Crops In World Research Articles

Winter Barley Grain Weight Stability under Different Management Practices at NARDI Fundulea

Cereals provide over 50% of the total world crop production, their seeds being an important resource for human and animal feed, as well as for the industry. From these, winter barley is an appreciated crops by farmers due its ability to adapt to less favourable environmental conditions and also give high and economically efficient yields. The barley grain weights (GW) along with grain size are universally considered to be closely correlated with the level of technological quality indicators required by the malt and beer industry. Grain weight is first trait used to classify the barley seed quality. The objective of this paper was to identify genotypic differences between seventeen Romanian winter barley genotypes in grain weight as related with grain yield and GW stability across different management practices. Large differences (8.2-20.8%) were found among the tested varieties and advanced lines for GW stability, underlined by the coefficient of variation (CV%). Based on regressions, varieties and lines can be grouped in more responsive to environments favourable to higher grain weight (winter two row barley lines DH 267-66 and DH 314-1), or able to maintain grain weight in less favourable environments (winter six row barley Ametist, Onix, Lucian and winter two row barley Gabriela varieties). The lack of correlation between GW and CV% and frequency of GW values above 42 g correlated significantly negative with GW average (r = -0.82), indicates that there are possibilities to improve this trait and also to have progress in its stability.

Intra-seasonal climate variability and crop diversification strategies in the Peruvian Andes: A word of caution on the sustainability of adaptation to climate change

Abstract Agricultural systems are highly sensitive to climate change. Most studies focus on the effect of heat and water availability on crop yields, but little is known about the impact of changes in intra-seasonal climate variability (particularly challenging in mountain regions). Also, beyond the effect on crop yields –mostly focused on single cropping systems and major world crops- little analysis has been done on more complex, diversified and low-input cropping systems like those prevalent in the Andean region. This study investigates whether Andean farmers respond to increasing climate variability by increasing crop diversity (measured by intercropping and crop diversification indices) and by switching to crops which better tolerate heterogeneous environmental conditions. Since previous studies show that crop diversification fosters resilience of agricultural systems, decreasing crop portfolio diversity in an increasingly variable environment may challenge farms sustainability. The data used in the analysis combines district-level socio-economic information from two agrarian censuses (1994 and 2012) with district-level climate estimates of mean temperature, temperature range and precipitation (averages for periods 1964–1994 and 1982–2012). Based on fixed effects models that allow for sub-region parameter heterogeneity, I find that an increase in intra-seasonal climate variability leads farmers in colder areas (

Plant-parasitic nematodes parasitizing saffron in Morocco: Structuring drivers and biological risk identification

Plant-parasitic nematodes (PPN) are the most destructive of all plant pathogens. They are an economically important group of soil pathogens, causing significant annual damages of up to 25% of world crop production. Morocco is considered to be a highly productive country for the colorant/medicinal/spice saffron (Crocus sativus L.). Taliouine and Taznakht regions are the most productive areas of this valuable neutraceutical. Due to its metabolic profile, and growth forms, saffron is susceptible to many plant diseases, including plant-parasitic nematodes (PPN). This work aims to assess the diversity of PPN communities in soils of Taliouine and Taznakht regions to facilitate understanding of links between their assemblages with biotic and abiotic parameters. Herein, nematode communities were characterized in 163 soil samples collected from 11 rural communes characterized by altitudinal gradients in Taliouine and Taznakht regions. Fifteen PPN genera belonging to 12 families were identified, among which the four genera Ditylenchus, Aphelenchoides, Pratylenchus and Helicotylenchus, potentiate serious limiting factors in saffron production. Their frequencies are respectively 92, 49, 48 and 36% in the area of Taliouine, while in Taznakht they represent 95, 69, 33, and 28% respectively. Regarding the assessment of diversity at different sites, the genus richness (R) index ranges from 2 to 10 distinct genera, whereas the Shannon diversity (H’) index varies from 0.9 to 1.5 and the Evenness (E) index tends to 1. The Co-inertia analyses revealed a substantial relationship between nematode communities and soil types. Soil texture is the major factor influencing the presence and the abundance of a considerable portion of genera. Multivariate analyses (MBPLS) indicated links between humidity, rainfall, minimum temperature and PPN taxa, though maximum temperature did not have an impact. Ditylenchus, Helicotylenchus, Pratylenchus and Paratylenchus were related to the humidity and silt soil that developed in Taliouine. Aphelenchoides, Tylenchus, Tylenchorynchus and Dorylaimus were more prevalent in rainy locations and clay soils of Taznakht. Suitable nematode controlling approaches may be applied and preventative measures should be considered at nursery and field level.

