Diversity of Fruit Quality Characteristics in Capsicum frutescens

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  • 1 USDA/ARS/PGRCU, 1109 Experiment Street, Griffin, GA 30224
  • 2 USDA/ARS/CSPL, 600 Avenue NW, Winter Haven, FL 33881
  • 3 Department of Food Science and Human Nutrition, University of Maine, Orono, ME 04469

Fruit of 40 genotypes of Capsicum frutescens L. from the US Department of Agriculture/Agricultural Research Service Capsicum germplasm collection were analyzed for a variety of fruit quality parameters, including fruit size, weight, and concentrations of capsaicinoids, sucrose, glucose, fructose, malic acid, and total acid equivalents. Fruit weight ranged from 0.23 g fresh weight to 4.04 g fresh weight (average 1.05g). Fruit length/width ranged from 1 to 8.0 (average, 3.61). Capsaicin concentrations ranged from 34 to 350 mg·100 g−1 fresh weight (average, 135 mg·100 g−1 fresh weight). Sucrose concentrations ranged from 0.28 to 1.0 g·100 g−1 (average, 0.6 g·100 g−1 fresh weight). Total sugar extracts ranged from 0.73% to 2.6% (average, 1.55%). Malic acid concentrations and total acid equivalents ranged from 0.62 to 2.29 g·100 g−1 fresh weight (average, 2.07 g·100 g−1 fresh weight) and 0.97 to 3.31 g·100 g−1 (average, 1.87 g·100 g−1) respectively. These data demonstrate an approximate 4 to 14-fold range in values for the characteristics examined, suggesting the presence of sufficient variability for these traits within this species to support the development of germplasm enhanced for specific or multiple fruit quality attributes.

Abstract

Fruit of 40 genotypes of Capsicum frutescens L. from the US Department of Agriculture/Agricultural Research Service Capsicum germplasm collection were analyzed for a variety of fruit quality parameters, including fruit size, weight, and concentrations of capsaicinoids, sucrose, glucose, fructose, malic acid, and total acid equivalents. Fruit weight ranged from 0.23 g fresh weight to 4.04 g fresh weight (average 1.05g). Fruit length/width ranged from 1 to 8.0 (average, 3.61). Capsaicin concentrations ranged from 34 to 350 mg·100 g−1 fresh weight (average, 135 mg·100 g−1 fresh weight). Sucrose concentrations ranged from 0.28 to 1.0 g·100 g−1 (average, 0.6 g·100 g−1 fresh weight). Total sugar extracts ranged from 0.73% to 2.6% (average, 1.55%). Malic acid concentrations and total acid equivalents ranged from 0.62 to 2.29 g·100 g−1 fresh weight (average, 2.07 g·100 g−1 fresh weight) and 0.97 to 3.31 g·100 g−1 (average, 1.87 g·100 g−1) respectively. These data demonstrate an approximate 4 to 14-fold range in values for the characteristics examined, suggesting the presence of sufficient variability for these traits within this species to support the development of germplasm enhanced for specific or multiple fruit quality attributes.

Capsicum frutescens L. is one of the five cultivated species in the genus Capsicum (Solanaceae) (Heiser and Pickersgill, 1969) and is closely related to C. chinense Jacq. (Baral and Bosland, 2004; Eshbaugh, 1976). Before Columbus, the neotropical range of C. frutescens extended from the Caribbean through northern South America (D'Arcy and Eshbaugh, 1974; Heiser and Smith, 1953). Numerous local land races of C. frutescens are cultivated in tropical and subtropical regions of the world (Heiser and Smith, 1953). The plants of C. frutescens are typically upright with one or sometimes two flowers per node, with green or greenish white corollas. Calyx teeth and a calyx constriction are lacking in C. frutescens. Fruit are typically upright, soft, and deciduous (D'Arcy and Eshbaugh, 1974).

