Showing papers in "Horticulture Environment and Biotechnology in 2015"

Blue LED light enhances growth, phytochemical contents, and antioxidant enzyme activities of Rehmannia glutinosa cultured in vitro

Abstract: The objective of the current study is to determine the effect of light quality on enhancement of growth, phytochemicals, antioxidant potential, and antioxidant enzyme activities at in vitro cultures of Rehmannia glutinosa Libosch. In vitro-grown shoot tip explants were cultured on the plant growth regulator (PGR)-free Murashige and Skoog (MS) medium and cultured under a conventional cool white fluorescent light (control), blue light emitting diode (LED) light or red LED light. After four weeks, the growth traits along with total phenol content, total flavonoid content, free radical scavenging activities, and antioxidant enzyme activities were measured. Interestingly, the blue or red LED treatments showed a significant increase in growth parameters compared with the cool white florescent light. In addition, the LED treatments increased the total phenol and flavonoid levels in leaf and root extracts. Furthermore, data on the total antioxidant capacity, reducing power potential, and DPPH radical scavenging capacity also revealed the enhancement of antioxidant capacity under both blue and red LED treatments. Especially, the blue LED treatment significantly increased the antioxidant enzyme activities in both the leaf and root, followed by the red LED treatment. Modulation in the spectral quality particularly by the blue LED induced the antioxidant defense line and was directly correlated with the enhancement of phytochemicals. Therefore, the incorporation of blue or red LED light sources during in vitro propagation of R. glutinosa can be a beneficial way to increase the medicinal values of the plant.

Growth, photosynthetic and antioxidant parameters of two lettuce cultivars as affected by red, green, and blue light-emitting diodes

Abstract: The addition of green light-emitting diodes (LEDs) to a combination of red and blue LEDs, which promote photosynthesis and growth in plants, is known to enhance plant growth in closed-type plant production systems. However, there is limited information on the effects of supplementary green light. This study aimed to determine the effect of red (R), green (G), and blue (B) LED ratios on the growth, photosynthetic, and antioxidant parameters in two lettuce (Lactuca sativa) cultivars, red leaf ‘Sunmang’ and green leaf ‘Grand Rapid TBR’. The seedlings were grown for 18 days and then cultivated in growth chambers equipped with LED lighting systems for 4 weeks. Combinations of six LED lighting sources (R:B = 9:1, 8:2, 7:3; R:G:B = 9:1:0, 8:1:1, 7:1:2) were manufactured to emit red (655 nm), blue (456 nm), or green (518 nm) lights under photosynthetic photon flux density of 173 ± 3 μmol·m-2·s-1. Red LEDs were found to improve growth characteristics such as fresh and dry weights of shoots and roots, and leaf area in combination with blue LEDs. The substitution of blue with green LEDs in the presence of a fixed proportion of red LEDs enhanced the growth of lettuce. In particular, the fresh weights of red leaf lettuce shoots under R8G1B1 were about 61% higher than those under R8B2. Furthermore, analysis of leaf morphology, transmittance, cell division rate, and leaf anatomy under treatments with green LEDs supported the enhanced growth of the two lettuce cultivars tested. Meanwhile, growth under blue LEDs led to the accumulation of antioxidant parameters in ‘Sunmang’. Thus, the results of this study suggest that the percentage of red, green, and blue LEDs is an important factor for the growth, development, and biosynthesis of secondary metabolites in plants and especially the supplemental irradiation of green LEDs based on the combination of red and blue LEDs can improve lettuce growth.

Growth, yield, chemical composition, and antioxidant activity of essential oils from two thyme species under foliar application of jasmonic acid and water deficit conditions

Abstract: Jasmonic acid (JA) exerts biological activity in plant responses to environmental stress as well as development. The effect of foliar application of JA and combination with deficit irrigation on some characteristics of two thyme species, including Thymus vulgaris and T. daenensis were investigated. Treatments comprised 0, 200, and 400 µL JA applied to plants under normal, slight drought, and mild drought stress conditions. Irrigation levels had a significant effect on growth traits in terms of herbage dry weight, plant height, number of branches, and leaf area index. Foliar application of JA influenced the essential oil yield and the main components of the oils. Percentages of carvacrol, γ-terpinene, and p-cymene in the oil extracted from the plants under stressed conditions were higher than non-stressed plants, whereas percentage of thymol was significantly reduced under drought stress. In both thyme species, the JA significantly improved carvacrol and thymol contents in the oils, antioxidant activity, plant height, and root length, but reduced the essential oil yield and amount of γ-terpinene in the oils. In conclusion, the foliar application of JA reduced the negative effects of water stress on thymol amount in T. daenensis, and γ-terpinene content in T. vuglaris.

Silicon alleviates salt stress by modulating antioxidant enzyme activities in Dianthus caryophyllus ‘Tula’

Abstract: Although silicon (Si) is not considered as an essential element, it is beneficial to the plant growth. Its effect is more evident under abiotic and biotic stress conditions. The objective of this study is to investigate the role of Si on the in vitro growth and resistance to salt stress of Dianthus caryophyllus ‘Tula’. The experiment was designed as a factorial design with 0, 50, or 100 mg·L−1 of potassium silicate (K2SiO3) in combination with 0, 50, or 100 mM sodium chloride (NaCl). The treatment of 50 mg·L−1 Si improved the growth of plant. However, the treatment of Si at 100 mg·L−1 reduced the growth. Although NaCl retarded the growth, addition of Si along with NaCl to the culture medium mitigated the effect of NaCl. A primary defense line by Si to overcome the photosynthetic depression was apparent from the increased chlorophyll content in the Si + NaCl treatment as compared to the treatment of NaCl alone. Enhancement of growth and resistance to salinity by Si was thought to be due to the modulation in activity of antioxidant enzymes, such as superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, and catalase. Therefore, our results suggested that 50 mg·L−1 Si supplementation could be optimal for improved growth in vitro and enhanced resistance against salinity in D. caryophyllus ‘Tula’.

