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This paper attempts to provide insights into the current network configurations of the food-trade system and to study the short-term effects of one of the ongoing and lasting global crises, the Ukraine War, on the link intensity. Towards this end, this analysis (1) reveals the pattern of countries' network positions in two most traded subcategories of the cereal network: wheat and meslin, and maize or corn, and (2) discusses the characteristics of the global cereal networks over the 2021–2022 period. The results highlight several features of the trade networks: (1) the distribution of cereal trade is highly concentrated, with considerable dependency on a small number of exporters and a low import diversification, making the system rigid and prone to shocks; (2) a central role of several key developed countries that leave many developing countries outside the centre of the networks; (3) a high network heterogeneity which confirms the propensity to have hub nodes. Particular indicators show that the highest level of interconnectivity is specific to the cereals' export network, the densest networks are the maize or corn ones, and the greatest heterogeneity appears for the cereals export network. [ABSTRACT FROM AUTHOR]

Climate-induced extreme events with fluctuations in climatic indicators like temperature and precipitation highly influence crop productivity. This study deals with quantitative analysis of climatic variability and crop production (1990–2018) using panel data regression analysis. The focus is on variability of three crops, i.e., paddy, maize, and wheat in the Rangit river basin of Sikkim Himalaya, India. Meterological data were acquired from the Indian Meteorological Department, agricultural data from the state agricultural department and a field survey were also conducted with the farmers, using a structured questionnaire, focused group discussion, and key informant observations. The acquired data was analyzed with the help of correlation and multiple linear regression analysis to analyze the relationship between climatic variability and crop production. The result of the study shows that all three crops are dependent on rainfall; however, paddy was the most sensitive to climatic variability. It was found that the overall grain production had an inverse relation to temperature, but it had a positive correlation with rainfall. It was observed that there was a continuous decline in the overall production of paddy and wheat. During deficiency years, it was found that when − 11.33% rainfall was deficient, paddy yield declined by − 1.52%. Further, a deviation of − 13.48% led to a decline of − 54.78% in wheat. The study advocates that timely policy interventions and strategies shall reduce climatic shocks and improve productivity. This would strengthen the livelihood security of the local communities, overcome the challenges of food security, and ensure long-term sustainability of Rangit River basin. [ABSTRACT FROM AUTHOR]

Drought is a most prevalent environmental stress affecting the productivity of rainfed wheat and maize in the semiarid Loess Plateau of China. Sustainable agricultural practices such as intercropping are important for enhancing crop performance in terms of better physiological and biochemical characteristics under drought conditions. Enzymatic and non-enzymatic antioxidant enzyme activities are associated with improved abiotic tolerance in crop plants, however, its molecular mechanism remains obscure. A 2-year field study was conducted to evaluate the influence of intercropping treatment viz. wheat mono-crop (WMC), maize mono-crop (MMC), intercropping maize (IM) and wheat (IW) crops, and nitrogen (N) application rates viz. control and full-dose of N (basal application at 150 and 235 kg ha−1 for wheat and maize, respectively) on chlorophyll fluorescence, gas exchange traits, lipid peroxidation, antioxidative properties and expression patterns of six tolerance genes in both crops under rainfed conditions. As compared with their respective monocropping treatments, IW and IM increased the Fo/Fm by 18.35 and 14.33%, PS-11 efficiency by 7.90 and 13.44%, photosynthesis by 14.31 and 23.97%, C-capacity by 32.05 and 12.92%, and stomatal conductance by 41.40 and 89.95% under without- and with-N application, respectively. The reductions in instantaneous- and intrinsic-water use efficiency and MDA content in the range of 8.76–26.30% were recorded for IW and IM treatments compared with WMC and MMC, respectively. Compared with the WMC and MMC, IW and IM also triggered better antioxidant activities under both N rates. Moreover, we also noted that intercropping and N addition regulated the transcript levels of six genes encoding non-enzymatic antioxidants cycle enzymes. The better performance of intercropping treatments i.e., IW and IM were also associated with improved osmolytes accumulation under rainfed conditions. As compared with control, N addition significantly improved the chlorophyll fluorescence, gas exchange traits, lipid peroxidation, and antioxidant enzyme activities under all intercropping treatments. Our results increase our understanding of the physiological, biochemical, and molecular mechanisms of intercropping-induced water stress tolerance in wheat and maize crops. [ABSTRACT FROM AUTHOR]

The production of crops secure the human food supply, but climate change is bringing new challenges. Dynamic plant growth and corresponding environmental data are required to uncover phenotypic crop responses to the changing environment. There are many datasets on above-ground organs of crops, but roots and the surrounding soil are rarely the subject of longer term studies. Here, we present what we believe to be the first comprehensive collection of root and soil data, obtained at two minirhizotron facilities located close together that have the same local climate but differ in soil type. Both facilities have 7m-long horizontal tubes at several depths that were used for crosshole ground-penetrating radar and minirhizotron camera systems. Soil sensors provide observations at a high temporal and spatial resolution. The ongoing measurements cover five years of maize and wheat trials, including drought stress treatments and crop mixtures. We make the processed data available for use in investigating the processes within the soil–plant continuum and the root images to develop and compare image analysis methods. [ABSTRACT FROM AUTHOR]

Molecular biology aims to understand cellular responses and regulatory dynamics in complex biological systems. However, these studies remain challenging in non-model species due to poor functional annotation of regulatory proteins. To overcome this limitation, we develop a multi-layer neural network that determines protein functionality directly from the protein sequence. We annotate kinases and phosphatases in Glycine max. We use the functional annotations from our neural network, Bayesian inference principles, and high resolution phosphoproteomics to infer phosphorylation signaling cascades in soybean exposed to cold, and identify Glyma.10G173000 (TOI5) and Glyma.19G007300 (TOT3) as key temperature regulators. Importantly, the signaling cascade inference does not rely upon known kinase motifs or interaction data, enabling de novo identification of kinase-substrate interactions. Conclusively, our neural network shows generalization and scalability, as such we extend our predictions to Oryza sativa, Zea mays, Sorghum bicolor, and Triticum aestivum. Taken together, we develop a signaling inference approach for non-model species leveraging our predicted kinases and phosphatases. An artificial-intelligence network is used to generate highly accurate predictions of proteins' functionality. The predictions on the identity of regulatory proteins is used to create regulatory networks and make discoveries about complex biological systems. [ABSTRACT FROM AUTHOR]

Crop-specific, high-resolution phosphorus rate information is essential for sustainable agricultural fertilizer management in China. However, substantial uncertainties exist in the current phosphorus fertilizer dataset because of only coarse national statistics used in dataset development and no crop-specific information provided. This study harmonized provincial and county-level phosphorus and component fertilizer statistics and crop distribution data to generate 1 km gridded maps of phosphorus rate for rice, wheat and maize in the years of 2004–2016 (CN-P). CN-P provides a comparable estimate on phosphorus rate for each crop over 2004–2016, and demonstrates an improved spatial heterogeneity. Existing dataset developed using national statistics tends to smooth out the variability within country and significantly underestimates actual phosphorus rate. CN-P shows that, during 2004–2016, wheat received the most phosphorus rate (8.7 g P2O5 m−2), while maize showed the rapidest increasing trend (2.36% yr−1). The CN-P dataset has the potential to be widely applied in modeling studies on sustainable agricultural fertilizer management strategies and phosphorus pollution. [ABSTRACT FROM AUTHOR]

