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PubMed1996

Consideration in selecting crops for the human-rated life support system: a Linear Programming model.

A Linear Programming model has been constructed which aids in selecting appropriate crops for CELSS (Controlled Environment Life Support System) food production. A team of Controlled Environment Agriculture (CEA) faculty, staff, graduate students and invited experts representing more than a dozen disciplines, provided a wide range of expertise in developing the model and the crop production program. The model incorporates nutritional content and controlled-environment based production yields of carefully chosen crops into a framework where a crop mix can be constructed to suit the astronauts' needs. The crew's nutritional requirements can be adequately satisfied with only a few crops (assuming vitamin mineral supplements are provided) but this will not be satisfactory from a culinary standpoint. This model is flexible enough that taste and variety driven food choices can be built into the model.

Crops, Agricultural↗
PubMed2002

Strategies for biological system management of nematodes in horticultural crops: fumigate, confuse or ignore them.

Integrated management of nematodes as well as other soil-borne pests and diseases in horticultural crops in the tropics and subtropics as well as in protected cultivation in temperate climates is often a lopsided approach based on soil fumigation. With the upcoming loss of methyl bromide (Mbr), because of its effects on the ozone layer of the atmosphere, growers will have to make changes in the way they look at the problem of controlling soil-borne nematodes, fungi, insects and weeds. They can no longer rely on eradication of all pest problems with a one-stroke fumigation process. This is a severe problem that requires sound scientific solutions. New control technologies need to be developed and established methods urgently refined that are acceptable to the growers. Alternative fumigants and systemic nematicides still on the market will not provide broad spectrum control equal to Mbr. More disturbing is a provocative statement made by an economist that due to pesticides nematologists have neglected developing suitable alternative IPM measures of control. Some people may agree with this statement, especially if they are not involved in soil-ecosystem research. If you are a nematologist, this thought-provoking statement is at first upsetting but it is not valid. My talk will concentrate on the biological and cultural control methodologies that have been developed by nematologist around the world for use in management systems. These are technologies that can compensate for the loss of methyl bromide to horticultural crops in many countries. Alternatives are available and new methodologies are being developed for restructuring IPM strategies in many crops. The compatibility of these new approaches with general farming practices needs to be assessed on a country by country basis. Mutually interacting technology packages are needed, that are logically structured in "biological system management" programs that stress biocontrol aspects of control and not pesticides as is often the case in standard IPM approaches.

Animals↗
PubMed2001

Unmanaged sexual reproduction and the dynamics of genetic diversity of a vegetatively propagated crop plant, cassava (Manihot esculenta Crantz), in a traditional farming system.

Occurrence of intervarietal or interspecific natural crosses has been reported for many crop plants in traditional farming systems, underlining the potential importance of this source of genetic exchange for the dynamics of genetic diversity of crop plants. In this study, we use microsatellite loci to investigate the role of volunteer seedlings (plants originating from unmanaged sexual reproduction) in the dynamics of genetic diversity of cassava (Manihot esculenta Crantz), a vegetatively propagated crop, in a traditional farming system in Guyana. A previous field study showed that farmers incorporate such plants into the germplasm for vegetative propagation, and that many of them are likely to be assigned by farmers to recognized varieties. Under strict vegetative propagation clonality of varieties is expected. The high proportion of polyclonal varieties observed suggests that incorporation of seedlings into the germplasm for propagation is a frequent event. The molecular variability assessed with microsatellite markers shows that there is high differentiation among heterozygous varieties, whereas populations of seedlings do not depart from the proportions expected under Hardy-Weinberg assumptions. Assignment of seedlings to a recognized variety on the basis of morphological similarity greatly increases genetic diversity within the variety. We argue that recombination and gene flow play a major role in the dynamics of genetic diversity of cassava in traditional farming systems. Documenting unmanaged sexual reproduction and its genetic consequences is a prerequisite for defining strategies of in situ conservation of crop plant genetic resources.

Alleles↗
PubMed2005

Operational seasonal forecasting of crop performance.