Effects of salt stress on physiological and postharvest quality characteristics of different Iranian genotypes of basil

Abstract: This study examined the effects of salt stress on the physiological responses and postharvest quality characteristics of fresh sweet basil (Ocimum basilicum L.). Plants were treated with 40 and 80 mM NaCl for 25 days during cultivation in 2014. Two green genotypes, Green Iranian and Genovese basil, were studied after harvest, and while two Iranian genotypes, Green and Purple Iranian basil, were compared during storage. Yield and the stem length were significantly reduced under salt stress only in the two Iranian cultivars. Salinity significantly reduced leaf thickness and the area of parenchyma cells in both Green Iranian and Genovese basil. As salt concentration increased, transpiration and the content of chlorophylls decreased significantly while the lipid peroxidation increased in the Genovese genotype. During storage at 12°C, the respiration rate of salt-stressed leaves was similar to that of control leaves. The visual quality of Purple Iranian basil was better preserved during storage than the Green Iranian basil. However, salt stress positively affected the visual quality of Green Iranian basil, decreasing darkening and maintaining the quality above the limit of marketability after 7 days of storage. The total content of phenolic acids and anthocyanins did not show significant differences between growth conditions. However, during storage of Green Iranian basil, salt stress increased the content of individual and total phenolic acids compared to the control. To summarize, the positive or negative effects of salt stress on basil depend on the degree of tolerance of the different genotypes.

Comparison of accumulation of stilbene compounds and stilbene related gene expression in two grape berries irradiated with different light sources

Abstract: In this study, the accumulation of stilbene compounds and the expression of genes related to their syntheses in ‘Campbell Early’ and ‘Kyoho’ grapes (Vitis sp.) were investigated by irradiating the harvested berries with four different light sources (white fluorescent and purple, blue, and red LED lights) for 48 hours. The total concentrations of five stilbene derivatives at 24 hours after irradiation differed in response to different light sources and cultivars. The accumulation of stilbenic compounds in the skins of two grape cultivars and the expression of PAL and STS1 genes were mainly induced under red and blue LED lights. The expression of PAL, CHS, CHI, STS1, STS12, and ROMT was differently induced in response to irradiation with different light sources in both grape cultivars. The mRNA levels of PAL and STS1 were higher than those of CHS, CHI, STS12 and ROMT in the two grapes berries. Overall, the results of this study indicated that red and blue LED induced the accumulation of stilbene compounds and the expression of genes related to their syntheses in grape berries, suggesting that irradiation with LEDs can be used to induce the accumulation of phytochemicals that have positive impacts on human health via the induction of related genes.

Short-term low temperature increases phenolic antioxidant levels in kale

Abstract: The objective of this study was to determine the effect of short-term low temperature on the concentration of phenolic antioxidant compounds in kale. For the low-temperature treatment, two kale cultivars (‘Manchoo Collard’ and ‘TBC’) grown for 3 weeks in a growth chamber were subjected to 4°C for 3 days, and subsequently allowed to recover for 2 days under normal growth conditions (20°C). Fresh and dry shoot and root weights, chlorophyll fluorescence (potential quantum yield in dark-adapted conditions), reactive oxygen species (O2 ·- and H2O2), total phenolic concentration, antioxidant capacity, individual phenolics, and phenylalanine ammonia-lyase (PAL) activity were measured before and after treatment. No significant difference was observed between the control and low-temperature treatments in the fresh or dry shoot or root weights of either cultivar. The Fv/Fm decreased during the low-temperature treatment in both cultivars, and O2 ·- and H2O2 were generated in ‘Manchoo Collard’ leaves treated with low temperature but not in ‘TBC’ leaves. ‘Manchoo Collard’ had a 15% higher total phenolic concentration than the control after 2 days of recovery, whereas that of ‘TBC’ was 16% lower than that of the control. Individual phenolic compounds, such as caffeic acid, ferulic acid, and kaempferol, exhibited a similar trend to the total phenolic concentration and antioxidant capacity. The increased PAL activity in ‘Manchoo Collard’ at low temperature was in accord with the total and individual phenolic content results. These results suggest that a short-term low temperature during cultivation of kale in a controlled environment is a potential strategy to increase the plant’s phenolic antioxidant compound content.

Growth and Cell Division of Lettuce Plants under Various Ratios of Red to Far-red Light-emitting Diodes

Abstract: We investigated the effects of various ratios of red to far-red light-emitting diodes (LEDs) on growth characteristics, physiological response, and cell division of red leaf lettuce. Sixteen-day-old lettuce seedlings were transferred into growth chambers and cultivated under various ratios of red (R) and far-red (FR) LEDs (R/FR = 0.7, 1.2, 4.1, and 8.6), only red LEDs (RED), or fluorescent lamps (control) for 22 days. Growth characteristics were measured at 11 and 22 days of treatment. In addition, cell division rate, epidermal cell density, chlorophyll fluorescence, and photosynthesis of leaves were analyzed. Fresh and dry weights and leaf area in all R/FR treatments were higher than those in the control at 22 days of treatment. The R/FR 1.2 had the highest values among R/FR treatments. The number of leaves appeared to increase as R/FR ratio increased. The specific leaf weights in the R/FR ratio of 0.7, 1.2, and 8.6 were similar to the control at 22 days of treatment. The SPAD values in all R/FR treatments were lower than that in the control. All R/FR treatments led to a longer leaf shape than the control. The percentage of cells in the G2M phase, indicating the cell division rate, increased in the R/FR treatments after 4 days of treatment, which supported the growth improvement in the R/FR treatments. The Fv/Fm and the photosynthetic rate in all treatments decreased due to the absence of blue light. The results of this study suggest that the supplementation with far-red LEDs should be considered when designing artificial lighting systems for closed-type plant factories since far-red light affects the vegetative growth of leafy vegetables such as lettuce.