Because of the effect of nitrogen (N) fertilization on soil-derived N uptake, N difference (FNRDiff) and 15 N tracer (FNR15N) methods may give significantly different estimates of the fertilizer N recovery (FNR) in crops. To better understand quantitative differences in FNR (∆FNR) between the two methods, we evaluated the effect of fertilizer N input rates on ∆FNR and soil-derived N uptake by considering data from field 15 N tracer experiments of cereal crops across China, including N-unfertilized treatments. The FNRDiff was significantly higher than the corresponding FNR15N in wheat (38% vs. 36%), maize (38% vs. 31%), and rice (40% vs. 31%) under fertilizer applications of 40–500 kg N ha−1. Except in wheat at 250–500 kg N ha−1, FNRDiff was higher than FNR15N at various N input rates in the three crops, and ∆FNR decreased with increasing rates of applied N. The ∆FNR apparently occurred because added-N interaction (ANI) increased soil-derived N uptake (by 5% for wheat, 11% for maize, and 24% for rice). For wheat in particular, ANI values decreased significantly as N input rates increased, with a switch from positive to negative above 252 kg N ha−1. This result suggests that the decrease in soil-derived N uptake is mainly caused by the negative rhizosphere N priming and the law of diminishing returns (current-season non-fertilizer N input or previous-season residual fertilizer N) under high N input, but not by the N pool substitution. Finally, we propose a new method for accurately distinguishing direct and indirect pathway contributions to ∆FNR. This study helps to improve understanding of the underlying mechanisms of discrepancies between the N difference method and the 15 N tracer method for estimating the fertilizer N recovery in crops. [ABSTRACT FROM AUTHOR]

Field experiments were conducted to evaluate eight different integrated crop management (ICM) modules for 5 years in a maize-wheat rotation (MWR); wherein, ICM1&2-ˈbusiness-as-usualˈ (conventional flatbed maize and wheat, ICM3&4-conventional raised bed (CTRB) maize and wheat without residues, ICM5&6-conservation agriculture (CA)-based zero-till (ZT) flatbed maize and wheat with the residues, and ICM7&8- CA-based ZT raised bed maize and wheat with the residues. Results indicated that the ICM7&8 produced significantly (p < 0.05) the highest maize grain yield (5 years av.) which was 7.8–21.3% greater than the ICM1-6. However, across years, the ICM5-8 gave a statistically similar wheat grain yield and was 8.4–11.5% greater than the ICM1-4. Similarly, the CA-based residue retained ICM5-8 modules had given 9.5–14.3% (5 years av.) greater system yields in terms of maize grain equivalents (MGEY) over the residue removed CT-based ICM1&4. System water productivity (SWP) was the highest with ICM5-8, being 10.3–17.8% higher than the ICM1-4. Nevertheless, the highest water use (TWU) was recorded in the CT flatbed (ICM1&2), ~ 7% more than the raised bed and ZT planted crops with or without the residues (ICM4-8). Furthermore, the ICM1-4 had produced 9.54% greater variable production costs compared to the ICM5-8, whereas, the ICM5-8 gave 24.3–27.4% additional returns than the ICM1-4. Also, different ICM modules caused significant (p < 0.05) impacts on the soil properties, such as organic carbon (SOC), microbial biomass carbon (SMBC), dehydrogenase (SDH), alkaline phosphatase (SAP), and urease (URE) activities. In 0.0–0.15 m soil profile, residue retained CA-based (ICM5-8) modules registered a 7.1–14.3% greater SOC and 10.2–17.3% SMBC than the ICM1-4. The sustainable yield index (SYI) of MWR was 13.4–18.6% greater under the ICM7&8 compared to the ICM1-4. Hence, this study concludes that the adoption of the CA-based residue retained ICMs in the MWR could sustain the crop yields, enhance farm profits, save water and improve soil properties of the north-western plans of India. [ABSTRACT FROM AUTHOR]

Multi-purpose crops as maize, rice, soybean, and wheat are key in the debate concerning food, land, water and energy security and sustainability. While strong evidence exists on the effects of climate variability on the production of these crops, so far multifaceted attributes of droughts—magnitude, frequency, duration, and timing—have been tackled mainly separately, for a limited part of the cropping season, or over small regions. Here, a more comprehensive assessment is provided on how droughts with their complex patterns—given by their compound attributes—are consistently related to negative impacts on crop yield on a global scale. Magnitude and frequency of both climate and yield variability are jointly analysed from 1981 to 2016 considering multiscale droughts, i.e., dry conditions occurring with different durations and timings along the whole farming season, through two analogous and standardized indicators enabling comparison among crops, countries, and years. Mainly winter wheat and then spring wheat, soybean and the main maize's season reveal high susceptibility of yield under more complex drought patterns than previously assessed. The second maize's season and rice present less marked and more uncertain results, respectively. Overall, southern and eastern Europe, the Americas and sub-Saharan Africa presents multi-crop susceptibility, with eastern Europe, Middle East and Central Asia appearing critical regions for the most vulnerable crop, which is wheat. Finally, yield losses for wheat and soybean clearly worsen when moving from moderate to extreme multiscale droughts. [ABSTRACT FROM AUTHOR]

The intercropping of legumes with cereals help to achieve sustainable intensification by their mutual complementarity at efficiently using radiation, nutrients, etc. Several studies indicated such beneficial effects on the other component crop however, little research has been conducted to quantify their effects on the subsequent crop in a cropping system. In this study, the effect of the legume intercropping on the entire cropping system, particularly the maize + legume-wheat system was studied. Four legumes intercropped to maize followed by wheat crop were studied for intensification measures such as wheat equivalent yield (WEY), land equivalent ratio (LER), sustainable value index (SVI), and economic returns. N saving effect of legumes on the subsequent wheat crop was quantified with two N levels. Maize + cowpea-wheat combination was the most productive and economic intercrop combination (LER = 1.71, SVI = 0.96) with an increase in net economic return (43.63%) with a B:C ratio of 1.94. An additional 25% N (37.5 kg ha−1) was saved in the wheat crop when the legume intercropping was undertaken with maize. The results suggest that intercropping is the key to diversification and reduces the risk of crop failures by enhancing land-use efficiency, soil fertility, and economic returns under weather vagaries. This will be beneficial to small and marginal farmers of many countries. [ABSTRACT FROM AUTHOR]

Irrigation is the largest sector of human water use and an important option for increasing crop production and reducing drought impacts. However, the potential for irrigation to contribute to global crop yields remains uncertain. Here, we quantify this contribution for wheat and maize at global scale by developing a Bayesian framework integrating empirical estimates and gridded global crop models on new maps of the relative difference between attainable rainfed and irrigated yield (ΔY). At global scale, ΔY is 34 ± 9% for wheat and 22 ± 13% for maize, with large spatial differences driven more by patterns of precipitation than that of evaporative demand. Comparing irrigation demands with renewable water supply, we find 30–47% of contemporary rainfed agriculture of wheat and maize cannot achieve yield gap closure utilizing current river discharge, unless more water diversion projects are set in place, putting into question the potential of irrigation to mitigate climate change impacts. There are big uncertainties in the contribution of irrigation to crop yields. Here, the authors use Bayesian model averaging to combine statistical and process-based models and quantify the contribution of irrigation for wheat and maize yields, finding that irrigation alone cannot close yield gaps for a large fraction of global rainfed agriculture. [ABSTRACT FROM AUTHOR]

