Evaluation of M6 Ofada Rice Mutant Selections and Parents for Grain Physico-Chemical and Nutritional Characters

Rice consumers are becoming more conscious of the varieties they consume in terms of nutritional quality. Selection for quality improvement would benefit from induced variability as innate sources are becoming exhausted. This study was carried out to assess the extent of improvement of rice grain quality yield for the benefit of the farmers and the consumers. Two Ofada rice varieties (FUNAABOR 1 and FUNAABOR 2) were irradiated with 60Co gamma rays to elicit variation towards selection for grain improvement in 2013. Individual seed selections from different treatment levels in M1 and subsequent generations were harvested and replanted for advancement to M6 generation. Harvested seeds from selected promising M6 mutants and parents were subjected to physical, chemical and nutritional analysis.  Analysis of Variance (ANOVA) was applied to data to generate character overall mean and variance estimates from which heritability estimates were computed. Means of the different mutants were compared with parents using Duncan Multiple Range Test (DMRT). Ofada rice mutants and parents varied significantly for all the studied grain traits. The mutants and parents had long grains (6.6mm - 7.1mm). Mutant, OG13602 _100 had high values for amylose content (20.01%), followed by OG13608_300 (19.47%). The two mutants (OG13602_100 and OG13608_300) respectively also recorded the highest values for crude protein (6.41% and 6.28%), fat (3.94% and 3.81%), fibre (2.14% and 2.05%), and ash content (3.92% and 3.71%). Overall, the entries clustered into two groups along the parental lines and present opportunities for hybridization. High heritability with concomitant high genetic advance was recorded for amylose, ash and moisture content. All selected promising Ofada rice mutants and parents had long grains. Specifically, mutants OG13602_100 and OG13608_300 which expressed superior amylose, protein, fat, fibre and ash contents present opportunities for further improvement for grain quality. The significant variability of the studied traits revealed additional gains from further selection

Assessment of 60Co gamma radiation on early phenological stages of two generations of OFADA rice

Traditional Ofada rice varieties from South-West, Nigeria is preferred for its unique taste, aroma and massive potential for export but has low yield. Based on this background, two Ofada rice varieties, FUNAABOR 1 and FUNAABOR 2 were irradiated to create genetic variability as it affects vegetative traits. Seeds from the varieties were exposed to nine levels of 60Co gamma irradiation (0, 50, 100, 150, 200, 250, 300, 350 and 400 Gy). The seeds were nursed for 30 days before M1 seedlings were transplanted into a well tilled soil in a two factorial RCBD with three replicates. Selections from M1 plants were used to establish M2 plants generation. The results revealed diverse effects of 60Co gamma irradiation treatments on different plant vegetative traits. The establishment rates of M1 Ofada rice population were unaffected (p > 0.01) by increasing gamma irradiation from 0 to 300 Gy but decreased at 350 Gy. Above 300 Gy, tiller numbers, plant height, lodging incidence, leaf number, leaf length and leaf angle decreased significantly when compared with control (p < 0.01) in both generations (M1 and M2). Moderately tillered (10 tillers), tall plant (116.9 cm) obtained from 350 dosage rate recorded highest grain weight of 7.8 g per panicle. High phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) promoted by the irradiation dosages in M1 selection indicate the extent of environmental influence. High broad sense heritability observed from leaf number, leaf angle, leaf length, leaf blade colour, basal leaf sheath colour and grain weight per panicle shows possibility of rapid genetic improvement of these characters through selection

Correlations of Vegetative and Reproductive Characters with Root Traits of Upland Rice under Imposed Soil Moisture Stress

An understanding of the relationship between traits related to plant performance is advantageous in rice breeding for tolerance to drought and increase in grain yield. Correlations studies involving root, vegetative and reproductive traits were carried out with sixteen rice genotypes under differing soil moisture through a combination of three amounts of moisture and two periods of application. Data from root,  vegetative and grain yield traits were used to compute phenotypic and genotypic coefficients of variation (CV), correlations and heritability. Phenotypic and genotypic CV were generally low, with the exception of root branching and grain weight per plant. Heritability estimates were also low. Among the root traits, the highest  heritability value of 36.6 and 30.5 was recorded by root thickness and root  branching respectively while the estimate for 100-grain weight (48.7), days to  flowering (47.8) and primary branching (45.9) were moderate. Genetic advance was highest for root thickness, root branching and grain weight per plant. Root volume showed significant negative correlation with root thickness at phenotypic and  genotypic levels (-0.124, -0.286), but had positive correlation with fresh root  weight (0.340, 0.917) and dry root weight (0.338, 0.910). Root volume and root  thickness exhibited counteracting relationships with primary branching, secondary branching, spikelets number per panicle and spikelet fertility. Root branching was significantly correlated with grain weight per plant at genotypic level. The diffused relationships of root traits with the vegetative and reproductive traits underscore their intricate nature and require consideration in trait selection for direct and indirect increase in grain production.Keywords: Root volume, root thickness, root dry weight, drought, grain yield

Genotype × environment analysis of cowpea grain production in the forest and derived savannah cultivation ecologies

Differential performance of genotypes in different cultivation environments has remained a challenge to farmers and plant breeders, the emphasis being the selection of high yielding and stable genotypes, across similar ecologies. A set of nine cowpea genotypes were  cultivated in Ago-Iwoye and Ayetoro, two locations representing high and moderate moisture zones. Plantings were done with the early and late season rains in Ago-Iwoye and mid-late season rains of Ayetoro. Statistical analysis was done to understand genotype reaction to the different environments and the plant and environment factors mediating the performance. The Additive Main Effect and Multiplicative Interaction (AMMI) model captured 61.30% of the total sum of squares (TSS). The main effects: genotype (G) environment (E) and their interaction (GxE) were significant with the largest contribution of 28.70% by the environment while the interaction and genotype fractionscaptured 20.20% and 12.40%, respectively. The percentage contribution of the main effects and GxE to total sum of squares (TSS) for traits was not consistent. The Genotype plus Genotype-by-Environment (GGE) analysis summarized 91.30% of the variation in genotype performance across environment. The cultivation environments were separated into two, with IT 95M 118 as the vertex genotype in the Ayetoro while TVU 8905 was the topmost genotype in Ago-Iwoye. The two genotypes recorded the highest grain weight per plant (GWPP) but were also the most unstable The stable genotypes IT 95M 120 and IT 86 D 716 flowered relatively late compared to others, are taller, had higher vegetative score and are low grain producers. Key words: AMMI, drought, GGE, stability, Vigna unguiculat