Emergent and Possible Invasive Pest Species of Weevils in Mexico

Mexico is a center of New World crop origins with many insect species associated with the wild crop relatives, some of which have become pests of cultivated plants. Many of these indigenous pests of Mexico are weevils (Coleoptera: Curculionidae), and some represent potential quarantine pests. In the present work, we present some of the most important species of weevils considered as crop pests, which are presently restricted primarily to Mexico with the potential to invade other regions. We also present species of weevils exotic to Mexico, considered by national quarantine authorities to be possible threats to Mexican agriculture. Potential quarantine weevil pests for avocado include Conotrachelus aguacatae Barber, Conotrachelus perseae Barber, Heilipus lauri Boheman, Heilipus albopictus Champion, and Copturus aguacatae Kissinger (all Coleoptera: Curculionidae). For guava, species include Conotrachelus dimidiatus Champion and Conotrachelus copalensis Salas-Araiza and Romero-Napoles (both Coleoptera: Curculionidae). Weevil pests reported with quarantine importance for sugar cane are Sphenophorus incurrens Gyllenhal (Coleoptera: Dryophthoridae), Apinocis angustus (Casey), and Apinocis subnudus (Buchanan) (both Coleoptera: Curculionidae). The weevil Rhyssomatus nigerrimus Fahraeus (Coleoptera: Dryophthoridae) recently has been observed damaging soybeans in northern and southern Mexico. Cactophagus spinolae Gyllenhal (Coleoptera: Dryophthoridae) is a generalist cactus pest. Scyphophorus acupunctatus Gyllenhal (Coleoptera: Dryophthoridae) is a well-known pest of cultivated and wild agaves. Several species of Epicaerus (Coleoptera: Curculionidae) have been reported on various crops in restricted areas including, among others, Epicaerus operculatus (Say) on garlic, and Epicaerus cognatus Sharp (both Coleoptera: Curculionidae) on potato. Amphidees latifrons (Sharp) (Coleoptera: Curculionidae) has been reported from apples in localized regions of northern Coahuila. Weevils exotic to Mexico of quarantine concern are Naupactus cervinus Boheman, Diaprepes abbreviatus (L.) (both Coleoptera: Curculionidae), and Rhynchophorus ferrugineus (Olivier) (Coleoptera: Dryophthoridae).

Potential adaptive strategies for 29 sub-Saharan crops under future climate change

Climate change is expected to severely impact cultivated plants and consequently human livelihoods1–3, especially in sub-Saharan Africa (SSA)4–6. Increasing agricultural plant diversity (agrobiodiversity) could overcome this global challenge7–9 given more information on the climatic tolerance of crops and their wild relatives. Using >200,000 worldwide occurrence records for 29 major crops and 778 of their wild relative species, we assess, for each crop, how future climatic conditions are expected to change in SSA and whether populations of the same crop from other continents, wild relatives around the world or other crops from SSA are better adapted to expected future climatic conditions in the region. We show that climate conditions not currently experienced by the 29 crops in SSA are predicted to become widespread, increasing production insecurity, especially for yams. However, crops such as potato, squash and finger millet may be maintained by using wild relatives or non-African crop populations with climatic niches more suited to future conditions. Crop insecurity increases over time and with rising GHG emissions, but the potential for using agrobiodiversity for resilience is less altered. Climate change will therefore affect sub-Saharan agriculture but agrobiodiversity can provide resilient solutions in the short and medium term. Future climate conditions threaten crops in sub-Saharan Africa. It is shown that most major sub-Saharan African crops have wild relatives that occur in regions better suited for future climate conditions, suggesting an opportunity for adaptation that does not require the adoption of new production systems.