Estimates of fluctuation in climatic condition have a large impact on the production of selected crops such as rice (Oryza sativa), wheat (Triticum aestivum), maize (Zea mays), pulse, and sugarcane (Saccharum officinarum) which are the most prominent crops over Indo-Gangetic Plains (IGP). The influence of El Nino/La Nina on monsoon rainfall directly or indirectly affects the Indian crop over the Agro-Climatic Zones of Indo-Gangetic Plain (IGP). The detailed analysis has been carried out to show the impact of El Nino/La Nina and its association with crop production over sub-regions of IGP (lower, middle, upper, and trans IGP) during 1966–2009. During El Nino years, the production and yield of Rice and sugarcane have been affected in the middle and upper regions of IGP. The production of wheat decreased during La Nina events in the middle regions of IGP. The rice production has been severely affected by El Nino events over middle and upper IGP regions whereas wheat production increased. The decrease in maize production is observed in the upper and trans regions of IGP during El Nino. Pulse production decreased mainly in the middle, upper, and trans IGP during both events. The sugarcane production was highly affected during La Nina events overall sub-regions of IGP. The correlations among crop production, monsoon rainfall, and sea surface temperature (SST) anomaly of Nino 3.4 region during monsoon season are very insignificant during El Nino events. On other hand, La Nina event shows significant correlation over IGP. It has been noticed that on many occasions, deficit rainfall over IGP during summer monsoon season was responsible for decrease in crop production. Hence, alteration in Indian summer monsoon rainfall (ISMR) and sea surface temperature modulation of Nino 3.4 might have caused increase/decrease in the production of the crop. [ABSTRACT FROM AUTHOR]

Northwest China is characterized by a high water deficit and regular water resource shortages. These issues have become limiting factors for agricultural and socioeconomic development. Based on a trend-preserving method of bias correction, we calibrated the maximum temperature and minimum temperature in four CMIP5 GCMs (CNRM, IPSL, BCC, and CMCC). Then, we investigated variations in the regional crop water requirement (CWR) in the total growth stages for five main crops (cotton, spring corn, summer corn, spring wheat, and winter wheat) in the past (1961–2005) and future (2006–2100). The results suggest that the MK test yielded insignificant decreasing CWR trends in the total growth stages of cotton (0.10 mm/year), spring corn (0.13 mm/year), and spring wheat (0.05 mm/year) and insignificant increasing trends for summer corn (0.02 mm/year) and winter wheat (0.32 mm/year) historically. In the future period, for the same type of crops (cotton), the CWRs in all scenarios (RCP 2.6, 4.5, and 8.5 scenarios) for all GCMs exhibited significant positive trends; for the same GCM (BCC), the CWRs projected for five major crops in the RCP 4.5 and 8.5 scenarios all exhibited extremely significant MK trends (99%); in addition, the CWRs' rate increases of the five crops projected in RCP8.5 scenario by BCC exhibited the following order: winter wheat (1.25 mm/year), summer corn (1.15 mm/year), spring corn (1.02 mm/year), cotton (0.97 mm/year), and spring wheat (0.87 mm/year). The maximum CWRs of winter wheat were mainly observed in southeastern Northwest China, while those of the other four crops occurred in southern Xinjiang. [ABSTRACT FROM AUTHOR]

The intensification of agriculture has increased production at the cost of environment and biodiversity worldwide. To increase crop yield in dry cereal systems, vast farmland areas of high conservation value are being converted into irrigation, especially in Mediterranean countries. We analyze the effect of irrigation-driven changes on the farm biota by comparing species diversity, community composition, and species traits of arable plants within crop fields from two contrasting farming systems (dry and irrigated) in Spain. We sampled plant species within 80 fields of dry wheat, irrigated wheat, and maize (only cultivated under irrigation). Wheat crops held higher landscape and per field species richness, and beta diversity than maize. Within the same type of crop, irrigated wheat hosted lower plant diversity than dry wheat at both field and landscape scales. Floristic composition differed between crop types, with higher frequencies of perennials, cosmopolitan, exotic, wind-pollinated and C species in maize. Our results suggest that irrigation projects, that transform large areas of dry cereal agro-ecosystems into irrigated crop systems dominated by maize, erode plant diversity. An adequate planning on the type and proportion of crops used in the irrigated agro-ecosystems is needed in order to balance agriculture production and biodiversity conservation. [ABSTRACT FROM AUTHOR]

The amylose/amylopectin ratio in cereal substrates is one of the parameters affecting starch hydrolysis and fermentation process. Waxy (less than 1 mass % of amylose) starch seems to be suitable for improving the fuel ethanol production. The main aim of this paper was to characterize the fermentation performance of corn and wheat waxy and non-waxy cultivars in terms of simultaneous saccharification and fermentation (SSF) as well as of the separated hydrolysis and fermentation (SHF) type. Two corn (waxy and non-waxy) and two wheat (waxy and non-waxy) cultivars were used for the comparison applying separate enzymatic hydrolysis and fermentation. In the SHF process, the glucose content was higher after saccharification in the waxy corn and wheat compared to that in non-waxy corn and wheat. In the SSF of waxy varieties, the glucose content after the pre-saccharification was also higher than in the non-waxy ones. Although the starch content did not vary significantly, differences in the glucose content after saccharification were observed. The ethanol yield obtained after the distillation of mash varied from 229.2–262.3 L per ton for the SHF fermentation, while it was in the range of 311.5–347.9 L per ton for the SSF process. [ABSTRACT FROM AUTHOR]

The Crop Growth Monitoring System (CGMS) has been applied for spatial biophysical resource analysis of Borkhar & Meymeh district in Esfahan province, Iran. The potentially suitable area for agriculture in the district has been divided into 128 homogeneous land units in terms of soil (physical characteristics), weather and administrative unit. Crop parameters required in the WOFOST simulation model for winter wheat and silage maize, have been calibrated based on experimental data from the study area. The study area has been classified into three cropping calendar zones based on average annual temperature, altitude and latitude. For each zone, a sowing date has been defined for each crop as the starting point of crop growth simulation. Growth of these crops has been simulated for the potential situation in each land unit for 20 years of historical daily weather data. Daily potential evapotranspiration and irrigation requirements of each crop per land unit have been calculated in a postsimulation, on the basis of model outputs. Outputs of the model are crop yield (marketable yield and total biomass) and irrigation requirements per decade. Spatial and temporal variation in irrigation requirements has been analyzed. The temporal variation in crop water requirements is larger than the spati3al variation. [ABSTRACT FROM AUTHOR]

