 1/4 K and 1/8 K, with a relatively smaller effect on fruit yield, Brix and acid content. Full article
(This article belongs to the Special Issue Hydroponics in Vegetable Production)
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18 pages, 1324 KiB  
Review
Temperate Fruit Trees under Climate Change: Challenges for Dormancy and Chilling Requirements in Warm Winter Regions
Horticulturae 2021, 7(4), 86; https://doi.org/10.3390/horticulturae7040086 - 19 Apr 2021
Cited by 25 | Viewed by 11997
Abstract
Adequate chill is of great importance for successful production of deciduous fruit trees. However, temperate fruit trees grown under tropical and subtropical regions may face insufficient winter chill, which has a crucial role in dormancy and productivity. The objective of this review is [...] Read more.
Adequate chill is of great importance for successful production of deciduous fruit trees. However, temperate fruit trees grown under tropical and subtropical regions may face insufficient winter chill, which has a crucial role in dormancy and productivity. The objective of this review is to discuss the challenges for dormancy and chilling requirements of temperate fruit trees, especially in warm winter regions, under climate change conditions. After defining climate change and dormancy, the effects of climate change on various parameters of temperate fruit trees are described. Then, dormancy breaking chemicals and organic compounds, as well as some aspects of the mechanism of dormancy breaking, are demonstrated. After this, the relationships between dormancy and chilling requirements are delineated and challenging aspects of chilling requirements in climate change conditions and in warm winter environments are demonstrated. Experts have sought to develop models for estimating chilling requirements and dormancy breaking in order to improve the adaption of temperate fruit trees under tropical and subtropical environments. Some of these models and their uses are described in the final section of this review. In conclusion, global warming has led to chill deficit during winter, which may become a limiting factor in the near future for the growth of temperate fruit trees in the tropics and subtropics. With the increasing rate of climate change, improvements in some managing tools (e.g., discovering new, more effective dormancy breaking organic compounds; breeding new, climate-smart cultivars in order to solve problems associated with dormancy and chilling requirements; and improving dormancy and chilling forecasting models) have the potential to solve the challenges of dormancy and chilling requirements for temperate fruit tree production in warm winter fruit tree growing regions. Full article
(This article belongs to the Section Biotic and Abiotic Stress)
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15 pages, 1033 KiB  
Article
Peach, Apple, and Pear Fruit Quality: To Peel or Not to Peel?
Horticulturae 2021, 7(4), 85; https://doi.org/10.3390/horticulturae7040085 - 17 Apr 2021
Cited by 13 | Viewed by 4335
Abstract
The nutritional value of the peeled and unpeeled fruit (peel plus flesh tissues) was studied using four peach (Prunus persica L.; Red Heaven, Maria Blanca, Big Top, and Queen Giant), two pear (Pyrus communis L.; Santa Maria, Pyrus pyrifolia N.; Nashi), [...] Read more.
The nutritional value of the peeled and unpeeled fruit (peel plus flesh tissues) was studied using four peach (Prunus persica L.; Red Heaven, Maria Blanca, Big Top, and Queen Giant), two pear (Pyrus communis L.; Santa Maria, Pyrus pyrifolia N.; Nashi), and three apple (Malus domestica Borkh.; Gala, Granny Smith, and Red Chief) cultivars. Based on principal components analysis (PCA) models, there was a clear differentiation among the cultivars’ and the peeled fruits’ nutritional characteristics in comparison to the unpeeled ones. Increased antioxidant capacity and content of total phenols and flavonoids of peaches (Red Heaven and Maria Blanca) versus nectarines (Big Top and Queen Giant) were recorded. In contrast, nectarines were characterized by higher hydroxycinnamates and dry matter. The apples’ cultivar Granny Smith exhibited a high level of titratable acidity (TA), while the Gala displayed a high level of soluble solids concentration (SSC), carotenoids, dry matter, hydroxycinnamic acids, and flavonols at the unpeeled fruit, whereas the Red Chief by increased anthocyanins, antioxidant capacity, total phenols, and flavonoids. Nashi pears with peel were more beneficial due to the strong skin contribution in the fruits’ beneficial compounds content. The peel of the Granny Smith cultivar was associated with an increased level of P, K, Ca, and Mg, whereas that of Red Chief with increased anthocyanins and Mg content. Full article
(This article belongs to the Special Issue Improving Quality of Fruit)
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13 pages, 2620 KiB  
Article
Exogenous EBR Ameliorates Endogenous Hormone Contents in Tomato Species under Low-Temperature Stress
Horticulturae 2021, 7(4), 84; https://doi.org/10.3390/horticulturae7040084 - 17 Apr 2021
Cited by 31 | Viewed by 3347
Abstract
Low-temperature stress is a type of abiotic stress that limits plant growth and production in both subtropical and tropical climate conditions. In the current study, the effects of 24-epi-brassinolide (EBR) as analogs of brassinosteroids (BRs) were investigated, in terms of hormone content, antioxidant [...] Read more.
