Genetic and Phenotypic Association between Yield Components in Hybrid Sorghum (Sorghum bicolor (L.) Moench) populations

Abstract

The magnitude of genetic expression and associations among traits are important for the prediction of response to selection in diverse environments and provide the basis for planning and evaluating breeding programs. In this regard, a cross classification mating design was used to produce hybrid sorghum populations, which were evaluated in a randomized completed block design with three replications at four environments in Northern Cameroon. Data on grain yield, days to anthesis, plant height, inflorescence length, threshing percentage and seed mass were collected and subjected to statistical genetic analyses. Significant genotype × environment interaction effects were observed for all traits. Genetic variance was essentially attributed to additive gene effects, with dominance variance for grain yield being negligible. However, the reverse was observed for threshability. Genetic variance components were much higher for plant height and grain yield than for days to anthesis, seed mass and threshability. Heritability estimates for plant height and inflorescence length were high (77 and 54 percent respectively) while the estimates for grain yield and threshability were low (14 and 5 percent respectively). Grain yield had positive genotypic correlation with most of the traits. Days to anthesis were negatively correlated with vegetative and reproductive traits. These results suggest that improvement of days to anthesis, plant height, and inflorescence length should be faster because of higher heritabilities and greater phenotypic variation. However, selection for earliness and reduced plant height would not be possible without hampering grain yield. Selecting for yield primary components namely inflorescence length and seed weight would be effective for increasing production. In addition, optimizing agronomic practices and improved experimental design would increase the selection efficiencies.

Caracterização de genótipos e estimativa de parâmetros genéticos de características produtivas de sorgo forrageiro

“…Na África, Ayana & Bekele (2000) registraram média de altura de 2,66 m (CV E = 40,66%) para 415 genótipos de sorgo e Kenga et al (2006), média de 2,28 m (CV E = 11,71%) para 75 híbridos de sorgo.…”

“…O genótipo mais precoce foi o 10-Ca84-B2SB88-BCa89 (50,67 dias). Média inferior (63 dias; CV E = 3%) à deste estudo foi descrita por Audilakshmi et al (1999), enquanto Kenga et al (2006) obtiveram média semelhante (73,7 dias; CV E = 4,6%) e Ayana & Bekele (2000), média superior (115,77 dias; CV E = 30,59%).…”

“…As estimativas de herdabilidade foram de magnitude moderada a alta e muito alta para a altura da planta (97,05%). Kenga et al (2006) obtiveram estimativas de herdabilidade entre 5 e 77% em diversas características, como altura da planta (77%) e número de dias para o florescimento (42%), cujos percentuais foram menores que os deste estudo.…”

Herdabilidade e correlações entre caracteres agronômicos em populações híbridas de trigo duro

“…Valores de médios a baixos foram estimados para massa de cem grãos para todos os cruzamentos, como analisado por Kenga et al (2006) em sorgo e por Van Sanford e Utomo (1995) em trigo de inverno. Entretanto, as estimativas da herdabilidade em sentido amplo realizadas por Annicchiarico e Pecetti (1998), em trigo duro, foram altas, discordando do presente trabalho.…”

“…O conhecimento das variâncias genéticas e fenotípicas bem como as associações entre os componentes da produção de grãos e suas herdabilidades é de grande interesse para o desenvolvimento de estratégias de seleção adequadas (Kenga et al, 2006).…”