Integrated, interdisciplinary crop performance forecasting systems, linked with appropriate decision and discussion support tools, could substantially improve operational decision making in agricultural management. Recent developments in connecting numerical weather prediction models and general circulation models with quantitative crop growth models offer the potential for development of integrated systems that incorporate components of long-term climate change. However, operational seasonal forecasting systems have little or no value unless they are able to change key management decisions. Changed decision making through incorporation of seasonal forecasting ultimately has to demonstrate improved long-term performance of the cropping enterprise. Simulation analyses conducted on specific production scenarios are especially useful in improving decisions, particularly if this is done in conjunction with development of decision-support systems and associated facilitated discussion groups. Improved management of the overall crop production system requires an interdisciplinary approach, where climate scientists, agricultural scientists and extension specialists are intimately linked with crop production managers in the development of targeted seasonal forecast systems. The same principle applies in developing improved operational management systems for commodity trading organizations, milling companies and agricultural marketing organizations. Application of seasonal forecast systems across the whole value chain in agricultural production offers considerable benefits in improving overall operational management of agricultural production.

Agriculture↗
PubMed2000

[Primary research on interface ecology in agroforestrial ecosystems].

In this paper, the fundamental conception, major research content of interface ecology and its application in agroforestrial systems were discussed. The action mechanism between trees and crops in agroforestrial systems mainly embodied aboveground interface for competitve light, quantity of heat and water, and underground interface for competitiye nutrient and water. It was showed in the interchange and transmission of nutrient, energy and information through interface.

Biomass↗
PubMedDate not supplied

Bioconversion systems for food and water on long term space missions.

An imperative for prolonged Space flight missions is the conservation of resources. Extensive resupply could pose technological and logistical challenges for those responsible for the management and successful completion of the mission. Therefore, the biological waste water reclamation system (BWWR) which requires little or no expendable supplies and the waste cellulose to edible mushroom conversion system (CMCS) which is conceived as a low energy crop waste recycling system are prototype instruments which have been conceived as solutions to the mission resupply problem. Out tests, conducted with relatively crude devices based on the original concepts, indicate that further research on the basic principles underlying the systems and refinement of the engineering designs will lead to hardware with the potential to satisfy the requirement for minimal re-supply while providing recycled water and edible mushrooms.

Agaricales↗
PubMed2003

Volatile metabolites of higher plant crops as a photosynthesizing life support system component under temperature stress at different light intensities.

The effect of elevated temperatures of 35 and 45 degrees C (at the intensities of photosynthetically active radiation 322, 690 and 1104 micromoles m-2 s-1) on the photosynthesis, respiration, and qualitative and quantitative composition of the volatiles emitted by wheat (Triticum aestuvi L., cultivar 232) crops was investigated in growth chambers. Identification and quantification of more than 20 volatile compounds (terpenoids--alpha-pinene, delta 3 carene, limonene, benzene, alpha- and trans-caryophyllene, alpha- and gamma-terpinene, their derivatives, aromatic hydrocarbons, etc.) were conducted by gas chromatograph/mass spectrometry. Under light intensity of 1104 micromoles m-2 s-1 heat resistance of photosynthesis and respiration increased at 35 degrees C and decreased at 45 degrees C. The action of elevated temperatures brought about variations in the rate and direction of the synthesis of volatile metabolites. The emission of volatile compounds was the greatest under a reduced irradiation of 322 micromoles m-2 s-1 and the smallest under 1104 micromoles m-2 s-1 at 35 degrees C. During the repair period, the contents and proportions of volatile compounds were different from their initial values, too. The degree of disruption and the following recovery of the functional state depended on the light intensity during the exposure to elevated temperatures. The investigation of the atmosphere of the growth chamber without plants has revealed the substances that were definitely technogenic in origin: tetramethylurea, dimethylsulfide, dibutylsulfide, dibutylphthalate, and a number of components of furan and silane nature.

Air Pollution, Indoor↗
PubMed2006

Efficient and stable transformation of Lactuca sativa L. cv. Cisco (lettuce) plastids.