Development of EST-SSR Markers and Analysis of Genetic Relationship it’s Resources in Hexaploid Oats

Oats are the fifth largest planted area in the world, and are the only cereal crops in the world to be among the top ten in the world. However, since oats are weak in cold weather, only four varieties are cultivated in Korea at present. Therefore, we constructed the DNA profile database using the EST-SSR marker for the oat 73 varieties kept in Korea. When the oat 73 cultivars marketed in Korea were tested with the eight EST-SSR marker developed in this study, 71.62 average alleles were detected per marker and the mean of PIC value was 0.337. According to the polymorphism of microsatellite markers, 73 varieties of oats were classified into 5 ~ 9 groups and most of the genetic resources investigated were identified when EST-SSR marker was used. In the future, EST-SSR markers developed in this study may be used to identify the seed disputes and breeds of oats. In addition, it predicts that it will be usefully used as a means of evaluating the characteristics of oat genetic resources, testing purity and studying the cultivation of varieties.

World Sulfur Use Efficiency for Cereal Crops

Sulfur (S) is an essential plant nutrient needed for higher crop yields and improved nutritional value. In recent decades, the occurrence of S deficiency has increased and fertilizer S use may steadily increase. This may lead to inefficient crop utilization of S and result into negative footprints on the environment. The objective of this work was to estimate world fertilizer sulfur use efficiency (SUE) for major cereal crops grown around the world. A 10‐yr data set (2005–2014) was obtained from the Food and Agriculture Organization, the US Geological Survey, and an array of other published research articles. Statistical analysis was performed using MS Excel to obtain total area for world and cereal crops, grain yield, and fertilizer S applied. The difference method [(Total grain S – grain S derived from the soil)/S applied] was used to compute world SUE. Cereal crops included in this study were barley (Hordeum vulgare L.), maize (Zea mays L.), rice (Oryza sativa L.), millet (Pennisetum glaucum L.), wheat (Triticum aestivum L.), sorghum (Sorghum bicolor L.), rye (Secale cereale L.), and oat (Avena sativa L.). Cereal production increased from 2669 M Mg in 2005 to 3346 M Mg in 2014. Sulfur use efficiency for cereal crops was estimated to be 18%. This low SUE may be attributable to S leaching from the soil profile, immobilization, retention in residues, and adsorption. As increased quantities of fertilizer S are likely to be applied in future to meet the ever‐growing demand for food, SUE could decline below 18%.Core Ideas World sulfur use efficiency for cereal crops is unknown. World sulfur use efficiency for cereal crops was estimated to be 18%. More precision agriculture research is necessary to improve sulfur use efficiency for cereal crops. Reasons for low sulfur use efficiency include sulfur; leaching, adsorption, retention in residues, and immobilization as well as failure to adhere to sound agronomic practices and 4R concepts.

A meta-analysis of global crop water productivity of three leading world crops (wheat, corn, and rice) in the irrigated areas over three decades

ABSTRACT The overarching goal of this study was to perform a comprehensive meta-analysis of irrigated agricultural Crop Water Productivity (CWP) of the world’s three leading crops: wheat, corn, and rice based on three decades of remote sensing and non-remote sensing-based studies. Overall, CWP data from 148 crop growing study sites (60 wheat, 43 corn, and 45 rice) spread across the world were gathered from published articles spanning 31 different countries. There was overwhelming evidence of a significant increase in CWP with an increase in latitude for predominately northern hemisphere datasets. For example, corn grown in latitude 40–50° had much higher mean CWP (2.45 kg/m³) compared to mean CWP of corn grown in other latitudes such as 30–40° (1.67 kg/m³) or 20–30° (0.94 kg/m³). The same trend existed for wheat and rice as well. For soils, none of the CWP values, for any of the three crops, were statistically different. However, mean CWP in higher latitudes for the same soil was significantly higher than the mean CWP for the same soil in lower latitudes. This applied for all three crops studied. For wheat, the global CWP categories were low (≤0.75 kg/m³), medium (>0.75 to <1.10 kg/m³), and high CWP (≥1.10 kg/m³). For corn the global CWP categories were low (≤1.25 kg/m³), medium (>1.25 to ≤1.75 kg/m³), and high (>1.75 kg/m³). For rice the global CWP categories were low (≤0.70 kg/m³), medium (>0.70 to ≤1.25 kg/m³), and high (>1.25 kg/m³). USA and China are the only two countries that have consistently high CWP for wheat, corn, and rice. Australia and India have medium CWP for wheat and rice. India’s corn, however, has low CWP. Egypt, Turkey, Netherlands, Mexico, and Israel have high CWP for wheat. Romania, Argentina, and Hungary have high CWP for corn, and Philippines has high CWP for rice. All other countries have either low or medium CWP for all three crops. Based on data in this study, the highest consumers of water for crop production also have the most potential for water savings. These countries are USA, India, and China for wheat; USA, China, and Brazil for corn; India, China, and Pakistan for rice. For example, even just a 10% increase in CWP of wheat grown in India can save 6974 billion liters of water. This is equivalent to creating 6974 lakes each of 100 m³ in volume that leads to many benefits such as acting as ‘water banks’ for lean season, recreation, and numerous ecological services. This study establishes the volume of water that can be saved for each crop in each country when there is an increase in CWP by 10%, 20%, and 30%.

