In order to assess the genetic diversity of Roselle (Hibiscus sabdariffa L.) in Nigeria, a survey was undertaken to collect the germplasm of the crop. The survey cut across 56 towns and 20 villages in 17 states including the Federal Capital Territory (FCT). Sixty three (63) farmers were interviewed and 60 accessions of Roselle were collected from them. Results showed that 41.7% of these accessions were having green calyx, while 31.7% were with red calyx. On the other hand, 20.0% of the accessions possessed deep red calyx while only 6.7% have light red and pink calyx. Collections from the North Central, North Eastern, North Western and South Western parts were replicated over states, towns and villages. The highest number of Roselle accessions was collected from Kaduna State (8 accessions) followed by Niger State (6 accessions); Jigawa State (6 accessions) while FCT and Bauchi State have 4 accessions each. This is an indication that these areas have the greatest diversity of the crop genetic resources in Nigeria and the states might be secondary centre of origin of the crop. However, morphological as well as molecular characterizations are required to arrange the Roselle accessions collected into a suitable group; this will eventually provide the raw materials needed for the Roselle improvement programme in Nigeria.

Genetic variability which is the basic material for selection and improvement of any crop is fast eroding in pearl millet as natural habitats of wild cultivated species are being destroyed and modern cultivars replacing the traditional cultivars. On this premise collection and characterisation of the crop germplasm was carried to identify elite accession(s) for the crop improvement. Thirty five (35) pearl millet accessions collected from the major cultivated states in Nigeria were evaluated for morphological and yield parameters using a Randomised Complete Block Design (RCBD) with replicate three each. Wide range of significant (P < 0.05) variability was observed in all the morphological characters assessed with different trait been favoured by different genotypes. The highest plant height was recorded in KD-CK-01 (371.85 cm) and the least height in accession NG-ZA-05 with the value of 170.58 cm. Accession NG-ZC-03 had the highest weight of seeds per plot and weight of seeds per hectare with the value of 738.52 g and 1318.78 kg/ha respectively. Phenotypic coefficient of variance was higher than the corresponding genotypic coefficient variance for all the traits studied. Moderate (30-60%) to high (>60%) heritability was obtained among the traits studied while genetic advanced ranged from 21.92 to 127.27. Cluster analysis grouped the accessions into four major clusters based on their morphological similarity; cluster I consisting 14.29% of the genotypes, 17.14% in cluster II, 40.00% in cluster III and 28.57% were clustered in IV. The high variability recorded in the germplasm couple with high heritability and genetic advance in most of the parameters studied, indicate that the accessions and traits could be explored in the crop improvement.

Estimates of some pollen parameters where used to assess the genetic diversity among some newly selected Nigerian Roselle (Hibiscus sabdariffa L.). Standard procedures were used to determine the pollen parameters such as: percentage pollen fertility, percentage pollen sterility, pollen diameters as well as anther diameters. The cytological results revealed significant (P ≤ 0.05) variation in the diameters of anther cap and pollen grains. Anther morphology and pollen grain morphology of the H. sabdariffa genotypes under light microscope showed fair diversity in the Anther and pollen grain sizes. The Roselle genotypes were grouped according to their anther sizes into small (< 400 μm), medium (400-700 μm) and large (> 700 μm); such character should be included in examining genetic diversity in this crop. The dendrogram produced from the cluster analysis of the different genotypes of the roselle based on diameters of the pollen grains and that of the anther cap-sizes also separate the genotypes into different groups. The results obtained in terms of percentage pollen fertility also showed some interesting variations. It is not untrue that larger pollen grain could serve as a better pollinizer than a smaller pollen grain; moreover, successes in crossing among such plants could be dependent on the sizes of the pollen. The pollen grain size variations obtained from this study is of good taxonomic value. The variation in the anther and pollen grain sizes could also be as a result of different genetic make of the Roselle genotypes and could serve as important diagnostic tool in differentiating Nigerian Roselle genotypes and achieving the cytotaxonomy of the crop. It is therefore concluded that there exist genetic variability among the pollen grains and anthers of the new selected Nigerian Roselle (H. sabdariffa) genotypes; these characters are good taxonomic parameters that could be used in evaluating genetic diversity of the crop in the study area. It is recommended that other pollen viability staining techniques should be employed to ascertain the level of the pollen fertility among the Roselle Genotypes. In addition, DNA-PCR technique should be used to further confirm the variability observed in this present study.

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Pollen viability and germinability are indispensable criteria in plant breeding programmes. This research evaluated eleven M4 mutant lines of gamma irradiated sesame (Sesamum indicum) for some pollen parameters. Seeds were obtained from the Department of Plant Biology, Federal University of Technology, Minna and were raised to maturity alongside their respective checks in a randomized complete block design (RCBD). The field experiment was conducted at the experimental field of the Upper Niger River Basin Development Authority, Minna. Pollen viability and diameter were determined using standard procedure. The germinability test was done using three different sucrose concentrations (10 %, 20 % and 30 %) with 1 % nutrient agar solution. The results revealed that all the M4 mutant lines had adequate pollen viabilities (over 80%) with ML-10 having the highest (97.56 %) viability followed by ML-7 (95.61 %), ML-8 (95.01 %) and Check-2 (95.60 %). The highest pollen germinability was recorded at 20 % sucrose concentration for all the mutant lines with line ML-7 (39.70 %) having the highest percentage. Check-1 at 10 % sucrose concentration recorded the least percentage (11.46 %) across the concentration and treatments. Highest pollen diameter (169.52μm) was recorded in Check-1. Suboblate shapes with 10-13 colpi was observed in all the mutant lines and the checks. Pollens from all the lines comprised of circular and elliptic pollens except in ML-7 and the checks where the pollens were solely circular in polar view. The study revealed that gamma-irradiation could be a reasonable tool for inducing variability in sesame and advantageous in increasing the pollen viability.

The study was carried using the Botanic Garden of the Kano State Zoological Garden as the control site in comparison with roadside in order to determine the effect of exhaust from vehicles on the number of stomata, epidermal cells, stomatal length, stomata breadth. Results obtained showed an increase in the number of stomata and epidermal cells per unit area in leaf samples collected from polluted sites than those from unpolluted site. However, the length and breadth of stomata, pore length and pore breadth in the polluted sites was lower than that of the control site. Furthermore, there was no significant difference based on the type of stomata in the species studied at the two different sites. An increase in number of stomata of epidermal cells and stomatal density was found in plants growing on the road side both on the abaxial and adaxial surfaces, a decrease was found on the stomatal length, stomatal breadth, pore length, pore breadth and stomatal index of the plant with those in the control site. These changes in stomata and epidermal cells per unit area could be used as an indicator of environmental stress which could be recommended in high traffic density areas for the early detection of urban air pollution.

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