Transgenic plastids offer unique advantages in plant biotechnology, including high-level foreign protein expression. However, broad application of plastid genome engineering in biotechnology has been largely hampered by the lack of plastid transformation systems for major crops. Here we describe the development of a plastid transformation system for lettuce, Lactuca sativa L. cv. Cisco. The transforming DNA carries a spectinomycin-resistance gene (aadA) under the control of lettuce chloroplast regulatory expression elements, flanked by two adjacent lettuce plastid genome sequences allowing its targeted insertion between the rbcL and accD genes. On average, we obtained 1 transplastomic lettuce plant per bombardment. We show that lettuce leaf chloroplasts can express transgene-encoded GFP to approximately 36% of the total soluble protein. All transplastomic T0 plants were fertile and the T1 progeny uniformly showed stability of the transgene in the chloroplast genome. This system will open up new possibilities for the efficient production of edible vaccines, pharmaceuticals, and antibodies in plants.

Chloroplasts↗
PubMedDate not supplied

Influence of soil moisture and land use history on denitrification end-products.

We investigated the effects of recent moisture history on the relative production of N2O and N2 during denitrification in soil from cropped and successional ecosystems. The soils were pedogenically identical but had been managed differently for the past decade. Sieved soils were amended with nitrate, glucose, and water. Long-wet and short-wet incubations received 80 and 0%, respectively, of prescribed water 2 d before incubation and the rest just before incubation. The N2O and N2 production and N2O mole fraction (N2O/[N2O + N2]) were measured using acetylene inhibition. The N2 production and soil 15N enrichment were measured by 15N-gas evolution. The response of N2O mole fraction to moisture history differed by ecosystem. Mean N2O mole fraction in the successional system was about the same for long-wet and short-wet treatments (0.34 and 0.33, respectively). For the cropped system, however, the N2O mole fraction was 0.36 for the long-wet and 0.90 for the short-wet treatment. Thus, in the cropped system a much smaller proportion of end product was N2O if soil had been wet for 2 d. For N2 fluxes, the isotope method gave the same pattern (r = 0.92) but only about one-third the magnitude, suggesting that N2 derived from two distinct pools. Differences in response of N2O mole fraction for successional and cropped soils may be due to differences in microbial communities. Further knowledge of ecosystem differences with respect to N2O mole fraction and recent moisture history may improve modeled estimates of local and global N2O fluxes.

Agriculture↗
PubMed1989

Fate of salmonellas in the alimentary tract of chicks pre-treated with a mature caecal microflora to increase colonization resistance.

Oral challenge with a strain of Salmonella kedougou, resistant to nalidixic acid, gave a time-course for salmonella survival in the alimentary tract of chicks pre-treated with a caecal culture from an eight-week-old bird to increase colonization resistance. In untreated, control chicks, salmonella colonization of the caeca resulted in counts of greater than 10(6)/g within 48 h and a mean generation time of 1.6 h. With treated birds, however, the salmonellas failed to multiply in the caeca and decreased to a low level over a 48-h period, thus suggesting a mainly bacteriostatic effect. Pre-treatment of chicks with the caecal culture also reduced the proportion of salmonella-positive crop samples. Growth of the salmonella in a feed-slurry system resembling moistened crop contents occurred rapidly at 37 degrees C but was prevented by addition of the treatment culture, a decline in numbers coinciding with Lactobacillus populations of ca 10(9)/g and a pH value of 5.5. Incorporation of a feed decontaminant, 1% formic acid (pH 4.0), rapidly eliminated both salmonellas and organisms added from the treatment culture.

Animals↗
PubMed2005

Crop yield and light/energy efficiency in a closed ecological system: Laboratory Biosphere experiments with wheat and sweet potato.