Effect of rootstock on growth, fruit production and quality of tomato plants grown under low temperature and light conditions

Abstract: We compared the growth of tomato plants ‘Jack’ grafted onto nine rootstocks with that of self-grafted and non-grafted plants, all grown in soilless culture in a heated greenhouse, to assess the capacity of commercial tomato rootstocks to improve fruit production and quality during the winter period under conditions of low temperature and light intensity. Neither vegetative development, estimated by the plastochron index, nor the thermal time required for a plastochron variation of one unit was significantly affected by the rootstock genotypes. Furthermore, the rootstock genotype did not mitigate the negative effects of low temperature and light conditions on fruit production. By contrast, the effect of the rootstock on the chemical composition of fruits and leaves was reflected by different allocation of N and C. Thus, the rootstocks affected the N contents of fruits and leaves and the C contents of fruits, but did not generally affect leaf C contents. The C/N ratios and mineral contents of fruits and leaves of grafted plants tended to decrease, leading to lower construction costs than in non-grafted or self-grafted plants. Thus, the use of rootstock reduced the energy needed to construct one unit of dry mass. Although the rootstock genotype did not affect fruit juiciness, titratable acidity (TA) or juice pH, it greatly influenced fruit quality parameters such as soluble solid content (SSC), SSC/TA ratio, juice electrical conductivity, ash contents, dry weight, firmness and puree consistency. Under the experimental conditions and in comparison with non-grafted and self-grafted plants, almost all rootstocks tended to be detrimental to the quality parameters considered.

Growth and quality of sprouts of six vegetables cultivated under different light intensity and quality

Abstract: Vegetable sprouts (alfalfa, broccoli, clover, kohlrabi, radish, and red radish) were cultivated under three monochromatic light regimes (red, green, and blue) with five different light intensities (0, 12.5, 25, 50, and 100 µmol·m−2·s−1) to investigate the effects of light intensity and quality on the growth and total phenolic content of the vegetable sprouts. The light quality and intensity had a direct effect on hypocotyl elongation in vegetable sprouts. Increasing blue light intensity enhanced suppression of hypocotyl elongation in all of the vegetable sprouts. Red light also reduced hypocotyl length in alfalfa and clover sprouts comparing those grown in darkness. The fresh weight of broccoli and radish sprouts markedly increased when red light intensity was 100 µmol·m−2·s−1; however, light use efficiency (LUE) decreased with increasing light intensity. Total phenolic content was reduced by increasing red light intensity in alfalfa and red radish sprouts.

Chemical composition and antioxidant properties of cultivated button mushrooms (Agaricus bisporus)

Abstract: Mushrooms contain a variety of secondary metabolites, including various phenolic compounds and ergothioneine, which have been shown to act as excellent antioxidants. The present study reports a comparison of the antioxidant properties, total phenolic, ergothioneine and mineral contents of the most-consumed strains of Agaricus bisporus (white or brown colors). The samples were fruiting body, mycelia produced at farm (old mycelium) and in vitro (young mycelium). The antioxidant activity was measured by DPPH, FRAP and ABTS assays. The analysis of phenolic compounds was performed by Folin-Ciocalteau method. The mushroom strain with the highest ergothioneine, phenolic compounds and antioxidant potential was the strain A-SPA15 (brown color). Generally, fruiting body samples revealed higher ergothioneine, phenolic compounds and antioxidant properties than mycelia obtained from farm and in vitro culture. There were variations in the mineral content of A. bisporus harvested from the fruiting body, old mycelium, and young mycelium. Furthermore, the lowest heavy-metal concentrations (Ni, Pb, Cd, and Cr) were detected in mycelium samples in each strain. Results demonstrated that mushrooms contained high amounts of copper, zinc, iron and manganese could be used in well-balanced diets. This study contributes to the data relative to A. bisporus consumed as fresh mushrooms and the possibility of in vitro production as a source of bioactive compounds.

Effect of maturity stage at harvest on antioxidant capacity and total phenolics in kiwifruits (Actinidia spp.) grown in Korea

Abstract: Six cultivars of kiwifruits grown in Korea, including Actinidia eriantha ‘Bidan’, A. arguta ‘Chiak’, A. arguta ‘Darae No. 2’, A. chinensis ‘Haegeum’, A. chinensis ‘Haehyang’, and A. arguta × A. deliciosa ‘Mansoo’, were harvested at various maturity stages to test whether kiwifruit maturity has an influence on antioxidant capacity or total phenolic and flavonoid contents. Kiwifruit extracts were isolated using absolute methanol and then 80% (v·v-1) aqueous methanol during homogenization. ‘Bidan’, collected at the second harvest stage, contained the greatest amount of total phenolics (775.3 mg gallic acid equivalents·100 g-1 fresh weight) and had the highest antioxidant capacity [816.5, 633.2, and 2,662.7 mg vitamin C equivalents·100 g-1 fresh weight for 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) scavenging, 1,1-diphenyl-2-picrylhydrazyl scavenging, and oxygen radical absorbance capacity assays, respectively] among cultivars tested, while ‘Haehyang’, collected at the first harvest, contained the greatest amount of total flavonoids (13.1 mg catechin equivalents·100 g-1 fresh weight). Kiwifruit cultivar and genotype influenced antioxidant capacity, as well as total phenolic and flavonoid contents. No trend, however, was observed in total phenolic and flavonoid contents, and in the antioxidant capacity with respect to maturity stage. Antioxidant capacity had a higher linear correlation coefficient with total phenolic contents than with total flavonoid contents. The results above suggest that kiwifruits at various maturity stages are a valuable source of phenolics and antioxidants for industrial application and consumer health benefit.