This article describes the use of microwave-assisted extraction (MAE) as a pretreatment technique for the determination of aflatoxins B, G, B, and G in grains and grain products. The optimal operation parameters, including extraction solvent, temperature, and time, were identified to be acetonitrile as the extraction solvent at 80 °C with 15 min of MAE. The extracts were cleaned up using solid-phase extraction followed by derivatization with trifluoroacetic acid and were determined by liquid chromatography-fluorescence detection. A Sep-Pak cartridge was chosen over Oasis HLB and Bond Elut cartridges. By the use of aflatoxin M as an internal standard, relative recoveries of the aflatoxins ranged from 90.7 to 105.7 % for corn and from 88.1 to 103.4 % for wheat, with relative standard deviations between 2.5 and 8.7 %. A total of 36 samples from local markets were analyzed, and aflatoxin B was found to be the predominant toxin, with concentrations ranging from 0.42 to 3.41 μg/kg. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Background and aims: Boron (B) deficiency depresses grain set and grain yield of wheat and maize while having little effect on their vegetative growth. This paper describes effects of B deficiency in rice and how these vary with planting season and variety. Methods: Three rice varieties (KDML105, CNT1, SPR1) were grown in sand culture without (B0) and with 10 μM (B10) B added to the nutrient solution, in the cool season of 2007/08 and 2008/09 and the hot season of 2011 in Chiang Mai, Thailand (18°47′N, 98°59′E). Boron responses were measured in growth and yield parameters, pollen viability and B concentration of the flag leaf and anthers at anthesis. Results: Grain weight was strongly depressed by B deficiency ranging from 28 % in SPR1 to 79 % in CNT1, and the yield was much lower in the cool season than in the hot season plantings. The variation in grain weight was closely associated with grain set and number of spikelets but not with shoot dry weight or tillering. Grain set was closely related to pollen viability, and both were increased with increasing anther B concentration at >20 mg B kg. In addition to its adverse effect on grain set, B deficiency also depressed grain filling and weight of individual grains in rice. Conclusions: Boron deficiency depressed rice grain yield through adverse effects on reproductive growth, panicle and spikelet formation and grain filling, in addition to grain set as in wheat and maize. [ABSTRACT FROM AUTHOR]

A limited battle involving the nuclear arsenals of India and Pakistan would have significant climatic impacts upon agricultural crop production in the United States; corn, soybeans, and winter wheat yields would be significantly reduced in the Corn Belt region of the US. The most severe impacts would occur during the second year after the modeled nuclear battle. [ABSTRACT FROM AUTHOR]

Aims: A field experiment was conducted where maintenance of indigenous arbuscular mycorrhizal (AM) fungal populations was attempted using AM host cover crops arranged temporally or spatially during growth of nonmycorrhizal crops. Methods: To arrange AM hosts temporally, sunflower or oat was grown as a cover crop after non-host cropping (cabbage) or fallowing. In order to arrange AM hosts spatially, red clover, white clover or vetch was intercropped during growth of non-host cabbage. Results: The AM colonization and growth of maize with previously introduced sunflower or oat were much greater than those without introduction of cover crops or those with introduction of non-host cover crops. The AM colonization and yield of winter wheat grown after cabbage with AM host intercropping were greater than those after cabbage only cropping, suggesting that arrangement of AM hosts between cabbage rows is effective for maintaining the AM fungal population in soil during non-host cropping. Conclusions: Mycorrhizal hosts cropped after or during non-host cropping is an effective means to increase indigenous AM fungal populations. The results show that AM colonization, P uptake and productivity of crops after cultivation of nonmycorrhizal crops can be improved by arranging AM hosts temporally or spatially as cover crops. [ABSTRACT FROM AUTHOR]

prototype imaging surface plasmon resonance-based multiplex microimmunoassay for mycotoxins is described. A microarray of mycotoxin-protein conjugates was fabricated using a continuous flow microspotter device. A competitive inhibition immunoassay format was developed for the simultaneous detection of deoxynivalenol (DON) and zearalenone (ZEN), using a single sensor chip. Initial in-house validation showed limits of detection of 21 and 17 ng/mL for DON and 16 and 10 ng/mL for ZEN in extracts, which corresponds to 84 and 68 μg/kg for DON and 64 and 40 μg/kg for ZEN in maize and wheat samples, respectively. Finally, the results were critically compared with data obtained from liquid chromatography-mass spectrometry confirmatory analysis method and found to be in good agreement. The described multiplex immunoassay for the rapid screening of several mycotoxins meets European Union regulatory limits and represents a robust platform for mycotoxin analysis in food and feed samples. [ABSTRACT FROM AUTHOR]

rapid and simple miniaturized liquid-liquid extraction method has been developed for the determination of topramezone in soil, corn, wheat, and water samples using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-electrospray ionization (ESI)/MS/MS). The established method for the extraction and purification procedure was based on liquid-liquid partitioning into an aqueous solution at a low pH (pH ≈ 2.5), followed by back-partitioning into water at pH > 9. Two precursor, product ion transitions for topramezone were measured and evaluated to provide the maximum degree of confidence in the results. Under negative ESI conditions, quantitation was achieved by monitoring the fragment at m/ z = 334 and the qualitative fragment at m/ z = 318, whereas also collecting the corresponding parent ion at m/ z = 362. Chromatographic separation was achieved using gradient elution with a mobile phase consisting of methanol and a 0.01% aqueous ammonium hydroxide solution. Recovery studies for soil, corn, wheat, and water were conducted at four different topramezone concentrations (5 or 10, 50, 100, and 1,000 μg kg); the overall average recoveries ranged from 79.9% to 98.4% with intra-day relative standard deviations (RSD) of 3.1~8.7% and inter-day RSD of 4.3~7.5%. Quantitative results were determined from calibration curves of topramezone standards containing 1-500 μg L with an R ≥ 0.9994. Method sensitivities expressed as limits of quantitation were typically 6, 8, 9, and 1 μg kg in soil, corn, wheat, and water, respectively. The results of the method validation confirmed that this proposed method was convenient and reliable for the determination of topramezone residues in soil, corn, wheat, and water. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate plant-available N pools and the role of N management index (NMI) in the surface (0-20 cm) of a fluvo-aquic soil after 18 years of fertilization treatments under a wheat-maize cropping system in the North China Plain. The experiment included seven treatments: (1) NPK, balanced application of chemical fertilizer NPK; (2) OM, application of organic manure; (3) 1/2OMN, application of half organic manure plus chemical fertilizer NPK; (4) NP, application of chemical fertilizer NP; (5) PK, application of chemical fertilizer PK; (6) NK, application of chemical fertilizer NK; and (7) CK, unfertilized control. Total organic N (TON), microbial biomass N (MBN), labile N (LN), inorganic N (ION, including ammonium (NH)-N and nitrate (NO)-N) contents, net ammonification rate (NAR), net nitrification rate (NNR), net N mineralization rate (NNMR), and NMI in the fertilized treatments were higher than in the unfertilized treatment. Application of chemical fertilizer N (NPK, NP, and NK) increased ION in soils, compared with application of organic N or control. Nitrate N prevailed over exchangeable NH-N in all treatments. Nitrogen storage of the OM- and 1/2OMN-treated soils increased by 50.0% and 24.3%, respectively, over the NPK-treated soil, which had 5.4-22.5% more N than NP-, PK-, and NK-treated soils. The MBN, LN, and ION accounted for 1.7-2.4%, 25.7-34.2%, and 1.4-2.9% of TON, respectively, in different fertilization treatments. The surface soils (0-20-cm layer) in all treatments mineralized 43.6-152.9 kg N ha year for crop growth. Microbial biomass N was probably the better predictor of N mineralization, as it was correlated significantly ( P < 0.01) with NNMR. The OM and 1/2OMN treatments were not an optimal option for farmers when the crop yield and labor cost were taken into consideration but an optimal option for increasing soil N supply capacity and N sequestration in soil. The NPK treatment showed the highest crop yields and increased soil N fractions through crop residues and exudates input, and thus, it may be considered as a sustainable system in the North China Plain. [ABSTRACT FROM AUTHOR]