Low-temperature stress is a type of abiotic stress that limits plant growth and production in both subtropical and tropical climate conditions. In the current study, the effects of 24-epi-brassinolide (EBR) as analogs of brassinosteroids (BRs) were investigated, in terms of hormone content, antioxidant enzyme activity, and transcription of several cold-responsive genes, under low-temperature stress (9 °C) in two different tomato species (cold-sensitive and cold-tolerant species). Results indicated that the treatment with exogenous EBR increases the content of gibberellic acid (GA3) and indole-3-acetic acid (IAA), whose accumulation is reduced by low temperatures in cold-sensitive species. Furthermore, the combination or contribution of BR and abscisic acid (ABA) as a synergetic interaction was recognized between BR and ABA in response to low temperatures. The content of malondialdehyde (MDA) and proline was significantly increased in both species, in response to low-temperature stress; however, EBR treatment did not affect the MDA and proline content. Moreover, in the present study, the effect of EBR application was different in the tomato species under low-temperature stress, which increased the catalase (CAT) activity in the cold-tolerant species and increased the glutathione peroxidase (GPX) activity in the cold-sensitive species. Furthermore, expression levels of cold-responsive genes were influenced by low-temperature stress and EBR treatment. Overall, our findings revealed that a low temperature causes oxidative stress while EBR treatment may decrease the reactive oxygen species (ROS) damage into increasing antioxidant enzymes, and improve the growth rate of the tomato by affecting auxin and gibberellin content. This study provides insight into the mechanism by which BRs regulate stress-dependent processes in tomatoes, and provides a theoretical basis for promoting cold resistance of the tomato. Full article
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13 pages, 3215 KiB  
Article
The Effects of Post-Harvest Treatments on the Quality of Agastache aurantiaca Edible Flowers
Horticulturae 2021, 7(4), 83; https://doi.org/10.3390/horticulturae7040083 - 15 Apr 2021
Cited by 10 | Viewed by 2702
Abstract
Agastache spp. are used as ornamental plants for their pleasant aroma and the different colors of flowers. Nowadays, their edible flowers have become attractive for their nutraceutical properties. Post-harvest treatment appears as a crucial point to avoid impairment of the nutraceutical compounds and [...] Read more.
Agastache spp. are used as ornamental plants for their pleasant aroma and the different colors of flowers. Nowadays, their edible flowers have become attractive for their nutraceutical properties. Post-harvest treatment appears as a crucial point to avoid impairment of the nutraceutical compounds and aroma, so different treatments were tested to analyze their effect on the bioactive metabolites and volatilome. Results indicated that freeze-drying was the best solution to prolong the shelf life of these flowers. The use of high temperatures (50, 60, 70 °C) led to altered the composition of antioxidant compounds (phenolic compounds, flavonoids, anthocyanins, carotenoids). Air-drying at 30 °C was a reasonable method, even though time consuming. Concerning the aroma profile, all samples were dominated by oxygenated monoterpene compounds. Pulegone was the main or one of the major constituents of all samples together with p-menthone. Gas Chromatography-Mass Spectrometry results showed a correlation between the temperature and the number of identified compounds. Both fresh and freeze-dried samples evidenced a lesser number (10 and 19, respectively); when the temperature raised, the number of identified constituents increased. Statistical analyses highlighted significant differences between almost all aromatic compounds, even if both Principal Component and Hierarchical Cluster analyses differed at 60 and 70 °C and from the other treatments. Full article
(This article belongs to the Special Issue Nutritional and Antioxidant Value of Horticulturae Products)
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10 pages, 2572 KiB  
Study Protocol
Antifreeze Protein Improves the Cryopreservation Efficiency of Hosta capitata by Regulating the Genes Involved in the Low-Temperature Tolerance Mechanism
Horticulturae 2021, 7(4), 82; https://doi.org/10.3390/horticulturae7040082 - 15 Apr 2021
Cited by 2 | Viewed by 2155
Abstract
In this study, whether the addition of antifreeze protein (AFP) to a cryopreservative solution (plant vitrification solution 2 (PVS2)) is more effective in reducing freezing injuries in Hosta capitata than PVS2 alone at different cold exposure times (6, 24, and 48 h) is [...] Read more.
In this study, whether the addition of antifreeze protein (AFP) to a cryopreservative solution (plant vitrification solution 2 (PVS2)) is more effective in reducing freezing injuries in Hosta capitata than PVS2 alone at different cold exposure times (6, 24, and 48 h) is investigated. The upregulation of C-repeat binding factor 1 (CBF1) and dehydrin 1 (DHN1) in response to low temperature was observed in shoots. Shoots treated with distilled water (dH2O) strongly triggered gene expression 6 h after cold exposure, which was higher than those expressed in PVS2 and PVS2+AFP. However, 24 h after cold exposure, gene expressions detected in dH2O and PVS2 treatments were similar and higher than PVS2 + AFP. The expression was highest in PVS2+AFP when the exposure time was extended to 48 h. Similarly, nitric reductase activities 1 and 2 (Nia1 and Nia2) genes, which are responsible for nitric oxide production, were also upregulated in low-temperature-treated shoots, as observed for CBF1 and DHN1 expression patterns during cold exposure periods. Based on the gene expression patterns, shoots treated with PVS2+AFP were more likely to resist cold stress, which was also associated with the higher cryopreservation efficiency of PVS2+AFP compared to PVS2 alone. This finding suggests that the improvement of cryopreservation efficiency by AFP could be due to the transcriptional regulation of CBF1, DHN1, Nia1, and Nia2, which might reduce freezing injuries during cryopreservation. Thus, AFP could be potentially used as a cryoprotectant in the cryopreservation of rare and commercially important plant germplasm. Full article
(This article belongs to the Section Genetics, Genomics, Breeding, and Biotechnology (G2B2))
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12 pages, 14992 KiB  
Article
Cultivation Conditions Change Aroma Volatiles of Strawberry Fruit
Horticulturae 2021, 7(4), 81; https://doi.org/10.3390/horticulturae7040081 - 14 Apr 2021
Cited by 8 | Viewed by 2775
Abstract
Volatile compounds principally contribute to flavor of strawberry (Fragaria × ananassa) fruit. Besides to genetics, cultivation conditions play an important role in fruit volatile formation. Compared to soil culture as control, effects of substrate culture on volatile compounds of two strawberry [...] Read more.