C. frutescens is best known as the origin of the Tabasco variety of pepper, which has been grown commercially in the United States since the 1840s for the production of Tabasco sauce (DeWitt and Bosland, 1996). This variety, originally introduced to Louisiana from Mexico, was replaced in the 1970s by a tobacco etch virus-resistant cultivar (Greenleaf et al., 1970). Despite its economic significance, improvements in commercially cultivated varieties of C. frutescens have occurred largely as a result of human selection within existing varieties, and limited information is available in the scientific literature regarding variability for agronomic or horticultural traits within the gene pool. Smith and Heiser (1957) did note that this species is much less variable than the other cultivated species in the genus. DeWitt and Bosland (1996) also noted that variability within C. frutescens for fruit shape, size, and color was more limited than within the more widely cultivated species C. annuum, C. baccatum L., and C. chinense, possibly as a result of less intense human selection within C. frutescens. In addition to its culinary uses, C. frutescens is a source of saponin and other compounds that are being evaluated as natural fungicides (Duke et al., 2003).

Pungency is a key characteristic associated with members of the genus Capsicum. It is also an important fruit quality attribute. The degree of pungency in Capsicum fruit is proportional to the combined concentrations of the various vanillyl amides that represent capsaicinoids (Suzuki and Iwai, 1984). Pungency values for Capsicum sp. fruit can range from 0 to 300,000 SHUs (DeWitt and Bosland, 1993) or more (Mathus et al., 2000). Zewdie and Bosland (2000a) examined the capsaicinoid concentrations in 10 accessions of C. frutescens. Within these, capsaicinoid and dihydrocapsaicin concentrations ranged from 53.08 to 73.44 mg·100 g−1 and from 20.34 to 38.59 mg·100 g−1 fresh weight respectively. Other fruit quality attributes, including concentrations of sucrose, fructose, and glucose, also affect fruit quality. The attribute sweetness was shown to be correlated with concentrations of sucrose and glucose in mature red fruit of C. annuum (Luning et al., 1994). The absence of sourness was similarly shown to be correlated with concentrations of various organic acids (Luning et al., 1994).

This study was undertaken to examine accessions of C. frutescens in the US Department of Agriculture/Agricultural Research Service Capsicum gene bank (Jarret et al., 1990) for variability of fruit composition attributes that might serve as the basis for efforts to enhance fruit quality.

Materials and Methods

Plant culture.

Fifteen to 20 plants of each genotype (Table 1) were transplanted to and grown in the field on the Georgia Experiment Station campus (Griffin, Ga.) in May 2004. Plants received periodic fertilization and irrigation, as required. A minimum of 100 mature red fruit were collected from 10 plants per genotype in three consecutive harvests at 1-week intervals (total of 300 fruit). In each instance, fruit were harvested from throughout the plants to reduce the effect of fruit position on the concentrations of the compounds to be analyzed (Zewdie and Bosland, 2000b). Variability in moisture content among fruit of accessions was determined to be ≈2%. After harvest, fruit calyxes were removed and the fruit was counted, measured, weighed, and frozen at −20 °C for up to 2 weeks before extraction. Digital images of the plant materials used can be seen at www.ars-grin.gov.

Table 1.

Variation in fruit weight, length, width, and length/width among fruit of 40 accessions of C. frutescens.

Table 1.
Table 2.

Variation in fruit concentrations of capsaicin (CAP), dihydrocapsaicin (DHC), and total capsaicinoids (TC) in milligrams per 100 g fresh weight, and the ratio of capsaicin to dihydrocapsaicin (C/D) in 40 genotypes of C. frutescens.

Table 2.
Table 3.

Variation (mean ± sd) in fruit concentrations of sucrose (S), glucose (G), fructose (F), malic acid (MA), and total acid equivalents (TAE) in 40 genotypes of C. frutescens.

Table 3.

Extraction of capsaicinoids.

All 100 fruit from each sample were chopped into small (<2.5 mm3) pieces, and subsequently blended to a slurry using a commercial food processor. Five-gram aliquots of the fruit slurry were homogenized in 25 mL 100% MeOH for 3 min in a 50-mL centrifuge tube using a Tissumizer (Tekmar Corp., Cincinnati) homogenizer at speed setting 8. The homogenate was centrifuged at 15,000 rpm for 15 min at 20 °C, and the supernatant containing total capsaicinoids was filtered through a syringe-mounted 22-μm filter into amber vials and stored at −4 °C for up to 2 weeks before analysis.

Extraction of carbohydrates and organic acids.

