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PubMed2003

Influence of herbicide tolerant soybean production systems on insect pest populations and pest-induced crop damage.

Conventional soybean weed management and transgenic herbicide-tolerant management were examined to assess their effects on soybean insect pest populations in south Georgia in 1997 and 1998. Soybean variety had very little impact on the insect species observed, except that maturity group effects were observed for stink bug, primarily Nezara viridula (L.), population densities on some sampling dates. Stink bugs were more abundant on the early maturing varieties in mid-season. Velvetbean caterpillar, Anticarsia gemmatalis Hübner, potato leafhopper, Empoasca fabae (Harris), and grasshoppers Melanoplus spp. were more numerous on either conventional or herbicide-tolerant varieties on certain dates, although these differences were not consistent throughout the season. Soybean looper, Pseudoplusia includens (Walker), threecornered alfalfa hopper, Spissistilus festinus (Say), and whitefringed beetles, Graphognathus spp , demonstrated no varietal preference in this study. Few weed treatment differences were observed, but if present on certain sampling dates, then pest numbers were higher in plots where weeds were reduced (either postemergence herbicides or preplant herbicide plus postemergence herbicide). The exception to this weed treatment effect was grasshoppers, which were more numerous in weedy plots when differences were present. In post emergence herbicide plots, there were no differences in insect pest densities between the conventional herbicides (e.g., Classic, Select, Cobra, and Storm) compared with specific gene-inserted herbicide-tolerant materials (i.e., Roundup and Liberty). Defoliation, primarily by velvetbean caterpillar, was different between soybean varieties at some test sites but not different between herbicide treatments. We did not observe differences in seasonal abundance of arthropod pests between conventional and transgenic herbicide-tolerant soybean.

Animals↗
PubMed2001

Electrolytic removal of nitrate from crop residues.

The Controlled Ecological Life Support System (CELSS) resource recovery system, which is a waste-processing system,uses aerobic and anaerobic bioreactors to recover plants nutrients and secondary foods from the inedible biomass. Crop residues contain a significant amount of nitrate. There are actually two major problems concerning nitrate: 1) both CELSS biomass production and resource recovery consume large quantities of nitric acid, and 2) nitrate causes a variety of problems in both aerobic and anaerobic bioreactors. The nitrate anion causes several problems in the resource recovery system in such a way that removal prior to the process is highly desirable. The technique proposed to remove nitrate from potato inedible biomass leachate and to satisfy the nitric acid demand was a four-compartment electrolytic cell. In order to establish the electrolytic cell performance variables, experiments were carried out using potato crop residue aqueous leachate as the diluate solution. The variables studied were the potato biomass leachate composition and electrical properties, preparation of compartment solutions to be compatible with the electrolytic system, limiting current density, nutrients removal rates as a function of current density, fluid hydrodynamic conditions, applied voltage, and process operating time during batch recirculation operation. Results indicated that the limiting current density (maximum operating current density) was directly proportional to the solution electrical conductivity an a power function of the linear fluid velocity in the range between 0.083 and 0.403 m/s. During the electrolytic cell once-through operation, the nitrate, potassium, and other nutrient removal rates were proportional to the current density and were inversely proportional to fluid velocity. The removal of monovalent ions was found to be higher than divalent ones. Under batch recirculation operation at constant applied voltage of 4.5 and 8.5 V, it was found that the nutrient removal rates were independent of applied voltage, but were proportional to the ions concentration and operating time.

Anions↗
PubMed2006

Three-year comparison of the content of antioxidant microconstituents and several quality characteristics in organic and conventionally managed tomatoes and bell peppers.

Understanding how the environment and production and cultivation practices influence the composition and quality of food crops is fundamental to the production of high-quality nutritious foods. In this 3-year study, total phenolics, percent soluble solids, ascorbic acid, and the flavonoid aglycones quercetin, kaempferol, and luteolin were measured in two varieties of tomato (Lycopersicon esculentum L. cv. Ropreco and Burbank) and two varieties of bell peppers (Capsicum annuum L. cv. California Wonder and Excalibur) grown by certified organic and conventional practices in a model system. Significantly higher levels of percent soluble solids (17%), quercetin (30%), kaempferol (17%), and ascorbic acid (26%) were found in Burbank tomatoes (fresh weight basis; FWB), whereas only levels of percent soluble solids (10%) and kaempferol (20%) were significantly higher in organic Ropreco tomatoes (FWB). Year-to-year variability was significant, and high values from 2003 influenced the 3-year average value of quercetin reported for organic Burbank tomatoes. Burbank tomatoes generally had higher levels of quercetin, kaempferol, total phenolics, and ascorbic acid as compared to Ropreco tomatoes. Bell peppers were influenced less by environment and did not display cropping system differences.

