Low Water Requirements Research Articles

Hydraulic performance and parameter optimisation of a microporous ceramic emitter using computational fluid dynamics, artificial neural network and multi-objective genetic algorithm

As the core of an irrigation system, microporous ceramic emitters (MPCEs) are closely related to the design, operation, and management of underground irrigation systems. In this study, computational fluid dynamics (CFD), an artificial neural network (ANN), and a multi-objective genetic algorithm (MOGA) were used to investigate the hydraulic performance of an MPCE and conduct parameter optimisation. A CFD software package was used to analyse the influence of the working parameters, structural parameters, and material properties on the flow characteristics of MPCE. Subsequently, an ANN and MOGA were used to optimise fabrication cost, flow rate, and flow index of the emitter. The results showed that a decrease in the bottom thickness or wall thickness of the MPCE increased the flow index of the emitter and the sensitivity of the flowrate to changes in pressure. Low working pressure was conducive to maintaining the active irrigation characteristic of the MPCE but the flowrate decreased. For crops with low water requirement, these conditions are ideal. The flow in the MPCE microchannel was mainly affected by the viscous resistance, whereas the inertial resistance only had an effect when the flow velocity was large. For field applications, the parameters can be optimised in the range obtained by the MOGA optimisation depending on the requirements of crop water demand, irrigation quality, and fabrication cost to achieve optimal irrigation performance. The results of this study provide references for the standardised fabrication of MPCEs.

Comparing the Grain Yields of Direct-Seeded and Transplanted Rice: A Meta-Analysis

Conventional transplanted rice (TPR) has been increasingly replaced by direct-seeded rice (DSR) because of its low water and labour requirements. Whether and how DSR can be as productive as TPR has received widespread attention. Here, a comprehensive meta-analysis was performed to quantify the effects of direct seeding on rice yield and identify the management and environmental factors that contribute to the yield gap between DSR and TPR. The results showed that, overall, the yield of DSR was 12% lower than that of TPR. However, the yield loss of DSR relative to TPR was highly variable depending on management practices, soil type, and climate conditions, ranging from −2% to −42%. Weed and water management and climatic stress had the largest impact on yield performance, resulting in over 15% yield variation. With respect to soil properties, the yield gap can be significantly reduced by planting in areas with high organic carbon content, such as clayed and acidic soils. Furthermore, the DSR yield penalty was only 4% in a high-yielding condition compared to 14% in a low-yielding condition. All these factors indicate that optimizing management practices is necessary to improve DSR yield performance and narrow the yield gap between DSR and TPR. In conclusion, DSR could produce comparable yields to TPR but is more prone to yield losses due to inappropriate management practices, unsuitable soil properties, and climatic stresses.

Effect of dew-irrigation on seed germination in flax, fenugreek, and fennel

Abstract Drought limits plants growth. In many parts of the world, crop productions depend on water availability. Seed germination is a sensitive and low water stage in plants. A pot experiment was designed to test the effect of dew-irrigation on seed germination percentage of fennel, flax, and fenugreek. Irrigation treatments included dew-irrigation and control (non-irrigation). Results showed that dew-irrigation increased seed germination compared to control. Treatment of dew-irrigation had seed germination of 92.7%, 78.7% and 63.5% for flax, fenugreek, and fennel, respectively. But none of the seeds of control treatment germinated. Among plants studied, flax which is a cold season plant had the highest percentage of germination by dew-irrigation, and the plants that are the most heat-sensitive, such as fenugreek and fennel, had the lowest germination percentage. Results of this experiment determined that the moisture content in the air is capable to provide the necessary moisture for seed germination of the plants studied. In conclusion, dew-irrigation, due to supply low water, is better to be used at stages with lower water requirement such as germination. The ability of water supply by dew-irrigation at whole plant stage can be studied in the next experiments.