Ten grams of fruit slurry were added to 40 mL 80% EtOH and homogenized using a Tissumizer (Tekmar Corp.) homogenizer at speed setting 8 in a 250-mL beaker. The homogenate was covered with a watch glass and was heated to boiling, with occasional stirring for 15 min. The homogenate was transferred to a 250-mL centrifuge bottle and was centrifuged for 10 min at 5000 rpm at 25 °C. The supernatant was brought to a final volume of 50 mL with 80% EtOH. For high-performance liquid chromatography (HPLC) analysis, aliquots of this preparation were filtered sequentially through a preprepared Sep-Pak Plus C18 cartridge filter (Waters Corp., Milford, Mass.) and a 0.45-μm syringe filter. Filtrates were stored in amber vials for up to 2 weeks at −20 °C before analysis.

Analysis of capsaicinoids, carbohydrates, and organic acids.

Capsaicin and dihydrocapsaicin were analyzed using HPLC as described previously (Jarret et al., 2003; Perkins et al., 2002). HPLC analysis of sugars was conducted as described by Baldwin et al. (1991). Individual sugars were analyzed by injecting 20 μL extract filtrate on a Sugar Pak column at 90 °C (Waters, Millipore Corp., Milford, Mass.) with a mobile phase of 0.0001 N methylenediamine tetraacetic acid disodium–calcium salt (CaEDTA), a flow rate of 0.5 mL·min−1, and a refractive index detector (Agilent 1100 series; Agilent Technologies, Palo Alto, Calif.).

HPLC analysis of acids was conducted by injecting 20 μL extract filtrate on a ThermoFinnigan SpectraSytem UV6000UL (Thermo Electron Corp., San Jose, Calif.) with a Prevail Organic Acid column at 35 °C (Alltech, Deerfield, Ill.), a mobile phase of 0.1N H2SO4, a flow rate of 0.2 mL·min−1, and a photo diode array (Thermo Electron Corp.) spectrophotometric detector at 210 nm.

Results and Discussion

Fruit size and shape were highly variable in C. frutescens (Table 1). Fruit weight averaged 1.05 g fresh weight with a range of 0.18 g fresh weight (PI 281346) to 4.04 g fresh weight (GRIF 9315) with an average of 1.05 g fresh weight. Zewdie and Zeven (1997) noted a 5.5-fold variation in fruit weight among 67 pungent varieties of C. annuum from Yugoslavia. We observed that fruit length varied from 1 cm (PI 368077 and PI 281396) to 8.5 cm (PI 439502). Most fruit were clearly elongate. However, the fruit length-to-width ratio varied from 1.0 (PI 585256) to 7 (PI 238059) with an average of 3.6.

Total capsaicinoids (capsaicin plus dihydrocapsaicin) content among the C. frutescens accessions varied by approximately ninefold from 53 (PI 439502 to 456 (PI 241675) mg/100 g fresh weight (Table 2). Values for the individual capsaicinoids (capsaicin and dihydrocapsaicin) ranged from 35 (PI 439502) to 350 (PI 241675) mg/100 g fresh weight and 18.5 (PI 439502) to 105 (PI 241675) mg/100 g fresh weight respectively. However, the ratio of capsaicin to dihydrocapsaicin averaged 2.94 and ranged from 0.94 (PI 594961) to 7.05 (PI 543203). Zewdie and Bosland (2001) noted an average capsaicin-to-dihydrocapsaicin ratio of 2:1 among 10 accessions of C. frutescens. Although capsaicin is typically the predominant capsaicinoid in hot peppers, the ratio of capsaicin to dihydrocapsaicin can vary substantially within and among species (Zewdie and Bosland, 2001). The individual capsaicinoids vary in their sensory properties (Krajewska and Powers, 1988), thus affecting the overall taste and degree of pungency. In addition to large genotypic effects on pungency, a portion of the variability in the observed capsaicinoid values may reflect the relative proportions of placental tissue to the total fruit mass, stage of maturation (Contreras–Padilla and Yahia, 1998), and local environment (Harvell and Bosland, 1997). As reported by Iwai et al. (1979), capsaicinoid synthesis and accumulation are restricted to the placental tissues.

