Search

China and India are the two top consumers of fertilizer nitrogen (N) in the world not only to provide food security to 36% of the global population living in the two countries but also due to fertilizer-related government policies being followed during the last more than 50 years. Excessive fertilizer N use is now a cause of N-related environmental pollution as well as a concern for climate change. Nitrogen use efficiency (NUE) at farmers' fields dictates both production of food crops as well as loss of N to the environment including efforts to curb climate change due to N2O emission. We used a gridded database on N input and N output for wheat, rice, and maize in China and India from 1961 to 2013 to synthesize the dynamics of NUE (percentage of applied N used by the crop) and surplus N (difference between total N input and N output) and in the light of relevant literature interpreted it in terms of past and future fertilizer N management scenarios and fertilizer related policies in the two countries. From 1961 to 2013, the percentage of fertilizer N in total N input in cereal crop production increased from 8-10% to 71-75% in India and from 30-37% to 80-84% in China. In both India and China, NUE has been continuously declining and in 2013 it was in the range of 20-24% (except 32% for wheat in India) due to several-fold increases in fertilizer N use and imbalanced use of fertilizer nutrients (particularly in India)--a consequence of huge subsidies provided by the governments on different fertilizer products. Estimates of maximum N output in the form of crop yield at saturating N input regimes determined from trajectories of N output as a function of total N input for 1961-2013 and 2001-13 revealed that crop and fertilizer N management for rice, wheat, and maize in India and China did not improve significantly since the Green Revolution era. As a large number of studies in India and China show that NUE can be increased by the advancement of technology front in terms of crop and fertilizer management and by reducing the fertilizer N rate without a significant reduction in the yield of crops, recommendations have been given for governments (to frame suitable policies), farmers, extension agencies, and fertilizer dealers. [ABSTRACT FROM AUTHOR]

Straw return is an effective measure to promote sustainable agriculture by significantly improving soil fertility. At present, few studies have been conducted on the most effective carbon enhancing management measures for various crops. Therefore, we conducted a meta-analysis using data collected from 184 literature sources, comprising 3297 data sets to analyze the carbon increase effects of straw returning in three main crops (rice, maize, and wheat) in China and to explore the influence mechanism of natural factors, soil properties, straw return measures, and cropping systems on the carbon enhancement effect. The study showed that straw return significantly increased soil organic carbon and the rate of increase was higher for wheat at 15.88% (14.74%–17.03%) than for rice at 12.7% (11.5%–13.91%) and maize at 12.42% (11.42%–13.42%), with varying degrees of improvement in other soil physicochemical properties. Natural factors have the greatest impact on the carbon increasing effect of rice fields, reaching 28.8%, especially at temperature between 10 °C and 15 °C, less than 800 mm precipitation, low latitude, and short frost-free period. Maize and wheat are most affected by soil properties, reaching 41% and 34.5% respectively. Furthermore, field management practices also play a pivotal role, organic carbon increasing obviously was observed when the C/N ratio of exogenous nutrients is bigger than 20 with the low initial organic matter. Shallow tillage and less than 7.5 t hm−2 straw returning with 3–10 years to the field are ideal for rice and maize. Crop rotation, especially in drylands, increased soil organic carbon more significantly than continuous. The results of our analysis can provide valuable insights into the effect of straw return on carbon increase. In the future, the soil carbon can be improved by adopting rational cropping patterns and straw return measures with taking into account climate and soil characteristics for different crops. [Display omitted] • The effects of straw return on soil organic carbon in three major crops were studied using meta-analysis. • SOC levels significantly increased for rice, maize, and wheat after straw return. • The impact of natural factors, soil properties, straw return measures, and cropping systems varied for different crops. • The increase in SOC for rice was largely influenced by natural factors, while for maize and wheat by soil properties. [ABSTRACT FROM AUTHOR]

The discrete element method (DEM) has become popular for modelling the behaviour of grain kernels during agricultural production, processing, and transportation. DEM simulations provide both qualitative and quantitative information on particle flow, which helps improve the understanding, design, and optimisation of grain handling equipment. The accuracy of the DEM models is greatly affected by the model input parameter values, such as the grain kernel material and interaction properties. However, precisely and properly quantifying these properties remains a challenging task due to the irregular shapes of kernels and the heterogeneity of these biological materials. In this study, the DEM simulation material and interaction properties of maize and wheat kernels were determined with a combination of direct measurements and calibration tests and validated against bulk material tests. The characterisation tests include X-ray micro-CT scanning for acquiring kernel size and shape information, the use of a reciprocating pin tribometer for coefficients of friction, and an inclined surface drop test for calibrating the coefficients of restitution. The measured model parameter values were used in DEM simulations of two common bulk material tests: the poured bulk density test and an angle of repose test. The percentage error of the bulk density test was 4.0% for maize and 8.4% for wheat, and the error in the angle of repose test was 0.4% for maize and 1.3% for wheat. DEM simulations of bulk density and angle of repose tests using the parameters measured with the characterisation tests are able to accurately predict the experimental measurements. • Material and interaction properties of maize and wheat were determined. • Glued-sphere particles were generated based on 3D scanned models. • A calibration test was developed to determine the coefficient of restitution. • Tribometer test provided measurements of the grain kernel friction coefficients. • Image analysis was used to quantitatively compare angles of repose. [ABSTRACT FROM AUTHOR]