The crop of desert truffle depends on agroclimatic parameters during two key annual periods

Desert truffles have become an alternative agricultural crop in semiarid areas of the Iberian Peninsula due to their much appreciated edible value and their low water requirements for cultivation. Although most studies related to desert truffle production point to the sole importance of precipitation, this work is the first systematic study carried out to characterize whether other important agroclimatic parameters, for example reference evapotranspiration, soil water potential, relative air humidity %, aridity index or air vapour pressure deficit, may have an impact on a desert truffle production in an orchard with mycorrhizal plants of Helianthemum almeriense × Terfezia claveryi for 15 years from the plantation. The results show for the first time that T. claveryi production has two key periods, during its annual cycle: autumn (September to October) and spring (end of March). The aridity index and soil water potential seem to be the most manageable parameters in the field and can be easily controlled by applying irrigation during the abovementioned periods. Agroclimatic parameters can influence the final crop a long time before the desert truffle fruiting season contrary to what happens with other edible mycorrhizal mushrooms. Four different models to manage desert truffle plantations are proposed based on these agroclimatic parameters in order to optimize and stabilize carpophore fructifications over the years.

Spring safflower water use patterns in response to preseason and in-season irrigation applications

The deep root system of safflower (Carthamus tinctorius L.) is an important adaptive trait under rainfed conditions in semi-arid agriculture. Lower water requirements and ability to tolerate abiotic stresses make safflower a potential alternative crop for the Southern High Plains (SHP). However, information on water extraction patterns of safflower and its role in oil yield formation under center pivot irrigation system that keeps only the surface soil profile wet with frequent irrigations is limited. Therefore, a field experiment was conducted in a split-plot design at Clovis, New Mexico during 2012 and 2013 growing seasons to assess the soil water use patterns, evapotranspiration, and oil yield of two spring safflower cultivars under different preseason and in-season irrigation levels. Half of the experimental units received 164 and 153 mm of preseason irrigation in 2012 and 2013, respectively, while the other half remained unirrigated. Five in-season irrigation levels (I1–I5) ranging from 88 to 392 mm in 2012 and from 83 to 373 mm in 2013 were applied to preseason and no-preseason irrigation blocks. On average, safflower extracted 70 and 28 mm of stored soil moisture in the preseason and no-preseason irrigation treatments, which significantly increased evapotranspiration (ET), water use efficiency (WUE), and oil yield in preseason compared to no-preseason irrigation treatment. Average water extraction decreased with increasing level of in-season irrigation and a decline of 32, 27, and 25% in soil moisture at the end of the season compared to initial soil moisture were observed in I1, I3, and I5, respectively. Since, WUE was not much affected by in-season irrigation treatment in both years, limiting the in-season irrigation level to I4 can save 17% of irrigation with a corresponding 9% reduction in oil yield. The relatively smaller differences were observed for water extraction and WUE among the cultivars. Overall, safflower was able to use preseason irrigation water more efficiently in semi-arid SHP. Growers can pre-irrigate safflower and reduce its in-season irrigation to allocate more water to high water requirement traditional-crops such as corn.

Land suitability assessments for yield prediction of cassava using geospatial fuzzy expert systems and remote sensing

Cassava has the potential to be a promising crop that can adapt to changing climatic conditions in Indonesia due to its low water requirement and drought tolerance. However, inappropriate land selection decisions limit cassava yields and increase production-related costs to farmers. As a root crop, yield prediction using vegetation indices and biophysical properties is essential to maximize the yield of cassava before harvesting. Therefore, the purpose of this research was to develop a yield prediction model based on suitable areas that assess with land suitability analysis (LSA). For LSA, the priority indicators were identified using a fuzzy expert system combined with a multicriteria decision method including ecological categories. Furthermore, the yield prediction method was developed using satellite remote sensing datasets. In this analysis, Sentinel-2 datasets were collected and analyzed in SNAP® and ArcGIS® environments. The multisource database of ecological criteria for cassava production was built using the fuzzy membership function. The results showed that 42.17% of the land area was highly suitable for cassava production. Then, in the highly suitable area, the yield prediction model was developed using the vegetation indices based on Sentinel-2 datasets with 10 m resolution for the accuracy assessment. The vegetation indices were used to predict cassava growth, biophysical condition, and phenology over the growing seasons. The NDVI, SAVI, IRECI, LAI, and fAPAR were used to develop the model for predicting cassava growth. The generated models were validated using regression analysis between observed and predicted yield. As the vegetation indices, NDVI showed higher accuracy in the yield prediction model (R2 = 0.62) compared to SAVI and IRECI. Meanwhile, LAI had a higher prediction accuracy (R2 = 0.70) than other biophysical properties, fAPAR. The combined model using NDVI, SAVI, IRECI, LAI, and fAPAR reported the highest accuracy (R2 = 0.77). The ground truth data were used for the evaluation of satellite remote sensing data in the comparison between the observed and predicted yields. This developed integrated model could be implemented for the management of land allocation and yield assessment in cassava production to ensure regional food security in Indonesia.