Rapid host-plant adaptation in the herbivorous spider mite Tetranychus urticae occurs at low cost.

The herbivorous spider mite Tetranychus urticae is a generalist world crop pest. Early evidence for host races, its fully sequenced genome resolved to the chromosome level, and the development of other molecular tools in this species suggest that this arthropod can be a good model to address host plant adaptation and early stages of speciation. Here, we evaluate this possibility by reviewing recent studies of host-plant adaptation in T. urticae. We find that evidence for costs of adaptation are relatively scarce and that studies involving molecular-genetics and genomics are mostly disconnected from those with phenotypic tests. Still, with the ongoing development of genetic and genomic tools for this species, T. urticae is becoming an attractive model to understand the molecular basis of host-plant adaptation.

An SSR-SNP Linkage Map of the Parasitic Weed Orobanche cumana Wallr. Including a Gene for Plant Pigmentation.

Sunflower broomrape (Orobanche cumana Wallr.) is a holoparasitic plant that causes major yield losses to sunflower crops in the Old World. Efforts to understand how this parasitic weed recognizes and interacts with sunflowers are important for developing long-term genetic resistance strategies. However, such studies are hampered by the lack of genetic tools for O. cumana. The objectives of this research were to construct a genetic linkage map of this species using SSR and SNP markers, and mapping the Pg locus that is involved in plant pigmentation. The genetic map was developed from the progenies of a cross between the O. cumana inbred lines EK-12 and EK-A1, which originated from populations belonging to two distant and geographically separated gene pools identified in Spain. The inbred lines also differed in plant pigmentation, with EK-A1 lacking anthocyanin pigmentation (pgpg genotype). A genetic map comprising 26 SSR and 701 SNP markers was constructed, which displayed 19 linkage groups (LGs), corresponding to the 19 chromosome pairs of O. cumana. The total length of the map was 1795.7 cM, with an average distance between two adjacent positions of 2.5 cM and a maximum map distance of 41.9 cM. The Pg locus mapped to LG19 between the SNP markers OS02468 and OS01653 at 7.5 and 3.4 cM, respectively. This study constitutes the first linkage map and trait mapping study in Orobanche spp., laying a key foundation for further genome characterization and providing a basis for mapping additional traits such as those having a key role in parasitism.

Investigation and development of maize fused network analysis with multi-omics

Maize is a critically important staple crop in the whole world, which has contributed to both economic security and food in planting areas. The main target for researchers and breeding is the improvement of maize quality and yield. The use of computational biology methods combined with multi-omics for selecting biomolecules of interest for maize breeding has been receiving more attention. Moreover, the rapid growth of high-throughput sequencing data provides the opportunity to explore biomolecules of interest at the molecular level in maize. Furthermore, we constructed weighted networks for each of the omics and then integrated them into a final fused weighted network based on a nonlinear combination method. We also analyzed the final fused network and mined the orphan nodes, some of which were shown to be transcription factors that played a key role in maize development. This study could help to improve maize production via insights at the multi-omics level and provide a new perspective for maize researchers. All related data have been released at http://lab.malab.cn/∼jj/maize.htm.

