Abstract
This work aimed to evaluate the genetic divergence among 16 sunflower hybrids. Experiment was developed in Umuarama County, Parana State, Brazil, in 2010/2011 cropping season. Experimental design used was randomized complete block with four replications. The characteristics evaluated were: Final stand, plant height, chapter curvature, chapter size, grain yield, weight of 1000 achene’s and oil content. Significant differences were detected for grain yield, chapter size and chapter curvature (1%). For final stand and oil content, significant differences (5%) was observed, suggesting that evaluated characters are important for genetic divergence characterization. Based on Mahalanobis Generalized Distance it was established that genetic dissimilarity measures, SULFOSOL and SYN 045 genotypes were the most dissimilar with D2ii’ of 134.54%. Clustering by Tocher method by using D2ii, divided hybrids into two groups. Grain yield and chapter size contributed significantly in genetic divergence observed between hybrids and it was possible to identify divergent genetic materials for obtaining lines and/or formation of new populations. Key words: Genetic variability, plant breeding, Helianthus annuus L., D2ii' analysis.
Highlights
Cultivation of sunflower (Helianthus annuus L.) has proved to be a cost-effective option in rotations systems with other grain crops, and it is arousing the interest of farmers, agriculture professionals and companies, due to the possibility of using its oil as raw material for manufacturing biodiesel (Castro and Farias, 2005; Backes et al, 2008)
STD and OIL (%) showed significant differences at 5% probability level, by F test, demonstrating the existence of variability among genotypes and suggesting that evaluated characters are important in characterizing genetic divergence, with the exception for Weight of achene (WTA) and Plant height (PH) parameters, that showed no significant differences
It is worth mentioning that during the grain filling period (December to January) in this present study, accumulated rainfall exceeds 240 mm, what contributed to higher grain yield
Summary
Cultivation of sunflower (Helianthus annuus L.) has proved to be a cost-effective option in rotations systems with other grain crops, and it is arousing the interest of farmers, agriculture professionals and companies, due to the possibility of using its oil as raw material for manufacturing biodiesel (Castro and Farias, 2005; Backes et al, 2008). According to Oliveira et al (2005), efforts are needed for the development of genotypes that presents, in the same genetic material, high oil content, early cycle, reduced height, resistance to biotic and abiotic factors, besides high grain yield. The incorporation of these characteristics of interest depends on the existence of genetic variability in germplasm available for the crop breeding programs. According to Barelli (2004), studies on genetic divergence have great importance in crop breeding programs since reporting parameters for identifying parents that, when hybridized, offer greater heterosis effect in progeny and a higher probability of Poletin et al 6055
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