Microstructure Evolution in Ordinary Portland Cement–Metakaolin–Red Mud-Based Ternary Blended Cement

The microstructure plays a vital role in governing the physical, chemical and strength properties of cement. Hence, microstructure analysis has been carried out by replacing 0% to 14% of the mass of ordinary Portland cement with metakaolin and red mud of different ratios. Studies have also been carried out to understand the effect of blending on the pH of cement paste and its influence on the setting time. The normal consistency of cement and red mud mix is found to be proportional to the percentage of replaced red mud and is attributed to the presence of finer particles in red mud. The cement paste without any addition has the lowest water requirement (28.5%) compared to the cement with metakaolin and red mud. The study shows that the strength of OPC having 80:20 MK:RM blend is high and is attributed to the pozzolanic reaction of MK and the RM particles which imparts filler effects to the concrete.

Nitrous oxide emission and mitigation from maize–wheat rotation in the upper Indo-Gangetic Plains

Due to its lower water requirement, methane emission and soil degradation, a maize–wheat rotation (MWR) may be a more attractive alternative to rice–wheat rotation (RWR), in the upper Indo-Gangetic plains (IGP) of India. However, N2O emission from MWR needs to be quantified to propose management practices for N2O mitigation. A field experiment was conducted at the Indian Council of Agricultural Research-Indian Agricultural Research Institute (ICAR-IARI), New Delhi, to assess the impacts of various N sources on N2O emission and its mitigation from the MWR. Six treatments –N0 (control), urea, urea + farmyard manure (FYM), FYM, urea + nitrification inhibitor (NI) and neem oil coated urea (NOCU) were investigated during 2012–2014. Results show ranges of N2O-N emissions from MWR of 0.59–0.69, 1.82–1.86, 1.81–1.85, 1.71–1.77, 1.38–1.52, 1.57–1.61 during 2012–2013, and of 0.62–0.68, 1.86–1.90, 1.78–1.84, 1.72–1.76, 1.40–1.46, 1.52–1.60 during 2013–2014, for N0, urea, urea + FYM, FYM, urea + NI and NOCU treatments, respectively. The 2-year pooled N2O-N emission of MWR decreased by 23% in urea + NI and by 16% in NOCU with higher grain yield as compared to conventional urea application. Application of FYM with urea and FYM alone also reduced N2O-N emission; however, the grain yields of these treatments were decreased. Thus, the study suggests that the application of NOCU and NI with urea can mitigate N2O-N emissions from the maize and wheat crops. Hence, the use of NOCU and application of NI with urea could be a better option to mitigate N2O-N emissions from MWR of the upper IGP of India.

Inhibitory potential of prickly pears and their isolated bioactives against digestive enzymes linked to type 2 diabetes and inflammatory response.

Prickly pears are potential candidates for the development of low-cost functional foods because they grow with low water requirements in arid regions of the world. They are sources of betalains and phenolic compounds, which have been reported to contribute to human health. The study of the biological activity of different varieties and of their isolated bioactive constitutes is fundamental in the design of functional foods. In this context, our objective is the assessment of the ability of Spanish and Mexican prickly-pear cultivars to inhibit enzymes related to type 2 diabetes and the inflammatory response, and the contribution of their bioactive compounds to their nutra-pharmaceutical potential. Prickly pear peels presented the highest antioxidant activity due to their high isorhamnetin glycoside content. Isorhamnetin glycosides showed significantly higher antioxidant and anti-inflammatory activity than aglycone, particularly isorhamnetin glucosyl-rhamnosyl-pentoside (IG2), which also reported antihyperglycemic activity. Morada, Vigor, and Sanguinos whole fruits exhibited moderate α-amylase inhibition and higher α-glucosidase inhibition, which is ideal for lowering glucose absorption in hyperglycemia management. Sanguinos peels presented the highest anti-inflammatory activity because of their high indicaxanthin content and isorhamnetin glycoside profile. In the design of prickly pear functional foods, technological processing should prioritize the retention or concentration of these bioactive compounds to preserve (or increase) their natural antioxidant, antihyperglycemic and anti-inflammatory activity. Peels of red and orange varieties should be further evaluated for antioxidant and anti-inflammatory purposes while whole fruits of red and purple varieties could be considered possible candidates for hyperglycemia management. © 2019 Society of Chemical Industry.