Using an alkaline calcareous soil, experiments were conducted to elucidate the effects of nitrification inhibitor dicyandiamide (DCD) on the fate of N-labelled urea applied to cotton, maize, and wheat under greenhouse conditions. Combined effects of DCD and two levels of wheat straw (applied to cotton) and of fertilizer application method (conventional broadcast vs. point injection in maize and wheat) on the recovery of the fertilizer N were also studied. High soil temperatures prevailed under cotton and maize, whereas the soil temperature was relatively moderate during the wheat growing season. The fertilizer N loss under cotton was lowest (44% of the applied) when urea was applied alone; the loss increased due to DCD (54%) or wheat straw (50-54%) and was highest (63-64%) when DCD and wheat straw were applied together. Under maize also, DCD increased the loss of the fertilizer N applied by the conventional method (51% without DCD vs. 66% with DCD) or by point injection (26% without DCD vs. 42% with DCD). With the conventional method under wheat, DCD had no effect on the fertilizer N loss (34-37% of the applied). The fertilizer N loss under wheat was least (16%) when urea solution was point-injected but increased (24-26%) due to DCD or/and when pH of the urea solution was reduced to 2. Besides, DCD significantly reduced the fertilizer N uptake and increased the fertilizer N immobilization in soil under cotton and maize. However, DCD applied in combination with a higher level of wheat straw significantly increased the cotton dry matter and N yields due to increased N availability from sources other than the fertilizer. The results suggested that the use of DCD may not be beneficial in alkaline calcareous soils and that point injection of urea solution without any amendment is more effective in conserving the fertilizer N as compared to the conventional broadcast method. [ABSTRACT FROM AUTHOR]

Croplands mainly act as net sources of the greenhouse gases carbon dioxide (CO) and nitrous oxide (NO), as well as nitrogen oxide (NO), a precursor of troposheric ozone. We determined the carbon (C) and nitrogen (N) balance of a four-year crop rotation, including maize, wheat, barley and mustard, to provide a base for exploring mitigation options of net emissions. The crop rotation had a positive net ecosystem production (NEP) of 4.4 ± 0.7 Mg C ha y but represented a net source of carbon with a net biome production (NBP) of -1.3 ± 1.1 Mg C ha y. The nitrogen balance of the rotation was correlated with the carbon balance and resulted in net loss (−24 ± 28 kg N ha y). The main nitrogen losses were nitrate leaching (−11.7 ±1.0 kg N ha y) and ammonia volatilization (−9 kg N ha y). Dry and wet depositions were 6.7 ± 3.0 and 5.9 ±0.1 kg N ha y, respectively. Fluxes of nitrous (NO) and nitric (NO) oxides did not contribute significantly to the N budget (NO: -1.8 ± 0.04; NO: -0.7 ± 0.04 kg N ha y) but NO fluxes equaled 16% of the total greenhouse gas balance. The link between the carbon and nitrogen balances are discussed. Longer term experiments would be necessary to capture the trends in the carbon and nitrogen budgets within the variability of agricultural ecosystems. [ABSTRACT FROM AUTHOR]

ificial selection (domestication and breeding) leaves a strong footprint in plant genomes. Second generation high throughput DNA sequencing technologies make it possible to sequence the gene complement of a plant genome within 3 to 5 months, and the costs of doing so are declining very quickly. This makes it practical to identify genomic regions that have undergone very strong selection. Available reference sequences of important crops such as rice, maize, and sorghum will promote the wide use of re-sequencing strategies in these crops. Marker/trait associations, especially haplotype (or haplotype block) association analyses, will help the precise mapping of important genomic regions and location of favored alleles or haplotypes for breeding. This mini-review examines a genomics approach to defining yield traits in wheat. [ABSTRACT FROM AUTHOR]

mospheric nitrogen (N) deposition is a serious problem on the North China Plain (NCP) because it imposes a considerable nutrient burden on the local environment. However, it also makes a substantial contribution to agricultural crop N requirements. The integrated total N input (ITNI) system is a method to quantify total atmospheric N deposition by using N-labeled monitor plants grown in pots. The effect of pot surface area and variety of indicator plant on the amount of airborne N input quantified by the ITNI system was investigated in this study. Total N deposition to the soil-maize/soil-wheat plant system at key growth stages was also quantified to improve N-fertilizer recommendations. When indicator plants having a high space requirement were used a correction factor was needed and this could be obtained only by simulating commercial field conditions, especially plant density, because the factor depends largely on pot area or the difference in plant density between pot conditions and field conditions. The total airborne N input measured by the ITNI system was not influenced by the variety of monitoring plant. N deposition was 20-25 kg N ha during growth from three expanded leaf to ten expanded leaf and also from ten expanded leaf to maturity of maize. N deposition was 29.1 kg N ha between planting and the jointing stage and 10.1 kg N ha from jointing to maturity of wheat. This high measured N deposition indicates that N deposition should be taken into account when calculating the N fertilizer requirements of maize and wheat in this region. [ABSTRACT FROM AUTHOR]

Interspecific interactions and soil nitrogen supply levels affect intercropping productivity. We hypothesized that interspecific competition can be alleviated by increasing N application rate and yield advantage can be obtained in competitive systems. A field experiment was conducted in Wuwei, Gansu province in 2007 and 2008 to study intercropping of faba bean/maize, wheat/maize, barley/maize and the corresponding monocultures of faba bean ( Vicia faba L.), wheat ( Triticum aestivum L.), barley ( Hordeum vulgare L.) and maize ( Zea mays L.) with N application rates of 0, 75, 150, 225 and 300 kg N ha. Total land equivalent ratios (TLER) were 1.22 for faba bean/maize, 1.16 for wheat/maize, and 1.13 for barley/maize intercropping over the 2-year study period. Maize was overyielding when intercropped with faba bean, but underyielding when intercropped with wheat or barley according to partial land equivalent ratios (PLER) based on grain yields of individual crops in intercropping and sole cropping. There was an interspecific facilitation between intercropped faba bean and maize, and interspecific competition between maize and either wheat or barley. The underyielding of maize was higher when intercropped with barley than with wheat. Fertilizer N alleviated competitive interactions in intercrops with adequate fertilizer N at 225 kg ha. Yield advantage of intercropping can be acquired with adequate nitrogen supply, even in an intensive competitive system such as barley/maize intercropping. This is important when using intercropping to develop intensive farming systems with high inputs and high outputs. [ABSTRACT FROM AUTHOR]