IMPACT OF CLIMATE CHANGE ON SUGARCANE CROP AND REMEDIAL MEASURES-A REVIEW

Increasing demand of bioenergy, sugar and other byproducts make sugarcane (Sacharum officinarum) very important and valuable crop in world. It is growing on the many diversified agroecological zones of 120 countries of the world. Brazil, India, China, Thailand, Pakistan, Mexico, Colombia, Indonesia, Philippines, and USA (number wise from area and production) are top ten sugarcane producing countries in the world. But yield production per hectare of these countries is ranged from 56-86 t ha-1 is much lower than the achievable potential 100-130 t ha-1. Amongst many other factors responsible for lowering the yield, change in environment is now growing a major factor. It is very difficult to increase area for sugarcane so efforts are made to increase the yield production at the same cultivated area, the per hectare yield production must be improved by adapting modern technologies suited for changing environment. The global warming is increasing due to change in environment by the increasing emission of green house gases. Sugarcane is sensitive for climatic parameters such as temperature, rainfall, sunlight and soil. The research indicated that global temperature will increased from 3-5oC in the end of 21st century. The enormous human activities are cause to accelerate the changing in our ecosystem with low or high rainfall, temperature, severity of pests pressure, unavailability of pollination services, decrease soil fertility, alter the water use efficiencies and crop behavior. Changes in temperature, rainfall, floods, drought, salinity stresses and frosts have been found major factor for lowering production of sugarcane in Pakistan is highly dependent on natural resources. Obtaining the high cane production with high quality juice in future, it is necessary to develop cane varieties and advanced farm management practices which will suitable under changing environment.

Late Holocene environmental change and the anthropization of the highlands of Santo Antão Island, Cabo Verde

Cabo Verde was the first tropical archipelago colonized by Europeans. Historians have suggested that the first colonizers initiated archipelago-wide ecosystem degradation, loss of vegetation cover, and erosion. However, the human–environment interactions that led to the archipelago's current environmental status remain poorly understood. Here, we report the first palaeoecological study of past vegetation change and disturbance regimes for Cabo Verde. We present a 2130-yr old sediment sequence from a volcanic caldera (Cova de Paúl) located at ~1200 m asl on Santo Antão Island, for which we analyzed fossil pollen, non-pollen palynomorphs (NPPs), charcoal, silica bodies, and grain size distribution. Our analyses do not show evidence of the presence of temperate, tropical or subtropical forests growing on the summits of Santo Antão in pre-human times. The pollen record shows that scrubland and grasslands dominated the highlands and underwent compositional changes ca. 1850 and 1300 cal yr BP. These shifts overlap with erosion phases and are linked to intensified seasonality. Steady rates of sedimentation marked the period 1230 to ca. 350 cal yr BP, but an increase in charcoal concentrations indicate a drying phase. Increases in regional and local fire, peaks of coprophilous fungi and the presence of New World crop pollen (Zea mays) are interpreted as the onset of Portuguese settlement of the highlands after 450 BP. Sustained erosion between ca. 350 and 100 cal yr BP indicate soil degradation, and the pollen record shows the increase in introduced herbaceous taxa (Rosaceae, Centaurea, Verbenaceae) and exotic tree taxa (e.g. Pinus), while shifting abundances of coprophilous fungi indicate changes in land-use. The record shows stabilization of soils in the last century due to recent afforestation of the highlands. Further palaeoecological studies have the potential to provide further detail of the long-term dynamics of Cabo Verde ecosystems and to inform conservation initiatives.

Physiological introspection into differential drought tolerance in rice cultivars of North East India

Drought is a vice to world crop production, exponentially enhanced by global climate change. Rice, a basic food crop for a major chunk of world populace, is largely affected by environmental challenges such as drought, salinity and heavy metal. This study brings to limelight differential drought tolerance capacity of rice varieties indigenous to North East India, a hot bed of indica rice diversity. Initial screening of rice varieties were performed through physiological dose-dependent studies under PEG (0%, 10%, and 20% which is equal to osmotic potential values of 0.001, 0.54 and 1.09 MPa, respectively), induced drought stress for three time intervals of 1, 3 and 5 days. Hierarchical clustering of the parameters on which the cultivars were analysed revealed Tampha and KMJ 1-12-3 to be relatively more tolerant whereas Chandan and Ketaki Joha as the sensitive ones. Biochemical studies for hydrogen peroxide (H2O2), proline, lipid peroxidation (MDA), lipoxygenase (LOX), superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (POX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR) were then performed on two cultivars (Tampha and Chandan) to elucidate the differential tolerance to drought, focusing on anti-oxidative response mechanism. The biochemical fingerprint showed significantly lower accumulation of H2O2 and MDA; higher accumulation of proline; and higher activity of SOD, CAT, DHAR, MDHAR and GR in the tolerant variety Tampha when compared to Chandan. In addition, alteration of chlorophyll fluorescence due to stress was also monitored to ascertain the variation in photosynthetic efficiency between the tolerant and sensitive cultivars. Tampha showed better photosynthetic activity in comparison to Chandan as quantified by measuring chlorophyll fluorescence. This manuscript thus throws new light into the drought stress response of the varieties from North East India with global implications.

