Produção e qualidade em gérbera de vaso cultivada com cloreto e silicato de potássio

The Gerbera is an ornamental perennial herb, belonging to the Asteraceae family. Its cultivation, as well as the entire market for flowers and ornamental plants, is now in full expansion phase. The objective of this study was to evaluate the growth and quality Potted gerbera cultivar Red, according to sources and doses of potassium. The experiment was conducted in a greenhouse at UNESP/Botucatu. The experimental design was randomized blocks, using a 2x5 factorial arrangement, with two sources (potassium silicate and chloride) and five doses (0, 50, 100, 150 and 200 mg. L-1) 4 replications and 5 plants per plot. Weekly throughout the experimental period, assessments were made of the number of leaves (NL) and the diameter of the plant canopy (DP). at the end of the season and the reproductive cycle, at 42 and 60 days after acclimatization (DAA), respectively, were determined by leaf area (LA), mass (dry leaves (MSF), the dry mass of inflorescence (MSI) and total dry matter (TDM). at the point of marketing is that of open stamens, when the inflorescence had at least two rounds of open, releasing pollen, we determined the number of inflorescences (NI), the diameter of inflorescence (DI), the stem height (AH), the shank diameter (DH) and plant height (PH). Regardless of the doses, potassium silicate promoted greater diameter, leaf area, greater MSF, MST and increased stem height, characteristics that favor the sale of potted gerbera.

Manejo do solo com lodo de esgoto na produção e qualidade de frutos em bananeira irrigada

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Características dos substratos na absorção de nutrientes e na produção de gérbera de vaso

The production systems on substrates have been employed in most commercial cultivation of flowers and ornamental plants, including gerbera. However, its introduction as potted flower is recent in Brazil and many studies, especially those related to the determination of substrates physical and chemical properties, which contribute to production quality are still needed. The present study aimed to assess the influence of substrates characteristics for nutrient absorption and production of potted gerbera. The experiment was carried out in greenhouse with the experimental design in randomized blocks, factorial arrangement 5x2 (5 substrates and 2 cultivars) and 4 replications. Treatments consisted of substrates with different physical and chemical characteristics and gerbera cultivars (Cherry and Red). Plants grown on substrate with pH above 7.0 had a reduction in iron absorption, resulting in lower intensity of green coloration in the leaves. Plants grown on substrate with pH below 5.0 showed toxic levels of manganese and lower dry mass. The characteristics of the substrate, especially the pH, influence the nutrients absorption and the production of potted gerbera, altering the final plant quality.

Essays in Greenhouse/Nursery Economics

This dissertation focuses on the greenhouse and nursery industry in the United States. Two major issues are explored: irrigation and plant disease. The first two essays examine wireless soil-moisture sensor networks, an emerging technology that measures soil moisture and optimizes irrigation levels in real time. The first essay describes a study in which a nationwide survey of commercial growers was administered to generate estimates of grower demand and willingness to pay for sensor networks. We find that adoption rates for a base system and demand for expansion components are decreasing in price, as expected. The price elasticity of the probability of adoption suggests that sensor networks are likely to diffuse at a rate somewhat greater than that of drip irrigation. In the second essay, yields, time-to-harvest, and plant quality were analyzed to measure sensor network profitability. Sensor-based irrigation was found to increase revenue by 62% and profit by 65% per year. The third essay investigates greenhouse nursery growers’ response to a quarantine imposed on the west coast of the United States from 2002 to present for the plant pathogen that causes Sudden Oak Death. I investigate whether growers choose to 1) improve their sanitation practices, which reduces the underlying risk of disease without increasing the difficulty of detecting the pathogen, 2) increase fungicide use, which also prevents disease but makes existing infections much harder to detect, or 3) change their crop composition towards more resistant species. First, a theoretical model is derived to formalize hypotheses on grower responses to the quarantine, and then these predictions are empirically tested using several public data sources. I do not find evidence that growers improve their sanitation practices in response to the quarantine. I do, however, find evidence that growers heavily increase their fungicide use in response to a quarantine policy that requires visual (as opposed to laboratory) inspection for the disease before every crop shipment, suggesting that the quarantine may have the adverse effect of making the pathogen harder to identify. I also do find evidence that growers shift away from susceptible crops and towards resistant crops.

Litter quality and its response to water level drawdown in boreal peatlands at plant species and community level

Changes in the structure of plant communities may have much more impact on ecosystem carbon (C) cycling than any phenotypic responses to environmental changes. We studied these impacts via the response of plant litter quality, at the level of species and community, to persistent water-level (WL) drawdown in peatlands. We studied three sites with different nutrient regimes, and water-level manipulations at two time scales. The parameters used to characterize litter quality included extractable substances, cellulose, holocellulose, composition of hemicellulose (neutral sugars, uronic acids), Klason lignin, CuO oxidation phenolic products, and concentrations of C and several nutrients. The litters formed four chemically distinct groups: non-graminoid foliar litters, graminoids, mosses and woody litters. Direct effects of WL drawdown on litter quality at the species level were overruled by indirect effects via changes in litter type composition. The pristine conditions were characterized by Sphagnum moss and graminoid litters. Short-term (years) responses of the litter inputs to WL drawdown were small. In longterm (decades), total litter inputs increased, due to increased tree litter inputs. Simultaneously, the litter type composition and its chemical quality at the community level greatly changed. The changes that we documented will strongly affect soil properties and C cycle of peatlands.