The International Maize and Wheat Improvement Center (CIMMYT) aims to genetically enhance both crops and generate public sector-provided products for the resource poor, e.g., drought tolerant wheat and insect resistant maize, and through international–national partnerships facilitate the acquisition of improved germplasm for non-mandate crops in the cropping systems where maize and wheat thrives; e.g., GM-papaya through a national food security undertaking in Bangladesh. The Center also engages in public awareness campaigns in projects such as Insect Resistance Maize for Africa (IRMA), which includes food, feed and environmental safety, monitoring of resistance and establishment of refugia, non-target effects and gene flow. Monitoring of genetic resources is a wide concern among the centers of the Consultative Group on International Agricultural Research (CGIAR), with an emphasis on the quality of gene banks. Decisions, policies and procedures about monitoring should be science-based, and this requires education, an area where CIMMYT and other CGIAR centers can play an important role. There will be a need to continue to evaluate the need for, and type of monitoring, as new (and unique) products are developed and released in the emergent economies of the world. [ABSTRACT FROM AUTHOR]

The sorption-desorption of water vapor by grains of potato, corn, and wheat native starch is studied. It is shown that water vapor is mainly sorbed inside starch grains. A model is proposed for water vapor sorption by starch grains. Constructed sorption isotherm is shown to adequately describe the process in a wide humidity range. The kinetics of the sorption and desorption of water vapor by starch grains is shown to have an abnormal character. [ABSTRACT FROM AUTHOR]

Permanent raised bed planting with crop residue retention is a form of conservation agriculture that has been proposed as an alternative to conventional tillage for wheat production systems in the Central Highlands of Mexico. A field experiment comparing permanent and tilled raised beds with different residue management under rainfed conditions was started at El Batán (State of Mexico, Mexico) in 1999. The percentage of small and large macroaggregates and mean weight diameter (MWD) was significantly larger in permanent raised beds compared to conventionally tilled raised beds both with full crop residue retention (average for maize and wheat), while the percentages free microaggregates was lower. The percentages of small and large macroaggregates and mean weight diameter (MWD) was significantly larger in permanent raised beds with residue retention compared to permanent raised beds with removal of the residue (average for maize and wheat), while the percentages free microaggregates and silt and clay fraction was lower. Cultivation of maize significantly reduced the large macroaggregates, while wheat reduced the silt and clay fraction (average over all systems). Cultivation of maize reduced the C and N content of the free microaggregates compared to soil cultivated with wheat, while removal of plant residue reduced the C and N content of the silt and clay fraction compared to soil where residue was retained. The C and N content of the coarse particulate organic matter (cPOM) and microaggregates within the macroaggregates was significantly larger in permanent raised beds compared to conventionally tilled raised beds both with full residue retention, while C and N content of the cPOM was significantly lower when residue was removed or partially removed compared to the soil where the residue was retained. The δ 13C ‰ signatures of the macroaggregates, microaggregates, the silt and clay fraction, cPOM and microaggregates within the macroaggregates were not affected by tillage or residue management when wheat was the last crop, but removal of residue reduced the δ 13C ‰ signatures of the macro-, microaggregates and microaggregates within the macroaggregates significantly compared to soil where the residue was retained. Retaining only 30–50% of the organic residue still improved the soil structure considerably compared to plots where it was removed completely. Permanent raised beds without residue retention, however, is a practice leading to soil degradation. [ABSTRACT FROM AUTHOR]

It is essential to have an indication of the sustainability of an agricultural system in addition to the potential, immediate benefits well before the catastrophic consequences of non-sustainability become apparent. Long-term experiments are best suited to test sustainability of a given system. This paper has a dual objective: (1) evaluate the Greenseeker handheld NDVI sensor as a tool for measuring within plot spatial variability, (2) address the question whether different management practices affect spatial within-plot crop growth variability and what this spatial variability tells us about the cropping system performance. Therefore, spatial and time variability of crop performance were measured during the 2004 and 2005 crop cycle for all plots of the different management treatments of a long-term (started 1991) tillage and residue management trial. The NDVI readings measured with the handheld sensor correlated well with the visual scoring in the field. The hand-held sensor is time-efficient and gave reproducible results. The potential for using this tool to detect spatial crop variability, both within and between plots/treatments, is promising. The coefficient of variation (CV) for the NDVI measurement sequence in each plot was determined. The CV’s throughout the crop season reflected the canopy expansion and senescence curve of maize and wheat. The CV was high at the beginning of the crop season, however, once the canopy began to close, leaves from larger plants covered the leaves and whorl of smaller plants, extending further into the linear row. Measurements to investigate spatial variability related to crop performance should thus be done after this initial stage at the end of the vegetative period when the vegetative biomass of the crops is fully established. Zero tillage systems without surface residue retention produced high CVs of the NDVI sequence and high spatial crop variability throughout the season, even after the vegetative period. As the only factors differing between the different plots are the tillage/residue/rotation practices and as similar patterns were found for all plots representing repetitions of the same management practice (zero tillage without residue retention), increased variability is an indicator of agronomic mismanagement or, conversely, of sound agriculturally production practices. [ABSTRACT FROM AUTHOR]

Significant progress has been made in the characterization of loci controlling traits of importance using molecular markers. A number of markers are currently available in wheat for genes of interest to the breeders. Markers can be used to better characterize parental material, thereby improving the efficiency and effectiveness of parental selection for crossing and to track genes in segregating progenies through the selection process. Although a number of breeding programs are using molecular markers at modest levels, the costs associated with marker assisted selection (MAS) are frequently cited as the main constraint to their wide-spread use by plant breeders. However, this is likely to change when user-friendly, high-throughput, automated marker technologies based on single nucleotide polymorphisms become available. These evolving technologies will increase the number of available markers, and will improve the efficiency, throughput, and cost effectiveness of MAS, thereby making it more attractive and affordable to many breeding programs. This article examines the extent to which molecular markers have been used at the International Maize and Wheat Improvement Center (CIMMYT) in applied wheat breeding and reviews the limited publicly available information on MAS from other wheat breeding programs. As markers are currently available for relatively few traits, we believe that MAS must be integrated with ongoing conventional breeding to maximize its impact. When used in tandem with phenotypic selection, MAS will improve response to selection for certain traits, thereby increasing rates of genetic progress. [ABSTRACT FROM AUTHOR]

The article provides information on the global symposium "Challenges to International Wheat Improvement" at Obregon Mexico in March 2006. It was organized by the International Maize and Wheat Improvement Center (CIMMYT) with the support of the Australian Center for International Agricultural Research (ACIAR). Doctor Normal Borlaug opened the symposium with an address entitled "Sixty-two years of fighting hunger: personal recollections."