Antioxidants↗
PubMedDate not supplied

Calcium bioavailability of vegetarian diets in rats: potential application in a bioregenerative life-support system.

Calcium bioavailability of vegetarian diets containing various proportions of candidate crops for a controlled ecological life-support system (CELSS) was determined by femur 45Ca uptake. Three vegetarian diets and a control diet were labeled extrinsically with 45Ca and fed to 5-wk old male rats. A fifth group of rats fed an unlabeled control diet received an intraperitoneal (IP) injection of 45Ca. There was no significant difference in mean calcium absorption of vegetarian diets (90.80 +/- 5.23%) and control diet (87.85 +/- 5.25%) when calculated as the percent of an IP dose. The amounts of phytate, oxalate, and dietary fiber in the diets did not affect calcium absorption.

Absorption↗
PubMed2002

[Development of APSIM (agricultural production systems simulator) and its application].

Soil-crop simulator model is an effective tool for providing decision on agricultural management. APSIM (Agricultural Production Systems Simulator) was developed to simulate the biophysical process in farming system, and particularly in the economic and ecological features of the systems under climatic risk. The current literatures revealed that APSIM could be applied in wide zone, including temperate continental, temperate maritime, sub-tropic and arid climate, and Mediterranean climates, with the soil type of clay, duplex soil, vertisol, silt sandy, silt loam and silt clay loam. More than 20 crops have been simulated well. APSIM is powerful on describing crop structure, crop sequence, yield prediction, and quality control as well as erosion estimation under different planting pattern.

China↗
PubMed2004

Regulating transgenic crops: a comparative analysis of different regulatory processes.

Transgenic crops have the potential to benefit both developed and developing countries. To ensure safe crops to humans and the environment, a strong, but not stifling, regulatory system needs to be established and properly implemented. This paper explores some essential components of a strong regulatory structure for transgenic crops. First, five different regulatory systems for transgenic crops--the United States, the European Union, South Africa, Taiwan, and Argentina--are described and explained. The major components of those systems are then compared to components necessary to a regulatory system that ensures safe products and engenders public trust. The key components discussed include: (1) mandatory pre-market approval; (2) established safety standards; (3) transparency; (4) public participation; (5) use of outside scientists for expert scientific advice; (6) independent agency decisions; (7) post-approval activities; and (8) enforcement authority and resources. Although no one of the existing systems analyzed adequately achieves all the necessary components of a strong regulatory system, those systems serve as models for deciding which regulatory procedures should be emulated and which should be avoided. A mandatory pre-market approval system that applies established safety standards in procedures that are transparent and allows for public participation with no pre-conceived notions or biases will best achieve both safe products and consumer trust.

Argentina↗
PubMed2003

[Pathways of soil sulfur input and output in agro-ecosystem under different cropping rotations].

This paper mainly dealt with the pathways of sulfur (S) input and output in agro-ecosystems under general cropping rotations in northern China. The results indicated that in a typical corn-wheat rotation system, S output by the crop products was 26.4 kg.hm-2, and 6.8 kg.hm-2 of S was returned to the soil through root and plant residues. Under wheat-soybean rotation, 24.4 kg.hm-2 of S was removed from and 7.2 kg.hm-2 of S were returned to the soil. Under the rotation of corn with rape, up to 45.4 kg.hm2 was taken out from and only 8.7 kg.hm-2 returned to the soil, respectively. 7.9, 6.4, 6.7 and 18.9 kg.hm-2 of S output by products and 2.6, 1.8, 4.3 and 5.6 kg.hm-2 of S input by residues were obtained in cotton, sorghum, peanuts and paddy rice, respectively. Through estimation of S balance for these systems, 6, 8.5, 24 and 7.1 kg.hm-2.yr-1 of S was lost from soil by growing wheat, corn, rape and paddy rice, respectively.

Crops, Agricultural↗
PubMed2001

Pest insect control in organically-produced crops of field vegetables.

