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The decision related to efficient breeding methods depends largely on the understanding of the type of gene action controlling the expression of the characters to be selected. The objective of this study was to estimate the gene action controlling yield and components in soybean (Glycine max L. Merrill). The study involved six basic soybean generations (P1, P2, F1, F2, BC1 and BC2) of two crosses, i.e. cross I (TGx1987-62F × TGx1830-20E) and cross II (TGx1987-10F × TGx1740-2F), at the Research farm of the International Institute for Tropical Agriculture, IITA, Ibadan. Data were subjected to generation mean analysis to determine gene actions and interactions, using Hayman model. The results obtained from the individual scaling test A, B, C indicated that the simple additive-dominance model was inadequate to reveal the inheritance of the gene governing most traits. Non-allelic gene interaction was crucial in the inheritance of most studied traits. The Hayman six-parameter genetic model demonstrated that the signs of [h] and [l] were contrasting for most of the traits; suggesting duplicate epistasis. In fact, the effect of dominance was important and significant in the genetic control of most of the traits studied. Therefore, improvement of soybean seed yield and its related characters need intensive selection and should be delayed until later generations. [ABSTRACT FROM AUTHOR]

A total of ten Okra [Abelmoschus esculentus L. (Moench)] accessions were evaluated over 2 years to determine the genetic diversity present in the germplasm accessions so that parents could be chosen for use in hybridization. Observations on days toflowering, number of branches and pods per plant, height at flowering, final plant height, pod length, pod width, and pod yield were recorded. There was a large degree of variability among genotypes for all traits and the metroglyph analysis classified the genotypes into 6 groups based on morphological differences. Genotype NHGB/09/008(B) had the highest total index. Groups II and V had the largest within group variation indicating that within group improvement was possible. Hybridization between Group III and Groups II and VI could yield desirable hybrids useful in Okra breeding program. [ABSTRACT FROM AUTHOR]

The complexity of relationships among traits that determine yield and the influence of environment on agronomic traits make the study of plant character correlation across environments necessary in plant breeding. Inter-character relationships of agronomic traits were evaluated on genotypes of okra [Abelmoschus esculentus(L). Moench] over three environments in Nigeria to compare the stability of relationships and determine traits to be targeted in development of an efficient selection index for okra yield improvement. Data were recorded on seed yield, pod yield, 100-seed weight, pod length, pod width, number of leaves and branches, stem diameter, plant height, and days to flowering. Components of variance and covariance were utilized to calculate environmental, genotypic, and phenotypic correlations among seed yield and other traits. Plant height, stem diameter, and pod yield had significant genotypic and phenotypic correlations among themselves and also had genotypic and phenotypic correlations with seed yield over environments. These traits could be utilized to develop a selection index to be applied across locations to increase seed yield in okra. [ABSTRACT FROM AUTHOR]

Inter-character correlations and path coefficient analyses of yield related characters were evaluated in some quantitative traits of okra (Abelmoschus esculentus (L.) Moench) grown under different cropping seasons. Data collected were subjected to correlation and path coefficient analyses to determine the relationships among the characters, as well as the direct and indirect effects of some yield related characters to seed yield. Correlation coefficients among characters varied among seasons. Days to flowering, number of pods per plant, length of matured pod, weight of matured pods per plant, number of ridges per pod, number of seeds per pod and 100 seed weight had significant genotypic correlations with seed yield/plant across the seasons. Environmental correlation coefficients were generally low and non significant except for number of leaves per plant, length of matured pod, width of matured pod and weight of matured pods per plant in all the seasons of study. The genotypic correlation coefficients of eight selected characters with seed yield were partitioned into their direct and indirect effects. Weight of matured pods per plant had the largest direct effect on seed yield/plant in early rain 2005 (season 1) and off season 2006 (season 2), branch length in the early rain 2006 (season 3) and stem height at flowering in late rain 2006 (season 4). The residual effects of 0.16 in season 1, 0.74 in season 2, 0.55 in season 3 and 0.38 in season 4 respectively accounting for 84%, 26%, 45% and 62%, contributed by the characters under study. [ABSTRACT FROM AUTHOR]

Inter-character correlations and path coefficient analysis of yield related characters were evaluated in some quantitative traits of okra (Abelmoschus esculentus (L.) Moench) grown in different cropping seasons. Data collected were subjected to correlation and path coefficient analyses to determine the relationships among the characters and the direct and indirect effects of some yield related characters on seed yield. Correlation coefficients among characters varied among seasons. Days to flowering, number of pods per plant, length of matured pod, weight of matured pods per plant, number of ridges per pod, number of seeds per pod and 100 seed weight had significant genotypic correlations with seed yield/plant across the seasons. Environmental correlation coefficients were generally low and non-significant except for number of leaves per plant, length of matured pod, width of matured pod and weight of matured pods per plant in all the seasons of study. The genotypic correlation coefficients of eight selected characters with seed yield were partitioned into their direct and indirect effects. Weight of matured pods per plant had the largest direct effect on seed yield/plant in early rain 2005, (season 1) and off season, 2006 (season 2), branch length in the early rain, 2006 (season 3) and stem height at flowering in late rain 2006 (season 4). The residual effects of 0.16 in season 1, 0.74 in season 2, 0.55 in season 3 and 0.38 in season 4 implied that 84%, 26%, 45% and 62%, respectively of the total variation could be accounted for by the characters utilized in this study. [ABSTRACT FROM AUTHOR]

Twenty five quantitative characters were observed on 25 accessions of West African okra of diverse ecological backgrounds for genetic variability through the technique of Principal Component Analysis (PCA) while the variation pattern among the accessions were classified by using the technique of Single Linkage Cluster Analysis (SLCA). The first three principal components accounted for 51.44% of the total variation while the first four axes accounted for 60.33. SLCA summarized the relationship among the accessions at various levels of similarity into a dendrogram, while the accessions were sorted into six distinct groups by the FASTCLUS technique. [ABSTRACT FROM AUTHOR]

Flooding is an important abiotic stress affecting rice production in rainfed lowlands of Asia and Africa. Highly tolerant donor rice accessions are needed to breed improved flood-tolerant rice varieties that can increase the productivity of the rainfed lowland ecology. A large collection of African rice (O. glaberrima; >2000 accessions) was screened separately for tolerance to flooding at germination (anaerobic germination ability; AG), submergence and stagnant flooding stresses. The entire collection was first screened in preliminary evaluation and best performing accessions were further evaluated in advanced screening. In the preliminary screenings, most of the O. glaberrima accessions were found to have good levels of anaerobic germination ability and stagnant flooding tolerance but were sensitive to submergence stress. Based on preliminary screening; 43, 20, and 42 accessions were selected for tolerance to AG, submergence and stagnant flooding respectively. Results identified six O. glaberrima accessions (TOG 5505-A, TOG 5485, TOG 5980-A, TOG 8347, TOG 7252-A, TOG 16704) for AG. One accession (TOS 6454) was selected for submergence while four O. glaberrima accessions (IG 48, GERVEX 2674, TOG 7148 and IG 133) were selected for stagnant flooding. All selected accessions were similar or better than the best O. sativa check. These accessions are potential sources of tolerance in breeding for flood tolerance in rice. [ABSTRACT FROM AUTHOR]