Repetitive extraction of botryococcene from Botryococcus braunii: a study of the effects of different solvents and operating conditions

As global temperatures continue to increase the move to renewable energy sources is becoming an essential step in achieving a sustainable future. Biofuels from microalgae, while still more expensive to produce than fossil fuels, are of great interest for the high microalgae biomass growth rates, high lipid content, relatively low water requirements, and ability to be grown on non-arable land. Botryococcus braunii is a freshwater green microalga which grows in colonies supported by an extracellular matrix (ECM) of liquid hydrocarbons. Recent studies have investigated the efficiency of non-destructive in situ solvent extraction of lipids from B. braunii with a variety of solvents. These lipids are encapsulated in a retaining wall coated by a sheath of amphiphilic fibrils which have been found to act as a barrier to solvents. By carrying out repeated in situ solvent extraction in a high shear environment, we found that access to the ECM can be significantly improved. Sustainable botryococcene and total lipid productivities respectively of 29.9 ± 8.5 and 71.3 ± 20.3 mg L−1 day−1 were achieved with heptane extraction, a shear rate of 415 s−1, initial culture density of 1.62 ± 0.12 g L−1, contact period of 4 h, and a recovery period of 3 days. Nutrient supplementation to replace those lost in the emulsion entrained biomass will be required to maintain a sustainable process. The combined presence of heptane with high shear proved to be an effective colony disruption method which could be an effective pre-treatment followed by a low shear, high solvent contact, and extraction method.

Microfiltration: A novel technology for removal of trub from hopped wort

AbstractRemoving hot and cold trub from hopped wort is important, because of yeast viability, beer filtration, quality and fermentation in Membrane Bioreactor. Trub can be removed by several methods, but Crossflow Microfiltration (CFMF) would be an alternative technology. For the filtration a wort was produced. The filtration was performed with the following parameters: temperature (10 ± 1°C), Transmembrane Pressure (0.4 bar), and Crossflow Velocity (0.4 m s−1). Membrane with pore size of 0.2 μm was applied. The fluxes were determined. Particle size distributions and analytical parameters of samples were measured and retentions were calculated. The initial and steady‐state fluxes were 16.75 and 4.89 L m−2 hr−1. According to the particle size distributions trub can be removed. Changing of the analytical parameters is appropriate, for example, retention of β‐glucan was 40.17% and Free Amino Nitrogen content did not change. CFMF is an alternative method for removing trub, but the optimization is essential.Practical applicationsCrossflow Microfiltration (CFMF) would be an alternative and novel technology for removal of hot trub and cold trub from hopped wort and the two processes can be performed simultaneously with the same CFMF equipment. The main advantages of the CFMF are less solid residues, lower energy consumption, lower water requirements, and microbiologically stable product.Our research has several practical applications as mentioned below.First removing at least some hot trub can decrease the production losses and improve yeast viability, beer filtration performance and the quality of finished beer, and removing at least some cold trub can improve yeast viability and the quality of finished beer.Furthermore, if primary fermentation is performed in Membrane Bioreactor (MBR), wort particles (e.g., cold trub) can cause fouling.Finally, it has been proven that hot trub and cold trub can be completely removed by CFMF and the changing of the analytical parameters is appropriate.

Enhancing Scenedesmus obliquus biofilm growth and CO2 fixation in a gas-permeable membrane photobioreactor integrated with additional rough surface

Microalgae biofilm photobioreactors (PBRs) have been gaining more and more attention worldwide attributed to their advantages of lower water requirement and simpler harvesting process. In this work, aiming at enhancing microalgae biofilm growth and gas-liquid mass transfer based on previous biofilm PBRs, a gas-permeable membrane PBR integrated with additional rough surface (GMPBR-RS) was designed. By attaching an additional piece of stainless steel mesh onto the upper surface of the newly prepared gas-permeable membrane, the roughness of the substratum surface for Scenedesmus obliquus biofilm adhesion was enhanced and therefore resulted in a 28.27% improvement in areal biomass density of S. obliquus relative to the control PBR. Moreover, responses of S. obliquus biofilm adsorption growth and CO2 fixation in the GMPBR-RS to various liquid flow rates and gas flow rates were investigated. Notably, the maximum areal biomass density of S. obliquus biofilm and CO2 removal efficiency of the GMPBR-RS reached 31.44 g m−2 and 65.05%, respectively.

