A ten – parent diallel experiment was carried out at the Teaching and Research Farms of the Federal University of Agriculture, Makurdi, Nigeria, to estimate combining ability and heterosis in rice. The design was a 10x10 alpha lattice with three replications and data was collected on plant height (PH), tiller numbers/plant (TN), leaf length (LL) and width (LW), days to flowering (DF), panicle length (PL), panicle exsertion (PE), spikelet numbers/panicle (SN), 100 seed weight (100SW) and days to maturity(DM). A preponderance of both additive and non – additive gene action with both negative and positive GCA, SCA and % heterosis was observed in the control of yield component traits in the studied rice varieties and their hybrids. Non – additive variance was higher, except for DF, SN and DM where additive variance was higher compared to non – additivity. Six parents, namely MGD 101, FARO 44, FARO 52, FARO 57, STRASSA 58 and IR 72 recorded the highest GCA values for most of the traits and the least values in terms of days to flowering and maturity. These parents were the most frequent in crosses with the highest SCA effects and % heterosis for Tiller number, Leaf length, leaf width, panicle length and Spikelet numbers/panicle. Crosses involving these six parents also recorded the least SCA effects and % heterosis for days to flowering and maturity. Based on the results of GCA, SCA and % heterosis, backcross breeding of F1s to their respective parents (the six parents), was recommended for improvement of yield component traits.
A six parent F 2 diallel of soybeans was evaluated in potted acid sand culture with the objective of estimating combining ability and heterosis for aluminium stress tolerance. Highly significant differences were observed among the genotypes, crosses (F 2 /R), Parents, F 2 , Reciprocals (R) and Parents Vs (F 2 /R) for the root dry weight, shoot dry weight and relative root surface area. Both general combining ability (GCA) and specific combining ability (SCA) mean squares were highly significant for the three traits, except the root dry weight, where the SCA was not significant. The result also showed the presence of both additive and dominance gene action and the preponderance of the former compared to the later, indicating the possibility of selection of pure lines from the genotypes studied. Selection from TGX 1896-3F and TGX 1844-18E and crosses involving these two genotypes on acid soil would enhance a rapid progress in the breeding of aluminium tolerant genotypes of soybeans.
<p>Experiments in acid sand culture, acid and neutral soil fields were carried out in 2003 with the objective of studying genetic variability and correlation among seedling and mature plant traits with a view of guiding breeders on appropriate selection options in breeding for aluminium/acid stress tolerant soybean in Nigeria. Genotypic variance was high for all the sand culture traits (root dry weight, shoot dry weight and relative root surface area), leading to the high heritability estimates of 77.85% to 83.72%. Genetic advance as a percentage of the mean (GA) was very high (85.51%-155.84%) for the sand culture traits. As expected, a better performance in terms of grain yield and yield components was observed for the neutral soil field compared to the acid soil field. However, higher heritability estimates were observed for the field traits measured on the acid soil field compared to the neutral soil field. Heritability estimates for the days to flowering and plant height were high (66.44%-79.63%) compared to the moderate heritability (47.42%-58.89%) observed for the number of pods/plant and grain yield on both soils. Conversely, the GA for days to flowering and plant height was lower (12.08%-26.49%) compared to the values (27.27%-41.56%) observed for number of pods/plant and grain yield on both fields. Higher genotypic and phenotypic coefficients of variation (GCV and PCV) were observed for the sand culture traits compared to the field traits. On the acid and neutral soil fields GCV and PCV values were lower for the days to flowering and plant height compared to the values observed for the number of pods/plant and grain yield, with highly significant correlation between/within the sand culture traits and the field traits. These results indicate that selection of soybean genotypes with high seedling root dry weight and relative root surface area in acid sand culture at 450 μM Al<sup>3+</sup> will enhance progress in the selection of high yielding acid tolerant tropically adapted genotypes of soybean on acid soils of Nigeria.</p>
Field experiments were conducted in 2010 and 2011 to evaluate maize with the objective of determining genetic variation and relationship among yield and yield component traits for simultaneous selection in dry and green maize. Phenotypic variance was mainly accounted for by the genetic component. Heritability was high for flowering, height and ear traits and grain yield. All the traits were positively correlated with grain yield, with the ear traits of kernel rows/cob and kernels/row on cob contributing most to grain yield. The high heritability coupled with the highest genetic advance observed for kernels per row on cob, kernel rows/cob and grain yield at 20% selection intensity indicates that concentrating on these three traits in selection programme will achieve a fast progress in selection. Thus grain yield could be simultaneously selected with kernels per row on cob and kernel rows/cob for improvement in dry and green maize production.
Seven improved tropical grass species, namely, Andropogon gayanus Kunth., Brachiaria ruziziensis Germain & Evrard, Cenchrus ciliaris L., Chloris gayana Kunth, Panicum maximum var. coloratum C.T, Paspalum orbiculare G. Forstand Sorghum almum Parodi were evaluated for yield and yield components at the Teaching and Research Farm of the Federal University of Agriculture, Makurdi, Nigeria in 2015 and 2016. The experiment was laid out in a randomized complete block design with three replications in each of the years. Results showed that the evaluated grass species could be cut at an early age when the leaf: stem ratio is high enough for the ruminants to derive maximum nutritional benefit and need not be delayed till 16 weeks after planting. The highest correlation between plant height and grain yield was observed at 4 weeks (r = 0.69) and 8 weeks (r = 0.70) after planting, implying that the taller the plant species at this stage of growth, the higher the probability for high grain yield. Identification and selection of tropical grass species for improvement in grain production should, therefore, be carried out between 4 and 8 weeks of growth. All the seven tropical forage grass species performed favourably well in terms of growth and yield, with the positive response to increasing rainfall and further studies on multi-location evaluation within the Southern Guinea Savanna agro-ecologicalal zone of Nigeria is recommended.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.