Volatile compounds principally contribute to flavor of strawberry (Fragaria × ananassa) fruit. Besides to genetics, cultivation conditions play an important role in fruit volatile formation. Compared to soil culture as control, effects of substrate culture on volatile compounds of two strawberry cultivars (‘Amaou’ and ‘Yuexin’) were investigated. GC-MS analysis revealed significant difference in volatile contents of ‘Amaou’ strawberry caused by substrate culture. No significant effect was observed for cultivar ‘Yuexin’. For ‘Amaou’ strawberry from soil culture produced higher volatile contents compared with substrate culture. This difference is contributed by high contents of esters, lactones, ketones, aldehydes, terpenes, hydrocarbons, acids, furans and phenols in ‘Amaou’ strawberry fruit from soil culture. Furanones, beta-linalool, trans-Nerolidol and esters are major contributor to strawberry aroma, whose contents are higher in soil culture planted fruit when compared to substrate culture. Moreover, strawberry fruit from soil culture had higher transcripts related to volatile biosynthesis were observed, including FaQR, FaOMT, FaNES1, FaSAAT and FaAAT2. Full article
(This article belongs to the Collection Advances in Fruit Quality Formation and Regulation)
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14 pages, 2778 KiB  
Article
Effect of Pre-Harvest Supplemental UV-A/Blue and Red/Blue LED Lighting on Lettuce Growth and Nutritional Quality
Horticulturae 2021, 7(4), 80; https://doi.org/10.3390/horticulturae7040080 - 14 Apr 2021
Cited by 14 | Viewed by 3627
Abstract
Blue light and ultra-violet (UV) light have been shown to influence plant growth, morphology, and quality. In this study, we investigated the effects of pre-harvest supplemental lighting using UV-A and blue (UV-A/Blue) light and red and blue (RB) light on growth and nutritional [...] Read more.
Blue light and ultra-violet (UV) light have been shown to influence plant growth, morphology, and quality. In this study, we investigated the effects of pre-harvest supplemental lighting using UV-A and blue (UV-A/Blue) light and red and blue (RB) light on growth and nutritional quality of lettuce grown hydroponically in two greenhouse experiments. The RB spectrum was applied pre-harvest for two days or nights, while the UV-A/Blue spectrum was applied pre-harvest for two or four days or nights. All pre-harvest supplemental lighting treatments had a same duration of 12 h with a photon flux density (PFD) of 171 μmol m−2 s−1. Results of both experiments showed that pre-harvest supplemental lighting using UV A/Blue or RB light can increase the growth and nutritional quality of lettuce grown hydroponically. The enhancement of lettuce growth and nutritional quality by the pre-harvest supplemental lighting was more effective under low daily light integral (DLI) compared to a high DLI and tended to be more effective when applied during the night, regardless of spectrum. Full article
(This article belongs to the Special Issue Smart Farming Techniques for Protected Horticulture Facilities)
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12 pages, 1264 KiB  
Article
Water-Yield Relationship and Vegetative Growth of Wonderful Young Pomegranate Trees under Deficit Irrigation Conditions in Southeastern Italy
Horticulturae 2021, 7(4), 79; https://doi.org/10.3390/horticulturae7040079 - 12 Apr 2021
Cited by 7 | Viewed by 2203
Abstract
This investigation was carried out through three successive seasons (2017, 2018, and 2019) on young pomegranate trees of the Wonderful cultivar to study the effect of four different irrigation treatments (100%, 75%, 50%, and 25% of crop evapotranspiration—ETc) on vegetative growth [...] Read more.
This investigation was carried out through three successive seasons (2017, 2018, and 2019) on young pomegranate trees of the Wonderful cultivar to study the effect of four different irrigation treatments (100%, 75%, 50%, and 25% of crop evapotranspiration—ETc) on vegetative growth and the water–yield relationship. The study was conducted in Foggia (Apulia region, Southern Italy), an agricultural area characterized by strong wind speeds and scarce water resources. The results showed the effects of the different irrigation levels and seasons on the vegetative growth and fruit yield characteristics. The cumulative trunk diameter, the annual shoot growth, the number of fruits per tree, and the yield decreased from the full water restitution (100% ETc) to the severe water restriction (25% ETc). The weight and the size of fruits decreased significantly with the restriction of water volumes applied to the crop. A linear relationship between water consumption and yield (R = 1.00 in 2018 and 1.21 in 2019; n = 12) was found. The water use efficiency (WUE) gave no statistical differences among irrigation treatments. The yield response factors (Ky: 1.06 in 2018 and 0.99 in 2019) showed the sensitivity of pomegranates to water deficits. Full article
(This article belongs to the Section Fruit Production Systems)
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29 pages, 2847 KiB  
Review
Genetic Engineering of Eggplant (Solanum melongena L.): Progress, Controversy and Potential
Horticulturae 2021, 7(4), 78; https://doi.org/10.3390/horticulturae7040078 - 11 Apr 2021
Cited by 17 | Viewed by 15674
Abstract
Eggplant (Solanum melongena) is the third most important vegetable in Asia and of considerable importance in the Mediterranean belt. Although global eggplant production has been increasing in recent years, productivity is limited due to insects, diseases, and abiotic stresses. Genetic engineering [...] Read more.
Eggplant (Solanum melongena) is the third most important vegetable in Asia and of considerable importance in the Mediterranean belt. Although global eggplant production has been increasing in recent years, productivity is limited due to insects, diseases, and abiotic stresses. Genetic engineering offers new traits to eggplant, such as seedless parthenocarpic fruits, varieties adapted to extreme climatic events (i.e., sub- or supra-optimal temperatures), transcription factor regulation, overexpressing osmolytes, antimicrobial peptides, Bacillusthuringiensis (Bt) endotoxins, etc. Such traits either do not occur naturally in eggplant or are difficult to incorporate by conventional breeding. With controversies, Bt-expressing eggplant varieties resistant to eggplant fruit and shoot borers have already been adopted for commercial cultivation in Bangladesh. However, to maximize the benefits of transgenic technology, future studies should emphasize testing transgenic plants under conditions that mimic field conditions and focus on the plant’s reproductive stage. In addition, the availability of the whole genome sequence, along with an efficient in vitro regeneration system and suitable morphological features, would make the eggplant an alternative model plant in which to study different aspects of plant biology in the near future. Full article
(This article belongs to the Section Genetics, Genomics, Breeding, and Biotechnology (G2B2))
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17 pages, 3407 KiB  
Article
‘Hass’ Avocado Internal Disorders under Simulated Export Conditions and Its Relationship with Flesh Mineral Content and Preharvest Variables
Horticulturae 2021, 7(4), 77; https://doi.org/10.3390/horticulturae7040077 - 10 Apr 2021
Cited by 5 | Viewed by 2988
Abstract
The most important issues that affect consumer fruit acceptance in the ‘Hass’ avocado international market are flesh disorders. These defects can be influenced by both pre- and postharvest factors. The aim of this work was to evaluate the effect of the harvest season, [...] Read more.