Exploring cultivation site of saffron (Crocus sativus L.) by utilizing GIS linked to AHP

Saffron (Crocus sativus L.) is the most expensive medicinal crop in the world. This crop plays a specific role in the economy and social life of Southern and Central Khorasan provinces. Its production has been recently popularized in the northwestern regions of Iran. Accordingly, the present study evaluates the climatic conditions for saffron production in Western Azerbaijan Province based on a ten-year statistics of 2005–2014. To this end, 10 meteorological stations were selected across the province and were modeled and subjected to spatial analysis of data in Arc GIS Software Package. Using optimum climatic conditions for each growth stage of saffron, the data layers were classified and the weight value of each zone was specified and the final map that showed the climatic potential for saffron growing based on the analytic hierarchy process. The results showed that the role of each individual climatic variable including precipitation, temperature, and number of sunny hours varied with the growth stage as well as the slope map and the land use in different regions of West Azerbaijan Province. Of 37,113.4 km2 of lands excluding Lake Urmia, 16.70% is highly limited, 70.30% is moderately limited, 11.16% is lowly limited and 1.84% is unlimited.

Irrigation management strategies in wheat for efficient water use in the regions of depleting water resources

Wheat is the second most important food crop in India and world. One of the major difficulties faced in the wheat growing regions is the depletion of water resources at an alarming rate. This study was conducted to test the hypothesis that the use of the reduced amount of irrigation water would maintain the grain yield of popular Indian wheat variety HD2967. Water use, crop yield and water use efficiency of wheat were evaluated for three consecutive years under thirteen different irrigation treatments. Highest yield (5372.4 kgha−1) was recorded when crop was irrigated with full irrigation (60 mm of water at all five critical crop growth stages); which were statistically at par to yields recorded under 25% deficit irrigation (45 mm) at all growth stages. The treatment with 50% irrigation (30 mm) at all five growth stages although saved 50% water, yield penalty was also significant (4788.1 kgha−1 = 10.9% loss). Treatments with normal recommended practice (60 mm) have achieved lower water use efficiency (WUE) values (1.88 kg m-3) whereas, 25% deficit irrigation i.e. 45 mm at all five stages recorded significantly higher WUE (2.23 kgm-3) in sandy loam soils. The treatment where a total of 750 m3 water was saved per hectare was the most remunerative option in addition to saving of cost on water, electricity and labour. Adoption of 45 mm irrigation at all crop growth stages can enhance both irrigation water use efficiency without any yield penalty and can be adopted as a water saving mechanism in the regions of depleting water resources.

Accuracies Achieved in Classifying Five Leading World Crop Types and their Growth Stages Using Optimal Earth Observing-1 Hyperion Hyperspectral Narrowbands on Google Earth Engine

