STRATIFIED MASS SELECTION IN SUNFLOWER IN DIFFERENT ENVIRONMENTAL-CONDITIONS

An open pollinated cultivar of sunflower (Helianthus annuus L.) was ma ss selected in two successive growing seasons with the main objective of evaluating the genetic progress obtained with two cicles of selecti on per year involving one cicle in stress conditions. Selection was pe rformed in the favorable environment only (spring), where sunflower is grown commercially, in the unfavorable environment only (summer), or continuously in both environments. The selection criteria were reducti on of cicle and plant height and improvement of achene yield, with mor e emphasis given to cicle reduction. Tested in the favorable environme nt, spring selections were superior to Summer selections. The continuo us selection was superior to both others in cicle and plant height red uction, but resulted in higher yield reductions.