Influence of fruit ripeness at the time of seed extraction on pepper (Capsicum annuum) seed germination

The influence of fruit ripeness (half ripe, fully ripe, overripe) at the time of seed extraction on seed germination behaviour, at 25 °C and 13 °C, was studied in two Spanish pepper cultivars for canning. Seeds from half ripe fruits had a poorer behaviour than those taken from fully ripe fruits, especially at 13 °C. Room ripening and overripening of half ripe fruits improved the germination behaviour of the seeds although this behaviour was poorer than that of seeds extracted from fully ripe fruits that were allowed to overripen. Overripening of fully ripe picked fruits slightly improved germination behaviour.     

Manganese nutrition of pepper (Capsicum annuum L.): Growth,Mn uptake and fruit disorder incidence

This research included two independent yet build up objectives: (i) to examine the effects of Mn concentration in the irrigation water on the yield and fruit quality of greenhouse-grown bell pepper exposed to heat stress; and (ii) to investigate in a laboratory experiment the role of Mn addition on oxidative and anti-oxidative components of fruit apoplast. The field experiment included four concentrations of Mn in the irrigation water (0, 0.2, 0.6 and 1.0 mg L⁻¹). The effect of Mn application rate on vegetative growth and total fruit yield was insignificant and despite low Mn concentrations in zero-Mn-fed plants, no visible foliar Mn symptoms were observed. A quadratic regression was obtained between high-quality fruit yield and Mn concentration in fruit. Based on the quadratic equation, maximum high-quality yield was obtained when fruit-Mn concentration approached 44 mg kg⁻¹ DW. The correlation also indicates that variations in high-quality yield could be explained by differences in fruit-Mn concentration. The combination of low-Mn nutrition and high air temperature which prevailed during the experiment (summer season) induced severe pale spots and blemished fruits; approximately 50% of fruits were infected in zero-Mn-fed plants. In a laboratory experiment with detached-fruit under high temperature the H₂O₂ concentration increased whereas ascorbic acid concentration decreased in the apoplast. In Mn-fed fruit the H₂O₂ concentration was attenuated and the activity of ascorbate oxidase was suppressed, with the result that apoplastic ascorbic acid concentration increased. In light of the known crucial role of Mn in enzyme activities and in detoxification of oxygen free-radicals, the pale spots might be related to Mn effect on oxidative stress-related apoplastic activities. The relationships between incidence of pale spots and plant-Mn concentration may support this hypothesis, but further research is needed to validate it.     

The genetics of non-virus vein-banding in aromatic pepper Capsicum annuum L.

Vein-banding is a genetically inherited trait controlled by one locus, Vb, which is expressed as a wave-like banding of the main and side veins of pepper leaves. It was studied as a morphological defect always present in the ‘Nsukka Yellow’ pepper, Capsicum annuum L., and was shown to be inherited as an incompletely dominant characteristic with an F₂ segregation ratio of 1:2:1. The F₁ population was uniformly mild in expression of the vein-handing characteristic of the parent ‘Nsukka Yellow’ pepper. VbVb was designated as the genetic constitution of severe vein-banding, and vbvb as a normal genotype, the F₁ being Vbvb. A selection of normal plants from the back-cross with the normal-leafed parent yield a stable normal-leafed strain of ‘Nsukka Yellow’ christened ‘UN-Yellow’.     

Temperature effects on male fertility and flower and fruit development in Capsicum annuum L.

Temperature conditions strongly influenced the development of flowers and fruits of pepper (Capsicum annuum L.) plants. Low temperatures (LTR; 18°C day/15°C night) had much more effect on flowers and fruits than intermediate (ITR; 23°C day/18°C night) or high (HTR; 28°C day/23°C night) temperatures. LTR caused the formation of abnormal petals, stamens and gynoecium in the flowers. Stamens produced were deformed, in some cases partly carpel-like, produced abnormal non-viable pollen, and were thus functionally male-sterile. In the gynoecium, the ovary size of LTR-grown flowers was larger than that of ITR and HTR flowers, but the style elongation was inhibited. Fruits produced under HTR were larger than ITR and were seeded under both temperature regimes. Under LTR, small seedless fruits were produced, but normal seeded fruits were formed if flowers were pollinated with pollen from ITR- or HTR-grown flowers.     

Fruits are more sensitive to salinity than leaves and stems in pepper plants (Capsicum annuum L.)