Enhanced salt tolerance of transgenic vegetable soybeans resulting from overexpression of a novel Δ1-pyrroline-5-carboxylate synthetase gene from Solanum torvum Swartz

Abstract: Vegetable soybeans [Glycine max (L.) Merrill] are susceptible to salt stress and, thus, soil salinity can severely affect their growth and productivity. To enhance the salt tolerance of vegetable soybeans, a novel Solanum torvum Swartz Δ1-pyrroline-5-carboxylate synthetase gene (StP5CS, GenBank accession number: JN606861) that encodes a critical regulatory enzyme in proline biosynthesis was transformed into the cultivar NY-1001 using an Agrobacterium-mediated transformation method. PCR and Southern blot analyses indicated that two independent T0 fertile transgenic plants were generated. The transgenic plants transmitted the transgenes into their T1 progeny in a 3:1 ratio. The T2 and T3 homozygous transgenic lines (HTLs) were examined for salt tolerance in pot and hydroponic cultures, respectively. The StP5CS overexpression conferred salt tolerance in T2 and T3 HTLs. Under NaCl stress conditions, the leaf scorch scores of T2 and T3 HTLs were significantly lower than those of wild-type (WT) plants. The plant height, leaf area, relative chlorophyll content, and number of fresh pods of T2 and T3 HTLs were significantly higher than those of WT plants. Compared with WT plants, T2 and T3 HTLs had significantly higher levels of proline and significantly lower levels of membrane lipid peroxidation. These results indicate that StP5CS overexpression in HTLs results in enhanced salt tolerance associated with higher levels of proline accumulation under salinity stress and that StP5CS can be utilized to improve salinity tolerance in vegetable crop genetic engineering.

Development of genomic SSR markers and genetic diversity analysis in cultivated radish ( Raphanus sativus L.)

Abstract: Radish (Raphanus sativus L.) is a major vegetable cultivated worldwide. As a member of the family Brassicaceae, this species has diverse morphological characteristics in root. Radish cultivars have been classified based on morphological traits, including root shape and color. Despite its economic importance in Asia, genomic research in radish is less well developed relative to Brassica rapa, a close relative of radish. In this study, we developed genomic simple sequence repeat (SSR) markers using a SSR-enriched library and investigated genetic diversity in a collection of 144 radish cultivars. A total of 237 primer pairs for SSRs were designed and 184 (77.6%) primer pairs produced PCR amplicons. Of these, we selected 27 SSR markers (14.7%) based on polymorphism in a subset of 11 cultivars and then used to assess genetic relationships in the germplasm panel. For these markers, the number of alleles per marker ranged from 2 to 18 with an average of 7.77 alleles and the polymorphism information content (PIC) values ranged from 0.491 to 0.906. The estimates of pairwise F st revealed significant genetic differentiation between the five market classes of 135 radish cultivars (74 big, 15 small, 29 young, 12 Altari, and 5 processing). Clustering analysis using NTSYS-pc and STRUCTURE software also found that the 74 big radishes were divided into 5–7 clusters. In addition, all 27 SSR markers were able to differentiate 64 big radish cultivars based on the UPGMA dendrogram and each of the 23 markers independently identified 1 to 17 big radish cultivars. These results suggest that cultivated radishes have different patterns of genetic variation and breeding practices should be a driving force for the genetic differentiation between and within market classes. The SSR markers developed in this study will be a useful resource for genetic study and protection of plant breeder’s intellectual property right through cultivar identification.

Sequence-characterized amplified polymorphism markers for selecting rind stripe pattern in watermelon (Citrullus lanatus L.)

Abstract: The inheritance of foreground stripe pattern in rind of watermelon fruits [Citrullus lanatus (Thunb.) Matsum. & Nakai] was evaluated and molecular markers for selecting the Jubilee-type (JT) stripe pattern were developed based on bulked segregant analysis (BSA). Divergence in rind pattern among F2 progeny derived from crossing Crimson-type (CT) ‘Arka Manik’ (AM) with JT ‘TS34’ (TS) indicated that stripe pattern is a quantitative trait controlled by more than one gene. The BSA of F2 plants (derived from a cross between ‘AM’ and ‘TS’) using 60 random amplified polymorphic DNA (RAPD) primers revealed a distinct RAPD band (AT14-900) polymorphic between ‘AM’ (CT) and ‘TS’ (JT). The AT14-900 sequence (925 bp) was blasted to the reference watermelon (97103) genome and high sequence similarity (97.8%) was identified on physical location of 26246077 to 26246993 bp on chromosome 6. Two expressed sequence tags (ESTs) designated ‘wsbin6-10’ and ‘wsbin6-11’ that were closely linked to AT14-900 on a genetic linkage map (developed using the F2 population derived from ‘AM’ x ‘TS’) were positioned 2,216 kb and 71 kb from AT14-900, respectively on the reference watermelon genome sequence. Marker genotyping of the F2 population showed that wsbin6-11 was tightly linked to the JT stripe pattern of ‘TS’ and could be a useful codominant marker for selecting this trait. In a test using 100 breeding lines, 34 of the 36 lines carrying the JT stripe pattern were homozygous for the wsbin6-11 marker (450 bp) derived from ‘TS’, while other lines (e.g., with no stripe or CT stripe pattern) were homozygous for the wsbin6-11 marker (420 bp) derived ‘AM’. These results indicated that wsbin6-11 would be a useful marker in watermelon breeding programs aiming to select for the JT stripe pattern from other various foreground and background rind patterns.

