Preliminary characterization of Psidium germplasm in different Brazilian ecogeographic regions

Caracterização preliminar de germoplasma de Psidium em diferentes ecorregiões brasileiras

NOTAS CIENTÍFICAS

Preliminary characterization of Psidium germplasm in different Brazilian ecogeographic regions

Caracterização preliminar de germoplasma de Psidium em diferentes ecorregiões brasileiras

Carlos Antonio Fernandes Santos^I; José Mauro da Cunha e Castro^I; Flavio de França Souza^II; Aloísio Alcântara Vilarinho^III; Francisco Ricardo Ferreira^IV; Juliano Gomes Pádua^IV; Rita Mércia Estigarribia Borges^I; Rosa Lia Barbieri^V; Aparecida das Graças Claret de Souza^VI; Marciene Amorim Rodrigues^I

^IEmbrapa Semi-Árido, Caixa Postal 23, CEP 56302-970 Petrolina, PE, Brazil. E-mail: [e-mail], [e-mail], [e-mail], [e-mail]

^IIEmbrapa Rondônia, Caixa Postal 406, CEP 78900-970 Porto Velho, RO, Brazil. E-mail: [e-mail]

^IIIEmbrapa Roraima, BR 174, Km 8, Distrito Industrial, CEP 69301-970 Boa Vista, RR, Brazil. E-mail: [e-mail]

^IVEmbrapa Recursos Genéticos e Biotecnologia, Caixa Postal 02372, CEP 70770-900 Brasília, DF, Brazil. E-mail: [e-mail], [e-mail]

^VEmbrapa Clima Temperado, Caixa Postal 403, CEP 96001-970 Pelotas, RS, Brazil. E-mail: [e-mail]

^VIEmbrapa Amazônia Ocidental, Caixa Postal 319, CEP 69010-970 Manaus, AM, Brazil. E-mail: [e-mail]

ABSTRACT

The objective of this work was to characterize 119 accessions of guava and 40 accessions of "araçá" sampled in 35 Brazilian ecoregions, according to the International Union for the Protection of New Varieties of Plants (UPOV) descriptors. The majority of "araçá" accessions presented wide spacing of leaf veins, while guava accessions presented medium to close spacing. Most fruits of "araçá" accessions were classified as small, contrasting with medium to large fruits of guava accessions. Most of "araçá" accessions (91%) presented white flesh fruit color, while 58% of guava accessions presented pale pink, pink and dark pink colors. Fruit differences among wild and cultivated Psidium species indicate fruit as the most altered trait under artificial selection.

Index terms:Psidium guajava, araçá, guava.

RESUMO

O objetivo deste trabalho foi caracterizar 119 acessos de goiabeira e 40 acessos de araçazeiro identificados em 35 ecorregiões brasileiras, de acordo com descritores da International Union for the Protection of New Varieties of Plants (UPOV). A maioria dos acessos de araçazeiro apresentou grandes espaços entre as nervuras da folha, enquanto os de goiabeira apresentaram espaços pequenos. Os frutos de araçazeiro foram classificados como pequenos, enquanto os de goiabeira apresentaram tamanho de médio a grande. A maioria dos acessos de araçazeiro (91%) apresentou cor branca para a polpa do fruto, enquanto 58% dos de goiabeira apresentaram cor de rosa-claro a rosa-escuro. As diferenças nos frutos entre Psidium selvagens e domesticados indicam que os frutos foram os mais alterados pela seleção artificial.

Termos para indexação:Psidium guajava, araçá, goiaba.

The Myrtaceae family comprises approximately 130 genera and 3,000 species of trees and shrubs, mostly evergreen and distributed mainly in the tropics and subtropics (Watson & Dallwitz, 2007). The genus Psidium (2n = 2x = 22) includes about 150 species, which are all fruit-bearing trees or shrubs (Jaiswal & Jaiswal, 2005). P. guajava L. (guava) is native of Northern South America and widely distributed in the tropical regions of America (Risterucci et al., 2005). "Araçá" is a general term used in Brazil to refer to wild Psidium spp., among which P. cattleyanum Sab., P. incanescens Martius, P. gradiflorum Martius and P. arboretum Vell. are native of South America (Raseira & Raseira, 1996).

