There has been a strong demand for oat genotypes that contain caryopsis with high chemical quality which can suit the different market niches. Therefore, the objectives of this study were to assess the general (GCA) and specific combining ability (SCA) of white oat cultivars through diallelic crosses providing information about the genetic effects on expression of grain chemical quality components.

RESUMO -As cultivares de aveia-branca (Avena sativa L.) cultivadas no sul do Brasil até princípios da década de 80 eram provenientes do Uruguai e da Argentina, apresentando problemas de adaptação ao ambiente de cultivo. A partir dos anos 70, programas de melhoramento começaram a produzir suas próprias populações segregantes, possibilitando o lançamento em escala comercial de cerca de 35 cultivares. Com o objetivo de estimar o progresso genético nos programas de melhoramento de aveia-branca do sul do Brasil, foi realizado um experimento envolvendo 15 cultivares lançadas em diferentes épocas, em dois locais, com quatro diferentes condições de manejo. Os resultados obtidos indicaram progresso genético linear para os caracteres ciclo vegetativo, rendimento de grãos, peso de grão e peso do hectolitro; a inexistência de efeitos quadráticos significativos sugeriram a possibilidade de ganhos posteriores a partir da seleção de novos genótipos. Os programas de melhoramento genético de aveia-branca do sul do Brasil, embora ainda não tenham atingido o patamar máximo, têm sido eficientes em produzir novas cultivares com maiores rendimento e qualidade de grãos e com caracteres agronômi-cos superiores.Termos para indexação: Avena sativa, ganho genético, métodos de melhoramento, adubação nitrogenada, fungicidas, características agronômicas, rendimento de grãos. GENETIC PROGRESS IN OAT BREEDING IN SOUTHERN BRAZILABSTRACT -The oat (Avena sativa L.) cultivars cultivated in Southern Brazil up to the beginning of the 80's were introduced from Uruguay and Argentina. They presented adaptation problems to the new environment. Starting from the 70's, oat breeding programs began to produce their own segregant populations. These programs already released 35 cultivars. Aiming to estimate the genetic progress in oat breeding programs from southern Brazil, an experiment with 15 cultivars released in different times was conducted in two locations using four different cultural practices. The results indicated linear genetic progress for days to flowering, grain yield, grain weight and test weight. The non significance of quadratic effects suggested the possibility of additional gains through selection of new genotypes. The oat breeding programs in southern Brazil have been efficient in producing new cultivars with higher grain yield, good grain quality, and with superior agronomic traits. However, a maximum breeding plateau was not reached for this species.

-Iron stress is a major stress factor in irrigated rice. The complete mechanism underlying iron metabolism and transport is still unknown. Irrigated rice (Oryza sativa L.) cultivars were exposed to Fe 2+ stress in hydroponic conditions, aiming to assess genotype performance under stress as well as to develop a protocol for genotype selection. The experimental design was completely randomized, using a triple factorial scheme 2 x 5 x 6 (time x dose x genotype). The trait shoot length and nine days under stress were favorable for genotype discrimination under iron stress. The genotypes BR IRGA 409 and BRS AGRISUL were, respectively, the most sensitive and tolerant genotypes to iron stress. According to the genotype performance, hydroponics can be recommended as an efficient cultivation technique for the selection of iron stress-tolerant rice genotypes.

No abstract