This study compared the meiotic recombination frequency between wheat doubled haploid (DH) populations obtained through two different methods, maize pollination (MP♀) and anther culture (AC♂). The comparison was based on a genetic linkage analysis, performed with DNA markers. Thirty-five polymorphic markers (15 SSR, 15 AFLP, 5 RAPD) were screened in MP♀ and AC♂ doubled haploids populations, derived from the same hybrid genotype (F1 of ‘Eta’ × ‘Darkhan 15’). Nine linkage groups, comprising 35 loci (the MP♀ lines) and 31 loci (the AC♂ lines), were constructed. The linkage groups in both DH populations showed identical orders of markers, except for one group mapping to chromosome 6B. The MP♀ and AC♂ linkage maps differed significantly in recombination frequencies for corresponding intervals. In total, the AC♂ linkage map (495.5 cM) was 40.5% longer than the MP♀ map (352.8 cM), indicating a significantly higher meiotic recombination rate in pollen mother cells. The enhancement in recombination was visible in five of nine linkage groups, and in 7 intervals between individual loci out of 19 compared. Moreover, for 6 other intervals a lack of linkage was observed in the AC♂ population, as compared to the MP♀ map. [ABSTRACT FROM AUTHOR]

Comparative genetic analysis has shown that different plant species often share orthologous genes for very similar functions, especially for cereal crops. In this study, we focused on analyzing the utility of EST-SSR markers among monocots in silico and by experiment. Based on 423,611 wheat ESTs, 101,299 were found to express commonly in rice, maize and barley ESTs, which accounted for 23.94% of wheat EST data. 1707 SSR-containing ESTs (SSR-ESTs) were mined from the 101,299 homologous ESTs, which accounted for 8.8% of all the 19,434 wheat EST-SSRs. It showed that the number of homologous SSR-ESTs much less than the homologous ESTs among grasses. The number of conserved ESTs and SSR-ESTs were inversely proportional to the evolutionary distance among species. Although these SSR-ESTs were in high similarity, the number of conserved SSRs between wheat and the other three crops decreased with the increased aligning regions, and only 13 types of SSR motifs in 21 ESTs were obtained by aligning sequences over a stretch of more than 40 bp. The variation at a microsatellite came from not only the differences in the numbers of repeat units and its location shift, but also base mutations flanking microsatellite repeats. From the 428 uni-SSR-ESTs universally in the four cereals, 243 primers were designed and tested in two genotypes of each species. 154 (63.4%) primers produced clear amplicons across the four species, which showed a high efficient transferability of wheat EST-SSR markers to the other three cereal crops. [ABSTRACT FROM AUTHOR]

A field experiment was carried out to quantify biological nitrogen fixation (BNF) using the 15N isotope natural abundance method in maize ( Zea mays L.)/faba bean ( Vicia faba L.) and wheat ( Triticum aestivum L.)/faba bean intercropping systems. Faba bean was yielding more in the maize/faba bean intercropping, but not in the wheat/faba bean intercropping. Biomass, grain yield and N acquisition of faba bean were significantly increased when intercropped with maize, and decreased significantly with wheat, irrespective of N-fertilizer application, indicating that the legume could gain or lose productivity in an intercropping situation. There was yield advantage of maize/faba bean intercropping, but no in wheat/faba bean intercropping. The grain yield of the faba bean intercropped with maize was greater than that of faba bean monoculture due to increases of the stems per plant and the pods per stem of faba bean. N fertilization inhibited N fixation of faba bean in maize/faba bean and wheat/faba bean intercropping and faba bean monoculture. The responses of different cropping systems to N-fertilizer application, however, were not identical, with competitive intercropping (wheat/faba bean) being more sensitive than facilitative intercropping (maize/faba bean). Intercropping increased the percentage of N derived from air (%Ndfa) of the wheat/faba bean system, but not that of the maize/faba bean system when no N fertilizer was applied. When receiving 120 kg N/ha, however, intercropping did not significantly increase %Ndfa either in the wheat/faba bean system or in the maize/faba bean system in comparison with faba bean in monoculture. The amount of shoot N derived from air (Ndfa), however, increased significantly when intercropped with maize, irrespective of N-fertilizer application. Ndfa decreased when intercropped with wheat, albeit not significantly at 120 kg N/ha. Ndfa was correlated more closely with dry matter yield, grain yield and competitive ratio, than with %Ndfa. This indicates that that total dry matter yield (sink strength), not %Ndfa, was more critical for the legume to increase Ndfa. The results suggested that N fixation could be improved by yield maximization in an intercropping system. [ABSTRACT FROM AUTHOR]

Very often, the accuracy of quantitative analytical methods for the determination of mycotoxins by liquid chromatography (LC)-mass spectrometry (MS) and LC-MS/MS is limited by matrix effects during the ionization process in the MS source. Stable isotope labeled standards are best suited to correct for matrix effects and to improve both the trueness and the precision of analytical methods employing LC-MS and LC-MS/MS. This paper describes the successful use of fully 13C isotope labeled deoxynivalenol [(13C15)DON] as an internal standard (IS) for the accurate determination of DON in maize and wheat by LC electrospray ionization MS/MS. To show the full potential of (13C15)DON as IS, maize and wheat extracts were analyzed without further cleanup. Subsequent to calibration for the LC-MS end determination, DON was quantified in matrix reference materials (wheat and maize). Without consideration of the IS, apparent recoveries of DON were 29±6% ( n=7) for wheat and 37±5% ( n=7) for maize. However, the determination of DON in the reference materials yielded 95±3% (wheat) and 99±3% (maize) when (13C15)DON was used as an IS for data evaluation. [ABSTRACT FROM AUTHOR]

Using an alkaline calcareous soil, pot experiments were conducted to elucidate the effects of NHvs. NOnutrition (50 or 100 mg kg−1 soil) of wheat and maize on microbial activity in the rhizosphere and bulk soils. Dicyandiamide was used as nitrification inhibitor to maintain NHas the predominant N source for plants grown in NH-treated soil. While maize grew equally well on both N sources, root and shoot growth of wheat was higher under NHthan under NOnutrition. Bacterial population density on roots, but not in the rhizosphere soil, was higher under NHthan under NO supplied at 150 mg N kg−1 soil; whereas at both N levels applied, NHcompared to NOnutrition of wheat and maize significantly increased microbial biomass in the rhizosphere soil. Under both plant species, NH vs. NOnutrition also increased aerobic and anaerobic respiration, and dehydrogenase activity in the rhizosphere. As microbial activity in the planted bulk and unplanted soils was hardly affected by the N-source, we hypothesize that the stimulation by NHof the rhizosphere microbial activity was probably due to higher availability of root exudates under NH than under NOnutrition. [ABSTRACT FROM AUTHOR]

Critical levels of selenium in raya ( Brassica juncea Czern L.), maize ( Zea mays L.), wheat ( Triticum aestivum L.) and rice ( Oryza sativa L.) were worked out by growing these crops in an alkaline silty loam soil treated with different levels of selenite-Se ranging from 1 to 25 μg g−1 soil. Significant decrease in dry matter yield was observed above a level of 5 μg Se g−1 soil in raya and maize; 4 μg Se g−1 soil in wheat and 10 μg Se g−1 soil in rice shoots. The critical level of Se in plants above which significant decrease in yield would occur was found to be 104.8 μg g−1 in raya, 76.9 μg g−1 in maize, 41.5 μg g−1 in rice and 18.9 μg g−1 in wheat shoots. Significant coefficients of correlation were observed between Se content above the critical level and dry matter yield of raya as well as rice ( r = −0.99, P ≤ 0.01), wheat ( r = −0.97, P ≤ 0.01) and maize (( r = −0.96, P ≤ 0.01). A synergistic relationship was observed between S and Se content of raya ( r = 0.96, P ≤ 0.01), wheat ( r = 0.89, P ≤ 0.01), rice ( r = 0.85, P ≤ 0.01) and maize ( r = 0.84, P ≤ 0.01). Raya, maize and rice absorbed Se in levels toxic for animal consumption (i.e. > 5 mg Se kg−1) when the soil was treated with more than 1.5 μg Se g−1. In case of wheat, application of Se more than 3 μg g−1 soil resulted in production of toxic plants. [ABSTRACT FROM AUTHOR]