Characterization and agronomic evaluation for P. guajava were reported by Rodriguez et al. (2004). Raseira & Raseira (1996) reported an extensive work on "araçá", including genotype characterization.

The objective of this work was to characterize guava and "araçá" accessions, according to the International Union for the Protection of New Varieties of Plants (UPOV) descriptors for Psidium guajava.

Prospecting of wild-growing Psidium germplasm species was carried out in 35 ecogeographic zoning regions (EGZRs) of ten Brazilian states, five in Maranhão (MA), five in Sergipe (SE), four in Pernambuco (PE), two in Piauí (PI), two in Bahia (BA), one in Rio Grande do Sul (RS), five in Goiás (GO), six in Rondônia (RO), two in Amazônas (AM) and three in Roraima (RR). An EGZR was defined as a region that has the same type of vegetation, soil and altitude, since it was assumed that Psidium spp. adaptation might have been influenced by these factors. An ecogeographic zoning map was used to define the ecoregions within five states of Brazil Northeast. In addition vegetation maps were used to define ecoregions in states of South, Central East and North regions of Brazil. Species samplings were made in EGZRs inhabited by the least developed rural human population, in order to avoid the prospecting of recently introduced guava germplasm. For the same reasons, sampling was avoided, when possible, within urban areas. For each individual plant, in situ pictures were taken and geographic coordinates with a GPS and physical reference sites were also recorded.

Guava and "araçá" plants sampled in different ecoregions were characterized for one, 20, 17 and two descriptors of stem, leaves, fruits and seeds, respectively (Table 1), according to UPOV guidelines (International Union for the Protection of New Varieties of Plants, 1987). Simple percentages were estimated for the applied UPOV guava descriptors, while for others, such as leaf and fruit length, leaf and fruit width and spacing of leaf veins, prior measurements were taken before grouping into a specific descriptor class.

A hundred nineteen accessions of guava and 40 accessions of "araçá" from 35 different ecoregions were characterized, with the following distribution by Brazilian state: MA – 25 of guava and one of "araçá"; PI – three of guava and one of "araçá"; SE – 12 of guava and two of "araçá"; BA – ten of guava and seven of "araçá"; PE – nine of guava and four of "araçá"; RS – five of guava and five of "araçá"; RO – 15 of guava and five of "araçá"; RR – seven of guava and four of "araçá"; GO – 17 of guava and seven of "araçá"; and AM – 16 of guava and four of "araçá".

The majority of "araçá" accessions (86%) presented wide spacing of leaf veins, while guava accessions presented medium (65%) and close (33%) spacing (Table 1). In the field, this descriptor was used to separate, in some cases, accessions of "araçá" from 53% of "araçá" accessions were classified into the short class. For fruit width, only a few guava accessions (3%) were grouped in the narrow class, while 56% of "araçá" accessions were classified into the narrow class (Table 1). These differences in fruit size could be attributed to the long-term selection to which guava, a Psidium cultivated species, has been submitted, in opposition to wild-growing "araçá".

Another difference among "araçá" and guava accessions was observed in the fruit shape at the stalk end: "araçá" accessions were grouped into the classes of broadly rounded and rounded (74%), while those of guava were grouped into the classes of pointed and necked (52%) (Table 1). Regarding flesh fruit color, "araçá" accessions were grouped as cream (80%), white (11%) and pale pink (9%), while guava accessions were almost evenly distributed among all seven classes of UPOV for this descriptor. The most common colors of guava flesh were pale pink (29%), pink (20%), dark pink (18%) and cream (18%). According to Gonzaga Neto et al. (2001), pink and orange colors are largely accepted by Brazilian market, which could explain the concentrations of prospected guava germplasm into these classes.

Acknowledgements

To European Community, for financial support.

Received on October 11, 2007 and accepted on February 27, 2008

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Publication Dates

• Publication in this collection
  06 May 2008
• Date of issue
  Mar 2008

History

• Accepted
  27 Feb 2008
• Received
  11 Oct 2007