Fabio Almeida de Freitas

Absorção de P, Mg, Ca e K e tolerância de genótipos de arroz submetidos a estresse por alumínio em sistemas hidropônicos

Soils with high aluminum (Al3+) concentrations can affect the development and nutrient absorption of rice plants. The goals of this study were to evaluate the absorption of P, Mg, Ca and K in 18 rice genotypes and their overall performance when subjected to Al3+ stress in hydroponic systems. The experimental design was randomized blocks with 3 replications and four Al3+ levels (0, 10, 20 and 30mg L-1). Plantlets were treated for 20 days and evaluated for root length (CR) and P, Mg, Ca and K contents. All variables presented significant reductions in their values, and the genotypes presented different performance in nutrient absorption when facing different treatments, with an exception for Mg absorption response in which all genotypes evaluated were similar. Based on the variable CR, the genotypes Felune and Taim were considered the most tolerant and sensitive to Al3+, respectively. Regarding nutrient absorption, the genotypes presented variable responses to each evaluated nutrient, nevertheless the genotype Felune presented also high absorption levels. All the variables presented significant correlations to each other.

Uma proposta de seleção para caracteres quantitativos e qualitativos em aveia

In oat (Avena sativa L.) techniques that minimize environmental effects on the expression of phenotype and facilitate the identification of high yielding genotypes are useful. Short stature and tolerance to toxic aluminum are important for the development of cultivars with adaptability to marginal areas. Thus, genotypes selected by the honeycomb method, in three different crosses, were subjected to simultaneous tests for aluminum tolerance (Al+3) and insensibility to gibberelic acid (AG3), aiming the identification of superior genotypes. This technique enabled the selection of high yielding, short stature and Al+3 tolerant genotypes and could be applied in plant breeding programs involving cultivated hexaploid oat.

Evaluation of Aluminum Tolerance in Rice

Abstract The objectives of the present work were to adjust the method for identifying genetic variability in rice through the use of minimal solution in hydroponic culture, and to identify the most important level and character for the study. The experiment consisted of the response evaluation of 18 rice genotypes to three levels of aluminum treatment. Five variables obtained from root and shoot lengths were evaluated. The data were subjected to the clustering methods of Tocher and nearest neighbor to evaluate the dissimilarity and the most adequate aluminum level. The results indicated that the 2 mg L−1 concentration and the difference between first and second measures of root length were the most useful for evaluating Al tolerance. Based on the results, it was possible to identify tolerant and sensitive cultivars to aluminum.

Flooding Tolerance in Oats

ABSTRACT The oat (Avena sativa L.) crop has been increasing its acreage in Southern Brazil very rapidly in the last decade. Areas novel to the crop, e.g., lowland areas, however, cannot be developed unless flooding-tolerant genotypes are available. With this goal, two experiments were designed using eight commercial genotypes: UPF 14, UPF 16, UFRGS 7, UFRGS 14, UFRGS 16, UFRGS 18, CTC 2 and ORLA 9248. Plants were subjected to flooding for at least 30 days and evaluated for plant height (PH), root length (RL), root dry matter (RDM) and total dry matter (TDM). The genotypes evaluated showed very different responses to flooding.