The interactive influence of winter and/or spring wheat genetic background on haploid induction parameters and trait correlation was studied by hybridizing five elite and diverse genotypes each of winter and spring wheat and their F1s (winter × winter, spring × spring, and winter × spring, generated in a diallel design excluding reciprocals) with a single genotype of maize. Data were recorded with respect to per cent seed formation, embryo formation, and regeneration. High genetic variability was present among the wheat genotypes (parents + F1s) for the three haploid induction parameters. Significant differences were obtained within and between different groups viz., spring wheats, winter wheats, spring × spring wheats, winter × winter wheats, and winter × spring wheats with respect to the three haploid induction parameters based on ANOVA. The winter genotypes (winter parents and winter × winter wheat hybrids) responded better than the spring groups (spring wheat parents, spring × spring and winter × spring wheat hybrids) with respect to embryo formation and winter × spring wheat hybrids yielded significantly the highest numbers of regenerants. Correlation studies amongst the haploid induction parameters indicated that the genes controlling seed formation and haploid plantlet regeneration are negatively correlated when the genetic backgrounds of both ecotypes are combined in winter × spring hybrids. Haploid embryo formation had no association with seed formation and regeneration in all genetic backgrounds, suggesting independent inheritance. [ABSTRACT FROM AUTHOR]

Doubled haploid (DH) lines are important in wheat (Triticum aestivum L.) breeding, and haploids produced via maize pollination precede DH line development. Although maize pollination has proven reliable and broadly applicable to wheat, its success is determined by the wheat and maize genotypes employed. A wheat genotype consisting of nuclear and cytoplasm components predisposing it to parthenogenesis was compared with three other genotypes, each possessing only one or neither component necessary for parthenogenesis. In a glasshouse experiment, each genotype was pollinated with maize and subsequently treated with a 2,4-Dichlorophenoxyacetic Acid (2,4-D) solution to determine if parthenogenesis affected embryo formation frequency (EFF) and haploid formation efficiency (HFE). Wheat genotypes were also treated with the 2,4-D solution alone to determine if embryos and haploid plants could be produced in vivo without maize pollination. `Salmon(K)', a parthenogenetic genotype consisting of a Salmon 1BL.1RS nucleus in a Ae. kotschyii cytoplasm, had a mean EFF of 32%; whereas, the non-parthenogenetic genotypes had mean EFF calculations ranging from 7 to 21%. Mean HFE for Salmon(K) was not significantly different than the mean HFE for non-parthenogenetic Salmon; however, EFF and HFE calculations for Salmon(K) and Salmon, each with a 1BL.1RS translocation, were generally higher than calculations for genotypes without the translocation. Salmon(K) was the only genotype to produce a 3% or higher EFF and HFE after treatment with 2,4-D alone. Parthenogenesis significantly affected the frequency at which embryos were produced after pollination with maize and the frequency at which embryos and haploid plants were produced after treatment with 2,4-D alone. [ABSTRACT FROM AUTHOR]

Gramineous plants, including the major agricultural crops wheat (Triticum aestivum L.), rye (Secale cereale L.) and maize (Zea inays L.), accumulate benzoxazinones (Bxs) as defensive compounds. Previously, we isolated cDNAs of the Bx biosynthetic genes in wheat, TaBx2-TaBx5, that encode the enzymes catalyzing the sequential hydroxylation of indole to Bxs. In this study we isolated a cDNA of TaBx1, which encodes the first enzyme of the Bx pathway of wheat. The level of identity (80%) in deduced amino-acid sequence between TaBx1 and the corresponding maize gene Bxl was as high as those shown between TaBx2-TaBx5 and the corresponding maize genes Bx2-Bx5, respectively. Southern blot analysis using the TaBx1-TaBx5 cDNAs as probes was conducted with aneuploid lines of hexaploid wheat in order to determine sub-chromosomal locations of the five Bx biosynthetic genes in Triticeae species. In wheat, TaBx1 and TaBx2 co-existed in specific regions of chromosomes 4A, 4B and 4D, and TaBx3-TaBx5 were localized together in the distal regions of the short arms of chromosomes 5A, 5B and 5D. TaBx3 and TaBx5 were found to have duplicated loci in the long arm and the short arm of chromosome 5B, respectively. In rye, homoeoloci of TaBx1 and TaBx2 were located on chromosome 7R and those for TaBx3- TaBx5 were located on chromosome 5R. In barley, no Southern blot band was detected with any of the probes under the highly stringent hybridization conditions, suggesting that the non-Bx phenotype of barley is attributable to the loss of Bx biosynthetic genes. [ABSTRACT FROM AUTHOR]

Precision agriculture was initiated in the mid 1980s, using newly available technologies, to improve the application of fertilizers by varying rates and blends as needed within fields. Presently, the concept has been adapted to a variety of practices, crops, and countries. Its adoption varies significantly by cropping system, regions, and countries but it is progressively introduced or evaluated around the world. Several types of challenges limit a broader adoption: socio-economical, agronomical, and technological. Socio-economical barriers are principally costs and lack of skills. Agronomical challenges are lack of basic information, inadequate sampling and scouting procedures, absence of site-specific fertilizer recommendations, misuse of information, and lack of qualified agronomic services. There are multiple technological barriers that relate to machinery, sensor, GPS, software, and remote sensing. However, these barriers will be progressively lifted and precision agriculture will be a significant component of the agricultural system of the future. It offers a variety of potential benefits in profitability, productivity, sustainability, crop quality, food safety, environmental protection, on-farm quality of life, and rural economic development. [ABSTRACT FROM AUTHOR]

Analyzes the use of phytochelatins as biomarkers for the diagnosis of heavy metals in maize and wheat. Relationship between the concentration of cadmium and phytochelatins in plant's shoot material; Decrease in shoot concentration of cadmium after the addition of copper; Inferences drawn from differences in metal uptake and xylary metal transport among the two plant species.

Emissions of ozone precursors are expected to multiply the next 20 years in China, and the levels of photo-oxidants may increase substantially. Increased surface ozone gives cause for concern regarding the prospects for Chinese agricultural production. We show that crop production may be substantially reduced in the future due to elevated ozone concentrations, and that productivity may already be affected for some crops. However, crop-yield loss estimates obtained by using alternative exposure-response functions vary substantially. Spring wheat,soybean, and corn may be especially vulnerable to future ozone increases, due to a likely concurrence of peak levels of ozone and the growth season of these crops. [ABSTRACT FROM AUTHOR]