Sucrose concentrations in fruit homogenates ranged from 0.28 (PI 543203) to 1.0 (PI 439509) g/100 g fresh weight with an average of 0.6 g/100 g fresh weight (Table 3). Glucose and fructose concentrations ranged from 0.43 (PI 358811) to 2.78 (PI 238055) g/100 g fresh weight and 0.63 (PI 631142) to 3.48 (PI 543203) g/100 g fresh weight respectively. Concentrations of total sugars were highest in GRIF 9315 (6.84 g/100 g fresh weight) and lowest (1.84 g/100 g fresh weight) in PI358811 and PI631142. These values are in general agreement with those reported by Luning et al. (1994) and Lopez–Hernandez et al. (1996), who demonstrated that concentrations of these sugars, and dry matter content, were related to the attribute sweetness in fully mature fruit of C. annuum.

Concentrations of organic acids were shown to be negatively correlated with sourness in mature fruit of C. annuum cvs. (Luning et al., 1994). Among the C. frutescens accessions examined, malic acid concentrations ranged from 0.62 (PI 238059) to 2.29 (PI 439494) g/100 g fresh weight with an average of 1.61 g/100 g fresh weight (Table 3). Total acid equivalents ranged from 0.86 (PI 631142) to 3.31 (PI 543203) with an average of 1.85.

Conclusion

Although a variety of compounds are known to affect the flavor (sweetness, sourness, pungency, etc.) and health-promoting benefits (vitamins, antioxidants, minerals, etc.) of pepper (Capsicum spp.) fruit, the scientific literature contains relatively little information on the extent of variability within the Capsicum germplasm for these characteristics. Information on fruit quality attributes can facilitate the development of varieties specifically enhanced for these characteristics by identifying genotypes to serve as potential parents in breeding programs, or for use in related research. The data reported here suggest that sufficient variability for fruit quality characteristic exists within the C. frutescens germplasm to support the development of varieties with specific flavor attributes.

Literature Cited

  • Baldwin, E.A., Nisperos–Carriedo, M.O., Baker, R. & Scott, J.W. 1991 Quantitative analysis of flavor parameters in six Florida tomato cultivars (Lycopersicon esculentum Mill) J. Agr. Food Chem. 39 1135 1140

    • Search Google Scholar
    • Export Citation
  • Baral, J.B. & Bosland, P.W. 2004 Unraveling the species dilemma in Capsicum frutescens and C. chinense (Solanaceae): A multiple evidence approach using morphology, molecular analysis, and sexual compatibility J. Amer. Soc. Hort. Sci. 129 826 832

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  • Contreras–Padilla, M. & Yahia, E.M. 1998 Changes in capsaicinoids during development, maturation, and senescence of chile peppers and relation with peroxidase activity J. Agr. Food Chem. 46 2075 2079

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  • D'Arcy, W.G. & Eshbaugh, W.H. 1974 New World peppers (Capsicum – Solanaceae) North of Colombia: A resume Baileya 19 93 105

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    • Search Google Scholar
    • Export Citation
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    • Search Google Scholar
    • Export Citation
  • Harvell, K. & Bosland, P.W. 1997 The environment produces a significant effect on pungency of chiles HortScience 32 1292

  • Heiser, C.B. Jr. & Pickersgill, B. 1969 Names for the cultivated Capsicum species (Solanaceae) Taxon 18 277 283

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  • Iwai, K., Suzuki, T. & Fujiwake, H. 1979 Formation and accumulation of pungent principle of hot pepper fruits, capsaicin and its analogues, in Capsicum annuum var. annuum cv. Karayatsubusa at different growth stages after flowering Agr. Biol. Chem. 43 2493 2498

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    • Export Citation
  • Jarret, R.L., Perkins, B., Fan, T., Prince, A., Guthrie, K. & Skoczenski, B. 2003 Using EIA to screen Capsicum spp. germplasm for capsaicinoid content J. Food Comp. Anal. 16 189 194

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    • Export Citation
  • Jarret, R.L., Spinks, M., Lovell, G. & Gillaspie, A.G. 1990 The S-9 plant germplasm collection at Griffin, Georgia Diversity 6 23 25

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    • Export Citation
  • Luning, P.A., van der Vuurst de Vries, R., Yuksel, D., Ebbenhorst–Seller, T., Wichers, H.J. & Roozen, J.P. 1994 Combined instrumental and sensory evaluation of flavor of fresh bell peppers (Capsicum annuum) harvested at three stages of maturity J. Agr. Food Chem. 42 2855 2861