In the UK, the demand for organic vegetable and salad crops is increasing, mainly as a result of the requirements of the multiple retailers. However, approximately 85% of the organic fruit and vegetable produce sold in the UK is imported. A major constraint to growing field vegetable crops, and particularly organically-produced crops, is the reduction in crop yield and quality caused by pest insects. This paper will consider the control techniques currently available to organic growers and other techniques that may become available in the future. Growing plant varieties with complete or even partial resistance to pest insects can be an effective way of reducing crop damage. There are already varieties of carrot, with resistance to carrot fly, and lettuce, with resistance to certain pest aphid species, which are available commercially. Cultural techniques to exclude, deter or avoid pest insects are also being used by some organic growers. Although isolating new crops from sources of infestation can be a highly effective control strategy, many organic growers cannot use it, as the land converted for organic production is still limited. Various crop covers can be used to prevent pest insects from damaging field crops, but to be effective such covers have to be in place before the pests enter the crop. Several researchers have tried to develop techniques to prevent pest insects from finding their host-plants. No technique involving semiochemicals has been sufficiently successful to be used in field vegetable production in the UK. Other studies have shown that the numbers of pest insects found on crop plants are reduced considerably when the crop is allowed to become weedy, is intercropped with another plant species, or is undersown with a living mulch. Hence, work is now needed to select background plant species that will both reduce pest insect numbers and cause the least reduction in yield to the harvested crop plants. There is also a need to obtain a better understanding of "companion planting", a practice used frequently by organic growers. To date, microbial control is the only biological technique that has been used successfully in field vegetable crops in the UK. However, only the toxicant produced by one microbial agent, the bacterium Bacillus thuringiensis, has so far been registered for use. The use of bacteria, fungi and viruses to control pests of field vegetable crops certainly has possibilities. However, in many cases there are still problems to be overcome to select pathogens that are compatible with, or can still be effective in, the wide fluctuations in temperature, humidity and soil moisture that occur under field conditions. Attempts are now being made to use entomopathogenic nematodes and predatory arthropods to control one major pest insect, the cabbage root fly. Techniques developed to improve the timing of application of various crop protection procedures in systems of conventional vegetable production apply equally well to organic production, despite the choice of control options being more limited. In particular, models to forecast the timing of pest insect attacks could be used to great effect, to indicate the best times to plant, protect and harvest a specific crop to minimise pest insect damage.

Agriculture↗
PubMed2002

Mars inflatable greenhouse analog.

Light intensities on the Martian surface can possibly support a bioregenerative life support system (BLSS) utilizing natural sunlight for hydroponic crop production, if a suitable controlled environment can be provided. Inflatable clear membrane structures offer low mass, are more easily transported than a rigid structure, and are good candidates for providing a suitable controlled environment for crop production. Cable culture is one hydroponic growing system that can take advantage of the beneficial attributes of the inflatable structure. An analog of a Mars inflatable greenhouse can provide researchers data on issues such as crew time requirements for operation, productivity for BLSS, human factors, and much more at a reasonable cost. This is a description of one such design.

Ecological Systems, Closed↗
PubMed2004

Volatilisation of crop protection chemicals from crop and soil surfaces under controlled conditions--prediction of volatile losses from physico-chemical properties.

Volatilisation of crop protection chemicals from soil and crop surfaces is one of a number of processes that may contribute to their dissipation in the environment. Therefore, information on the potential of a chemical to volatilise from these surfaces is required by international and national registration authorities. This paper reports the results of more than 190 experiments, which were carried out with 80 different crop protection chemicals under controlled conditions (laboratory and/or greenhouse) according to the BBA guideline. Percent loss values observed during 24 h after application are reported for 123 soil and 71 crop volatility studies. Generally, volatile losses from crop surfaces were found to be greater than from soil surfaces under comparable experimental conditions. It has been previously proposed that volatile losses from soil surfaces, from crops, and from aqueous systems can be estimated from physico-chemical parameters. The data are therefore analysed to determine whether a correlation exists between volatilisation and physico-chemical parameters, such as vapour pressure, Henry's law constant, water/air and soil/air distribution coefficients. It was found that these parameters can be used to make reasonable predictions of volatile losses from crop and soil surfaces, which can be expected for crop protection chemicals under controlled conditions. Vapour pressure was the best predictor of losses from soil and crops. The use of the soil/air distribution coefficient is an alternative for predicting/estimating the volatility potential of a chemical from soil. Based on direct measurements, no noticeable volatility can be expected from compounds with a vapour pressure below 10(-3) Pa from soil and 10(-4) Pa from crops, this is fully confirmed by indirect measurements. A tiered volatility testing scheme including appropriate trigger values is proposed.

Agrochemicals↗
PubMed2002

Nutrient management in food production: achieving agronomic and environmental targets.