The effects of NaCl stress on plant growth, gas-exchange, activity of superoxide dismutase (SOD), rate of lipid peroxidation, and accumulation of Na⁺ ion and sugar were investigated in leaves and fruits of pepper plants (Capsicum annuum L.). Especially, the gene expression of l-galactono-1,4-lactone dehydrogenase (GalLDH), which is the last enzyme of ascorbic acid (AsA) biosynthesis, and the relationships between AsA level and Na⁺ concentration in plant tissue were investigated with increasing salinity. Plants were treated with three treatments: the control (0 mM NaCl) and two salinity levels (50 and 100 mM NaCl) for 21 days under greenhouse conditions. Plant growth was markedly restricted due to the reduction of photosynthetic rate and the increase of Na⁺ accumulation in leaves with the increasing intensity of NaCl stress. Salinity had more effect on fruit growth comparing to leaf growth, suggesting that fruits could be more sensitive to salinity than leaves. In comparison with the control, salt stress significantly increased lipid peroxidation (as measured as malondialdehyde content) but decreased SOD activity in both fruits and leaves although the effect was larger in fruits; and the rate of the decrease in SOD activity was greater than that of the increase in lipid peroxidation. The AsA concentration transiently increased first 7 days but it slightly decreased from the initial level in the end of treatment day 21. The change in GalLDH gene expression was similar to AsA concentration. The accumulation of Na⁺, the reduction of AsA level at severe salinity stress were greater in fruits than in leaves; and AsA level had a negative relationship with Na⁺ concentration in both leaves and fruits. These results suggest that the difference in salt sensitivity between fruits and leaves in pepper plants can be related to the difference in inhibition of AsA synthesis, which in turn is probably due to the toxicity of extreme accumulation of Na⁺.     

Refinement of shed-microspore culture protocol to increase normal embryos production in hot pepper (Capsicum annuum L.)

A low percentage of normal-looking embryos (20%) is still a problem in an efficient shed-microspore culture of hot pepper (Capsicum annuum L.) and it is more a serious problem in other androgenesic culture systems of pepper. Therefore, several factors were investigated to refine the protocol in order to increase the percentage of normal-looking embryos. The most important factors which improved the protocol and resulted in a significantly higher percentage of normal-looking embryos produces (>50%), were delayed enrichment of the liquid upper layer medium with 2.5 μM Zeatin and 5 μM IAA, and reduced incubation temperature from 28 °C to 21 °C, both after 3 weeks of culture. Addition of 1% activated charcoal in the solid lower layer of the medium enhanced the total embryo yield only, while an application of abscisic acid and increased osmolality medium had a detrimental effect on embryo production. The use of doubled haploid lines as anther donor plants has clearly decreased the variability and improved the statistical analysis of treatment effects. A higher percentage of normal embryos are produced with this refined protocol, and is therefore more suitable for implementation in the breeding programs of hot pepper.     

Agronomic characteristics and carotenoid content of five Bola-type paprika red pepper (Capsicum annuum L.) cultivars

The production of sweet paprika in Spain uses exclusively fruit of Bola-type Capsicum annuum L. This work describes the evaluation of the agronomic behaviour of five new cultivars of the Bola-type paprika red pepper, selected in the Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), and grown in Extremadura for 3 years. The colour and the pigment content of the paprika elaborated following the traditional procedure of La Vera were also studied.     

Genetics and distribution of fertility restoration associated RAPD markers in inbreds of pepper (Capsicum annuum L.)

Experiments were conducted to study genetics of fertility restoration and to examine distribution of RAPD markers (OPW19₈₀₀ and OPP13₁₄₀₀) linked with fertility restoration gene (Rf) in pepper (Capsicum annuum L.) inbreds. Forty-two hot and five sweet pepper inbreds were crossed on a cytoplasmic male sterile (cms) line CCA-4261 and F₁s were evaluated for fertility restoration under open field conditions. DNA of 5 plants of CCA-4261 and individual plants of 47 inbreds was isolated and PCR reaction was performed using OPW19 and OPP13 primers. The results revealed that most of the hot pepper lines posses Rf gene. The Rf gene associated two markers, viz., OPW19₈₀₀ and OPP13₁₄₀₀ were not frequently distributed in the restorer inbred lines because presence of marker bands often does not coincide with the presence of Rf gene identified in many restorer inbreds. The case specific applications of both the RAPD markers have been described.     