    • Search Google Scholar
    • Export Citation
  • Mathus, R., Dangi, R.S., Dass, S.C. & Malhotra, R.C. 2000 The hottest chili variety in India Curr. Sci. 79 287 288

  • Perkins, B., Bushway, R., Guthrie, K., Fan, T., Stewart, B., Prince, A. & Williams, M. 2002 Determination of capsaicinoids in salsa by liquid chromatography and enzyme immunoassay JAOAC Int. 85 82 85

    • Search Google Scholar
    • Export Citation
  • Smith, P.G. & Heiser, C.B. Jr. 1957 Taxonomy of Capsicum sinense Jacq and the geographic distribution of the cultivated Capsicum spp Bull. Torrey Bot. Club 84 413 420

    • Search Google Scholar
    • Export Citation
  • Suzuki, T. & Iwai, K. 1984 Constituents of red pepper species: Chemistry, biochemistry, pharmacology, and food science of the pungent principle of Capsicum species 238 248 Brossi A. The alkaloids: Chemistry and pharmacology Academic Orlando, Fla

    • Search Google Scholar
    • Export Citation
  • Zewdie, Y. & Bosland, P.W. 2000a Capsaicinoid inheritance in an interspecific hybridization of Capsicum annuum x C. chinense J. Amer. Soc. Hort. Sci. 125 448 453

    • Search Google Scholar
    • Export Citation
  • Zewdie, Y. & Bosland, P.W. 2000b Pungency of chile (Capsicum annuum L.) is affected by node position HortScience 35 1174

  • Zewdie, Y. & Bosland, P.W. 2001 Capsaicinoid profiles are not good chemotaxonomic indicators for Capsicum species Biochem. Syst. Ecol. 29 161 169

  • Zewdie, Y. & Zeven, A.C. 1997 Variation in Yugoslavian hot pepper (Capsicum annuum L.) accessions Euphytica. 97 81 89

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Contributor Notes

To whom reprint requests should be addressed; e-mail bjarret@ars-grin.gov

  • Baldwin, E.A., Nisperos–Carriedo, M.O., Baker, R. & Scott, J.W. 1991 Quantitative analysis of flavor parameters in six Florida tomato cultivars (Lycopersicon esculentum Mill) J. Agr. Food Chem. 39 1135 1140

    • Search Google Scholar
    • Export Citation
  • Baral, J.B. & Bosland, P.W. 2004 Unraveling the species dilemma in Capsicum frutescens and C. chinense (Solanaceae): A multiple evidence approach using morphology, molecular analysis, and sexual compatibility J. Amer. Soc. Hort. Sci. 129 826 832

    • Search Google Scholar
    • Export Citation
  • Contreras–Padilla, M. & Yahia, E.M. 1998 Changes in capsaicinoids during development, maturation, and senescence of chile peppers and relation with peroxidase activity J. Agr. Food Chem. 46 2075 2079

    • Search Google Scholar
    • Export Citation
  • D'Arcy, W.G. & Eshbaugh, W.H. 1974 New World peppers (Capsicum – Solanaceae) North of Colombia: A resume Baileya 19 93 105

  • DeWitt, D. & Bosland, P.W. 1993 The pepper garden. Ten Speed Press Berkeley, Calif

  • DeWitt, D. & Bosland, P.W. 1996 Peppers of the world: An identification guide Ten Speed Press Berkeley, Calif

  • Duke, S.O., Schrader, K.K., Wedge, D.E., Arthur, F.H., Akey, D.H., Tellez, M.R., Dayan, F.E., Baerson, S.R., Scheffler, B.E., Rimando, A.M., DeLucca, A.J., Gibson, D.M., Harrison, H.F., Peterson, J.K., Gealy, D.R., Tworkoski, T., Wilson, C.L. & Morris, J.B. 2003 United States Department of Agriculture–Agricultural Research Service. Natural products for pest management Pest Man. Sci. 59 708 717

    • Search Google Scholar
    • Export Citation
  • Eshbaugh, W.H. 1976 XII. Genetic and biochemical systematic studies of chile peppers (Capsicum – Solanaceae) Bull. Torrey Bot. Club 102 396 403

    • Search Google Scholar
    • Export Citation
  • Greenleaf, F.J., Martin, J.A., Lease, J.G., Sims, E.T. & van Blaircom, L.O. 1970 Greenleaf Tabasco, a new tobacco etch virus resistant ‘Tabasco’ pepper variety (Capsicum frutescens L.) Alabama Agr. Expt. Sta. Auburn University Ala