The perfect knowledge of yield before harvest has been a wish puzzling human being since the beginning of agriculture because seasonal forecast of crop yield plays a critical role in decision making for different stakeholders--from farmers to policy makers to governments for food security, to commodities traders. Different methods have been used to forecast yield with different levels of granularity, accuracy and timing. This chapter presents a critical review of the current seasonal crop yield forecasting methods found in the scientific literature. Extensive research has been conducted on crop yield forecast, particularly for wheat, maize, rice, barley, and soybean. Yield forecast are mainly based on field surveys, statistical regressions between historical yield and in-season variables (agrometeorological, or remotely sensed data), crop simulation models, or on integration between statistical modeling with dynamic process-based crop simulation models. A low number of studies rely on field surveys as a means to forecast yield, but they remain the main methods of yield forecast and estimation in several countries (i.e., USA). This chapter aims to report results found in peer-review journals for different crops, methods, geographies, and accuracies, and to end with a critical perspective on the advantage and disadvantage of the different methods currently employed by researchers and stakeholders. [ABSTRACT FROM AUTHOR]

Abstract Wheat ( Triticum aestivum L.) and maize ( Zea mays L.) are important cereal crops grown worldwide. In Pakistan, various varieties of wheat and maize are grown and a number of biotic and abiotic factors influence its production. These are mainly used as a food source and raw material for animal feed. Bipolaris sorokiniana is a hemibiotrophic phytopathogenic fungus that affects various grass species and causes number of diseases on small grains. An investigation was undertaken to evaluate the comparative expression of pathogenesis-related protein genes in wheat and maize under B. sorokiniana stress. After stress, these crops showed disease resistance by improving biochemical parameters like proline, protein, sugar and chlorophyll content. Morpho-physiological parameters including shoot length, root length, relative water content and fresh as well as dry weight were affected by fungal stress. Expression analysis of PR-proteins in stressed plants of wheat confirmed their role in plant defence. PR-1, Thaumatin-like protein (TLP), and β 1,3 glucanase were highly expressed under stress in wheat variety (RWP13), it suggests the role of these genes in the prescribed variety. These genes did not show their expression in susceptible wheat variety (SWG13). Zm PR-5 and Zm 1,3 β-glucanase were highly expressed in maize variety (RMN27) after stress which suggests their role in defence mechanism of this variety. While on the other hand, no significant expression of these genes was observed in susceptible maize variety (SMIG). In future, these genes can be over-expressed in transgenic plants to make them resistant against a number of biotic and abiotic factors. Highlights • Plants are being challenged by number of biotic and abiotic stresses. • Plants protect themselves by activating different mechanisms. • Wheat and maize crops are seriously affected by biotic and abiotic stresses at world level. • B. sorokiniana a hemibiotrophic phytopathogenic fungus that infects various kinds of crops at world level. • The pathogenesis-related (PR) protein genes protect these crops against biotic and abiotic stresses. [ABSTRACT FROM AUTHOR]

The Crop Environment Resource Synthesis (CERES) models have been developed and utilized for the last 30 years to simulate crop growth in response to climate, soil, genotypes and management across locations throughout the world. We reviewed 215 papers found in the literature that contained field observed data where the CERES models were tested. Over 30 simulated variables of the CERES models have been tested in 43 different countries under various experimental treatments. Across all testing conditions, the CERES models simulated grain yield with a root mean square error (RMSE) of less than 1400 kg/ha (~10% relative error, RE), 1200 kg/ha (~20% RE) and 800 kg/ha (~10% RE) for maize, wheat, and rice, respectively. Phenological development was simulated with less than 7 days difference from the observations in most studies. The CERES models simulated aboveground biomass, harvest index, evapotranspiration, and soil water reasonably well too. The simulations of grain number (up to 4340 root mean square error, RMSE), grain weight (up to 22% error), intercepted photosynthetically active radiation (IPAR, up to 0.41 MJ/plant), leaf area index (LAI, 31.9% error), soil temperature (over 10°C difference), and nitrogen (N) dynamics (up to 80% error) were less accurate. In fact the average error of CERES model simulations tends to be higher under marginal crop growing conditions such as extreme heat or cold, water and nutrient deficit conditions. [ABSTRACT FROM AUTHOR]

