Resumo em Inglês:

ABSTRACT Knowledge on nitrogen absorption rate by crops can indicate important managements, especially the definition of rates of this nutrient and the best time for topdressing application. This study aimed to evaluate and compare the accumulation of biomass and nitrogen in white oat cultivated under severe, moderate and no water deficit. Treatments consisted of levels of irrigation, with four repetitions. The treatments under severe water deficit (L1), moderate deficit (L3) and no deficit (L5) received 11%, 60% and 100% of the water volume evapotranspired by the crop (ETc). For each treatment, six plants were collected in each replicate. After collection, plants were separated into leaves, culm and reproductive structures (panicle + grains). Second and third order regressions were tested to model the behavior of biomass and nitrogen accumulation in white oat leaves, culms, reproductive structures and total over time. The maximum total nitrogen accumulation in white oat plants in the treatments L1, L3 and L5 was 50 kg ha-1, 163 kg ha-1 and 246 kg ha-1, respectively. Severe water deficit drastically reduced biomass and nitrogen accumulation in white oat. Severe water deficit causes earlier peak of biomass and nitrogen accumulation, reduces nitrogen accumulation rate and shortens cycle of white oats.

Resumo em Inglês:

ABSTRACT The aim of the current study is to develop an electronic system capable of automatically replacing hydraulic spray nozzles, based on psychrometric air conditions such as temperature and relative air humidity, in order to help improving the efficiency of application technologies. The system comprised one microcontroller, two solenoid valves, one temperature and relative humidity sensor, and a control algorithm. The system was installed in a hydropneumatic sprayer adapted with two semi-arcs. One semi-arc was equipped with JA-2 and other semi-arc with CVIA-015 hydraulic nozzles. After the algorithm interpreted the momentary psychrometric air conditions, it activated the JA-2 (when VPD < 20 hPa) or the CVIA-015 nozzle (when VPD > 20 hPa). The system was evaluated based on technical spraying parameters and on the response time to replace the hydraulic nozzle. Based on the results, the smallest-diameter droplets were the most influenced by psychrometric air conditions. VPD > 20 hPa tended to increase the VMD values and to reduce droplet density, although it did not change the SPAN index. The necessary mean time to switch from the JA-2 to the CVIA-015 nozzle was 0.742 s, whereas the necessary mean time to switch from the CVIA-015 to the JA-2 nozzle was 0.684 s.

Resumo em Inglês:

ABSTRACT Thinning is a cultural practice that leads to balance between fruit yield and quality. It is carried out in a short period of time and requires qualified workforce, whose shortage ends up increasing costs. This study aimed at evaluating the thinning effect of metamitron on peach trees at different periods of time after bloom. The experiment was carried out in a commercial orchard of ‘Sensação’ peach trees located in Morro Redondo, Rio Grande do Sul (RS) state, Brazil, in 2015-2016 crops. Treatments were the application of 200 mg L-1 metamitron, 20, 30, 40, 50 and 60 days after full bloom (DAFB), and manual thinning 40 DAFB. Fruit abscission, effective fructification, period of manual and chemical thinning, number of fruits and yield per plant, mean fruit mass and fruit caliber were evaluated. When metamitron was applied 40 DAFB, percentages of fruit abscission and fruit set, besides the number of fruits, were similar to the ones found when manual thinning was carried out. The intensity of the thinning effect of metamitron in peach trees depends on the application period.

Resumo em Inglês:

ABSTRACT Cassava has a high yield potential that can be achieved with adequate liming and fertilization of the soil. The objective of this study was to evaluate the effect of organic fertilizer application, in association or not with liming, on yield and morphological characteristics of cassava roots and on chemical and physical properties of the soil. The experiment was arranged in the split plot design. The plots corresponded to limestone rates (0 and 2.5 t ha-1) and the sub-plots to chicken manure rates (0, 4, 8, and 12 t ha-1). Yield showed no response to limestone application, but responded to manure, producing 43 t ha-1 of roots at the rate of 8 t ha-1. The treatments had no influence on soil density and total porosity. The addition of manure increased the concentrations of P and K, while the addition of limestone increased Ca and Mg in the soil. The pH was affected only by limestone. Therefore, limestone does not affect crop yield and soil physical properties up to the amount used. Use of chicken manure up to 8 t ha-1 increased yield. Limestone and manure affect soil fertility in different ways.