    • Search Google Scholar
    • Export Citation
  • Harvell, K. & Bosland, P.W. 1997 The environment produces a significant effect on pungency of chiles HortScience 32 1292

  • Heiser, C.B. Jr. & Pickersgill, B. 1969 Names for the cultivated Capsicum species (Solanaceae) Taxon 18 277 283

  • Heiser, C.B. Jr. & Smith, P.G. 1953 The cultivated Capsicum peppers Eco. Bot. 7 214 226

  • Iwai, K., Suzuki, T. & Fujiwake, H. 1979 Formation and accumulation of pungent principle of hot pepper fruits, capsaicin and its analogues, in Capsicum annuum var. annuum cv. Karayatsubusa at different growth stages after flowering Agr. Biol. Chem. 43 2493 2498

    • Search Google Scholar
    • Export Citation
  • Jarret, R.L., Perkins, B., Fan, T., Prince, A., Guthrie, K. & Skoczenski, B. 2003 Using EIA to screen Capsicum spp. germplasm for capsaicinoid content J. Food Comp. Anal. 16 189 194

    • Search Google Scholar
    • Export Citation
  • Jarret, R.L., Spinks, M., Lovell, G. & Gillaspie, A.G. 1990 The S-9 plant germplasm collection at Griffin, Georgia Diversity 6 23 25

  • Krajewska, A.M. & Powers, J.J. 1988 Sensory properties of naturally occurring capsaicinoids J. Food Sci. 53 902 905

  • Lopez–Hernandez, J., Oruna–Concha, M.J., Simal–Lozano, J., Vazquez–Blanco, M.E. & Gonzalez–Castro, M.J. 1996 Chemical composition of Padron peppers (Capsicum annum (L.) grown in Galicia (N.W. Spain) Food Chem. 57 557 559

    • Search Google Scholar
    • Export Citation
  • Luning, P.A., van der Vuurst de Vries, R., Yuksel, D., Ebbenhorst–Seller, T., Wichers, H.J. & Roozen, J.P. 1994 Combined instrumental and sensory evaluation of flavor of fresh bell peppers (Capsicum annuum) harvested at three stages of maturity J. Agr. Food Chem. 42 2855 2861

    • Search Google Scholar
    • Export Citation
  • Mathus, R., Dangi, R.S., Dass, S.C. & Malhotra, R.C. 2000 The hottest chili variety in India Curr. Sci. 79 287 288

  • Perkins, B., Bushway, R., Guthrie, K., Fan, T., Stewart, B., Prince, A. & Williams, M. 2002 Determination of capsaicinoids in salsa by liquid chromatography and enzyme immunoassay JAOAC Int. 85 82 85

    • Search Google Scholar
    • Export Citation
  • Smith, P.G. & Heiser, C.B. Jr. 1957 Taxonomy of Capsicum sinense Jacq and the geographic distribution of the cultivated Capsicum spp Bull. Torrey Bot. Club 84 413 420

    • Search Google Scholar
    • Export Citation
  • Suzuki, T. & Iwai, K. 1984 Constituents of red pepper species: Chemistry, biochemistry, pharmacology, and food science of the pungent principle of Capsicum species 238 248 Brossi A. The alkaloids: Chemistry and pharmacology Academic Orlando, Fla

    • Search Google Scholar
    • Export Citation
  • Zewdie, Y. & Bosland, P.W. 2000a Capsaicinoid inheritance in an interspecific hybridization of Capsicum annuum x C. chinense J. Amer. Soc. Hort. Sci. 125 448 453

    • Search Google Scholar
    • Export Citation
  • Zewdie, Y. & Bosland, P.W. 2000b Pungency of chile (Capsicum annuum L.) is affected by node position HortScience 35 1174

  • Zewdie, Y. & Bosland, P.W. 2001 Capsaicinoid profiles are not good chemotaxonomic indicators for Capsicum species Biochem. Syst. Ecol. 29 161 169

  • Zewdie, Y. & Zeven, A.C. 1997 Variation in Yugoslavian hot pepper (Capsicum annuum L.) accessions Euphytica. 97 81 89