Effects of 1-MCP on reactive oxygen species, polyphenol oxidase activity, and cellular ultra-structure of core tissue in ‘Yali’ pear (Pyrus bretschneideri Rehd.) during Storage

Abstract: 1-methylcyclopropene (1-MCP) has been shown to delay fruit ripening and senescence during storage. In this study, we investigated the effects of 1.0 μL·L−1 1-MCP on the biochemical changes and cellular ultra-structure of the core tissue in ‘Yali’ pear (Pyrus bretschneideri Rehd.) fruits stored at 25 ± 2°C. Our results showed that 1-MCP treatment significantly decreased the rates of respiration and ethylene production before their climacteric peaks, inhibited the development of core browning, lowered the chlorogenic acid content and polyphenol oxidase activity before the onset of core browning, and preserved high levels of superoxide dismutase activity, ascorbic acid, and glutathione contents. Furthermore, it suppressed the accumulation of hydrogen peroxide, superoxide anion, and malondialdehyde in the core tissue, maintained the integral structure of the cell membrane and organelle, and delayed the accumulation of electron-opaque matters in the vacuoles of core cells. These results suggested that 1-MCP treatment could reduce the injury caused by reactive oxygen, inhibit the oxidation of phenolics, and keep the cell membrane intact in core cells, thus, delaying the core browning in ‘Yali’ pear during storage.

Effects of foliar fertilization containing titanium dioxide on growth, yield and quality of strawberries during cultivation

Abstract: We addressed the question of whether it is useful to apply a titanium dioxide (TiO2) solution to promote the growth of strawberry plants in a greenhouse when they suffer from insufficient solar radiation during the winter season. A TiO2 solution was sprayed on strawberry plants three times during the growth period. This treatment occurred once on the 5th day of each month from December to February at concentrations of 50, 100 or 150 mg·kg -1. The control strawberry plants were treated with a foliar solution lacking TiO2. The length of the petiole was inhibited by TiO2 treatments, especially those in January and February. In terms of the fruits, the TiO2 applications were found to increase the yield and hardness of strawberries compared to the control. In addition, the contents of chlorophyll a and b in the leaves of the strawberries were increased by the treatment with TiO2 foliar spray. In contrast, the phenolic compounds of the fruits were decreased as a result of the TiO2 treatments. Combined, our results reveal that the application of TiO2 can promote the yield and quality of strawberry plants sufferings from a shortage of sunlight in a plastic greenhouse during the winter season.

Control of Post-harvest Anthracnose Infection in Guava (Psidium guajava) Fruits with Phosphites, Calcium Chloride, Acetyl Salicylic Acid, Hot Water, and 1-MCP

Abstract: The control of anthracnose (Colletotrichum simmondsii) during the post-harvest stage in guava fruits (Psidium guajava L.) was performed by the application of phosphites [phosphite-K (40% P2O5 and 30% K2O) and phosphite-Ca (10.7% P2O5, 3.89% Ca, and 0.5% B)] including the Carbendazim as reference, calcium chloride (CaCl2), acetyl salicylic acid (ASA), hot water (HW), and 1-methylcyclopropene (1-MCP). These treatments were applied individually or in combination each other with two or three compounds. The evaluated parameters were diameter of anthracnose lesion (DL), number of lesions (NL), and fruit quality (fresh weight loss, pH, total soluble solids, and titrable acidity]. The fruits were disinfested, inoculated, and maintained in an incubator containing fluorescent lights at 75 µmol·m-2·s-1 (25°C, 12h photoperiod) for 5 days and were then analyzed. The results showed that the DL and the NL were reduced following treatments, and that the HW (47°C for 20 min) was the strongest and the 1-MCP treatment was the least effective. The physico-chemical characteristics of fruits were affected by some treatments without compromising fruit quality. The combination of treatments was also able to alleviate the anthracnose effect on fruits compared to individual treatments and the control without affect the fruit quality. The combinations which included the HW treatment showed the best performance to control this disease, particularly when combined with the 1-MCP and phosphite.

Photosynthesis of Chinese cabbage and radish in response to rising leaf temperature during spring

Abstract: Photosynthesis in leaves, exposed to temperature change, was measured during spring to provide information for modeling of cropping systems for Chinese cabbage (Brassica campestris subsp. napus var. pekinensis) and radish (Raphanus sativus) in Jeju Island. The net photosynthetic rates (A) of Chinese cabbage and radish were depressed at temperatures above approximately 25°C (corresponding to the optimum temperature for photosynthesis), due in part to high rates of respiration above 25 or 30°C. Chinese cabbage was more sensitive to high temperature than radish. Above 25°C, stomatal conductance (g s) declined steeply with a sharp increase in the vapor pressure deficit (VPD) and transpiration rate (E), suggesting that stomatal closure could not be associated with transpiration rate, particularly in Chinese cabbage. Dramatic declines in water use efficiency (WUE), instantaneous transpiration efficiency (ITE), and carboxylation efficiency (CE) above 30°C indicated that the plants could be severely affected negatively by high temperatures above 30°C. However, compared to Chinese cabbage, radish had high light use efficiency and potential to assimilate CO2, judged by their high quantum yield (φ) and maximum photosynthetic rate (A max). Radish utilized high levels of photosynthetic photon flux and strongly acclimated to the light environment, considering their high light saturation point (Q sat) and low light compensation point (Q comp). These results suggested that rising temperature might substantially alter water availability of plants by itself and/or through effects on the rate of water loss from leaves of Chinese cabbage and radish under diurnal and/or seasonal fluctuations of temperature, and/or global temperature change. To maintain the high productivity and quality of these crop species, it may be necessary to harvest them until early June, when the daily maximum temperature is below 25°C in Jeju Island.