The most important issues that affect consumer fruit acceptance in the ‘Hass’ avocado international market are flesh disorders. These defects can be influenced by both pre- and postharvest factors. The aim of this work was to evaluate the effect of the harvest season, storage time, mineral content, and preharvest variables on internal fruit disorders. Here, fruit was sampled from four farms in Antioquia (Colombia) at 22%, 26%, and 30% dry matter (DM) content. Samples were stored and ripened under simulated export conditions. Then, flesh bruising, flesh discoloration, body rots, vascular browning, stem end rot, and mineral content were assessed. The results showed that flesh disorders differ among farms and by harvest index and storage time. The most frequent defects found were vascular browning and stem end rot. Boron, calcium, nitrogen, manganese, magnesium, and potassium have a strong relationship with flesh disorders. Therefore, high boron and calcium contents, as well as a harvest at 26% DM, can substantially reduce avocado flesh disorders and improve internal fruit quality. Farmers that had a high flesh and soil mineral content and low rainfall and temperature produced fruits with fewer internal disorders. Full article
(This article belongs to the Section Postharvest Biology, Quality, Safety, and Technology)
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16 pages, 1883 KiB  
Article
Nutrient Concentration of African Horned Cucumber (Cucumis metuliferus L) Fruit under Different Soil Types, Environments, and Varying Irrigation Water Levels
Horticulturae 2021, 7(4), 76; https://doi.org/10.3390/horticulturae7040076 - 10 Apr 2021
Cited by 3 | Viewed by 2686
Abstract
The nutrient concentration of most crops depends on factors such as amount of water, growing environment, sunlight, and soil types. However, the factors influencing nutrient concentration of African horned cucumber fruit are not yet known. The objective of the study was to determine [...] Read more.
The nutrient concentration of most crops depends on factors such as amount of water, growing environment, sunlight, and soil types. However, the factors influencing nutrient concentration of African horned cucumber fruit are not yet known. The objective of the study was to determine the effect of different water stress levels, soil types, and growing environments on the nutrient concentration of African horned cucumber fruit. Freeze-dried fruit samples were used in the quantification of β-carotene and total soluble sugars. The results demonstrated that plants grown under the shade net, combined with severe water stress level and loamy soil, had increased total soluble sugars (from 8 to 16 °Brix). Under the shade-net environment, the combination of moderate water stress level and loamy soil resulted in increased crude protein content (from 6.22 to 6.34% °Brix). In addition, the severe water stress treatment combined with loamy soil, under greenhouse conditions, resulted in increased β-carotene content (from 1.5 to 1.7 mg 100 g−1 DW). The results showed that African horned cucumber fruits are nutrient-dense when grown under moderate water stress treatment on the loamy or sandy loam substrate in the shade-net and open-field environments. Full article
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16 pages, 2365 KiB  
Article
Quality of Immature and Mature Pepper (Capsicum annuum L.) Seeds in Relation to Bio-Priming with Endophytic Pseudomonas and Bacillus spp.
Horticulturae 2021, 7(4), 75; https://doi.org/10.3390/horticulturae7040075 - 07 Apr 2021
Cited by 5 | Viewed by 3477
Abstract
Fruit maturity for seed production can occur at various times because of the continual flowering of pepper plants. Accordingly, seeds with different maturity are acquired as the fruits are collected in a single harvest. Immature seeds obtained in this harvest may lead to [...] Read more.
Fruit maturity for seed production can occur at various times because of the continual flowering of pepper plants. Accordingly, seeds with different maturity are acquired as the fruits are collected in a single harvest. Immature seeds obtained in this harvest may lead to a decrease in the quality of seed lots. Therefore, this research aimed to evaluate the influence of four different endophytic bacteria strains (Pseudomonas fluorescens strain L5b, Pseudomonas gessardii strain L13, Bacillus subtilis strain Bs1 and Bacillus mojavensis strain ApBm) on germination and seedling vigor of immature and mature bell pepper seeds. To obtain seeds with different maturity levels, fruits were collected 45–49 days after flowering for immature seeds and 65–69 days for mature seeds. The effectiveness of these bacteria strains was examined by coating seeds with four different endophytic bacteria strains separately. Additionally, to see the activity of endophytic bacteria more clearly, a mock treatment with sterile water was added to the experiment as a control (+) group. Bio-priming (especially strain Bs1 and L13) improved germination and seedling emergence characteristics of both immature and mature seed lots compared to control groups (p < 0.05). The results demonstrate that bio-priming with beneficial endophytic bacteria can be used to stimulate the quality of both immature and mature seeds from the pepper. Full article
(This article belongs to the Section Propagation and Seeds)
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9 pages, 789 KiB  
Article
Calcium Carbonate Can Be Used to Manage Soilless Substrate pH for Blueberry Production
Horticulturae 2021, 7(4), 74; https://doi.org/10.3390/horticulturae7040074 - 07 Apr 2021
Cited by 15 | Viewed by 4161
Abstract
Blueberry (Vacciniumcorymbosum interspecific hybrids) production in soilless substrates is becoming increasingly popular. Soilless substrates have low pH buffering capacity. Blueberry plants preferentially take up ammonium, which acidifies the rhizosphere. Consequently, soilless substrates where blueberry plants are grown exhibit a tendency to [...] Read more.
