Genetic Variability in some Sunflower (Helianthus annuus L.) Hybrids Evaluated in North Agadi Area under Rainfed Conditions

Abstract

Twenty locally generated hybrids of Sun flower (Helianthus annuus L.) hybrids were evaluated in two seasons (2012 and 2013) for yield and yield components at North Agadi area, Blue Nile State under rainfed conditions. A randomized complete block design with six replications was used for laying out the field experiments. The seeds were sown in the second and third week of July in the first and second seasons, respectively. The plot size was 6x3m2. Each plot was divided into four ridges 70cm apart and 6 meter long. Three seeds were sown in holes of 20 cm distance along the ridge then thinned into one plant per hole three weeks after sowing. Weeding was practiced three times to control weeds. The rainfall was recorded during the two seasons. Fertilizers were not applied. The heads of the sample were bagged during the seed filling period using paper bags to avoid birds attack. Data were collected on the following characters: Days to 50% flowering, days to maturity, plant height, stem diameter, head diameter (cm), number of seeds/head, percentage of empty seed, 1000-seed weight (g), seed yield/plant (g) and seed yield (t/ha). Phenotypic, genotypic and environmental variances were determined. The results in season 2012 revealed highly significant differences among the undertaken hybrids for plant height, stem diameter, head diameter, empty seed %, 1000-seed weight, seed yield/pant and seed yield (t/ha), whereas only two characters were significant in 2013. These were empty seed% and 1000-seed weight. The phenotypic coefficients of variation values were greater than their corresponding genotypic ones. Heritability values were low for all characters in both seasons. Genetic advance as percentage from the overall mean values were greater in 2012 than their corresponding ones in 2013 for most traits. More investigation should be done for the promising hybrids SHA5, SHA18 and SHA22.