Diallel Analysis in Cassava Adapted to the Midaltitude Valleys Environment

Abstract

can produce in degraded soils, and offers resistance to its most important diseases and pests. It is naturally Cassava (Manihot esculenta Crantz) is an important commodity tolerant to acidic soils and offers the convenient flexibilfor industrial processes in tropical countries as one of the few alternaity to be harvested when the farmers need it. Cassava tives to compete with imported maize (Zea mays L.). To maintain has benefited by technological inputs in the area of this competitiveness, cassava breeding needs to be as efficient as possible. This study provides one of the first attempts to produce breeding (Kawano et al., 1998;Kawano, 2003) to sucquantitative genetic data to aid breeding efficiency, through the analycessfully satisfy the needs of farmers and processors. sis of a diallel set among nine parental clones adapted to the midalti-The general scheme for cassava breeding is indeed a tude valleys environment. Thirty clones represented each F 1 cross phenotypic masal selection. Large numbers of segregat-(with three exceptions). Evaluations were conducted in two coning genotypes is evaluated in a lengthy process that retrasting environments with three replications in each location. The quires as many as 6 yr for completion (Jennings and specific combining ability (SCA) effects were relatively more impor-Iglesias, 2002). Individual genotypes (clones) are setant than general combining ability (GCA) effects for root yield. In lected and then multiplied to take advantage of the the case of harvest index, dry matter content (DMC) and plant type vegetative propagation of the crop. architecture GCA effects were about twice as large as those from Little progress in understanding the inheritance of SCA effects. Reaction to mites (Mononychellus tanajoa Bondar) and white flies (Aleurotrachelus socialis Bondar) (based on single-Aé reo 6713, Cali, Colombia. H. Ceballos, also Univ. Nacional de from these 30 plants were obtained. Minor selection was un-Colombia, Carrera 32, Chapinero vía Candelaria, Palmira, Colombia. avoidable at this stage based on the capacity of the botanical Received 21 May 2004. Crop Breeding, Genetics & Cytology. *Correseeds to produce vigorous seedlings and plants capable of sponding author (h.ceballos@cgiar.org).producing six good quality vegetative cuttings.

Yield traits as selection indices in seedling populations of cassava

“…Genotypes with high general combining ability (GCA) for percentage DMC or yield identified through studies by Jaramillo et al (2005); were crossed following standard procedures described by Kawano (1980). Parents for crossing were planted in a crossing block in CIAT, Palmira.…”

“…When seedlings were 20 to 25 cm tall, they were transplanted to a well-prepared seedbed in the field, in Palmira, Colombia. Palmira is located at lat 3 0 06' N, long 76 0 32' W and 965 m asl; has an annual temperature of 24 0 C with clay soil texture (Jaramillo et al 2005, Kawano 2003. Seedlings were planted on ridges 1.5 m apart, with spacing of 0.6 m between plants.…”

Capacidade de combinação de genitores de batata para caracteres de aparência e rendimento de tubérculos

“…Para a seleção de genitores, uma das metodologias mais eficientes e comumente utilizadas em programas de melhoramento genético é a análise dialélica, a qual propicia estimativas de parâmetros úteis à seleção de genitores para hibridação e ao entendimento da ação dos genes envolvidos na determinação dos caracteres e da existên-cia de heterose (Cruz et al, 2004), proporcionando, assim, grandes avanços para a seleção (Jaramillo et al, 2005).…”

Capacidade de combinação por meio de análise multivariada para caracteres fenotípicos em maracujazeiro-doce

“…Entre os métodos de escolha de genitores, um dos mais eficientes e comumente utilizados em programas de melhoramento genético é a análise dialélica, que determina o potencial dos genitores em combinações híbridas, a ação gênica que controla os caracteres, a herança dos caracteres e a existência de heterose, e proporciona avanços para a seleção (Jaramillo et al, 2005). Existem vários métodos usados na análise de cruzamentos dialélicos, sendo que o método proposto por Griffing (1956) é um dos mais empregados.…”

“…A análise dos caracteres isoladamente pode não ser suficiente, pois não considera as correlações existentes entre eles. É importante ressaltar, no entanto, que essas análises vêm gerando um grande volume de informações para programas de melhoramento genético de diversas espécies (Barbosa & Pinto, 1998;Jaramillo et al, 2005;Lorencetti et al, 2006;Rodrigues et al, 2006). Existe a alternativa da utilização da análise multivariada em cruzamentos dialélicos, que permite combinar as múltiplas informações obtidas na unidade experimental, o que facilita a seleção e possibilita a discriminação das populações mais promissoras, principalmente no contexto da seleção de genitores para melhoramento genético (Ledo et al, 2003).…”