Agriculture2015, 5(3), 400-411; doi:10.3390/agriculture5030400 (registering DOI) - published 3 July 2015 Show/Hide Abstract
Abstract: Botrytis cinerea is a fungus that causes gray mold on many fruit crops. Despite the availability of a large number of botryticides, the chemical control of gray mold has been hindered by the emergence of resistant strains. In this paper, tests were done to determine the botryticidal efficacy of selected plant extracts alone or combined with kresoxim-methyl. In total,eight South African medicinal plants vizArtemisia afra, Elyptropappus rhinocerotis, Galenia africana, Hypoxis hemerocallidea, Siphonochilus aetheopicus, Sutherlandia frutescens, Tulbaghia violacea and Tulbaghia alliacea were screened. Allium sativum, a plant species known to have antifungal activity, was included in the in vivo studies.For the in vitro studies, synergistic interactions between the plant extracts and the kresoxim-methyl fungicide were testedwith radial growth assays. Data indicated synergistic inhibitory effects between the fungicide and the plant extracts. Next, different doses of plant extracts combined with kresoxim-methyl were used for decay inhibition studies on Granny Smith apples. Synergistic and additive effects were observed for many of the combinations. Even though this study was done using only one strain of B. cinerea, results showed that the tested indigenous South African plant species possess natural compounds that potentiate the activity of kresoxim-methyl.
Abstract: This concept paper summarizes key “hotspots” for waste generation along the food supply chain and identifies a range of existing solutions/measures that can help producers, retailers and consumers reduce the amount of food that is wasted. The majority of food waste of 71–92 kg/head/year in Western Europe was found to originate from private households (61%), followed by restaurants and canteens (17%) and then supermarkets (5%); 59%–65% (of this food waste (71–92 kg) can be avoided and 54% thereof are fruit and vegetables. Since ethylene accelerates fruit ripening and its accumulation can lead to fruit decay and waste and new portable instruments now enable continuous in-situ determination of ethylene along the food chain, there is a possible key to reducing food waste of perishable, fresh produce. Hence, suggested countermeasures at the field level are use of ethylene inhibitors (AVG as “Retain” or MCP as “Harvista”), the former prevents pre-mature fruit drop in pome fruit, incentives for processing fruit of industrial grade and whole crop purchase (“WCP”). Along the supply chain, applications of ethylene inhibitors (e.g., 1-MCP as “SmartFresh”) absorber strips (e.g., “It’s Fresh”, Sensitech), bags (e.g., “Peakfresh”) as well as simply cooling and venting, and shading to avoid sun exposure. Countermeasures also include superstores no longer promoting multi-packs, e.g., “two strawberry punnets for the price of one”, abandon the “Display until” or “Sell by” date, conservative consumer shopping behavior, and sale of class II produce (“Wunderlinge” in Billa or “Kleine Äpfel” in REWE, “Ünique” in Coop), collection (rather than wasting) of perishable food by volunteers (“Die Tafel”), or “Food Sharing” of private household left-over perishable on social media, or any combination of the above to aid reducing fresh produce waste.
Abstract: Bioelectrochemical systems (BES) are a newly emerged technology for energy-efficient water and wastewater treatment. Much effort as well as significant progress has been made in advancing this technology towards practical applications treating various types of waste. However, BES application for agriculture has not been well explored. Herein, studies of BES related to agriculture are reviewed and the potential applications of BES for promoting sustainable agriculture are discussed. BES may be applied to treat the waste/wastewater from agricultural production, minimizing contaminants, producing bioenergy, and recovering useful nutrients. BES can also be used to supply irrigation water via desalinating brackish water or producing reclaimed water from wastewater. The energy generated in BES can be used as a power source for wireless sensors monitoring the key parameters for agricultural activities. The importance of BES to sustainable agriculture should be recognized, and future development of this technology should identify proper application niches with technological advancement.
Abstract: Backcross hybrids between the important forage legume white clover (Trifoliumrepens L.), which is stoloniferous, and the related rhizomatous species Caucasian clover (T.ambiguum M. Bieb), have been produced using white clover as the recurrent parent. The effect of drought on the parental species and two generations of backcrosses were studied in a short-term glasshouse experiment under three intensities of drought. Plants of Caucasian clover maintained a higher leaf relative water content and leaf water potential than white clover at comparable levels of drought, with the response of the backcrosses generally intermediate between the parents. Severe drought significantly reduced stolon growth rate and leaf development rate of white clover compared to the control, well-watered treatment, whilst differences between these two treatments in the backcross hybrids were relatively small. The differences between parental species and the backcrosses in root morphology were studied in 1m long vertical pipes. The parental species differed in root weight distribution, with root weight of Caucasian clover significantly greater than white clover in the 0.1 m to 0.5 m root zone. The backcrosses exhibited root characteristics intermediate between the parents. The extent to which these differences influence the capacity to tolerate drought is discussed.
Abstract: Aflatoxins, produced by the fungus Aspergillus flavus,occur naturally in maize. Contamination of maize grain with aflatoxin is a major food and feed safety problem and greatly reduces the value of the grain. Plant resistance is generally considered a highly desirable approach to reduction or elimination of aflatoxin in maize grain. In this investigation, a diallel cross was produced by crossing 10 inbred lines with varying degrees of resistance to aflatoxin accumulation in all possible combinations. Three lines that previously developed and released as sources of resistance to aflatoxin accumulation were included as parents. The 10 parental inbred lines and the 45 single crosses making up the diallel cross were evaluated for aflatoxin accumulation in field tests conducted in 2013 and 2014. Plants were inoculated with an A. flavus spore suspension seven days after silk emergence. Ears were harvested approximately 60 days later and concentration of aflatoxin in the grain determined. Parental inbred lines Mp717, Mp313E, and Mp719 exhibited low levels (3–12 ng/g) of aflatoxin accumulation. In the diallel analysis, both general and specific combining ability were significant sources of variation in the inheritance of resistance to aflatoxin accumulation. General combining ability effects for reduced aflatoxin accumulation were greatest for Mp494, Mp719, and Mp717. These lines should be especially useful in breeding for resistance to aflatoxin accumulation. Breeding strategies, such as reciprocal recurrent selection, would be appropriate.
Abstract: A model which describes tiller density dynamics in bahiagrass (Paspalum notatum Flügge) swards has been developed. The model incorporates interrelationships between various morphogenetic and structural components of the sward and uses the inverse of the self-thinning rule as the standard relationship between tiller density and tiller weight (a density-size equilibrium) toward which tiller density progressively changes over time under varying nitrogen (N) rates, air temperature and season. Water and nutrient limitations were not considered except partial consideration of N. The model was calibrated against data from swards subjected to different N rates and cutting intensities, and further validated against data from a grazed sward and swards under different cutting intensities. As the calibration and validation results were satisfactory, the model was used as a tool to investigate the responses of tiller density to various combinations of defoliation frequencies and intensities. Simulations identified defoliation regimes required for stabilizing tiller density at an arbitrary target level, i.e., sustainable use of the sward. For example, the model predicted that tiller density can be maintained at a medium level of about 4000 m−2 under conditions ranging from weekly cuttings to an 8 cm height to 8-weekly cuttings to 4 cm. More intense defoliation is needed for higher target tiller density and vice versa.