Arroz de terras altas no sistema plantio direto.

O presente trabalho foi conduzido com o objetivo de adequar o cultivo do arroz no Sistema Plantio Direto pela adoção de semeadoras e de genótipos mais adaptados ao sistema.bitstream/CNPAF/19921/1/comt_47.pd

Genetic control of traits related to phosphorus use efficiency in tropical maize.

Knowing the inheritance of traits is essential to establish selection strategies in breeding programs. The aim of this study was to determine the genetic control of traits related to the phosphorus use efficiency in maize. A total of 280 progenies were developed according to design III, which were evaluated in the field under high and low phosphorus (P) availability. The genetic variance components were estimated for the agronomic traits and indices that define P use efficiency. The results indicated that the additive and dominance effects were important in explaining the genetic variability for the flowering time, grain yield and P efficiency indices. However, dominance effects prevailed, indicating that breeding efforts should be made to develop hybrids exploiting the heterosis for traits related to P use efficiency

Predição do teor de proteína bruta em biomassa de capins braquiária por meio de espectroscopia NIR.

bitstream/item/87622/1/ct-205.pd

Evaluation of high quality protein maize (QPM) hybrids obtained by conversion of normal inbred lines.

Two experimental QPM hybrids obtained by lhe partial conversion of three elite inbred lines by modified backcrossing were evaluated and compared to the normal versions of the same hybrids. Thirteen agronomic and 12 grain quality traits were evaluated. The hybrids were also anaJyzed by SSR markers in order to evaluate the genetic relationship among them. Results demonstrated that the converted QPM hybrids presented a better protein quality and a similar agronomic performance for most of the evaluated traits, including grain yield, in comparison to their normal versions. However, some of the deficiencies generally ascribed to QPM hybrids, such as a higher lodgíng percentage, thicker cobs, and shorter kernels were maintained up to this stage of the conversion process. In comparison to more recent elite hybrids, the normal versions as well as the converted QPM hybrids presented the worst performances in relation to the grain yield, thus indicating a loss of competitiveness

Depth-stratified soil sampling for assessing nematode communities.

This study assessed the importance of stratified soil sampling on the detection (and therefore the distribution) of nematode communities and the differentiation of ecosystems by collecting stratified soil samples at intervals of 10 cm and non-stratified samples from 0 to 30 cm in two soil management systems (no-tillage and conventional tillage) and in a native forest fragment. The nematode frequency and prominence values were obtained after extraction by successive screening operations, sugar floatation clarification and the identification of nematodes to the genus level. The nematode communities were compared two-by-two based on Sorensen’s community coefficient (CC) and the percentage similarity (PS). Relative abundances of functional guilds were subjected to a principal component analysis (PCA) and classified in dendrograms. Thirty-two edaphic nematode genera were found, and the nematode communities sampled on a non-stratified basis in the soil profile exhibited a high level of similarity because they could not be accurately characterized. Genera with low abundances were not detected. In the stratified samples, we were able to classify and group the nematodes present at different depths, mainly from 0 to 10 cm. Stratified soil sampling allowed a more accurate characterization and greater differentiation of nematode communities, identifying taxa that occurred at lower abundance levels, irrespective of frequency

Cultivo do milho: zoneamento agrícola.

bitstream/CNPMS/15593/1/Com_37.pd