UV-C Treatments Enhance Antioxidant Activity, Retain Quality and Microbial Safety of Fresh-cut Paprika in MA Storage

Abstract: Fresh-cut paprika was treated with 245 nm UV-C irradiations of 7, 15, and 28 kJ·m-2, packaged using a laser ablation breathable film with permeability of 20,000 mL O2·m-2·day-1·atm-1, and was stored in general distribution temperature at 8°C. The paprikas were evaluated antioxidant activity and internal quality, reducing microbial populations, modifying composition of CO2, O2 and ethylene content in packages. Fresh-cut paprika irradiated with 15 kJ·m-2 UV-C has shown the lowest fresh weight loss and highest overall quality during MA storage. The gas composition (CO2 and O2 concentrations) of UV-C 15 kJ·m-2 treatment showed the closest conditions to CA conditions of paprika. All UV-C treatments presented higher ethylene concentration in package as compared to those of the control as well as NaOCl treatment, because the ethylene content was elevated in response to abiotic stress, possibly by the treatment of UV-C in paprika. After 7 days of storage at 8°C, the antioxidant activity (DPPH activity), total phenolic compound and vitamin C contents of fresh-cut paprika were maintained highest by UV-C 15 kJ·m-2 treatments, followed by 7 kJ·m-2 and 28 kJ·m-2. The microbial population was reduced by UV-C treatment on the 7 days of MA storage, with the fungal incidence rate lowest in 15 kJ·m-2 and 28 kJ·m-2 UV-C treatment and total bacterial numbers showed the lowest in UV-C 15 kJ·m-2 treatment representing lower than 6.0 log CFU·g-1 which was the reference limit for microbial contamination. These results suggest that the application of UV-C 15 kJ·m-2 on fresh-cut paprika represents the most favorable results of gas composition in package, antioxidant capacity (e.g., vitamin C contents) and sterilization of fungi and bacteria during MA storage, and extending the shelf life.

Non-deep simple morphophysiological dormancy in seeds of Thalictrum rochebrunianum, an endemic perennial herb in the Korean Peninsula

Abstract: The aims of this study were to determine the requirements for dormancy break and germination and to characterize the type of seed dormancy of T. rochebrunianum. Ripe seeds (achenes) were collected in late Sept. To determine the temperature requirements for embryo growth and germination in the field, the seeds were sown in field soil. Every 1 or 2 weeks, the seeds were exhumed, and the phenology of embryo growth, germination and seedling emergence were investigated. In the laboratory, effects of temperature and GA3 treatment on embryo growth and germination were also investigated to characterize the type of seed dormancy. Seeds had underdeveloped embryos, which were about 20% of the size of those in fully matured seeds. In natural conditions, embryo growth and germination occurred in early and late March next year, respectively, and embryos in the seeds of this species had to grow to a critical length before germination was possible. Thus, the seeds had morphological dormancy (MD). When tested at the time of dispersal, few seeds germinated after 4 weeks of incubation at 25/15°C. Therefore, the seed dormancy type for T. rochebrunianum seemed to be morphophysiological. Embryos in the seeds grew rapidly at warm temperature conditions following cold stratification at low temperatures. After 4–12 weeks of cold stratification at 1°C or 5°C, the seeds germinated rapidly during an incubation at 25/15°C. Cold stratification requirements could be substituted by GA3 treatment in seeds of T. rochebrunianum. After 1000 mg·L-1 GA3 treatment, high percentages (≥ 80%) of the seeds germinated after 4 weeks of incubation at 15/6, 20/10, and 25/15°C. Consequently, seeds of T. rochebrunianum could be characterized as expressing non-deep simple morphophysiological dormancy (MPD). The cold stratification requirements for dormancy break enabled the seeds to produce seedlings at the beginning of the growing season in natural conditions.

DNA profiling of commercial pumpkin cultivars using simple sequence repeat polymorphisms

Abstract: Pumpkin (Cucurbita spp.) is a major vegetable crop grown worldwide. Three species, C. pepo, C. moschata, and C. maxima, are economically important cultivated pumpkins. To develop a core set of markers for DNA profiling and cultivar identification, we used a total of 300 SSRs consisting of 158 CMTp and 142 CMTm that were previously identified in C. pepo and C. moshata, respectively. Polymorphisms in these primers were tested using a subset of 22 cultivars selected from a collection of 160 commercial cultivars. A total of 12 CMTp and 28 CMTm markers were selected based on polymorphism and number of alleles, and these 40 markers were used to genotype all 160 cultivars. Of these, 29 markers (5 CMTp and 24 CMTm) accurately detected a total of 215 alleles with an average of 7.41 alleles per marker in our collection of pumpkin cultivars. Their PIC values ranged from 0.327 to 0.894 with an average of 0.674. Analysis of genetic similarity using the 29 SSR markers revealed that the 160 cultivars were divided into five major clusters representing C. maxima×C. moshata hybrids (cluster I), C. moshata (cluster II), C. maxima (cluster III), C. pepo (cluster IV), and C. ficifolia (cluster V). In clusters I-IV, the cultivars were further separated into 2-3 sub-clusters. In addition, we found that 29 SSR markers were able to differentiate all 160 cultivars. Results from our study will facilitate genetic study and protection of breeders’ intellectual property rights in pumpkins.

