This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT An experiment was conducted to evaluate genetic variation among twenty-one fluted pumpkin genotypes for seedling traits. The seeds of the fluted pumpkin were germinated in nursery bags filled with saw dust at the Federal University of Agriculture, Abeokuta and the Federal University of Technology, Akure, Nigeria between July and August, 2013. The experiment was laid out in completely randomized design with three replications. Characters evaluated were emergence percentage (E%), emergence index, emergence index rate, vine length (cm), leaf area (cm 2 ), number of leaves, shoot dry weight (g), and seedling vigour index (SVI). Significant (P≤0.05) differences were observed among the fluted pumpkin genotypes for the evaluated characters. High E% was observed for genotypes Ftn45 (94.80%), Ftn43 (93.30%), Ftn57 (93.30%), Fte41 (90.0%), Ftn61 (86.70%), and Ftm11 (83.30%). Also, these genotypes had above average values for SVI. High phenotypic coefficients of variation and genotypic coefficients of variation were observed for leaf area (75.44%) and dry shoot weight (55.85%), respectively while heritability estimates above 50% was observed for leaf area (82.0%), dry weight (77.78%), E% (70.84%), and SVI (51.98%). The genetic advance was high for E% (38.37), SVI (38.09), and leaf area. SVI, E%, vine length, and leaf area had significant positive correlation with most of the traits therefore, they can be used as selection criteria in fluted pumpkin. Therefore, genetic improvement of early seedling can be used for selection programme in fluted pumpkin.

Seed and seedling vigour is an aspect of seed quality which affects field establishment and performance. Low maize yields have been reported to be affected by several factors in which poor quality seed with low seed and seedling vigour. Information is scarce on seed and seedling vigour in maize inbred lines developed for tropical environments. Fifteen genotypes of tropical maize (Zea mays L.) inbred lines were evaluated to determine the level of differences in seed and seedling vigour traits, and extent of relationships among traits and their heritability. A substantial amount of genetic variability was found, which suggested that most of the traits under study could be improved through selection and utilized in breeding programs. Positive and significant interrelationship among seed germination and seedling traits and a positive correlation between seed germination and seed vigour and field emergence showed that these could be given due consideration in crop improvement for seed and seedling vigour. High genotypic coefficient of variation, heritability and genetic advance were obtained for seed germination, seed emergence, shoot length and seedling vigour index I and II, revealing the possibility of improvement in these characters through direct selection. The principal component analysis (PCA) identified seed emergence, shoot length, seedling vigour index I and II and tetrazolium vigour as characters that contributed greatly to variation in seed vigour in the maize inbred lines. Cluster analysis partitioned the genotypes into two groups, with group I consisting of seven genotypes and group II comprised the other eight genotypes, which suggested that hybridization between the two groups could lead to high level of heterosis. Genotype V 5 had superior seedling vigour traits compared to other genotypes. Seedling emergence, shoot length, seedling vigour index I, seedling vigour index II and tetrazolium vigour are effective characters for good seedling vigour traits in maize inbred lines investigated.

The present study reported the effectiveness of two PCR-based molecular techniques, inters simple sequence repeats (ISSRs) and amplified fragment length polymorphisms (AFLPs), for genetic assessment of amaranth. The polymorphic loci ranged from 110 among A. caudatus to 228 among A. cruentus and 16 among A. tricolor to 56 among A. hypochondriacus for AFLP primer combinations and ISSR primers, respectively. Among the two marker systems used, ISSR fingerprinting detected the highest number of alleles per locus (1.83) compared to AFLPs (1.63). However, the assay efficiency index for AFLP was 14.49, more than five-fold higher than ISSR (1.75). The study also revealed that ISSR primers with di-nucleotide repeats gave a good fingerprint, indicating that di-nucleotide repeats are more frequent in amaranth genome. The reproducibility of the two marker systems was confirmed by the narrow gene diversity (0.03 ± 0.11 to 0.07 ± 0.17) observed between the controls. Bayesian consensus and neighbor-joining trees were constructed to describe the cluster arrangement among the Amaranthus spp. The cluster pattern was similar for both markers, though the cluster order in the trees was slightly different. The results of this study confirm the usefulness of AFLPs and ISSRs for the genetic assessment of amaranth.

For plant genetic improvement, it is paramount to determine genetic components for the selection of desirable traits. Eighteen Amaranthus cruentus and 11 Amaranthus hypochondriacus genotypes were evaluated at two locations in Nigeria differing in temperature/precipitation to determine the influence of environment on genetic gain. Genotype × environment was significant for all analysed morphological parameters and for grain yield, 1000 seed weight and no. of days to 50% flowering in A. cruentus. In A. hypochondriacus genotype × environment was significant for plant height, leaf length and width, leaf area, inflorescence length, 1000 seed weight and grain yield. Higher genotypic coefficient of variability, heritability estimates, and genetic advance was observed for the traits at Abeokuta (more wet) than Ibadan (more dry) conditions. Grain yield had positive association with the traits at the two locations except the number of leaves and inflorescence length. Inflorescence length was positively associated with grain yield at Abeokuta and negatively associated at Ibadan. Path analysis indicated simultaneous improvement of grain yield with petiole length and leaf length at Abeokuta but with petiole length and leaf area at Ibadan. In general, the locations had potential for genetic improvement of traits of amaranth grain; therefore, selection criteria for improving grain yield should be considered with respect to environment.

Investigating genetic structure and diversity is crucial for rice improvement strategies, including mapping quantitative trait loci with the potential for improved productivity and adaptation to the upland ecology. The present study elucidated the population structure and genetic diversity of 176 rice germplasm adapted to the upland ecology using 7063 genome-wide single nucleotide polymorphism (SNP) markers from the Diversity Array Technology (DArT)-based sequencing platform (DArTseq). The SNPs were reasonably distributed across the rice genome, ranging from 432 SNPs on chromosome 9 to 989 SNPs on chromosome 1. The minimum minor allele frequency was 0.05, while the average polymorphism information content and heterozygosity were 0.25 and 0.03, respectively. The model-based (Bayesian) population structure analysis identified two major groups for the studied rice germplasm. Analysis of molecular variance revealed that all (100%) of the genetic variance was attributable to differences within the population, and none was attributable to the population structure. The estimates of genetic differentiation (PhiPT = 0.001; P = 0.197) further showed a negligible difference among the population structures. The results indicated a high genetic exchange or gene flow (number of migrants, Nm = 622.65) and a substantial level of diversity (number of private alleles, Pa = 1.52 number of different alleles, Na = 2.67; Shannon's information index, I = 0.084; and percentage of polymorphic loci, %PPL = 55.9%) within the population, representing a valuable resource for rice improvement. The findings in this study provide a critical analysis of the genetic diversity of upland rice germplasm that would be useful for rice yield improvement. We suggested further breeding and genetic analyses.