Brazilian Cashew Germplasm Bank

Transcription

1 Brazilian Cashew Germplasm Bank A.C.R. Castro, P.N. Bordallo, J.J.V. Cavacanti and L.M. Barros Embrapa Tropical Agroindustry Corporation Dra. Sara Mesquita Fortaleza (CE) Brazil Keywords: Anacardium occidentale, characterization, genetic resource, plant breeding Abstract The cashew germplasm bank located in Pacajus, Ceará State, Brazil, holds 621 accessions, most of which belong to Anacardium occidentale. Introduction of plants into the germplasm bank started in the 1950s. Nowadays, the main goals of the cashew germplasm bank is to document and conserve plant material, which can then be used to enrich the available genetic variation in the species, serve as a basis for agronomic and morphological characterizations of accessions, and support breeding programs. The accessions have been characterized with morphological, agronomic and molecular descriptors. The genetic variability contained in the collection has allowed development of early dwarf cashew clones, recommended for commercial planting in northeastern Brazil since the 1980s until today. The genetic basis of early dwarf cashew has been expanded by natural and artificial hybridization with regular cashew genotypes from the germplasm bank, to increase the weight and size of nut and kernel. Interspecific hybrids of A. occidentale A. othonianum and A. occidentale A. microcarpum have been produced in order to transfer anthracnose resistance alleles and desired quality traits to table cashew. Passportization data have been submitted to the SIBRAGEN data bank. INTRODUCTION Cashew (Anacardium occidentale L.) belongs to the Anacardiaceae family, which comprises about 70 genera and 600 species. Cashew plants vary in size from shrubs (rarely subshrubs) to large trees, and are mainly restricted to tropical and subtropical regions, with relatively few representatives in temperate climates (Barros et al., 1999). They are found throughout the Brazilian territory but most abundantly in the northeastern parts. The cashew tree is considered to be one of the most important plants cultivated in the tropics. The cashew crop occupies an estimated area of 3.39 million hectares in the world, with the edible kernel being the main product and having great economical value (Cavalcanti and Wilkinson, 2007). According to IBGE, the planted area in Brazil is around 741,607 hectares (Amyot, 2009). The cashew tree occupies an important position among the tropical fruit bearing trees on account of the growing commercialization of its main products: the nut, the cashew nut shell liquid (CNSL), and the cashew apple. The CNSL is used for making phenolic resins and friction powders for the automotive industry, and it also contains bioactive substances. The cashew nut and peduncle are used for human consumption, and have high nutritional importance (Santos et al., 2007). Cashew apples can be consumed either raw or processed as juice, candy, ice cream, raisins, honey, brandy, soft drink (cajuína) and vinegar. The fibers (bagasse or residue) are also used in cooking to prepare meats and burgers. The nut is appreciated after roasting, and the flowers are attractive to bees. The wood is suitable for construction and carpentry. Large populations of cashew trees are found in different Brazilian ecosystems, and show variability in physiological and morphological characters. However, little is known about this variability, as well as its potential use in commercialization (Paiva et al., 2003). Despite all the social importance and economical potential, many natural plant materials found in the wild, have a strong tendency to diminish or even disappear due to Proc. XXVIII th IHC III rd IS on Plant Genetic Resources Ed.: K.E. Hummer Acta Hort. 918, ISHS

2 irrational exploitation of the ecosystems in which they occur. Along with these genetic resources, a range of favorable genes and desirable traits like, e.g., fruit quality, resistance to pests and diseases, adaptation to different cropping systems and high productivity, could become extinct by genetic erosion. The introduction of material into the Brazilian cashew germplasm bank, the main source of adequate materials for the development of commercial products, started in the 1950s. The aim of this presentation is to describe the main activities and goals of the Embrapa Tropical Agroindustry Cashew Germplasm Bank. MATERIALS AND METHODS The Brazilian cashew germplasm bank is located in Pacajus, Ceara State (Fig. 1), with the coordinates S; W and an altitude of 70 m above sea level. The region has a tropical climate and average temperatures of C (IPECE, 2009). The principal activities of the germplasm bank are conservation, collection, characterization and documentation of the accessions of cashew. Collection activities started in the 1950s and have been going on until the present time, in different places in Brazil, especially in the northeast (Fig. 2). The cashew trees are planted at 4 4 m, with a minimum of five replicates. Morphological characteristics have been evaluated according to IBPGR (Table 1). Evaluations have been made in five plants for each specific descriptor. Experimental data presented refer to the observations in the years 2007 to The data were recorded in spread sheets for studies of genetic divergence. Passportization data for each accession have been deposited in a data base platform for genetic resources at Embrapa. RESULTS AND DISCUSSION The cashew germplasm bank holds 621 accessions, with the majority belonging to A. occidentale. Morphologically, this species shows variability in most traits especially leaves and apple attributes (Figs. 1 and 3). Results from analyses of chemical contents in material of two species and two commercial clones are reported in Table 2. Since the consumption of raw cashew has increased, species with low tannin content in the stalk have become important in breeding programs. Apples of A. microcarpum had the lowest average tannin (0.12%) when compared with the clones (CCP 09 and CP 76), suggesting its importance as a genetic resource for cultivar improvement (Table 2). Crisóstomo et al. (2002) analysed cashew apple of plants from crosses (F1 and RC1) between the species Anacardium occidentale and A. microcarpum, and observed a low tannin content in A. microcarpum (0.14%) compared to clones of A. occidentale (0.33%), again demonstrating the suitability of A. microcarpum for a breeding program focussing on cashew apple quality. Furthermore, it was noted that hybrids between A. microcarpum and A. occidentale exhibited higher values than the parent s average in relation to tannin content, acidity and texture, and lower values in relation to ph and soluble solids. The genetic variability available in the cashew germplasm collection has allowed development of early dwarf cashew clones, which have been recommended for commercial planting in northeastern Brazil since the 1980s until today. Another 132 early dwarf cashew clones and 40 common cashews are still under evaluation. These results have had a direct impact on the Brazilian cashew agribusiness. Furthermore, it has been possible to expand the genetic basis of early dwarf cashew by natural and artificial hybridization with regular cashew genotypes from the germplasm bank, thus allowing a significant increase in the weight and size of nut and kernel. Interspecific hybrids of A. occidentale A. othonianum and A. occidentale A. microcarpum have also been produced with the goal of transferring anthracnose resistance alleles and desired quality traits to table cashew. This material is still under evaluation. The high variability found among genotypes demonstrates a potential use for breeding. 858