Comparison of total soluble protein in various horticultural crops and evaluation of its quantification methods

Abstract: Various horticultural crops have been considered as potential heterologous expression systems for plant-made recombinant pharmaceutical proteins. However, there is little information concerning the total soluble protein (TSP) levels of major horticultural crops. Ten major horticultural crops-Chinese cabbage, broccoli, garlic, onion, cabbage, bunching onion, cucumber, zucchini, radish, and carrot, along with tobacco and Arabidopsis, were selected to investigate the TSP levels in their individual tissues. In tobacco, SDS-PAGE assay showed that leaf tissues had stronger protein bands than stem tissues, and freshly harvested samples had slightly stronger band density than the −70°C frozen samples, suggesting that fresh leaf should be used to measure the total soluble proteins without any protein loss or degradation. Bicinchoninic acid (BCA) protein assay revealed that among various horticultural crops, garlic (41.4 mg·g−1 FW), broccoli (21.9 mg·g−1 FW), and Chinese cabbage (11.9 mg·g−1 FW) had the highest TSP levels suggesting that these horticultural crops could be good candidates for plant molecular biofarming to produce highly valuable recombinant proteins. The inner clove tissue in garlic, the flower tissue in broccoli, and the green leaf tissue in Chinese cabbage showed the strongest protein band density as compared to other tissues. The TSP of Arabidopsis tissues was quantified by SDS-PAGE, BCA, and Nano-drop methods. In general, the middle leaf tissue showed the highest TSP levels. To evaluate TSP levels of various horticultural crops, these three different methods were compared. The correlation and regression analyses between SDS-PAGE and BCA, and SDS-PAGE and Nano-drop suggested that there were significant correlations between SDS-PAGE and BCA protein assays as compared to SDS-PAGE and Nano-drop assays, indicating that BCA assay is reliable to quantify TSP levels. In conclusion, the TSP levels varied depending on the horticultural crops and their tissue types, and BCA assay could be applied to quantify the TSP.

Micropropagation of Cattleya: improved in vitro rooting and acclimatization.

Abstract: The present study reports optimization of in vitro rooting of Cattleya shoots with the aim to increase survival rate during acclimatization. Shoots (2.0–2.5 cm) which were regenerated in vitro were cultured on Murashige and Skoog (MS) medium and the effect of various parameters such as type and concentration of auxin [0.3, 0.6, 1.2 and 2.4 mg·L−1 indole butyric acid (IBA) and naphthaleneacetic acid (NAA)], medium strength (full and half strength), sucrose concentration (0, 15 and 30 g·L−1) and light intensity [photosynthetic photon flux density (PPFD) of 30, 60, 90 μmol·m−2·s−1] were tested. Half strength MS medium supplemented with 2.4 mg·L−1 IBA, 3% sucrose and 60 μmol·m−2·s−1 PPFD were found as suitable conditions for optimal induction of roots. In vitro regenerated Cattleya plantlets were successfully transferred to potting medium containing bark:perlite:peatmoss (1:1:1) and perlite:peatmoss (1:1), and 98.3 and 80.7% were survived respectively.

The Processes of Graft Union Formation in Tomato

Abstract: Despite the long and widespread use of grafting in tomato cultivation, the structural changes that occur at the graft union during the early stages of the union remain poorly understood. In this study, the structural development of the graft union in tomato plants was examined 3, 5, 8, 11 and 14 days after grafting (DAG) using scanning electron microscopy (SEM) and a paraffin sectioning technique. The paraffin-sectioned images of the transection revealed that parenchymal cells from the graft union divided and proliferated in most combinations, and these cells could be detected at various stages of development. The SEM images of the scion and rootstock longitudinal sections showed that many interconnecting structures appeared at 8 DAG and were followed by a vascular rearrangement that did not connect the scion and rootstock. Vascular bundle bridges appeared at 11 DAG and connected the scion and rootstock. The connection of graft union between rootstock and scion is influenced by the plant growth condition. In our managed environment, period for formation of the connection structure formation between the rootstock and scion was 7-14 days after grafting.

Silicon-mediated enhancement of physiological and biochemical characteristics of Zinnia elegans ‘Dreamland Yellow’ grown under salinity stress

Abstract: This study investigated the effects of silicon (Si) nutrition on hydroponically grown Zinnia elegans under salinity stress. In this study, six treatments, the control (basal nutrients without NaCl or Si), Si 50 (1.8 mM), Si 100 (3.6 mM), NaCl 50 (50 mM), Si 50 + NaCl 50 (1.8 mM Si; 50 mM NaCl), and Si 100 + NaCl 50 (Si-3.6 mM + NaCl-50 mM), were employed. After 15 days of treatment, growth parameters, biochemical measurements, and antioxidant enzyme activities were examined. Salinity stress significantly reduced plant growth, biomass, photosynthetic parameters, and pigments, and increased the electrolyte leakage potential (ELP), lipid peroxidation, and hydrogen peroxide level. Interestingly, with Si supplementation, Z. elegans recovered from salinity stress. Si enhanced growth and photosynthesis, and prevented the decomposition of photosynthetic pigments. Moreover, the addition of Si increased membrane integrity, thereby reducing the ELP and lipid peroxidation levels under salinity stress. Furthermore, Si modulated the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX) in scavenging excess reactive oxygen species (ROS). Additionally, Si increased the macronutrient and micronutrient contents. Therefore, augmentation with Si provided salinity resistance and enhanced the growth of Z. elegans.

Effects of cultivar and harvest time on the contents of antioxidant phytochemicals in strawberry fruits

Abstract: The effects of cultivar and harvest time on the yield, amount of soluble solids, and antioxidant content of five strawberry (Fragaria × ananassa Duch.) genotypes were investigated. The three cultivars and two breeding selections were cultivated in a greenhouse. The yields of the five genotypes were compared, and contents of total anthocyanins, total phenolic acids, soluble sugars and organic acids were analyzed from February to May 2014. The breeding selection San × Aki 2 produced the highest yield. Total amounts of anthocyanins, sucrose, glucose, and fructose were greatest in February and slowly decreased subsequently. Total amounts of phenolic and organic acids varied depending on the month of observation for all cultivars and selections. Total anthocyanin content was the highest in ‘Seolhyang’ strawberry fruits in February and in the breeding selection San × Seol 13 from March to May. The breeding selection San × Aki 2 showed notably high total phenolic acid levels. Soluble sugars decreased over time, with the highest sucrose content found in ‘Seolhyang’, the highest glucose content in ‘Santa’, and the highest fructose content in San × Aki 2. The highest citric acid content was found in ‘Santa’, and the highest malic acid content in San × Seol 13. The sugar/acid ratio was highest in ‘Seolhyang’ and gradually declined over time. The breeder selections San × Aki 2 and San × Seol 13 showed particular promise for their high yields and high concentrations of antioxidant phytochemicals.

