Frank B. Matta

Phytotoxicity of mercury in Indian mustard (Brassica juncea L.).

This study investigated the phytotoxicity of mercury to Indian mustard (Brassica juncea L.). Two common cultivars (Florida Broad Leaf and Long-standing) were grown hydroponically in a mercury-spiked solution. Mercury exhibited a significant phytotoxicity in these two cultivars of Indian mustard at elevated concentrations (>or=2 mg L(-1)). Mercury uptake induced a significant reduction in both biomass and leaf relative water content. Microscopy studies indicated that elevated mercury concentrations in plants significantly changed leaf cellular structure: thickly stained areas surrounding the vascular bundles; decreases in the number of palisade and spongy parenchyma cells; and reduced cell size and clotted depositions. The palisade chloroplasts exhibited decreases in their amounts and starch grains as well as a loss of spindle shape. However, due to high accumulation of mercury in plants, especially in the roots, Indian mustard might be a potential candidate plant for phytofiltration of contaminated water and phytostabilization of mercury-contaminated soils.

Effects of Kaolin Clay Application on Flower Bud Development, Fruit Quality and Yield, and Flower Thrips [Frankliniella spp. (Thysanoptera: Thripidae)] Populations of Blueberry Plants

Abstract Three separate studies were conducted to report the effects of kaolin applications (Surround WP) on southern highbush blueberries (Vaccinium corymbosum L.) and rabbiteye (V. ashei Reade) blueberries. When applied to mature blueberry plants, kaolin clay emulsion dried to form a white reflective film that affected bud development, fruit set and development, plant growth, and fruit yield, but had no effect on fruit quality parameters. When kaolin was applied before fruit set, yield was increased with no significant residue left on the fruit. Surround WP consistently reduced the number of flower thrips (Frankliniella spp.) within the canopy of rabbiteye blueberry plants by approximately 50%. Kaolin applications were not phytotoxic to blueberry buds, flowers, leaves, or fruit and were harmless to foraging bees.

Effect of Starch-Based Edible Coatings on Quality of Minimally Processed Pummelo (Citrus maxima Merr.)

A study on the effect of starch-based edible coatings on shelf life and quality of minimally processed pummelo was conducted during storage at 4°C for 21 days. Starch-based coatings were developed from two types of native starches (rice and cassava) and mixed with two concentrations of pummelo juice (5 and 10% by volume) as anti-browning agents. It was found that the property of edible coating from cassava starch had a lower water vapor transmission rate of 785 g/m2/day compared with the coating modified from rice starch in which the water vapor transmission rate was 1,230 g/m2/day. Results showed that coated minimally processed pummelo had a lower weight loss of 4.8–7.7% compared to the control (non-coated minimally processed pummelo). Total sugars of minimally processed pummelo coated with rice and cassava starch increased. Titratable acidity and vitamin C content of minimally processed pummelo coated with rice and cassava starch was low compared to the control. The hue angle of surface color of minimally processed pummelo coated with the two starches did not differ from the control.

Integrated Fruit Production—Enhancing Production, Quality, and Safety of Fruit Production and Packing of Mango in Brazil as a Model

The development and implementation of ecosystem-based technologies in plant protection have been important objectives of the International Organization for Biological Control (IOBC) since its foundation in 1956. Integrated Production/Integrated Farming is a system that produces high quality and safe food and other products by using natural resources and regulating mechanisms to replace polluting inputs and to secure sustainable farming. The objectives and principles of Integrated Production (IP) are based in a holistic view of the system, combining strategies such as Integrated Pest Management (IPM), safety, fertilization, and agronomic measures to enhance their effectiveness. It relies on ecosystem regulation, food safety, the importance of animal welfare, and on the preservation of natural resources. The expansion of the mango growing area in Brazil depends on the generation and adaptation of production technologies, as well as on consumer market tendencies that currently require better quality fruit. Brazil needs to adjust itself to agricultural production systems like Fruit Integrated Production (FIP) that has the objective of economically producing high quality fruit obtained by ecologically safer methods, which minimizes the collateral undesirable effects of the use of pesticides, increasing environmental protection and improving human health. The FIP System in the São Francisco River Valley began in 2000, with the elaboration of an environmental diagnosis of the region followed by the monitoring of insects and diseases, training of technicians and farmers, study of the production chain, and elaboration of databases and procedures for integrated mango production. Today, the program counts on the participation of 287 mango producer farms, amounting to a monitored area of 8,780 ha. This program is based on the integration of scientists, farmers, consultants, and extension people, both from public and private institutions. Research studies are being carried out in order to generate and diffuse new technologies, products, and services that can be adapted to the situation of the Brazilian mango farmers.