Nuevos datos sobre la distribución de mamíferos (Mammalia) en las dunas de Erg Chebbi (Marruecos)

El progresivo aumento del turismo de aventura en el entorno de las dunas de Erg Chebbi, amenaza, desde hace casi dos décadas, la conservación del único complejo dunar (Erg) de todo Marruecos. Con el propósito de valorar algunos de los efectos de esta actividad sobre la comunidad de mamíferos locales, entre marzo y abril de 2018 se llevó a cabo un muestreo intensivo utilizando 5 métodos de detección distintos. El objeto principal era evaluar la presencia y distribución actual de las especies de mamíferos presentes, teniendo como referencia las citadas en la zona desde 1900 (Aulagnier et al., 2017). De las 16 especies históricamente citadas, 9 han sido detectadas en el presente trabajo, lo que representa un 56.2%. Resulta de interés la ausencia total de datos sobre 5 de las especies potencialmente más abundantes como son: Gerbillus amoenus (de Winton, 1902), Gerbillus gerbillus Olivier, 1801, Gerbillus tarabuli (Thomas, 1902), Pachyuromis duprasi Lataste, 1880 y Psammomys obesus Cretzschmar, 1828. Algunos datos apuntan a la drástica reducción de los recursos hídricos experimentada en los últimos años, como una de las causas de la aparente reducción de sus poblaciones. Al mismo tiempo, otras especies de requerimiento hídricos menores, tales como: Meriones libycus Lichtenstein, 1823 o Jaculus jaculus Linnaeus, 1758, presentan un aparente buen estado de conservación. Se confirma la presencia de Poecilictis libyca Hemprich & Ehrenberg, 1833, tras 32 años de ausencia de datos.

Centrifugal unit of combined method of grinding for mechanoactivation of technogenical materials

Analysis of the raw material resources of the Russian Federation has shown that the most large-tonnage raw material is the waste of wet magnetic separation (WMS), formed during the beneficiation of ores. A complex of studies on the use of WMS wastes showed that their most effective use is to mechanically activate a mixture of wastes and cement and to prepare a new class of binders — finely ground multi-component cements and binders with low water requirements. To carry out complex experimental studies, taking into account the existing requirements, an experimental centrifugal grinding unit (CGU) with specified trajectories of the grinding chambers was chosen. The developed grinder is intended for mechanical activation of fragile materials with different physical and mechanical properties by the combined method of grinding (dry and wet), both in periodic and in continuous modes. Analysis of the results of experimental studies indicate the effectiveness of the use of centrifugal grinding unit for the wet method of grinding and also allow us to conclude about the significant superiority of wet grinding for the production of fine raw materials.

Taking the climate risk out of transplanted and direct seeded rice: Insights from dynamic simulation in Eastern India

Rice productivity in Eastern Indo-Gangetic plains (EIGP) is extremely low, in part due to the prevailing practice of cultivating long-duration transplanted rice under rainfed conditions which leads to water stress and significant yield losses in many seasons. Rice establishment alternatives such as direct seeded rice (DSR) require less water at planting but also are accompanied by climate risks that constrain adoption. For both conventional transplanted and DSR systems, successfully addressing climate-based production risks may provide a strong basis for sustainable rice intensification in EIGP. In this ex ante study of rice yield and yield variability, the APSIM cropping system model was used to evaluate the efficacy of risk-reducing management practices in both transplanted and DSR systems. Simulations were conducted with 44 years (1970–2013) of historical weather data from central Bihar, India. Results confirm that the prevailing farmer practice of transplanting long-duration cultivars under rainfed conditions (fTR) often results in delayed transplanting and the use of older seedlings, leading to low (median 1.6 t ha−1) and variable (Standard deviation (SD) 2.1 t ha−1) rice yields. To improve the fTR system, simulations suggest that adoption of medium-duration hybrid rice (3.2 t ha−1), provision of supplemental post-establishment irrigation (3.2 t ha−1), or transplanting appropriately aged seedlings (3.4 t ha −1) can double yields as single interventions while, in the case of supplemental irrigation, significantly reducing inter-annual production variability. Additional gains are achievable when interventions are layered: supplemental irrigation paired with medium-duration hybrids increased median rice yields to 4.6 t ha−1 with much lower variability (SD 1.0 t ha−1). In these improved systems where irrigation is used to transplant the crop, simulations revealed the importance of timely planting: high and stable yields are achievable for long-duration cultivars when transplanting is completed by 2 August with this window of opportunity extending to 16 August for medium-duration hybrids. In rainfed DSR systems, the potential pay-offs from single interventions were even higher with medium-duration hybrids resulting in a median yield of 4.5 t ha-1 against 1.8 t ha−1 with long-duration cultivars. For irrigated DSR systems, an optimum sowing window of early to mid-June was identified which resulted in higher and more stable yields with lower water requirements. Simulation results suggest several risk-reducing intensification pathways that can be selectively matched to farmer risk preferences and investment capabilities within the target region in EIGP.