Responses of some different pepper (Capsicum annuum L.) genotypes to inoculation with two different arbuscular mycorrhizal fungi

Eight different pepper genotypes inoculated by two different arbuscular mycorrhizal fungi (AMF) [Glomus intraradices (Gi) and Gigaspora margarita (Gm)] in a growth chamber experiment under normal seedling growing conditions were evaluated for seedling traits, colonization and relative mycorrhizal dependency (RMD). In general, inoculated plants had greater dry weights compared to non-inoculated plants. Five cultivars responded positively to inoculation with AM fungi and three responded negatively. A great variation in mycorrhizal colonization dependency was observed among the pepper genotypes, with the N52 genotype showing the highest RMD and the Karaisali genotype the lowest. RMD and dry weights of pepper genotypes were inversely correlated.     

Evaluation of crucial factors for implementing shed-microspore culture of Indonesian hot pepper (Capsicum annuum L.) cultivars

A shed-microspore culture protocol was developed in Wageningen for producing doubled haploid plants in several genotypes of Indonesian hot pepper (Capsicum annuum L.). For transfer of technology to Indonesia, three factors were studied that appeared crucial for successful implementation in practice. First, application in the culture medium of a combination of the antibiotics timentin and rifampicin at the concentrations of 200 and 10 mg/l, respectively, prevented bacterial contamination from the donor explants. Second, in vitro application of colchicine (100 μM) during the first week of culture was highly effective in increasing the percentage of doubled haploid plants. Third, a comparative analysis of the ploidy level of plants regenerated from shed-microspore-derived embryos using chloroplast counts in guard cells of leaf stomata and flow cytometric measurement of leaf nuclear DNA content, revealed that the first procedure is a reliable and an easy to use method for ploidy determination with hot pepper.     

Enriched production of N-hydroxycinnamic acid amides and biogenic amines in pepper (Capsicum annuum) flowers

The biosynthesis of N-hydroxycinnamic acid amides (HCAAs), such as feruloyltyramine, p-coumaroyltyramine, feruloylserotonin, and p-coumaroylserotonin, in pepper plants was investigated in view of the activity of their corresponding enzymes and substrate levels. Almost all HCAAs were found in flowers, whereas the enzyme activity essential for HCAA biosynthesis seemed to be expressed constitutively in all tissues tested. The highest levels of the biogenic amines tyramine and serotonin, the key amine substrates, were also found in flowers, indirectly suggesting that the amine substrates play an important regulatory role in the synthesis of HCAAs.     

A SCAR marker linked to the N gene for resistance to root knot nematodes (Meloidogyne spp.) in pepper (Capsicum annuum L.)

The root-knot nematodes (Meloidogyne spp.) are important nematode pests and cause serious diseases in pepper in the world. No molecular markers linked to the nematodes resistance N gene have been reported. In this paper, ‘Carolina Wonder’ (Capsicum annuum L.), a sweet pepper line resistant to root-knot nematode with N gene, ‘20080-5-29’ (C. annuum L.), an inbred line susceptible to root-knot nematode with good horticultural characteristics, and their F₂ progeny with 320 individuals were used as materials. Evaluation of resistance and susceptibility of parental lines, F₁ and F₂ progeny inoculated with root-knot nematodes (Meloidogyne incognita) were carried out. ‘Bulked segregant analysis’ method was used to search for polymorphic markers from 512 pairs of AFLP primers. Based on the assessment of resistance and susceptibility and polymorphism of the AFLP marker in F₂ population, the genetic linkage distance between the AFLP marker and the N gene was estimated. One AFLP marker E39/M41-339 was obtained and transferred to a SCAR marker amplifying a 315 bp DNA fragment linked to the N resistant allele and a 331 bp fragment linked to the N⁺ susceptible allele. The distance between the molecular marker and the nematodes resistance N gene is 6.3 cM. This research delivered a valuable tool for the marker assisted selection of nematodes resistance in pepper.     

Effectiveness of water pillow irrigation method on yield and water use efficiency on hot pepper (Capsicum annuum L.)