Resumo em Inglês:

ABSTRACT Low bud fertility index is frequently observed in different grapevine varieties grown in high altitude of Santa Catarina Sate; in many cases less than one cluster per bud is observed. The objective of this study was to assess bud fertility of twenty six Vitis vinifera L. varieties and from this information, to recommend the method of pruning more suitable for these varieties in high altitude conditions. The grapevine canes and buds were collected from production vineyards located in São Joaquim, Santa Catarina State, in two consecutive vintages. Fifteen cane cuttings containing 10 nodes per variety were collected to determine bud fertility and placed in a growth chamber with controlled relative humidity, light, temperature. After budbreak, buds were classified as fertile or non-fertile according to the presence or absence of the inflorescence. The bud fertility varies according to the variety and its position in the cane. Merlot, Cabernet Franc, Cabernet Sauvignon, Tinta Roriz and Tinta Caiada, which present higher fertility in basal buds, are recommended for short or long pruning. The varieties Chardonnay, Manzoni Bianco, Sauvignon Blanc, Sangiovese, Pinot Gris, Tempranillo, Pinot Noir, Syrah, Montepulciano, and Touriga Nacional should be pruned preferentially in long pruning. While the varieties Viognier, Glera (Prosecco), Fiano, Garganega, Vermentino, Nebbiolo, Teroldego, Rebo, Canaiolo Nero and Touriga Francesa must be pruned exclusively with long pruning in order to ensure adequate cluster production.

Resumo em Inglês:

ABSTRACT The effects of foliar application of Mo and use of N from cover crops (Crotalaria juncea L. and Canavalia ensiformis (L.) DC) on the performance of common beans were investigated in this study. Field experiments were carried out in a succession planting system (cover crops - common beans), and nitrate reductase activities were evaluated in the laboratory. The production of cover crops was done in a 2 x 4 factorial scheme installed in random blocks with four replications. The two cover crops sunn hemp and jack bean composed the first factor and the molibdenum doses (0, 40, 80, and 120 g ha-1) the second. These doses were applied as foliar fertilization using sodium molybdate (Na2MoO4) as Mo source. For bean cultivation, an unfertilized control treatment was evaluated.. Sunn hemp showed a linear positive response to Mo application in terms of shoot dry matter and N accumulation, while jack bean showed a quadratic negative response for shoot dry matter; for N accumulation, there was no adjustment of the regression models. Nitrate reductase activity in the common beans was up to three times higher at the Mo dose of 0 g ha-1 when compared to the treatments with Mo application to both cover crops. Cover crops or Mo doses had no significant effect on bean productivity.

Resumo em Inglês:

ABSTRACT Castor bean is a very important crop, however, in Brazil it still has relatively low productivity, 0.47 Mg ha-1 as a mean. Besides that the Country has significant castor oil demand and depends on international commerce to complement its production. The solution of these problems goes through the development of genotypes highly productive and adapted to the producing regions. So, the objective of this research was to evaluate the productive potential and selection of castor progenies of the cultivar FCA-PB, resulting from three types of pollination, in two crops and in two localities of the State of São Paulo. Grain productivity was evaluated, and some genetic parameters were estimated. In relation to the 2005/2006 crop, the progeny 49 cultivated in the locality of São Manuel produced 4170.66 kg ha-1 of grains. The highest heritability coefficients were observed in the 2005/2006 crop in the locality of Araçatuba. Progenies 1, 5, 6, 8, 15, 18, 19, 21, 27, 31, 35, 36, 38, 45, 49, 55, 56 and 58 were selected. Genotype interaction with the location indicated productive materials and adapted to the state of São Paulo.

Resumo em Inglês:

ABSTRACT The objective of this study was to evaluate the responses of Raphanus sativus to the application of the herbicide tepraloxydim by analyzing photosynthetic and biometric characteristics of the plants. The experiment was conducted in a greenhouse and treatments were instituted when the plants had five expanded leaves. The herbicide tepraloxydim was applied at doses of 0, 75, 100, and 125 g of active ingredient per hectare (g a.i. ha-1). The herbicide dose of 125 g a.i. ha-1 led to a small decrease in the photosynthetic rate, water use efficiency, effective quantum yield of PSII, rate of electron transport, and the concentration of chloroplastidic pigments in the leaves of R. sativus. On the other hand, there was a small increase in CO2 concentration in the substomatal chamber. The number of branches, leaves, flowers, plant height and dry mass of the stem and flowers were reduced more prominently in response to herbicide doses than the photosynthetic characteristics. Therefore, treatment with tepraloxydim inhibits the growth and formation of the leaves, branches and flowers of R. sativus at the stage of development analyzed. However, doses of 75, and 100 g a.i. ha-1 neither compromise the photosynthetic apparatus nor the stability of cell membranes.