As the global population increases, we face increasing demand for food and nutrition. Remote sensing can help monitor food availability to assess global food security rapidly and accurately enough to inform decision-making. However, advances in remote sensing technology are still often limited to multispectral broadband sensors. Although these sensors have many applications, they can be limited in studying agricultural crop characteristics such as differentiating crop types and their growth stages with a high degree of accuracy and detail. In contrast, hyperspectral data contain continuous narrowbands that provide data in terms of spectral signatures rather than a few data points along the spectrum, and hence can help advance the study of crop characteristics. To better understand and advance this idea, we conducted a detailed study of five leading world crops (corn, soybean, winter wheat, rice, and cotton) that occupy 75% and 54% of principal crop areas in the United States and the world respectively. The study was conducted in seven agroecological zones of the United States using 99 Earth Observing-1 (EO-1) Hyperion hyperspectral images from 2008–2015 at 30 m resolution. The authors first developed a first-of-its-kind comprehensive Hyperion-derived Hyperspectral Imaging Spectral Library of Agricultural crops (HISA) of these crops in the US based on USDA Cropland Data Layer (CDL) reference data. Principal Component Analysis was used to eliminate redundant bands by using factor loadings to determine which bands most influenced the first few principal components. This resulted in the establishment of 30 optimal hyperspectral narrowbands (OHNBs) for the study of agricultural crops. The rest of the 242 Hyperion HNBs were redundant, uncalibrated, or noisy. Crop types and crop growth stages were classified using linear discriminant analysis (LDA) and support vector machines (SVM) in the Google Earth Engine cloud computing platform using the 30 optimal HNBs (OHNBs). The best overall accuracies were between 75% to 95% in classifying crop types and their growth stages, which were achieved using 15–20 HNBs in the majority of cases. However, in complex cases (e.g., 4 or more crops in a Hyperion image) 25–30 HNBs were required to achieve optimal accuracies. Beyond 25–30 bands, accuracies asymptote. This research makes a significant contribution towards understanding modeling, mapping, and monitoring agricultural crops using data from upcoming hyperspectral satellites, such as NASA’s Surface Biology and Geology mission (formerly HyspIRI mission) and the recently launched HysIS (Indian Hyperspectral Imaging Satellite, 55 bands over 400–950 nm in VNIR and 165 bands over 900–2500 nm in SWIR), and contributions in advancing the building of a novel, first-of-its-kind global hyperspectral imaging spectral-library of agricultural crops (GHISA: www.usgs.gov/WGSC/GHISA).

Green synthesis of silver nanoparticles using latex extract of Euphorbia tirucalli: A novel approach for the management of root knot nematode, Meloidogyne incognita

In recent years, research on novel nematicides has gained great interest to reduce world crop losses caused by plant parasitic nematodes. In this study, we explored the synthesis of silver nanoparticles (Et-AgNPs) by using latex extract of Euphorbia tirucalli against root-knot nematode species, Meloidogyne incognita. The physico-chemical properties of newly synthesized Et-AgNPs were determined using UV–Vis spectroscopy, Field Emission Scanning Electron Microscopy (FE-SEM), Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD). The nematicidal activity of Et-AgNPs against second stage juveniles (J2) of M. incognita was tested based on in-vitro (mortality and hatching) and in-planta trials (infectivity and crop protection) at different concentrations. The findings indicated that Et-AgNPs were lethal to J2 and also inhibited egg hatching (in-vitro). In-planta trials suggest that infestation on tomato roots was significantly reduced when the Et-AgNPs were applied as a root dip treatment. Tomato plants treated with Et-AgNPs had healthier growth parameters with a concurrent reduction in overall gall formation, egg masses on roots, number of eggs per egg mass and J2 populations within the plants. From this study, it was concluded that Et-AgNPs are helpful for the management of M. incognita and will be an effective replacement for synthetic nematicides.

Maize and precolonial Africa

Columbus's arrival in the New World triggered an unprecedented movement of people and crops across the Atlantic Ocean. We study a largely overlooked part of this Columbian Exchange: the effects of New World crops in Africa. Specifically, we test the hypothesis that the introduction of maize increased population density and slave exports in precolonial Africa. We find robust empirical support for these predictions. We also find little evidence to suggest maize increased economic growth or reduced conflict. Our results suggest that rather than stimulating development, the introduction of maize simply increased the supply of slaves during the slave trades.

Preservation bias: is rice overrepresented in the archaeological record?

Most charring experiments are carried out in the muffle furnace in highly controlled conditions and tackle the taphonomic issues of seed shrinkage and distortion caused by carbonisation. This paper presents the results from charring experiments conducted using real fire conditions. The objective of this study is to reproduce the charring processes that occur naturally and so address the issue of preservation biases which occurred in prehistoric contexts of carbonisation. This is particularly important in addressing the possible overrepresentation of rice over other taxa in the archaeological record. Prior charring experiments focus on Old World crops, but in this study the taxa used are East, South and Southeast Asian cereals and pulses. An ethnographic study conducted in Thailand examining the rice processing stages of dehusking and winnowing is also included since differential preservation may also result from crop processing. Archaeological results from sites in Mainland Southeast Asia are then interpreted using the results of the charring experiments and the ethnographic data.