A study was conducted to elucidate the effect of water pillow (WP) irrigation method, a new alternative method to furrow irrigation, on the yield and water use efficiency (WUE) of hot pepper in a semi-arid climatic condition. In this research, treatments used were: (i) WP method and its 7-day irrigation interval (WP₇), (ii) WP method and its 9-day irrigation interval (WP₉), (iii) WP method and its 11-day irrigation interval (WP₁₁) and (iv) furrow irrigation (FI) method and its 5-day irrigation interval (control) were employed. Although the plants were grown under different irrigation methods and interval conditions, there were no statistical differences in yield and biomass of hot pepper plants between FI and WP treatments (P < 0.05). Water use efficiency (WUE) and irrigation water use efficiency (IWUE) values significantly increased with the application of WP irrigation method (P < 0.05). The highest WUE and IWUE values obtained from WP₁₁ treatment in both years. As a result, we conclude that WP method is a way to save water and increase the yield in semi-arid areas where climatic conditions require repeated irrigation in the hot pepper production area.     

Influence of growing season and donor plant age on anther culture response of some pepper cultivars (Capsicum annuum L.)

The effects of growing season and donor plant age on anther culture in Capsicum were investigated. Pepper cultivars Kekova and Sera Demre 8 were grown under unheated greenhouse conditions in winter season and field conditions in summer season. Flower buds were collected and cultured in weekly intervals from November to May in winter and from April to December in summer. The results of this study indicated that anthers from these two pepper genotypes gave different embryogenic response to seasonal effects. Kekova cultivar gave the highest embryogenic yield in summer season while this was occurred in winter season for Sera Demre 8 cultivar. The results of the study revealed that the effect of donor plant age was also an important factor in anther culture of pepper. Since 4-month-old plants gave the highest embryo yield in both cultivars in each seasons, it is possible to say that anthers collected from old plants have sufficient embryogenic response when the optimum developmental stage is selected.     

Defence responses in leaves of resistant and susceptible pepper (Capsicum annuum L.) cultivars infected with different inoculum concentrations of Phytophthora capsici Leon

Three pepper cultivars (PM-702: resistant, Demre-8 and KM-hot: susceptible) with different resistances to Phytophthora capsici-22 (P. capsici-22) were inoculated with different concentrations of zoospores to analyze the time course of phenylalanine ammonia lyase (PAL) activity, malondialdehyde (MDA), hydrogen peroxide (H₂O₂), proline and total protein.     

Towards crop improvement in bell pepper (Capsicum annuum L.): Transgenics (uid A::hpt II) by a tissue-culture-independent Agrobacterium-mediated in planta approach

Agrobacterium tumefaciens-mediated transformation has been one of the methods used to generate transgenic plants in bell pepper. An alternate transformation method that avoids/minimizes tissue culture would be beneficial for the improvement of bell pepper due to its recalcitrant nature. In this report, transgenic bell pepper plants have been developed by a tissue-culture-independent A. tumefaciens-mediated in planta transformation procedure. In the present study, two open pollinated varieties viz., Arka Gaurav and Arka Mohini were used for transformation. Agrobacterium strain EHA105 harboring the binary vector pCAMBIA1301 that carries the genes for β-glucuronidase (uid A) and hygromycin phosphotransferase II (hpt II) was used for transformation. GUS histochemical analysis of T₀ and T₁ plants at various stages of growth followed by molecular analysis using PCR, Southern analysis and RT-PCR allowed selection of transgenics. The method resulted in 17.8% and 11.4% of the T₀ plants in Arka Gaurav and Arka Mohini being selected as chimeric and 35.0% and 29.7%, respectively, were identified as stable transformants in the T₁ generation based on PCR analysis.     

Methods to break seed dormancy in Cyclocarya paliurus (Batal)Iljinskaja

Cyclocarya paliurus is native to China and is the sole species in its genus. However, the seeds remain deeply dormant for 2 years in their natural environment. We tested different pretreatments of chemical scarification and exogenous application of gibberellic acid (GA₃) for efficacy in breaking dormancy and speeding germination. In contrast to scarified seeds, non-scarified seed did not germinate, indicating that C. paliurus seeds have hard, impermeable seed coat dormancy. Exogenous application of GA₃ significantly enhanced germination of scarified seeds. Compared with seeds stratified in sand with water, the germination of seeds stratified in sand moistened with 400 ppm GA₃ for 60 days was significantly increased and germination rate was over 90% after 120 days. Analysis of variance indicated that both GA₃ concentration and stratification medium had significant effects on seed germination and final germination percentage. Germination was higher for longer stratification periods, but no significant difference in germination was observed after 90 days. These results suggested that C. paliurus seeds exhibit both exogenous and endogenous dormancy. A combination of chemical scarification and exogenous application of GA₃ alleviated seed dormancy in a relatively short period of time.     