3 ACKNOWLEDGEMENTS The authors thank FUNCAP and the Brazilian Agricultural Research Corporation - Embrapa Tropical Agroindustry for supporting this work. Literature Cited Amyot, D Analise pelo Supply Chain Management da cadeia produtiva da castanha de caju no Rio Grande do Norte. 103p. Dissertação (mestrado) -Universidade Federal do Rio Grande do Norte (UFRN), Natal. Barros, L.M., Paiva, J.R., Crisóstomo, J.R. and Cavalcanti, J.J.V Hibridação do cajueiro. p In: A. Borém (ed.) Hibridação artificial de plantas. UFV, Viçosa. Cavalcanti, J.J.V. and Wilkinson, M.J The first genetic maps of cashew (Anacardium occidentale L.). Euphytica 157: Crisóstomo, J.R., Cavalcanti, J.J.V., Moura, L.B., Alves, R.E., Freitas, J.G. and Oliveira, J.N Melhoramento do cajueiro anão precoce: avaliação da qualidade do pedúnculo e a heterose dos seus híbridos. Revista Brasileira de Fruticultura 24: de Paiva, J.R., Crisóstomo, J.R. and Barros, L.M Recursos genéticos do Cajueiro: Coleta, Conservação, Caracterização e Utilização. Fortaleza: Embrapa Agroindústria Tropical. 43p. (Embrapa Agroindústria Tropical. Documentos, 65). IBPGR Cashew descriptors. International Plant Genetic Resource Institute, Rome. 33p. IPECE (Instituto de Pesquisa e Estratégica Economica do Ceará) Pacajus: perfil básico municipal, Fortaleza. 17p. Santos, R.P., Santiago, A.A.X., Gadelha, C.A.A., Cajazeiras, J.B., Cavada, B.S., Martins, J.L., Oliveira, T.M., Bezerra, G.A., Santos, R.P. and Freire, V.N Production and characterization of the cashew (Anacardium occidentale L.) peduncle bagasse ashes. J. Food Engin. 79: Tables Table 1. Morphological and agronomic descriptors for cashew used in the Embrapa Tropical Agroindusty Fortaleza-CE. Morphological descriptors Tree Leaves Flower Apple Habit Height Canopy diameter Pest presence Disease presence Young leaf Mature leaf Apple biochemical traits Nut Male flower Length Brix Length Bisexual flower Shape Vit. C Width Area Sex ratio Width Acidity Quality traits Shape Brittleness Flowering duration Diameter Firmness, ph 859

4 Table 2. Average values for tannin, acidity, soluble solids and ph for clones of Anacardium occidentale, A. microcarpum and hybrids under evaluation at Fortaleza- CE. Genotype Chemical contents Tannin (%) Acidity (%) Soluble solids (%) ph A.microcarpum 0.12 c 0.14 c 12.4 b 5.2 a A. occidentale 0.16 b 1.33 a 13.8 a 3.4 d Clone CP a 0.25 b 12.1 c 4.8 c Clone CP a 0.26 b 12.0 c 4.6 b Means followed by the same letter in a column did not differ from each other according to the Tukey test (P<0.05). Figurese Fig. 1. Different types of leaves found in the Brazilian Cashew Germplasm Bank: (a) elliptical, (b) wide-elliptical, (c) obovate, (d) oblanceolate and (e) oblong. 860

5 RR AM PA PI CE RN PB MT GO BA SP RJ Fig. 2. Locations where material has been collected for the Brazilian Cashew Germplasm Bank: AM Amapá, BA Bahia, CE Ceará, GO Goiás, MT Mato Grosso, PA Pará, PB Paraiba, RR Roraima, RJ Rio de Janeiro, PI Piaui, RN Rio Grande do Norte, SP São Paulo. Fig. 3. Embrapa cashew clones recommended for commercial planting: CCP 06 and CCP 1001 (rootstock preferential use); CP 09; CCP 76; Embrapa 50; Embrapa 51; BRS 189 (nut and natural consumption preferential use); Bahia 12 (coastal plains indication) and BRS 226 (gummosis resistance). 861