Two crop growth experiments in the soil-based closed ecological facility, Laboratory Biosphere, were conducted from 2003 to 2004 with candidate space life support crops. Apogee wheat (Utah State University variety) was grown, planted at two densities, 400 and 800 seeds m-2. The lighting regime for the wheat crop was 16 h of light-8 h dark at a total light intensity of around 840 micromoles m-2 s-1 and 48.4 mol m-2 d-1 over 84 days. Average biomass was 1395 g m-2, 16.0 g m-2 d-1 and average seed production was 689 g m-2 and 7.9 g m-2 d-1. The less densely planted side was more productive than the denser planting, with 1634 g m-2 and 18.8 g m-2 d-1 of biomass vs. 1156 g m-2 and 13.3 g m-2 d-1; and a seed harvest of 812.3 g m-2 and 9.3 g m-2 d-1 vs. 566.5 g m-2 and 6.5 g m-2 d-1. Harvest index was 0.49 for the wheat crop. The experiment with sweet potato used TU-82-155 a compact variety developed at Tuskegee University. Light during the sweet potato experiment, on a 18 h on/6 h dark cycle, totaled 5568 total moles of light per square meter in 126 days for the sweet potatoes, or an average of 44.2 mol m-2 d-1. Temperature regime was 28 +/- 3 degrees C day/22 +/- 4 degrees C night. Sweet potato tuber yield was 39.7 kg wet weight, or an average of 7.4 kg m-2, and 7.7 kg dry weight of tubers since dry weight was about 18.6% wet weight. Average per day production was 58.7 g m-2 d-1 wet weight and 11.3 g m-2 d-1. For the wheat, average light efficiency was 0.34 g biomass per mole, and 0.17 g seed per mole. The best area of wheat had an efficiency of light utilization of 0.51 g biomass per mole and 0.22 g seed per mole. For the sweet potato crop, light efficiency per tuber wet weight was 1.33 g mol-1 and 0.34 g dry weight of tuber per mole of light. The best area of tuber production had 1.77 g mol-1 wet weight and 0.34 g mol-1 of light dry weight. The Laboratory Biosphere experiment's light efficiency was somewhat higher than the USU field results but somewhat below greenhouse trials at comparable light levels, and the best portion of the crop at 0.22 g mol-1 was in-between those values. Sweet potato production was overall close to 50% higher than trials using hydroponic methods with TU-82-155 at NASA JSC. Compared to projected yields for the Mars on Earth life support system, these wheat yields were about 15% higher, and the sweet potato yields averaged over 80% higher.

Biomass↗
PubMed2003

Effects of different growing systems and fertiliser rates on attractiveness of maize crop to beetles of Diabrotica virgifera virgifera LeConte and larvae dammage.

Monitoring of plant lodging, yield reaction due to root injures caused by western corn rootworm larvae (WCR) (Diabroticia virgifera virgifera Le Conte) and adults abundance with yellow Multigard and Pherocone AM and pheromone Csalomon traps, were performed in three field trials. First one with 4 variants of maize growing system; maize continuous cropping, two crop rotation (wheat-maize, soybean-maize) and three crop rotation (wheat-soybean-maize), set up in 1985. Second one with 54 variants, both conducted in Zemun Polje. A large scale trial with three rates of NPK mineral fertilizers; (NPK 0 kg/ha, 170 kg/ha and 270 kg/ha with two type of N applied in side dressing (N 0 kg/ha, 50 kg/ha and 80 kg/ha) was set up in Crepaja in 1997, 1998 and 1999. Each variant of fertilizers had two combinations; one treated with insecticide and another one untreated check. Feeding on root system of WCR larvae, in the variants with insecticide application, resulted in plant lodging that ranged in average from 2.1% in 1997, to 61.6% in 1999, while in variant without insecticide application, root damage resulted in plant lodging from 19.5% in 1997, to 56.6% in 1999. Increasing of the nitrogen rates in the variants without application of insecticide tended to raise the percentage of plant lodging Yield reaction on nitrogen application was positive in 1997, first year and 1998, second year of maize monoculture, while in 1999 was negative. Larval injury affected maize yield in the higher extend in extremely dry year 2000, when yield index was 0.37 comparing 2.86 t/ha in maize monoculture to 7.66 t/ha in three crop rotation, 0.54 (2.86: 5.28 maize monoculture: wheat-maize) and 0.55 (2.86: 5.22 maize monoculture: soybean-maize). Adult abundance monitored with yellow sticky and pheromone traps indicate that maize in three crop rotation has the smallest attraction to the migratory WCR beetles. The choice of three crop rotation seems to be the most promising choice for maize growing, which will result with the lowest risk of plant lodging and yield decrease.

Agriculture↗
PubMed1984

Prolactin's mitogenic action on the pigeon crop-sac mucosal epithelium involves direct and indirect mechanisms.