Blueberry (Vacciniumcorymbosum interspecific hybrids) production in soilless substrates is becoming increasingly popular. Soilless substrates have low pH buffering capacity. Blueberry plants preferentially take up ammonium, which acidifies the rhizosphere. Consequently, soilless substrates where blueberry plants are grown exhibit a tendency to get acidified over time. Agricultural lime (CaCO3) is commonly used to raise soil and substrate pH in other crops, but it is rarely used in blueberry cultivation. We hypothesized that substrate amendment with low rates of agricultural lime increases substrate pH buffering capacity and provides nutritional cations that can benefit blueberry plants. We tested this hypothesis in a greenhouse experiment with ‘Emerald’ southern highbush blueberry plants grown in rhizoboxes filled with a 3:1 mix of coconut coir and perlite. We found that substrate amendment with CaCO3 did not cause high pH stress. This amendment maintained substrate pH between 5.5 and 6.5 and provided Ca and Mg for plant uptake. When blueberry plants were grown in CaCO3-amended substrate and fertigated with low pH nutrient solution (pH 4.5), they exhibited greater biomass accumulation than plants grown in unamended substrates. These results suggest that low rates of CaCO3 could be useful for blueberry cultivation in soilless substrates. Full article
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18 pages, 3334 KiB  
Article
Biochemical Responses and Leaf Gas Exchange of Fig (Ficus carica L.) to Water Stress, Short-Term Elevated CO2 Levels and Brassinolide Application
Horticulturae 2021, 7(4), 73; https://doi.org/10.3390/horticulturae7040073 - 07 Apr 2021
Cited by 6 | Viewed by 2744
Abstract
The identification of the key components in the response to drought stress is fundamental to upgrading drought tolerance of plants. In this study, biochemical responses and leaf gas exchange characteristics of fig (Ficus carica L.) to water stress, short-term elevated CO2 [...] Read more.
The identification of the key components in the response to drought stress is fundamental to upgrading drought tolerance of plants. In this study, biochemical responses and leaf gas exchange characteristics of fig (Ficus carica L.) to water stress, short-term elevated CO2 levels and brassinolide application were evaluated. The ‘Improved Brown Turkey’ cultivar of fig was propagated from mature two- to three-year-old plants using cuttings, and transferred into a substrate containing 3:2:1 mixed soil (top soil: organic matters: sand). The experiment was arranged as a nested design with eight replications. To assess changes in leaf gas exchange and biochemical responses, these plants were subjected to two levels of water stress (well-watered and drought-stressed) and grown under ambient CO2 and 800 ppm CO2. Water deficits led to effects on photosynthetic rate, stomatal conductance, transpiration rate, vapour pressure deficit, water use efficiency (WUE), intercellular CO2, and intrinsic WUE, though often with effects only at ambient or elevated CO2. Some changes in content of chlorophyll, proline, starch, protein, malondialdehyde, soluble sugars, and activities of peroxidase and catalase were also noted but were dependent on CO2 level. Overall, fewer differences between well-watered and drought-stressed plants were evident at elevated CO2 than at ambient CO2. Under drought stress, elevated CO2 may have boosted physiological and metabolic activities through improved protein synthesis enabling maintenance of tissue water potential and activities of antioxidant enzymes, which reduced lipid peroxidation. Full article
(This article belongs to the Special Issue The Metabolic Adaptations of Plants to Climate Change)
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6 pages, 573 KiB  
Article
Weekly Question-and-Answer Extension Radio Show Helps Listeners Adopt Environmentally Sound Horticulture Practices
Horticulturae 2021, 7(4), 72; https://doi.org/10.3390/horticulturae7040072 - 06 Apr 2021
Cited by 3 | Viewed by 2257
Abstract
Cooperative Extension has a long history of using radio broadcasts in educational programming. The Minneapolis, MN-based CBS affiliate WCCO Radio 830AM contacted the University of Minnesota Extension (UMNExt) in 2013 to reinstate an 8:00 AM Saturday live gardening show titled “Smart Garden”. After [...] Read more.
Cooperative Extension has a long history of using radio broadcasts in educational programming. The Minneapolis, MN-based CBS affiliate WCCO Radio 830AM contacted the University of Minnesota Extension (UMNExt) in 2013 to reinstate an 8:00 AM Saturday live gardening show titled “Smart Garden”. After several years of doing the radio show, we wanted to determine the effectiveness of getting information to listeners, what people were doing differently because of what they heard on the show, and how much they used the Extension’s resources after listening to the program. After analyzing 410 responses to an online survey, we found 78% of respondents reported they frequently or always learned something new when listening, and 56% reported adopting environmentally important practices, such as pollinator gardens, less chemical use, better lawn care, water conservation, and removing invasive plants. We concluded that this educational programming was making a positive impact on consumer horticulture practices. Full article
(This article belongs to the Special Issue Consumer Horticulture Advancement)
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8 pages, 1028 KiB  
Article
Multiple Amino Acids Inhibit Postharvest Senescence of Broccoli
Horticulturae 2021, 7(4), 71; https://doi.org/10.3390/horticulturae7040071 - 04 Apr 2021
Cited by 9 | Viewed by 2880
Abstract
The function of free amino acids in protein synthesis, as a source of energy and unique roles in catabolism have been well studied in plant development but their function in postharvest fruit and vegetables has received little attention. This study evaluated 11 amino [...] Read more.
The function of free amino acids in protein synthesis, as a source of energy and unique roles in catabolism have been well studied in plant development but their function in postharvest fruit and vegetables has received little attention. This study evaluated 11 amino acids—arginine, alanine, aspartic acid, glutamic acid, glycine, ornithine, phenylalanine, serine, tyrosine, tryptophan and valine—on the development of senescence of broccoli. Broccoli florets were dipped in 5 mM solution of amino acids, then stored at 10 °C in air containing 0.1 µL L−1 ethylene. Senescence was assessed by green life, ethylene production, respiration rate and ion leakage. Green life was increased by all the amino acids except valine. Similarly, ethylene production and ion leakage were decreased by all the amino acids except valine, while respiration rate was reduced by all amino acids. It is speculated that the early reduction in ethylene production could be the mechanism by which the amino acids delayed senescence. The beneficial effect of naturally occurring amino acids in inhibiting senescence has potential commercial relevance, as the amino acids have Generally Recognised As Safe (GRAS) status which should assist gain regulatory approval, and gain acceptance by consumers wary of synthetic chemicals on foods. Full article
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14 pages, 4496 KiB  
Article
Genome-Wide Analysis and Expression Tendency of Banana (Musa acuminata L.) Calcineurin B-Like (MaCBL) Genes under Potassium Stress
Horticulturae 2021, 7(4), 70; https://doi.org/10.3390/horticulturae7040070 - 03 Apr 2021
Cited by 5 | Viewed by 2471
Abstract
Calcineurin B-like (CBL) proteins are reported to play significant roles in plant development and ion-transport regulation. Potassium shortages are a serious problem in banana cultivation. However, to date, the members of the banana CBL gene family, and their function in regulating potassium stress, [...] Read more.
