Combining Ability for Quality of Maize Flour in A 6-Parent Diallel Cross

Whole maize (Zea mays L.) grains from 15 F1 hybrids obtained form a diallel cross of six maize cultivars consisting of one waxy and five non-waxy were ground into flour and used to prepare "tuwo", a thick porridge. "Tuwo" was prepared by heating a mixture of 10g flour in 30ml of water and evaluated for firmness, stickiness and time of gelatinization. Mean square for general combining ability (GCA) was highly significant for stickiness and firmness of "tuwo". Gelatinization time was highly significant for specific combining ability (SCA). Additive gene effects were substantially more important for firmness and stickiness, while gelatinization time was considerably influenced by non-additive genes. The waxy maize contributed more unfavourable GCA effects for softness and stickiness of "tuwo" than the remaining five cultivars

Combining Ability for Quality of Maize Flour in A 6-Parent Diallel Cross

Whole maize (Zea mays L.) grains from 15 F1 hybrids obtained form a diallel cross of six maize cultivars consisting of one waxy and five non-waxy were ground into flour and used to prepare "tuwo", a thick porridge. "Tuwo" was prepared by heating a mixture of 10g flour in 30ml of water and evaluated for firmness, stickiness and time of gelatinization. Mean square for general combining ability (GCA) was highly significant for stickiness and firmness of "tuwo". Gelatinization time was highly significant for specific combining ability (SCA). Additive gene effects were substantially more important for firmness and stickiness, while gelatinization time was considerably influenced by non-additive genes. The waxy maize contributed more unfavourable GCA effects for softness and stickiness of "tuwo" than the remaining five cultivars

Clonal stability of latex yield in eleven clones of Hevea brasiliensis Muell. Arg.

Eleven Hevea brasiliensis clones were evaluated for clonal stability of latex yield. A randomized complete block design was used with four replicates, two locations, seven years and three periods per year. Stability analysis was based on clone x year and clone x year x location interactions. Five stability parameters viz environmental variance, shukla's stability variance, regression of clonal latex yield on environmental index, variance due to regression and variance due to deviation from regression were applied. There was significant clone x environment effect at the two levels of interaction. Among the eleven clones, C 162 was outstanding for clonal stability and it can serve as donor parent for stability alleles. Three clones (C 76, C 150 and C 154) were also stable. The four stable clones (C 76, C 150, C 154 and C 162) are suitable for broad-spectrum recommendation for latex yield. Five clones (C 83, C 143, C 163, C 202 and RRIM 600) will require environment-specific recommendation because of their unstable phenotype. The stability feature of two clones (C 145 and C 159) was not clear and this will be investigated in subsequent studies

Predição de parâmetros e valores genéticos para caracteres de crescimento e produção de látex em progênies de seringueira Genetic parameters and values prediction for growth and latex production traits in rubber tree progenies

O trabalho objetivou estimar parâmetros e valores genéticos para os caracteres altura, diâmetro, produção de látex e produtividade de progênies de seringueira. As progênies meio-irmãos foram estabelecidas sob delineamento de blocos ao acaso, com 28 tratamentos (progênies), cinco repetições e dez plantas por parcela. Aos três anos de idade, as progênies foram avaliadas quanto aos caracteres: a) altura total (cm); b) diâmetro (mm); c) Produção de borracha seca (g) e produtividade (g cm-2). As estimativas dos coeficientes de herdabilidades individuais (0,33; 0,24 e 0,51) para os caracteres altura, diâmetro e produtividade, respectivamente, foram consideradas expressivas. Para o caráter produção de borracha seca, a estimativa do coeficiente de herdabilidade individual, no sentido restrito (9%), embora de baixa magnitude, revela excelente possibilidade de seleção, pois conduziram a estimativa da herdabilidade, em nível de médias de família, a um valor equivalente a 68%. A acurácia entre os valores genéticos preditos e os verdadeiros foram de 0,80 para altura, 0,76 para diâmetro, 0,62 para produção de borracha seca e 0,86 para produtividade. As estimativas de herdabilidades individuais associadas às de médias de progênies podem maximizar os ganhos genéticos com a seleção na população. A inclusão do caráter produtividade foi promissora e deve ser utilizada na seqüência das avaliações, subsidiando o programa de melhoramento genético da espécie no Estado de Mato Grosso do Sul.<br>This study aimed to estimate genetic values and parameters for plant height, diameter, rubber yield and productivity (g cm-2) of rubber tree progenies. Half-sib progenies were established in a complete randomized block, with 28 treatments, five replicates and 10 plants per plot. At three years of life, the progenies were evaluated regarding the following characters: diameter, rubber production and productivity (g cm²). The estimative coefficients of individual heritabilities (0.33; 0.24 and 0.51) for plant height, diameter and area production, respectively, were considered expressive. For the character of rubber yield the estimative of the coefficient of individual heritability, towards restrictive (9%), although of low magnitude, indicates an excellent chance once selection, it led to an estimate of heritability at family average level, to an equivalent value of 68%. The accuracy among the genetics values predicted and the true ones were of 0.80 for height, 0.76 for diameter, 0.62 for rubber yield and 0.86 for productivity (g cm²). The estimative of individual heritability associated with the average of progenies can maximize the genetic gains with selection in to the population. The inclusion of productivity character is promising and should be considered in future evaluations, supporting the species genetic improvement program in Mato Grosso do Sul State