Resumo em Inglês:

ABSTRACT South American natural grasslands are composed of several species with different growth strategies, with variations in specific leaf area (SLA), leaf dry matter content (LDMC), specific root length (SRL) and specific root area (SRA). The objective of this study was characterizing in grasses cultivated with different levels of phosphorus (P) in the soil if species with higher leaf and root area production per unit of dry matter have higher tissue P concentration, P use efficiency and higher dry matter yield. The plant species were grown in a greenhouse in pots with 5 kg of soil in a completely randomized design with four replicates and two conditions of P availability: addition of 60 mg kg-1 soil and without addition of P. The species with the highest SRA had a higher leaf and root P concentration. The higher production of leaf or root surface area per unit of dry matter did not represent higher tissue P use efficiency. The group formed by species of genre Paspalum had a higher leaf and root P use efficiency, therefore, areas composed of this genre are preferred for P fertilization.

Resumo em Inglês:

ABSTRACT Knowledge of the nutritional efficiency of species can help revegetation of forest areas, guiding the use of species that best adapt to environmental humidity, altitude and diversity. The objective of this study was to evaluate the nutrient utilization efficiency of N, P, K, Ca and Mg of dominant species in tropical dry forest and rainforest environments. The work was carried out in two areas, both in Pernambuco state, characterized as: Tropical Dry Forest of Caatinga and Tropical Rainforest of Atlantic Forest. A floristic and phytosociological survey was carried out. Species with highest density were evaluated, four from the dry forest and three from the rainforest. For each species, leaves of five healthy individuals of similar size were sampled and nutrient contents were determined. Leaf biomass was estimated by allometric equations. Rainforest species were more efficient in the use of N and K, and dry forest species in the use of P and K. In the dry forest environment, the species Pilocarpus spicatus and Guapira oposita stored more nutrients, and in the rainforest, the species Dialuim guianese was more efficient. These species are essential for the balance of ecosystems and the continuous and sustainable cycling of nutrients.

Resumo em Inglês:

ABSTRACT The use of residues for agricultural production is an alternative for the achievement of sustainability. When mixed with diatomaceous earth (DE) from biofuel filtration, sewage sludge (SS) plays an important role as soil conditioning agent. As a result, the objective of this work was to make a DE vermicompost at different proportions: 0; 7.53; 15.06; 22.59 and 30.12% v/v in relation to a SS pre-compost (PC) and gardening pruning residues. The experiment was carried out in 100-L containers in a randomized block design, with 5 treatments and 5 replications, in which Eisenia foetida earthworms were used in the pre-composting and vermicomposting processes. After four months, the physical characteristics of the vermicompost were analyzed. It was verified that the diatomaceous earth can be vermicomposted, even when soaked in biofuel oil, at amounts of up to 30.12% v/v, with no visible physical damage to earthworms and plants, and this proportion of DE reduced the concentration of nutrients, but improved the physical properties of the vermicompost, making it an excellent physical conditioner for use as a substrate of plants and fertilization of soils.

Resumo em Inglês:

ABSTRACT Grafting technique has been presented as an alternative for Araucaria angustifolia propagation. However, vegetative rescuing mature trees and obtaining large numbers of propagules is difficult, because the use of branch grafts has not been indicated due to its plagiotropic and morphogenic characteristic, generally resulting in undesired growth of the graft. So we aimed to describe the unpublished fact occurred in four plants of A. angustifolia grafted with grafts from primary branches that resulted in conversion to trunk. Plant growth and morphology were evaluated ten years after grafting. We verified vertical growth and organization of trunk and persistent branches with defined whorls, same to plants grafted with trunk grafts. Field tests with grafted plants using grafts obtained from the four plants resulted in same development pattern, proving the permanent morphogenic change and opening new perspectives for araucaria vegetative rescue and grafting. We concluded that trunciform shoots can be obtained by A. angustifolia grafting with plagiotropic primary branches. Despite the morphological clarity of trunciform shoots on grafted plagiotropic primary branches, it has not yet been possible to identify the causes of this reversion.