Calcineurin B-like (CBL) proteins are reported to play significant roles in plant development and ion-transport regulation. Potassium shortages are a serious problem in banana cultivation. However, to date, the members of the banana CBL gene family, and their function in regulating potassium stress, remain unclear. In this study, 11 CBL genes were identified from the banana genome and grouped into four groups (Group I–IV) based on their phylogenetic relationships. The genomic features of these MaCBL genes were analyzed, focusing on their gene structures, standpat motifs, chromosomal distributions, and evolutionary history. Expression pattern analysis revealed that the MaCBLs were function-specific. Further qRT-PCR analysis indicated that the presence of MaCBL2 was indeed a response to potassium deficiency stress. The MaCBL2 gene was cloned, and sequence alignment indicated that it contained four elongation factor hand (EF-hand) domains, the conserved N-terminal myristoylation domain “MGCXXS/K(T)” and the “FPSF” motif. Subcellular location analysis showed that MaCBL2 was located in the plasma membrane, nucleus and cytoplasm. The overexpression of MaCBL2 could restore the growth of the yeast mutant R5421 on a K+-deficient medium. The overexpression of MaCBL2 could promote the root length of transgenic seedlings on K+-deficient medium. These findings indicate that MaCBL2 was, in our study, the key gene of the CBL family in responding to potassium deficiency in bananas. Our discoveries have established a considerable basis for the further study and application of MaCBL genes. Full article
(This article belongs to the Section Genetics, Genomics, Breeding, and Biotechnology (G2B2))
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14 pages, 280 KiB  
Article
Fruit Yield and Physicochemical Quality Evaluation of Hybrid and Grafted Field-Grown Muskmelon in Pennsylvania
Horticulturae 2021, 7(4), 69; https://doi.org/10.3390/horticulturae7040069 - 03 Apr 2021
Cited by 7 | Viewed by 3540
Abstract
Selecting vegetable cultivars suitable to local environmental conditions and with quality traits desired by the evolving market and consumer needs is an important production decision farmers face annually. As seed companies continue to expand their offerings of new cultivars and rootstocks, selecting the [...] Read more.
Selecting vegetable cultivars suitable to local environmental conditions and with quality traits desired by the evolving market and consumer needs is an important production decision farmers face annually. As seed companies continue to expand their offerings of new cultivars and rootstocks, selecting the best cultivar and/or scion/rootstock combination can be challenging for farmers. Land-grant universities, through their integrated research and extension programs, can provide an unbiased, science-based evaluation of the available cultivar and rootstock options to assist farmers in making this important selection. A two-year study was conducted to evaluate 20 hybrid cultivars and two grafted entries of muskmelons at three locations in Pennsylvania in 2018 and 2019 to provide farmers with science-based recommendations focused on fruit yield and physicochemical quality characteristics. Most cultivars did not differ in fruit yields from the standard “Aphrodite”. “Sugar Cube” produced more, smaller sized melons than “Aphrodite”. However, the combination of the soluble solids concentration, flesh pH, and titratable acidity values was not as favorable, indicating that consumer preference may be lower for “Sugar Cube” than for other cultivars. Yield from grafted entries was not different from the non-grafted “Aphrodite”; although, biotic and abiotic stressors favoring the use of grafting were not present throughout the study. Physicochemical evaluation of the combination of “Aphrodite” scion and “Flexifort” rootstock was more favorable than “Aphrodite/RS841” and non-grafted “Aphrodite”. This combination may be desirable even in the absence of yield stressors. Full article
(This article belongs to the Special Issue Grafting to Improve Yield and Quality of Vegetable Crops)
12 pages, 640 KiB  
Article
Effects of Plant Age and Root Damage on Internalization of Shiga Toxin-Producing Escherichia coli in Leafy Vegetables and Herbs
Horticulturae 2021, 7(4), 68; https://doi.org/10.3390/horticulturae7040068 - 02 Apr 2021
Cited by 5 | Viewed by 2719
Abstract
Our previous study reported that fresh produce grown in aquaponic and hydroponic systems can pose potential food safety hazards due to an accidental introduction of contaminated fish and cross-contamination between the systems. In this study, we examined the effects of plant species and [...] Read more.
Our previous study reported that fresh produce grown in aquaponic and hydroponic systems can pose potential food safety hazards due to an accidental introduction of contaminated fish and cross-contamination between the systems. In this study, we examined the effects of plant species and age on the likelihood and level of internalization of Shiga toxin-producing Escherichia coli (STEC) in aquaponic and hydroponic systems. Four plant species, basil (Ocimum basilicum L. cv. Genovese), cilantro (Coriandrum Sativum L.), lettuce (Lactuca sativa cv. Cherokee), and kale (Brassica oleracea var. sabellica), received root damage treatment as seedlings before transplanting or mature plants at three weeks after transplanting by cutting off 1-cm tips of one-third of the roots. Enrichments and selective media were used for the isolation, and presumptive positive colonies were confirmed by PCR for the presence of stx1 gene in plant tissues, recirculating water, and fish feces collected at four weeks after transplanting. In hydroponic systems, STEC was found neither in the solution nor in the roots and leaves of all four plant species, possibly through improved sanitation and hygiene practices. However, consistent with our previous findings, STEC was found in the water, on the plant roots, and in the fish feces in aquaponic systems, even after thorough sanitation prior to the study. Regardless of plant age, STEC was internalized in the roots of all plant species when the roots were damaged, but there was no difference in the degree of internalization with STEC among plant species. STEC was present in the leaves only when seedlings received root damage treatment and were grown to maturity, indicating that root damage allows STEC to internalize in the roots within a week, but a longer period is required for STEC to internalize into the leaves. We concluded that root damage on seedlings can cause the internalization of E. coli O157:H7 in the edible parts of leafy vegetables and herbs in soilless production systems. Full article
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14 pages, 4131 KiB  
Article
Rangeland Management and Ecological Adaptation Analysis Model for Astragalus curvirostris Boiss
Horticulturae 2021, 7(4), 67; https://doi.org/10.3390/horticulturae7040067 - 02 Apr 2021
Cited by 30 | Viewed by 2667
Abstract
The present study investigates the ecological requirements of Astragalus curvirostris Boiss, with emphasis on determining the ecological factors that affect the distribution of plant species, and the species’ response to changes in ecological factors using a Generalized Additive Model (GAM) in the Iranian [...] Read more.