Flower Sex Expression in Lychee (Litchi chinensisSonn.) Is Affected by Gibberellic Acid and Naphthalene Acetic Acid

ABSTRACT Gibberellic acid (GA3) at 25, 50, and 100 mg-L−1 and naphthalene acetic acid (NAA) at 20, 40, and 80 mg-L−1 were sprayed to runoff on flower panicles of 15-year-old lychee trees one week after panicle emergence. Trees sprayed with water only were used as the control. The number of male flowers was increased quadratically by NAA compared to the control in 2000, and 2001. The number of hermaphrodite flowers functioning as female (HF-F) and the number of hermaphrodite flowers functioning as male (HF-M) was reduced quadratically by all concentrations of NAA both years. The greater the NAA concentration, the greater the reduction. The total number of flowers was also reduced by all NAA concentrations both years. Fruit set (percentage of total HF-F flowers) was reduced quadratically by NAA in 2001, but had no effect in 2000. The number of male flowers was increased quadratically by GA3 both years. Regression analysis also showed a positive relationship between GA3 and HF-F flowers both years. However, hermaphrodite flowers functioning as male (HF-M) was reduced quadratically by GA3 both years. In addition, the total number of flowers and fruit set was increased quadratically by GA3 both years. GA3promotion of male flowers, HF-F production, and increased fruit set may have important bearing on yield improvement.

Bioavailability and Stability of Mercury Sulfide in Armuchee (USA) Soil

Because of the adverse effects of elemental mercury and mercury compounds upon human health, the U.S. Department of Energy (DOE) is engaged in an on-going effort to monitor and remediate mercury-contaminated DOE sites. In order to more cost effectively implement those extensive remediation efforts, it is necessary to obtain an improved understanding of the role that mercury and mercury compounds play in the ecosystem. We have conducted pilot scale experiments to study the bioavailability of mercury sulfide in an Armuchee (eastern US) soil. The effects of plants and incubation time on chemical stability and bioavailability of HgS under simulated conditions of the ecosystem have been examined, as has the dynamics of the dissolution of mercury sulfide by various extractants. The results show that mercury sulfide in contaminated Armuchee soil was still to some extent bioavailable to plants. After planting, soil mercury sulfide is more easily dissolved by both 4 M and 12 M nitric acid than pure mercury sulfide reagent. Dissolution kinetics of soil mercury sulfide and pure chemical reagent by nitric acid are different. Mercury release by EDTA from HgS-contaminated soil increased with time of reaction and soil mercury level. Chelating chemicals increase the solubility and bioavailability of mercury in HgS-contaminated soil.Copyright

Effects of Kaolin Clay Particle Film on Southern Highbush (Vaccinium corymbosumL.) Blueberry Plants

Abstract Two separate studies were conducted to study the effects of kaolin applications (Surround WP) on southern highbush blueberries (Vaccinium corymbosumL.). When applied to mature blueberry plants, kaolin clay emulsion dried to form a white reflective film and affected bud development, fruit set and development, plant growth, and fruit yield, but had no effect on fruit quality attributes. ‘Cooper’ received a single application of kaolin during flowering (bud stages 3-6) which increased fruit set and reduced the rate of flower bud development. Berry size was reduced with kaolin, perhaps due to increased number of fruit present. ‘Magnolia’ received a single application of kaolin at four different stages of maturity resulting in a linear increase in plant volume with early applications. When kaolin was applied before fruit set, yield was increased with no significant residue left on the fruit.