RESPONSES OF WHEAT TO LOW-LUMINOSITY STRE SS AND THEIR RELATIONS WITHGENETIC BREEDING

The work was carried out at the Estacao Experimental Agronomica of UFR GS, in Eldorado do Sul, Rio Grande do Sul, Brazil, in 1988. The object ive was to investigate the influence of low luminosity stress (60% of incident natural light) on six traits in four wheat (IFS 20-Iassul, IA C 5-Maringa Trigo BR 34 e PF 84431) genotypes and on their correspondi ng F-2 segregating populations (six combinations). When the treatments with and without low luminosity stress were compared, a differentiate d behaviour of the parents, as well as of the F-2 segregating populati ons, was observed for all traits assessed. According to this work, evi dences indicate that there are greater possibilities of success in imp roving the main traits involved in wheat yield components if plant sel ection is made in an environment that favors phenotypic expression of its genetic potencial, that is, in an environment without stress.