The present study investigates the ecological requirements of Astragalus curvirostris Boiss, with emphasis on determining the ecological factors that affect the distribution of plant species, and the species’ response to changes in ecological factors using a Generalized Additive Model (GAM) in the Iranian Province of Zanjan from 2017 to 2019. Randomized-systematic sampling was used to collect vegetation data. Data analysis was performed using SPSS17 and CANOC4.5 software. The results showed that the growth and development of A. curvirostris change according to environmental factors linked to the composition of the soil and the variety of the other species present. This model is indicative of a competitive limitation along the environmental gradient. By understanding all environmental parameters, the necessary steps could be taken towards planning proper management programs, including rangeland grazing management and determining the proper moment for seed collection, which will result in the conservation, improvement, and restoration of rangelands. Full article
(This article belongs to the Special Issue Sustainable Horticulture under Biotic and Abiotic Stresses)
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22 pages, 15887 KiB  
Review
Edible Flowers: Antioxidant Compounds and Their Functional Properties
Horticulturae 2021, 7(4), 66; https://doi.org/10.3390/horticulturae7040066 - 01 Apr 2021
Cited by 16 | Viewed by 6449
Abstract
Edible flowers have been widely consumed for ages until now. The attractive colors and shapes, exotic aroma, and delightful taste make edible flowers very easy to attain. Moreover, they also provide health benefits for consumers due to the unique composition and concentration of [...] Read more.
Edible flowers have been widely consumed for ages until now. The attractive colors and shapes, exotic aroma, and delightful taste make edible flowers very easy to attain. Moreover, they also provide health benefits for consumers due to the unique composition and concentration of antioxidant compounds in the matrices. Knowing the bioactive compounds and their functional properties from edible flowers is necessary to diversify the usage and reach broader consumers. Therefore, this reported review could be useful for functional product development, engaging the discussed edible flowers. We present a comprehensive review of edible flower composition and the functional properties of their antioxidant compounds, mainly phenolics. Full article
18 pages, 4616 KiB  
Article
Genetic Diversity Analysis of Tomato (Solanum lycopersicum L.) with Morphological, Cytological, and Molecular Markers under Heat Stress
Horticulturae 2021, 7(4), 65; https://doi.org/10.3390/horticulturae7040065 - 26 Mar 2021
Cited by 19 | Viewed by 4848
Abstract
Tomatoes are usually consumed daily in the human diet. High temperatures reduce the number of tomato yields per year. Heat stress has been considered one of the most prominent causes of alterations in morphological and molecular characteristics in crops that decrease normal growth, [...] Read more.
Tomatoes are usually consumed daily in the human diet. High temperatures reduce the number of tomato yields per year. Heat stress has been considered one of the most prominent causes of alterations in morphological and molecular characteristics in crops that decrease normal growth, production, and yield in diverse plants, including tomatoes (Solanum lycopersicum L.). In this study, we evaluated six tomato lines, namely G1, G2, G3, G4, G5, and G6, at morphological, molecular, and cytological levels under heat stress. The average results of two seasons (2018 and 2019) clarified that the G6, G1, and G2 lines recorded the highest flowering values, as well as some fruit and vegetative growth traits. Furthermore, G6 and G2 had the maximum number of fruits/plant, whereas G2 and G1 produced the highest yield/plant under high temperatures. The number of chromosomes in all lines was 2n = 24, except for G5, in which the number was 2n = 26, whereas chromosome sizes were small, ranging from 323.08 to 464.48 µm. The G1 cultivar was a symmetrical cultivar (primitive), having the highest total form percentage (TF%) and symmetry index (Syi) values and the minimum karyotype asymmetry index (ASK) value, whereas G4 was asymmetrical (advanced). Molecular marker analysis demonstrated that intersimple sequence repeat (ISSR) primers 49A, HB-14, 49A, 49B, and 89B presented the highest values for polymorphism percentage P%, marker index (MI), effective multiplex ratio (EMR), and polymorphism information content (PIC), respectively. In contrast, OP-A3, OP-B3, SCoT 2, and SCoT 12 primers showed the highest PIC, EMR, MI, P%, and resolving power (Rp) values across the studied random amplified polymorphic DNA (RAPD) and start codon-targeted (SCoT) primers. Moreover, ISSR revealed the highest number of unique specific markers (6), followed by RAPD (4) and SCoT (3) markers. Cluster analysis of combined cytological data and data relating to molecular marker attributes separated the G1, G2, and G3 lines into one group, whereas the other lines were clustered in another group. On the whole, the application of combined analysis using morphological, cytological, and molecular genetics techniques could be considered to provide suitable parameters for studying the evolution of the genetic divergence between the studied tomato lines. Full article
(This article belongs to the Special Issue Molecular Plant Breeding in Tomatoes)
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15 pages, 2722 KiB  
Article
Optimization of Substrate and Nutrient Solution Strength for Lettuce and Chinese Cabbage Seedling Production in the Semi-Arid Environment of Central Myanmar
Horticulturae 2021, 7(4), 64; https://doi.org/10.3390/horticulturae7040064 - 26 Mar 2021
Cited by 4 | Viewed by 3360
Abstract
The growing population of tropical countries has led to a new awareness of the importance of vegetables as a source of essential foods and nutrients. The success of vegetable cultivation depends to a large extent on high-quality seedlings. This work aimed at evaluating [...] Read more.
