Roberta Jeske Kunde

Fracionamento químico e físico da matéria orgânica de um argissolo vermelho sob diferentes sistemas de uso

The objective of this study was to evaluate the total organic carbon and the physical and chemical fractions of organic matter in an Alfisol under different use systems. The land use systems evaluated was homogeneous forestry of Eucalyptus grandis, agrosilvopastoral system and native grassland, in layers from 0.000-0.025 and 0.025-0.075m depth. The coarse fraction (CFG) and the carbon associated minerals (CAM) were obtained by physical fractionation. The free light fraction (FLL), light occluded (FLO) and heavy (FP) were obtained by densimetric physical fractionation. The non-humicfractions (NH), fulvic acid (AF), humic acid (HA) and humin (HU) were obtained by chemical fractionation. The Eucalyptus grandis system promoted higher total organic carbon, CFG, FLL and FLO and AF. In the surface layer, the protective recalcitrance mechanisms by organic matter molecular and chemical stabilization are overlapping stability which result from aggregates occlusion. As is difficult to form aggregates due to sandy soil matrix, carbon youth which enter the system is decomposed by microorganisms going to a more advanced stage of decomposition, forming in this case associations with silt and clay particles. This occurs in soils where the clay percentage is low. Through the fractionation it was observed that most of the soil organic matter is stored in the form of HU.

Enraizamento de estacas lenhosas de três cultivares de mirtileiro com diferentes concentrações de AIB

Commercially, propagation of blueberry by cutting is the very usual method, which gives a range of results according to the cultivar. This research aimed to evaluate the effect of indol-butyric acid (IBA) on rooting of blueberry hardwood cuttings. It was used segments of secondary branches with four buds and mean diameter of 4.5mm. The experimental design was totally randomized in a 5x3 factorial, five concentrations of IBA (0; 1500; 3000; 4500 and 6000mg L-1) and three cultivars (Delite, Bluebelle and Briteblue). It was used four replications and ten cuttings per plot. After cutting, the base of the cuttings was dipped for 10 seconds into a solution of IBA. Then, they were put to root in a mix of thick sand and commercial substrate Turfa Fertil® (1:1) with pH 5.5 and manually irrigated. After 138 days from trial installation, percentage of rooted cuttings, number of root per cutting, length of the largest root, number of shoots, length of the largest shoot and percentage of surviving cuttings were evaluated. According to the results it was not verified interaction among different factors. It was verified difference among cultivars only in the length of the largest root, number of root per cutting and percentage of surviving cuttings. For concentration of IBA, it was verified by regression analysis, a linear behavior for the variables increasing rooted and survived, but the response was quadratic for the longest root length. It was concluded that the concentration up to 6000mg L-1 IBA is not sufficient to express the maximum rooting potential of the blueberry cuttings cultivars Delite, Bluebelle and Briteblue.