Growth, physiology, and abiotic stress response to abscisic acid in tomato seedlings

Abstract: The effect of abscisic acid (ABA) on growth, abiotic stress tolerance, and physiology of tomato seedlings was investigated. To examine the effect of ABA concentration on growth and abiotic stresses, six ABA concentrations (0, 10, 50, 100, 150, or 200 mg·L-1) were applied by foliar spraying once a day for 10 days. The effect of ABA application number was also studied by using different timing at one ABA concentration (100 mg·L-1) once a day for 1, 3, 5, 7, and 9 days. The effect of ABA on physiology of tomato seedlings was examined by using two concentrations (50 and 100 mg·L-1) as compared to the control (non-ABA). Foliar application of ABA decreased the growth characteristics of tomato seedlings in a concentration-dependent manner; however, no statically significant difference was observed between the 50 and 100 mg·L-1 treatments. Furthermore, although growth parameters decreased statistically with increasing number of ABA treatments, there was no difference between the 3 and 5 application treatments. Application of ABA enhanced stress tolerance (cold and drought) of tomato seedlings by delaying the starting time of wilting point in drought conditions and reducing the relative ion leakage and chilling injury index in low temperature in all treatments. The transpiration rate decreased significantly, while stomatal diffusive resistance increased significantly with increasing ABA concentration. The relative water content decreased significantly during the period without irrigation. However, relative water content increased with increasing ABA concentration. The ABA enhanced drought tolerance of tomato seedlings by delaying the start time of wilting point from day 3 in the control to day 5 and 7 in the 50 and 100 mg·L-1 treatments, respectively. Integrating this result data, we can determine the ABA’s ability to maintain of seedling quality at low temperature and water deficit condition.

Effectiveness of exogenous salicylic acid on root and shoot growth attributes, productivity, and water use efficiency of water-deprived fennel genotypes

Abstract: This study was carried out to investigate the response of fennel (Foeniculum vulgare Mill.) to water deficit and exogenous application of salicylic acid (SA). Six fennel genotypes, from Iran (namely ‘Urmia’, ‘Hamadan’, ‘Kerman’, ‘Shiraz’, ‘Birjand’ and ‘Yazd’) were subjected to two levels of irrigation consisting of either irrigation after 35% (control) or 75% depletion of available soil water (water deficit) and 3 levels of treatment with SA (0.0, 0.5 and 1.0 mM). Root growth attributes, yield and yield components as well as irrigation water use efficiencies for seed, oil and dry masses of the shoot and whole plant were studied. Shoot dry mass, grain yield and essential oil yield were decreased due to water deficit. Furthermore, root growth attributes were decreased under water deficit, except for root diameter and dry mass, and root/shoot ratio. With the exception of irrigation water use efficiency for seed yield, all irrigation water use efficiency aspects were increased when fennel was subjected to water deprivation. Fennel genotypes were grouped according to their stress susceptibility indices (SSI) into drought-tolerant, moderately drought-tolerant and drought-sensitive groups. The largest drought-induced decreases in root length, root dry mass, root length density, number of fruits per umbel, seed yield, 1000-seed weight, seed essential oil yield, and irrigation water use efficiency for seed and oil yield were observed in genotype ‘Hamadan’ from the drought-sensitive group. Salicylic acid led to increases in root growth and yield attributes, seed essential oil content and yield, and irrigation water use efficiency aspects under both moisture conditions. Overall, foliar application of SA appeared to attenuate the negative effects of drought stress on fennel through increases in most of the root growth and yield attributes and the attenuation was more substantial in the drought-tolerant set of fennel genotypes.

Comparison of bulb and leaf quality, and antioxidant compounds of intermediate-day onion from organic and conventional systems

Abstract: This study aimed to compare bulb and leaf characteristics, leaf diseases, physiological disorder, bulb nutritional quality, and storage loss of onion from both organic and conventional farms in southeastern Korea during the 2011/2012 growing season. Soil and plant samples were collected from 8 certified organic fields managed organically for more than 5 years and 8 conventional fields adjacent to the organic fields. Onion bulb fresh weight and marketable bulb yield were significantly higher in the conventional field than in the organic field. At harvest, tops-down and leaf yellowing were 15.0 and 16.9%, respectively, lower in organic onions compared to conventional onions. Total phenolic compounds were significantly higher in conventional than organic onions, while there were no significant differences in pyruvic acid, soluble solid and flavonoids content between conventional onions and organic onions. In principal component analysis, highly weighted variables under PC1 included the number of scales, leaf yellowing, soluble solids, pyruvic acid, flavonoids, phenolics and storage loss in organic onions, but bulb weight and leaf weight in conventional onions. In organic onions, leaf yellowing correlated positively with flavonoids (p = 0.015), but negatively with soluble solids (p = 0.040); soluble solids were negatively correlated with flavonoids (p = 0.049). By contrast, conventional onions showed a positive correlation between bulb weight and leaf weight (p = 0.038), and between soluble solids and phenolics (p = 0.019), but a negative correlation between leaf weight and leaf yellowing (p = 0.016).