The growing population of tropical countries has led to a new awareness of the importance of vegetables as a source of essential foods and nutrients. The success of vegetable cultivation depends to a large extent on high-quality seedlings. This work aimed at evaluating the effects of different substrates and different nutrient solution concentrations on the development of lettuce and Chinese cabbage seedlings in a semi-arid tropical area. Three independent experiments were conducted at the Soil and Water Research Station at Yezin Agriculture University, Myanmar (Myanmar, 19.83° N; 96.27° E). In all experiments a randomized block design was implemented with four treatments and three repetitions. In the first experiment the adaptability of lettuce seedling to two substrates (namely a Hulls Manure mix composed by 50% of mature cattle manure and 50% of carbonized rice husk and a soil based substrate constituted by 70% local soil, 20% burned rice husk, and 10% fresh cattle manure) and two nutrient solutions with different electrical conductivities (ECs) (W0.1, stored rainwater with EC = 0.13 dS m−1 and NS1.2, nutrient solution with EC = 1.20 dS m−1) were tested. In the second and third experiments, two species (lettuce and Chinese cabbage) were assessed for their response to nutrient solution concentrations. In both crops, 4 fertigation treatments (W0.1; NS0.6; NS1.2; and NS1.8) were supplied, by modulating the concentration of a compound mineral fertilizer (15:15:15) in the following ranges: W0.1: 0 g L−1, electrical conductivity (EC) 0.13 dS m−1, NS0.6: 0.3 g L−1, EC of 0.60 dS m−1; NS1.2: 0.6 g L−1, 1.2 dS m−1 EC, and NS1.8: 0.9 g L−1, 1.8 dS m−1 EC. Adopting different substrates and applying different nutrient solutions significantly affected growth (fresh weight and leaf morphology) and some physiological parameters (stomatal conductance, leaf temperature, and leaf chlorophyll content) of lettuce and Chinese cabbage seedling. From the first experiment, the combination of the soil based substrate and NS1.2 treatments allowed us to improve the seedlings’ growth. In the second experiment, highest growth of lettuce and Chinese cabbage seedlings was associated with NS1.2 and NS1.8, respectively. The presented results allow for the optimization of both growing media and nutrient solution management when lettuce and Chinese cabbage seedling are produced in the Central Dry Zone of Myanmar. Full article
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13 pages, 1643 KiB  
Article
The Use of Halophytic Companion Plant (Portulaca oleracea L.) on Some Growth, Fruit, and Biochemical Parameters of Strawberry Plants under Salt Stress
Horticulturae 2021, 7(4), 63; https://doi.org/10.3390/horticulturae7040063 - 26 Mar 2021
Cited by 6 | Viewed by 3302
Abstract
Strawberry is a salt-sensitive plant adversely affected by slightly or moderately saline conditions. The growth, fruit, and biochemical parameters of strawberry plants grown under NaCl (0, 30, 60, and 90 mmol L−1) conditions with or without a halophytic companion plant ( [...] Read more.
Strawberry is a salt-sensitive plant adversely affected by slightly or moderately saline conditions. The growth, fruit, and biochemical parameters of strawberry plants grown under NaCl (0, 30, 60, and 90 mmol L−1) conditions with or without a halophytic companion plant (Portulaca oleracea L.) were elucidated in a pot experiment. Salt stress negatively affected the growth, physiological (stomatal conductance and electrolyte leakage), and biochemical parameters such as chlorophyll contents (chl-a and chl-b); proline, hydrogen peroxide, malondialdehyde, catalase, and peroxidase enzyme activities; total soluble solids; and lycopene and vitamin C contents, as well as the mineral uptake, of strawberry plants. The companionship of P. oleracea increased fresh weight, dry weight, and fruit average weight, as well as the total fruit yield of strawberry plants along with improvements of physiological and biochemical parameters. This study showed that the cultivation of P. oleracea with strawberry plants under salt stress conditions effectively increased strawberry fruit yield and quality. Therefore, we suggest that approaches towards the use of P. oleracea could be an environmentally friendly method that should be commonly practiced where salinity is of great concern. Full article
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9 pages, 13642 KiB  
Article
Efficacy of an Eco-Friendly Bloom Thinning Formulation on Mango Trees and Its Olfactory Effect on an Insect Pollinator, Apis mellifera
Horticulturae 2021, 7(4), 62; https://doi.org/10.3390/horticulturae7040062 - 24 Mar 2021
Cited by 1 | Viewed by 2693
Abstract
In various orchard fruit trees, thinning of blossoms and fruits is important to increase fruit size and quality and to promote a new bloom in the following season. Several chemical thinning agents are currently commercially available, but they are inconsistent and produce side [...] Read more.
In various orchard fruit trees, thinning of blossoms and fruits is important to increase fruit size and quality and to promote a new bloom in the following season. Several chemical thinning agents are currently commercially available, but they are inconsistent and produce side effects in crop plants and insect pollinators. Because of environmental concerns, developing alternative eco-friendly bloom thinning agents is necessary. We developed an eco-friendly bloom thinning formulation (BTF) using minerals and extracts of various medicinal plants. Our BTF spray (0.1%, w/v) decreased the number of fruits per tree (46.5%) and fruit yield per tree (81.5%) but increased the fruit weight (196.8%) compared with the control treatment; the spray induced a small number of larger mango fruits in the treated trees. We also investigated the effect of BTF on the olfactory behavior of Apis mellifera L. (Hymenoptera, Apidae), a major insect pollinator. We analyzed the behavioral changes of adult workers at two different concentrations (0.1% and 1%) of nine different BTF spray components using a Y-tube olfactometer. The behavioral responses of honey bees to nine BTF components showed significant differences. However, honey bees showed no clear attraction or repellent behavior towards the tested BTF components. Our results suggest that the newly developed eco-friendly BTF is practically applicable in mango orchards without interrupting honey bee behavior. Full article
(This article belongs to the Section Fruit Production Systems)
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