The Properties of Blended Cement Containing Palm Oil Fuel Ash

Burning of the palm oil fibres and palm oil shells at the palm oil plantation mill has generated abundant amount of palm oil fuel ash (POFA). Recycling and reuse of POFA through thermal activation to produce a new Portland POFA cement (PPC) is one alternative that can be proposed to reduce the environmental problems due to improper POFA disposal. This paper reports on the chemical and physical properties, and the pozzolanic reactivity of POFA heated at 700°C for 1 hour, which interground and blended together with the Ordinary Portland Cement (OPC) in order to produce the PPC cement at 20, 40, and 50% of POFA replacement level. To investigate the physical and chemical properties of the PPC, the specific gravity, soundness, density, and LOI tests were conducted. The flowability and compressive strength were also determined to identify its effect on the pozzolanic reactivity. The results showed that the PPC has high compressive strength due to its high pozzolanic reaction. The flowability is higher than the OPC, signifying that PPC has low water requirement. The compressive strength and pozzolanic reactivity increased with increasing of TGP content (up to 50%). The findings showed that there is a possibility of using POFA in producing blended POFA cement which is environmental green product for use in the concrete construction.

The effect of cow manure application and watering interval on patchouli growth in regosol soil

Soil has an important role for plants, aside for a growing medium and rooting, it also provides water, air, and nutrients. The types of soil affect plant growth and development. Regosol is one type of soil, which has a coarse grain texture and low capacity of water and mineral holding, and widely used for plants with relatively low water requirement. The purpose of the study was to examine the effect of cow manure and watering on patchouli (Pogostemon cablin Benth) growth on regosol soil. This study used factorial Complete Randomized Block Design (CRBD), with cow manure fertilizer dose as first factor (0, 500, and 1000 g/plant) and watering interval (every day, 2, 4, 6, and 8 days) as second factor; each treatment combination have three replications. The results showed that the application of cow manure combined watering intervals did not affect patchouli growth, but each manure treatment or watering interval independently affected plant height, number of branches, number of leaves, fresh weight of roots, fresh weight of leaves and branches, total fresh weight, root dry weight, leaf and branch dry weight, and patchouli total dry weight within 22 weeks after planting.

Genetic Diversity and Population Structure of a Camelina sativa Spring Panel.