The notion of management has undergone many changes during the past century. Nowadays, management is perceived as "specialized activity to achieve targets." Skill in management is the single most important factor determining the economic and environmental performance of agroecosystems. Nutrient management is "management of nutrients to achieve agronomic and environmental targets;" it requires proper understanding of nutrient cycling, site- and farm-specific guidelines and technology, and often direct coaching. These activities are diverse and complicated, especially in mixed farming systems that involve both crop and animal production. To be effective, economic and environmental targets must be coherent, flexible, and controllable. They also must be defined and implemented quantitatively at strategic, tactical, and operational levels. Data from farms in Poland and The Netherlands are used to show how economic incentives, provided through governmental policies and measures in both countries, can improve nutrient-use efficiency by a factor of 2 on many intensively managed mixed farming systems.

Agriculture↗
PubMed2005

Effects of water protection measures on the profitability of farms.

The effect of different management measures on the nutrient losses from crop and animal husbandry systems, in particular nitrogen, and on the total income of model farming enterprises was investigated. Such measures are considered as powerful options for meeting the requirements of "cross compliance" within the Agenda 2000 midterm review of the CAP. Optimisation of the storage and handling of animal manure was shown to be the most important and cost effective measure to reduce nutrient losses on farms. Other measures such as protein and phosphorus adapted feeding, maintaining a year-round cover crop on arable land and conservation tillage were also effective and it is recommended that these are adopted into farming practices. In general, measures that have both a high potential to reduce nutrient losses and are cheap to apply, and therefore have little effect on the overall profitability of farms, should be given priority in water protection policies.

Agriculture↗
PubMed2006

Generation Challenge Programme (GCP): standards for crop data.

The Generation Challenge Programme (GCP) is an international research consortium striving to apply molecular biological advances to crop improvement for developing countries. Central to its activities is the creation of a next generation global crop information platform and network to share genetic resources, genomics, and crop improvement information. This system is being designed based on a comprehensive scientific domain object model and associated shared ontology. This model covers germplasm, genotype, phenotype, functional genomics, and geographical information data types needed in GCP research. This paper provides an overview of this modeling effort.

Crops, Agricultural↗
PubMed2002

Use of molecular markers in cereal breeding.

Great advances have been made in recent years in marker detection systems and in the techniques used to identify markers linked to useful traits. While RFLP markers have been the basis for most work in crop plants, useful markers have been generated using RAPD and AFLP methods. More recently, microsatellite or simple sequence repeat (SSR) markers have been developed for major crop plants and this marker system is predicted to lead to even more rapid advances in both marker development and implementation in breeding programs. Identification of markers linked to useful traits has been based on complete linkage maps and bulked segregant analysis. However, alternative methods, such as the construction of partial maps and combination of pedigree and marker information, have also proved useful in identifying marker/trait associations. The value of markers in analysing the inheritance of traits in crop plants and understanding genome structure and organization is now well established. The different properties of markers systems and their applications in genome analysis and molecular breeding of cereals species are discussed.

Breeding↗
PubMed1993

Economic and health needs of Wisconsin migrant farm workers.

Migrant farm workers play an essential role in the planting and harvesting of crops in our agricultural production system. In the United States today, about 6 percent of the paid farm labor force "follow the crops" across the nation. This article reports on the economic and health care needs of migrant farm workers who travel from the border areas of Texas to Wisconsin each year. Surveys conducted in 1978 and 1989 show that this population remains in serious need of health care and access to financial assistance programs. During the 11-year interval between surveys, little change occurred in the health care status or use patterns of Wisconsin migrant workers, although housing and sanitary conditions in the work environment improved somewhat due to the passage of new federal regulations. This article discusses the problems and barriers that migrants continue to face and offers recommendations for government action.

Adolescent↗
PubMed1996

Processing of nutritious, safe and acceptable foods from CELSS candidate crops.

A controlled ecological life-support system (CELSS) is required to sustain life for long-duration space missions. The challenge is preparing a wide variety of tasty, familiar, and nutritious foods from CELSS candidate crops under space environmental conditions. Conventional food processing technologies will have to be modified to adapt to the space environment. Extrusion is one of the processes being examined as a means of converting raw plant biomass into familiar foods. A nutrition-improved pasta has been developed using cowpea as a replacement for a portion of the durum semolina. A freeze-drying system that simulates the space conditions has also been developed. Other technologies that would fulfill the requirements of a CELSS will also be addressed.

Biomass↗