It has long been known that prolactin (PRL) induces proliferation of the mucosal epithelial lining of the pigeon crop-sac. This system was used to study possible interactions of other hormones with PRL's mitogenic effect directly on the crop-sac cells. Injection of a sheep pituitary powder into the loose skin between the leg and abdomen of pigeons increased the responsiveness of the crop-sac to direct, local application of PRL. Similar systemic injections of anterior pituitary hormones, ACTH and TSH (alone or together), or a combination of LH and FSH, were without effect on the local response to PRL. However, systemically injected PRL and GH resulted in a dramatic augmentation of the response of the organ to local injection of PRL. PRL was more potent than GH in this regard. These results suggest that PRL has at least two modes of action as a mitogen on this epithelium--its well-known direct action on the cells and an indirect action as well that is possibly mediated by the secretion of another factor into the blood stream. Because it was previously found that somatomedin-like molecules, including proinsulin, act synergistically with PRL to promote proliferation of these cells when coinjected locally with PRL (T. R. Anderson, J. Rodriguez , D. S. Pitts , E. M. Spencer, and C. S. Nicoll , 1983, In "Insulin-like Growth Factors/Somatomedins," de Gruyter , Berlin), The effects of systemic injections of proinsulin were also tested. Proinsulin had a potentiating effect similar to that of the pituitary powder and of GH or PRL. These results are consistent with the following interpretations: When PRL promotes crop-sac proliferation to produce crop-milk in pigeons and doves, the hormone acts through at least two mechanisms. One of these is a direct effect on the crop-sac, which sensitizes the mucosal epithelium to the mitogenic action of a somatomedin-like growth factor. The second effect is an increase in the production and/or secretion of the factor, which then acts synergistically with PRL to promote proliferation of the crop-sac mucosal cells. More direct evidence for this proposal was provided by the finding that serum from saline- or PRL-treated pigeons did not stimulate crop-sac mucosal growth when it was injected locally. However, the serum from PRL-treated birds had a much higher level of an activity that augmented the effects of PRL when the sera were locally injected in combination with PRL.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2005

Effects of incorporated corn residues on glyphosate mineralization and sorption in soil.

In modern agricultural systems employing conservation tillage practices, glyphosate is widely used as a preplant burndown herbicide in a wide range of crops. Conservation tillage systems are characterized by a significant presence of crop residues at the soil surface so that glyphosate is applied to a soil matrix rich in poorly decomposed crop residues. Incorporation of corn residues in the range from 0.5 to 4% caused different effects on mineralization and sorption of [14C]glyphosate in sandy and sandy loam soils. More specifically, low levels of incorporated corn residues did not affect or slightly stimulated herbicide mineralization in the sandy and sandy loam soils, respectively. In the sandy soil, incorporation of the highest level of corn residues (4%) caused a decrease in [14C]glyphosate mineralization. [14C]Glyphosate sorption on both soil types was reduced in samples receiving high amounts of incorporated corn residues.

Adsorption↗
PubMed1994

Map-based cloning in crop plants. Tomato as a model system: I. Genetic and physical mapping of jointless.

A map-based cloning scheme is being used to isolate the jointless (j) gene of tomato. The jointless locus is defined by a single recessive mutation that completely suppresses the formation of the fruit and flower pedicel and peduncle abscission zone jointless was mapped in an F2 population of an interspecific cross between Lycopersicon esculentum and Lycopersicon pennellii to a 7.1 cM interval between two restriction fragment length polymorphism (RFLP) markers TG523 and TG194. Isogenic DNA pools were then constructed from a subset of the mapping population and screened with 800 random decamers for random amplification of polymorphic DNA (RAPD) polymorphisms. Five new RAPD markers were isolated and mapped to chromosome 11, two of which were mapped within the targeted interval. One marker, RPD158, was mapped 1.5 cM to the opposite side of jointless relative to TG523 and thus narrowed the interval between the closest flanking markers to 3.0 cM. Physical mapping by pulse-field gel electrophoresis using TG523 and RPD158 as probes demonstrated that both markers hybridize to a common 600 kb SmaI restriction fragment. This provided an estimate of 200 kb/cM for the relationship between physical and genetic distances in the region of chromosome 11 containing the j locus. The combined results provide evidence for the feasibility of the next step toward isolation of the jointless gene by map-based cloning--a chromosome walk or jump to jointless.

Base Sequence↗
PubMed2004

Integrated waste management for rural development in Egypt.