There is a need to explore renewable alternatives (e.g., biofuels) that can produce energy sources to help reduce the reliance on fossil oils. In addition, the consumption of fossil oils adversely affects the environment and human health via the generation of waste water, greenhouse gases, and waste solids. Camelina sativa, originated from southeastern Europe and southwestern Asia, is being re-embraced as an industrial oilseed crop due to its high seed oil content (36–47%) and high unsaturated fatty acid composition (>90%), which are suitable for jet fuel, biodiesel, high-value lubricants and animal feed. C. sativa’s agronomic advantages include short time to maturation, low water and nutrient requirements, adaptability to adverse environmental conditions and resistance to common pests and pathogens. These characteristics make it an ideal crop for sustainable agricultural systems and regions of marginal land. However, the lack of genetic and genomic resources has slowed the enhancement of this emerging oilseed crop and exploration of its full agronomic and breeding potential. Here, a core of 213 spring C. sativa accessions was collected and genotyped. The genotypic data was used to characterize genetic diversity and population structure to infer how natural selection and plant breeding may have affected the formation and differentiation within the C. sativa natural populations, and how the genetic diversity of this species can be used in future breeding efforts. A total of 6,192 high-quality single nucleotide polymorphisms (SNPs) were identified using genotyping-by-sequencing (GBS) technology. The average polymorphism information content (PIC) value of 0.29 indicate moderate genetic diversity for the C. sativa spring panel evaluated in this report. Population structure and principal coordinates analyses (PCoA) based on SNPs revealed two distinct subpopulations. Sub-population 1 (POP1) contains accessions that mainly originated from Germany while the majority of POP2 accessions (>75%) were collected from Eastern Europe. Analysis of molecular variance (AMOVA) identified 4% variance among and 96% variance within subpopulations, indicating a high gene exchange (or low genetic differentiation) between the two subpopulations. These findings provide important information for future allele/gene identification using genome-wide association studies (GWAS) and marker-assisted selection (MAS) to enhance genetic gain in C. sativa breeding programs.

Rainfall and its distribution influences on rain-fed saffron yield and economic analysis

Spatial and temporal variability of precipitation events and rainfall depth are the major uncontrolled inputs in planting rain-fed crops and the prediction of their annual yield. Saffron (Crocus sativus L.) is a strategic crop in Iran and due to its low water requirement and high income is considered in sustainable agricultural strategies. This study was carried out using a dataset from an 8-year rain-fed saffron experiment conducted in Bajgah region (Fars province), Iran. The objective was to determine the effects of annual rainfall, its distribution, and air temperature on saffron yield, and to determine the critical rainfall periods for rain-fed saffron yield. Also, economic analysis was considered for the saffron yield in the study region. Results showed that saffron yield cannot be predicted with adequate accuracy by the annual rainfall. Instead, fall and winter seasonal indices and annual index can be used to predict the rain-fed saffron yield when combined with saffron age and mean maximum daily air temperature in the given season. Results also indicated that rain-fed saffron yield is reversely related to the maximum daily air temperature in winter since warm winter causes the leaves to wither earlier and shortens the vegetative growth period. Internal rates of return for interest rates of 4, 8, and 12% were 30.9, 56.7, and 95.9% respectively which is economically feasible for rain-fed saffron production in the study area.

Simulation of efficient irrigation management strategies for grain sorghum production over different climate variability classes

The Texas High Plains (THP) is a productive agricultural region, and it relies heavily on the exhaustible Ogallala Aquifer for irrigation water for crop production. Efficient use of irrigation water is critical for the sustainability of agriculture in the THP. Grain sorghum is one of the major crops grown in the region, and it is known for its drought tolerance and lower water requirement compared to other cereal crops such as corn. In this study, the CERES-Sorghum and CROPGRO-Cotton modules of the Decision Support System for Agrotechnology Transfer (DSSAT) were evaluated using data from cotton-sorghum rotation experiments at Halfway, Texas over a period of nine years (2006–2014). The evaluated CERES-Sorghum model was then used to identify the optimum (i) initial soil moisture at planting (ISM); (ii) threshold to start irrigation (ITH); (iii) threshold to terminate irrigation; and iv) deficit/excess (DFI) irrigation strategy for grain sorghum production based on simulated sorghum yield, irrigation water use efficiency (IWUE), and grain water use efficiency (WUE). In addition, the effect of weather conditions on simulated strategies was elucidated by dividing the long-term (1977–2016) weather data into cold, warm, wet, dry, and normal climate variability classes based on the 33rd and 66th percentiles of growing season temperature and precipitation. The DSSAT model adequately simulated the grain sorghum and seed cotton yields during calibration (average Percent Error (PE) of 1.3% (sorghum) and 3.4% (cotton)) and evaluation (average PE of −2.2% (sorghum) and −10.5% (cotton)). The results from long-term simulations indicated that weather conditions played a key role in selecting appropriate irrigation management strategies. Under normal/cold/wet weather, ISM of 75% available water holding capacity (AWC), ITH of 50%, and DFI 85% were found to be adequate for irrigated grain sorghum production. However, in warm/dry weather, ISM of 75%, ITH 60%, and DFI at 100% reduced sorghum yield loss.