This study aimed at evaluating i) zinc sequestration potential of ninety seven (97), eighty (80) and twelve (12) cultivars of rice, wheat and maize respectively, ii) their response to agronomic Zn biofortification, iii) its impact on Fe concentration in grains and straw/stalk and iv) Zn and Fe concentration in the food prepared from Zn biofortified grains. Zinc and Fe were estimated following standard methods in soils and the harvested grains and straws/stalks and the breads and cooked rice prepared out of the grains of all the different cultivars of those three cereals raised with no zinc (Zn 0 ) and Zn fertilizer (ZnSO 4 , 7H 2 O) applied through soil (as basal) + two foliar sprays at maximum tillering/6–8 leaf and flowering/silking stages (Zn 1 ) of the crops. Zinc fertilization yielded Zn densed but Fe starved grains and straws/stalks of most of the cultivars (∼90%) of all the three cereals tested. Cultivars inherently high in Zn were stubborn to such Zn fertilization. Zinc fortified grains again yielded Zn enriched food products but with significant loss of both Zn and Fe (>60% in rice and 40% for wheat and maize) during their processing. Among the three cereals, wheat was most effective for Zn biofortification program. [ABSTRACT FROM AUTHOR]

• Folate quantification of cereal grains was optimised and validated. • The effects of mono-/di-/tri-enzyme extraction were attempted. • Di-enzyme treatment with α-amylase and rat conjugase showed better efficiency. • The developed LC–MS/MS method had great reproducibility and sensitivity. Folates are essential micronutrients for human health. To determine the total folate content, the extraction and quantification of seven monoglutamate folate derivatives in cereals (maize, rice, and wheat) were optimised and validated in this study. Di-enzyme treatment with α-amylase and rat conjugase was proved ideal for folate extraction from the cereal grains. The quantification method by liquid chromatography-tandem mass spectrometry was validated based on its matrix effect, linearity, sensitivity, recovery, inter-day and intra-day precision. The limits of detection and quantification of folate derivatives ranged from 0.03–0.88 and 0.1–1.0 μg/100 g among the three cereal samples. The absolute recoveries of most folate derivatives were 72–96 % for these cereal samples, with the exception of dihydrofolate, tetrahydrofolate, and folic acid (44–65 %). The inter-day and intra-day precisions were < 12 % for the three cereals. Analysis of folate content and composition in several cereal grains showed that the total folate levels were approximately 26−37 μg/100 g, with 5-methyl-tetrahydrofolate and 5-methyl-tetrahydrofolate as the dominant. MeFox, an oxidation product of 5-methyltetrahydrofolate, was detected at concentrations 20–39-fold higher than those of total folates in rice and wheat grains. This validated method is an efficient approach for folate determination in cereal crops. [ABSTRACT FROM AUTHOR]

• Seed inoculation with several Pseudomonas isolates improved wheat and maize yields. • Inoculation effect was assessed along 3 consecutive seasons in 3 different sites. • Isolates' biocontrol potential index correlates positively with relative yields. • Isolates' direct growth potential index correlates negatively with relative yields. • In vitro biocontrol potential of pseudomonads could predict their field performance. Agricultural bioproducts became interesting alternatives for sustainable agricultural practices, because they aim to reduce the use of agrochemicals without losing crop yields. As Pseudomonas genus has been largely studied for the high number of plant probiotic species it contains, in this work we evaluated the field performance of 10 genetically diverse native Pseudomonas that have been isolated from productive plots of the Argentine Pampas. Previously, they have been characterized in vitro , and we have developed several indexes to organize the isolates' collection based on their potential to perform biocontrol of fungal pathogens (BPI), to promote plant growth by direct mechanisms (DGPI), or by integrated direct plus indirect mechanisms (PGPI). At three geographical sites, we tested the effect of single- and co-inoculations with a commercial bio-input based on the fungus Trichoderma harzianum Th2, in wheat and maize crops during 3 consecutive seasons. Most of single inoculations improved wheat and maize grain yields. For wheat, improvement seemed to be related with a higher plant emergence by the positive correlation between yield and plant number; whereas for maize increased yields would be rather associated with a better plant structure by the positive correlation between yield and the vegetation index NDVI. The co-inoculation of Th2 with different P. chlororaphis isolates also increased the grain yield of both grain crops, despite P. chlororaphis strains displayed fungal inhibition in dual culture in vitro tests. We found a positive and significant correlation between BPI and the yield percentage improvement of both crops, but a negative correlation with DGPI. Thus, this work shows the usefulness of the in vitro characterization of biocontrol-related traits and the estimation of a biocontrol potential index as a proxy for crop yield performance, but not of direct plant growth-promoting features. [ABSTRACT FROM AUTHOR]