Rural areas generate a large amount of plant and animal residues that can be recycled and utilized instead of relocation and/or burning. This will lead to increasing the benefits from agricultural sector in rural communities and ensuring a better environment. To increase the economic output and environmental benefits of recycling agricultural residues, integrated system should be considered, e.g., energy--compost-recycled water system; composting--co-composting system; food-feed compost system, ensilage of crop residues. The present work was a pilot study for optimizing integrated systems for bioconversion agricultural residues completed by establishing a Training Center for Recycling Agricultural Residues (TCRAR) thereby ensuring the dissemination of the technical, environmental, and socioeconomic aspects to farmers, live stock producers, extensions service staff, and private sector. Three integrated subsystems for bioconversion of agricultural residues were developed. They were based on (i) energy--manure-recycled water system, (ii) composting and co-composting system, and (iii) food-feed/compost system.

Agriculture↗
PubMed2026

CasY7: An optimized Cas12i system for enhanced genome editing in monocot crops.

The CRISPR-Cas12 family nucleases, particularly the Cas12i subtypes, are considered promising alternatives to Cas9 for genome editing in plants. We previously developed a new Cas12i variant, CasY7, which has been successfully applied in clinical trials; its performance in plants remains to be investigated. Initial testing in stable transgenic maize and rice showed that the codon-optimized CasY7 (pCasY7e1) achieved average editing efficiencies of 58.7% and 62.3% across five target sites, respectively, outperforming the typical Cpf1 (pCpf1) control that targets the same sites. To further enhance activity, we fused T5 exonuclease to CasY7 (pCasY7e2), which shifted mutation profiles toward larger deletions, and subsequently integrated an MS2 aptamer into the crRNA scaffold (pCasY7e3). The optimized pCasY7e3 system increased editing efficiencies to 87.7% in maize and 82.9% in rice-approximately 2.7-fold higher than pCpf1. We further demonstrated multiplexed editing in maize, generating biallelic dwarf mutants, and validated functionality in hexaploid wheat with editing efficiencies up to 58.8%. Overall, our comprehensive validation across 942 transgenic plants confirmed robust editing in maize, rice, and wheat, establishing CasY7 as a high-efficiency addition to the CRISPR toolkit.

Zea mays↗
PubMed1993

Effects of grazing allowance and system on the use of corn-crop residues by gestating beef cows.

Duplicate fields of corn-crop residues were grazed by 3- to 11-yr-old Charolais x Angus and Charolais x Angus x Simmental cows (average BW = 630 kg) in midgestation at allowances of .41, .82, and 1.64 ha/cow in a continuous-stocking system for 56 d in 1988 (yr 1) and 1989 (yr 2) and for 51 d in 1990 (yr 3), or at .41 ha/cow in a strip-stocking system for 56 and 51 d in yr 2 and 3, respectively. Body weight gains by cows grazing continuously stocked fields at .41, .82, and 1.64 ha/cow were -.06, -.01, and .41 kg/d (P = .02), respectively. Body weight changes by cows grazing continuously stocked and strip-stocked fields at .41 ha/cow were .15 and .30 kg/d in yr 2 and -.33 and -.53 kg/d in yr 3 (system x year, P = .08), respectively. Percentages of in vitro OM disappearance (IVOMD) of crop residues selected by ruminally fistulated steers (P = .22) and cow crop residue DMI (% of BW; P = .03) were 52.5, 1.64; 60.1, 2.87; and 61.7, 2.97 in fields continuously stocked at .41, .82, and 1.64 ha/cow after 21 to 35 d of grazing in yr 2 and 3, respectively. Selected crop residue IVOMD (P = .04) and crop residue DMI (percentage of BW, P = .07) were 58.0 and 2.46, respectively, in fields strip-stocked at .41 ha/cow. Mean yields of OM (P < .01) and IVOMD (P < .01) were 4,605, 2,136; 5,347, 2,495; and 5,761, 2,688 kg/ha in fields continuously stocked at .41, .82, and 1.64 ha/cow, respectively. Results imply that cows grazing corn-crop residues in continuously stocked fields are less likely to gain BW at grazing allowances < 1.64 ha/cow for 56 d. Differences in BW gains between cows grazing strip-stocked and continuously stocked crop residue fields were weather-dependent.

Animal Feed↗