Effects of shoot pruning and inflorescence thinning on plant growth, yield and fruit quality of greenhouse tomatoes in a tropical climate

The combined effects of shoot pruning (one or two stems) and inflorescence thinning (five or ten flowers per inflorescence) on greenhouse tomato yield and fruit quality were studied during the dry season (DS) and rainy season (RS) in Central Thailand. Poor fruit set, development of undersized (mostly parthenocarpic) fruits, as well as the physiological disorders blossom-end rot (BER) and fruit cracking (FC) turned out to be the prevailing causes deteriorating fruit yield and quality. The proportion of marketable fruits was less than 10% in the RS and around 65% in the DS. In both seasons, total yield was significantly increased when plants were cultivated with two stems, resulting in higher marketable yields only in the DS. While the fraction of undersized fruits was increased in both seasons when plants were grown with a secondary stem, the proportions of BER and FC were significantly reduced. Restricting the number of flowers per inflorescence invariably resulted in reduced total yield. However, in neither season did fruit load considerably affect quantity or proportion of the marketable yield fraction. Inflorescence thinning tended to promote BER and FC, an effect which was only significant for BER in the RS. In conclusion, for greenhouse tomato production under climate conditions as they are prevalent in Central Thailand, the cultivation with two stems appears to be highly recommendable whereas the measures to control fruit load tested in this study did not proof to be advisable.

Ectomycorrhizal symbiosis can enhance plant nutrition through improved access to discrete organic nutrient patches of high resource quality

It is known that roots can respond to patches of fertility; however, root proliferation is often too slow to exploit resources fully, and organic nutrient patches may be broken down and leached, immobilized or chemically fixed before they are invaded by the root system. The ability of fungal hyphae to exploit resource patches is far greater than that of roots due to their innate physiological and morphological plasticity, which allows comprehensive exploration and rapid colonization of resource patches in soils. The fungal symbionts of ectomycorrhizal plants excrete significant quantities of enzymes such as chitinases, phosphatases and proteases. These might allow the organic residue to be tapped directly for nutrients such as N and P. Pot experiments conducted with nutrient-stressed ectomycorrhizal and control willow plants showed that when high quality organic nutrient patches were added, they were colonized rapidly by the ectomycorrhizal mycelium. These established willows (0.5 m tall) were colonized by Hebeloma syrjense P. Karst. for 1 year prior to nutrient patch addition. Within days after patch addition, colour changes in the leaves of the mycorrhizal plants (reflecting improved nutrition) were apparent, and after I month the concentration of N and P in the foliage of mycorrhizal plants was significantly greater than that in non-mycorrhizal plants subject to the same nutrient addition. It seems likely that the mycorrhizal plants were able to compete effectively with the wider soil microbiota and tap directly into the high quality organic resource patch via their extra-radical mycelium. We hypothesize that ectomycorrhizal plants may reclaim some of the N and P invested in seed production by direct recycling from failed seeds in the soil. The rapid exploitation of similar discrete, transient, high-quality nutrient patches may have led to underestimations when determining the nutritional benefits of ectomycorrhizal colonization.

Estimating quality costs in an automotive stamping plant through the use of simulation

The pressures of modern manufacturing require that the quality-cost benefits are determined when evaluating new procedures or alternative operating policies. Traditionally, cost reports and other quality metrics have been used for this purpose. However, the interactions between the main quality cost drivers cannot be understood at the superficial level and the effect that a new process or an alternative operating policy may have on quality costs is difficult to determine. An alternative to the traditional costing methods is simulation. The current work uses simulation to evaluate quality costs in an automotive stamping plant where the quality control is determined by operator inspection of their own work. Self-inspection quality control provides instantaneous feedback of quality problems, allowing for quick rectification. However, the difficult nature of surface finish inspection of automotive panels can create inspection and control errors. A simulation model was developed to investigate the cost effects of inspection and control errors and it was found that inspection error had a significant effect in increasing total quality cost, with the magnitude of this increase dependent on the level of control. Further, the simulation found that the lowest cost quality control policy was that which allowed a number of defective panels to accumulate before resetting the press-line.

Impact of saltmarsh disturbance on seed quality of Sarcocornia (Sarcocornia quinqueflora), a food plant of an endangered Australian parrot

The article presents a study which evaluates the impact of saltmarsh perturbation on seed quality of Sarcocornia which is a food for the endangered Orange-bellied parrot in Australia. It notes the significant impact of grazing on the energy and availability of Sarcocornia seeds in saltmarshes and indicates that graze-free saltmarshes with regular inundation provide the highest potential for Sarcocornia seed availability. Further, the substantial factor of soil characteristics and salinity of flood water and inundation on the seed production of Sarcocornia is also discussed.