Influence of pollination methods on fruit development and sugar contents of oriental melon (Cucumis melo L. cv. Sagyejeol-Ggul)

This study was conducted at the Seongju Fruit Vegetable Experiment Station for 2 years, 2002–2003 to investigate the effect of pollination methods on development and sugar content of oriental melon fruits. Oriental melon fruit was pollinated by honeybees (Apis indica) and bumblebees (Bombus ignitus) and fruit setting growth regulators was used as a control treatment. Fruits pollinated by honeybees and bumblebees has lesser length and width of fruit compared to the control. Pollinated by bumblebees increased hardness and soluble solids of fruits by 27% and 4–5% and that of honeybees increased hardness and soluble solids of fruits by 12% and 5–10% compared to the control, respectively. Fermented fruit ratio (%) of oriental melon fruit pollinated by honeybees, bumblebees, and growth regulator was 6.7%, 9.1%, and 28.1%, respectively. Glucose, fructose and sucrose contents of fruits by HPLC (high performance liquid chromatography) were very low throughout the ripening stage, but abruptly increased at harvesting stage. In fructose content of fruits, pollination of bumblebees and honeybees was higher by 9% and by 13% than those of control, respectively. The amount of total sugar content in fully ripen fruits of oriental melon was not different between the treatments (P > 0.05). Total sugar content (%) of fruits pollinated by bumblebees was slowly decreased until 15 days after storage compared to that of other treatment. For the low fermented fruit ratio (%) and slowly reduced total sugar content at storage of fruits, the pollination of bees was more useful than fruit setting growth regulators in early cultivation of oriental melon under plastic houses. The economic analysis according to the pollination method will be needed in the near future.     

Behavior of arazá (Eugenia stipitata Mc Vaugh) fruit quality traits during growth,development and ripening

The period between fruit set and full ripening of arazá fruit grown in the Colombian Amazonia was 55 ± 5 days. Three stages of a sigmoidal growth were identified and longitudinal and equatorial traits fitted a logistic model better than three-degree polynomial models. Fruit growth clearly exhibited three different physiological stages, identified as follows: S1, involving cellular division during the first 14 days; S2, maximum fruit growth, during which cellular expansion took place (up to day 50), and a final S3 state of 5 days to reach physiological maturity. After this time, the fruit can be harvested with a dull green coloration. Parenchyma was the principal fruit tissue, and no support tissues (sclerenchyma or collenchyma) were evident. The respiratory pattern of arazá fruit was climacteric, with maximum respiration rates of around 200 mg CO₂ kg⁻¹ h⁻¹, preceded by a peak of ethylene production (20 μL C₄H₄ kg⁻¹ h⁻¹), a change in skin color from green to yellow, a total soluble solids value of 5°Brix, an increase in the sucrose and fructose content up to 2.8 μmol g⁻¹, a pH which increased to 3 units, and a decrease in titratable acidity to 400 mmol H⁺ L¹⁻. Malic acid was the main organic acid in the edible pulp and ascorbic acid was present in a concentration of 17.8 μmol g⁻¹. Skin color (as measured by hue angle) combined with titratable acidity and fruit firmness can be recommended as harvest indices for arazá fruit.     

Antioxidant potency of white (Brassica oleracea L. var. capitata) and Chinese (Brassica rapa L. var. pekinensis (Lour.)) cabbage: The influence of development stage,cultivar choice and seed selection

The accumulation of total phenols (TP, Folin-Ciocalteu method) and total flavonoids (TF, colorimetric assay with AlCl₃) and the evolution of antioxidant capacity (FRAP assay, DPPH and ABTS radical scavenging assays) have been monitored in juices of Croatian white cabbage (Brassica oleracea var. capitata) cultivars Vara?dinski and Ogulinski, as well as Chinese cabbage (Brassica rapa var. pekinensis), at various developmental stages. Measurements were performed every four weeks, starting from planting to full maturity, throughout the course of eight months. In the first 8–12 weeks, the TP and TF contents as well as antioxidant capacity increased significantly in all analyzed juice samples and in most even doubled. This rapid increase was followed by a gradual decrease in values derived from all assays, over the course of 12–30 weeks, to the final values which were in all cases lower than the values measured at week 4. The results also point to significant variability in TP and TF contents and antioxidant capacity at the fully mature stage between white and Chinese cabbage juices and between juices extracted from cultivars Ogulinski and Vara?dinski.