NOVAS VARIEDADES DE ALGODÃO OBTIDAS NO BRASIL: 15 ANOS DE COLABORAÇÃO ENTRE A COODETEC E O CIRAD

Resumo

A Cooperativa Central de Pesquisa Agrícola (Coodetec) e o Centro de Cooperação Internacional em Pesquisa Agronômica para o Desenvolvimento (Cirad) desenvolveram no Brasil, em 1990, um programa de criação de variedades de algodão para a América do Sul. A diversidade de pragas, doenças e invasoras dos sistemas de produção acarretaram a hierarquização dos objetivos de seleção, em cada região agroecológica e conforme o tipo de sistema de cultivo. Os principais objetivos visam introduzir fatores de resistência à doença-azul (de origem viral, transmitida pelos pulgões), à bacteriose, a doenças fúngicas (ramulose e ramulariose) e a nematóides. O mercado internacional requer aumento da produtividade e melhoria da qualidade da fibra. Utiliza-se um esquema de seleção genealógica a partir de populações intra-específicas, de ampla base genética, que recorre amplamente ao uso de ferramentas da biologia molecular, o que permite aplicar métodos de seleção assistida por marcadores. Esse programa comercializou sete variedades, CD401 a CD407, abrangendo cerca de 15% do mercado de sementes brasileiras e 30% do mercado do Paraguai. Os sucessos comerciais dessas variedades deram à Coodetec a possibilidade de autofinanciar seu programa de pesquisa algodoeira, ao passo que o Cirad pôde manter uma equipe pluridisciplinar no Cone Sul-Americano. Os novos desafios consistem em criar cultivares adaptadas a sistemas específicos de cultivo (plantio direto sob cobertura vegetal, algodão de segundo ciclo ou adensado) e participar, em breve, do lançamento, no Brasil, de variedades de algodoeiro geneticamente modificadas.

Termos para indexação: produção vegetal, métodos e técnicas.

BREEDING NEW COTTON VARIETIES IN BRAZIL: 15 YEARS
OF COLLABORATION BETWEEN COODETEC AND CIRAD
ABSTRACT

Since 1990, Coodetec (Cooperativa Central de Pesquisa Agrícola) and Cirad (Centre de Coopération Internationale en Recherche Agronomique pour le Développement) have been developing a program in Brazil to breed improved cotton cultivars for South America. The objectives of cotton breeding are geared towards meeting the needs of specific agrosystems due to the broad range of different cotton pests and cropping systems–ranging from labour-intensive but relatively non-intensified systems in Southern Brazil and Paraguai to highly intensive and completely mechanised systems in the Central-Western Brazilian Cerrados region. The goal is to overcome the main constraints by introducing traits of resistance or tolerance to viral (blue disease), bacterial (bacterial blight) and fungal (ramulose and grey mildew) diseases and nematodes. Farmers are constantly striving to increase their cotton yields, especially in the current setting of highly fluctuating world market prices for cotton fibre, but it is even more crucial to enhance fibre quality since this product is targeted for export markets. Improved cotton cultivars are created using a pedigree-breeding schedule applied to populations obtained via broad-based intraspecific crossing of cotton varieties and lines from all over the world. The efficiency of this cotton improvement program could be boosted by taking advantage of a new molecular biology tool – marker-assisted selection – especially with respect to introgressing blue disease resistance characters. New cotton varieties can now be officially recommended on the basis of results obtained in a varietal and agronomic experimental network that spans eight Brazilian States (Paraná, São Paulo, Mato Grosso do Sul, Minas Gerais, Goiás, Bahía, and Mato Grosso) and Paraguai. Since it was founded, 15 years ago, this program has released a series of improved varieties, i.e. CD401 to CD407, which are all resistant or tolerant to blue disease and bacterial blight, CD405 being the most nematode-tolerant variety. The very early CD401 variety yields excellent fibre and has been very well received by smallholders, while CD406, with the most indeterminate growth cycle, is designed for intensive Cerrado cropping conditions. These varieties have accounted for around 15% of the Brazilian market and 30% of the Paraguaian market in 2003-2004 despite very tight competition from many other public and private breeder companies. This commercial success has enabled Coodetec to entirely self-finance its cotton research program and Cirad to set up a multidisciplinary team to deal with a broad range of new research issues. The challenge is now to breed and promote cultivars tailored to specific cropping systems (direct seeding, mulch-based, cropping systems (DMC), secondary crop systems called safrinha systems, and high-density cropping – Ultra Narrow Row Cotton) and to prepare for the imminent release of genetically-modified cotton varieties.

Index terms: vegetal production, tools and methods.

DE NOUVELLES VARIÉTÉS DE COTONNIER
OBTENUES AU BRÉSIL: 15 ANS DE COLLABORATION
ENTRE LA COODETEC ET LE CIRAD
RÉSUMÉ

Au Brésil, la Coopérative centrale de recherche agricole (Coodetec) et le Centre de coopération internationale en recherche agronomique pour le développement (Cirad) ont développé depuis 1990 un programme de création de variétés de cotonniers pour l'Amérique du Sud. La diversité des bioagresseurs et des systèmes de production a conduit à hiérarchiser les objectifs de sélection pour chaque grande région agroécologique et selon les types de systèmes cotonniers. Les principaux objectifs visent l'introduction de facteurs de résistance à la maladie bleue (d'origine virale, transmise par les pucerons), à la bactériose, à des maladies fongiques (ramulose et ramulariose) et aux nématodes. Le marché international exige une augmentation de la productivité, et l'amélioration de la qualité de la fibre. Un schéma de sélection généalogique à partir de populations intra-spécifiques à large base génétique est utilisé. Il recourt largement à l'utilisation des outils de biologie moléculaire, permettant la mise en oeuvre de sélections assistées par marqueurs. Ce programme a commercialisé sept variétés, CD401 à CD407, couvrant en 2004 près de 15% du marché de semences brésilien et 30% du marché paraguayen. Les succès commerciaux de ces variétés permettent à la Coodetec d'autofinancer son programme de recherche cotonnière et au Cirad de maintenir une équipe pluridisciplinaire dans le cône sud-américain. Les nouveaux défis sont de créer des cultivars adaptés à des systèmes de culture spécifiques (semis direct sur couverture végétale, coton de deuxième cycle ou à forte densité) et de participer au lancement prochain au Brésil de variétés de cotonnier génétiquement modifiées.

Termes d'indexation: Productions végétales, méthodes et outils.