Hamid Reza Eshghizadeh

Climate change significantly affects the water use efficiency (WUE) and yield of field crops. This study evaluates the impacts of climate change on biological yield, grain yield, water consumption, and WUE of two barley genotypes, Goharan and Reyhan 03, under autumn and spring planting regimes using the CERES-Barley model within the Decision Support System for Agrotechnology Transfer (DSSAT) software. Data provided for model calibration and validation were sourced from the field experiments conducted at the Isfahan University of Technology research farm located in Najafabad, Iran. Meteorological data for the period of 2003 to 2016 were obtained from the Najafabad weather station, while future climate projections for 2020–2050 were generated using the MarkSim weather generator under the Representative Concentration Pathway (RCP) 8.5 scenario. Planting dates were analyzed within a ±35-day window relative to baseline dates of October 22 for autumn and March 3 for spring. The model demonstrated high accuracy in calibrating key traits, including days to anthesis, days to maturity, leaf area index, grain yield, and biological yield. Elevated temperatures associated with climate change reduced grain and biological yields across both planting seasons, with biological yield exhibiting a more pronounced decline, particularly under spring planting. During the 2040–2050 period, water consumption peaked at 387.5 mm for Goharan in autumn planting, while spring planting recorded a minimum of 239 mm for Reyhan 03. Delaying autumn planting by 20–25 days enhanced WUE, while planting earlier in the spring )10–20 days (improved WUE by exploiting cooler temperatures. Evapotranspiration increased by 399 mm in autumn but decreased by 267 mm in spring. The earlier-maturing Reyhan 03 genotype demonstrated smaller yield losses in spring planting due to climate change. The findings of this study suggest that programmed adjustments to planting dates may mitigate the adverse impacts of climate change on barley production, thereby enhancing sustainability.

Milk thistle ( Silybum marianum L.) is highly valued for its medicinal properties. It is renowned for its capacity to flourish in dry environments, making it an attractive option for farming in areas with scarce water resources. This study aimed to assess how drought stress, foliar potassium sulfate application, and their interaction affect different milk thistle genotypes. Ten different genotypes (nine Iranian and one Hungarian) were assessed under three levels of soil water availability including control, moderate, and severe water stress, with depletion rates of 40%, 60%, and 80% of available water, respectively. Also, two foliar treatments were applied (non‐spray and K ₂ SO ₄ spray). Foliar K ₂ SO ₄ application was applied twice, 7 days apart, during the flower bud development stage, using a 2% concentration in both 2020 and 2021. Drought stress adversely affected physiological parameters such as relative leaf water content and photosynthetic efficiency but enhanced antioxidant enzyme activities and osmotic adjustment mechanisms. K ₂ SO ₄ foliar application exhibited dual effects, increasing yield while reducing key bioactive compounds including phenol and flavonoids content of seeds. Genotype‐specific responses highlighted varying degrees of tolerance to drought stress and potassium application. Sari exhibited sensitivity to drought, while Isfahan and Hungary genotypes showed tolerance to moderate water stress with potassium foliar spray. Principal component analysis revealed the relationship of traits and genotypes by traits in each moisture condition. The study underscores the complexity of drought response mechanisms and the need for tailored management strategies and genotype selection to ensure resilience and optimize yield in milk thistle cultivation.

This study aimed to investigate vetch genotypes’ responses to moderate and severe drought stress and identify stress tolerance markers in arid conditions. Ten vetch genotypes (Vicia dassycarpa Ten., V. pannonica Crantz., V. michauxii Spereng., V. sativa-Ardebil, V. sativa-Dashtyar, V. sativa-Fereydonshahr, V. sativa-Mashhad, V. sativa-Semirom, V. sativa-Shahrekord and V. villosa Roth.) were cultivated under three water-deficit conditions: control, moderate and severe drought stress. These conditions represented maximum allowable depletion levels of 30, 50 and 85% of soil available water, applied after the six-leaf stage in the 2019–20 and 2020–21 growing seasons. The findings highlight the vetch's response to drought stress is influenced by stress severity and genotype. The result indicated a wide range of genetic diversity in agro-physiological traits among the studied vicia germplasm. Vicia dassycarpa Ten. shows highest straw yield and shorter days to flowering and maturity. Vicia michauxii Spreng. demonstrates high grain yield and advantageous traits like increased water content, photochemical efficiency of photosystem II, chlorophyll b, carotenoids and membrane stability index. It has lower soluble carbohydrate, DPPH (2,2-diphenyl-1-picrylhydrazyl) and proline content. Additionally, V. michauxii Spreng. exhibits superior agronomic traits such as more seeds per pod, per plant and higher 1000 seeds weight, serving as reliable markers for drought tolerance. The results emphasize V. dassycarpa Ten. for fodder and V. michauxii Spreng. for grain production in water-limited regions. Further research on gene expression related to drought tolerance traits should enhance our understanding of vetch.

Barley (Hordeum vulgare L.) is a crucial cereal crop globally, and its productivity is influenced by environmental factors, including elevated carbon dioxide (CO₂) levels and water stress. The aim of this study is to investigate the effects of water stress and increased CO₂ concentration on the growth, physiological responses, and yield of two-row and six-row barley genotypes. Univariate data analysis revealed significant effects of CO₂ concentration on most traits except chlorophyll a (Chla), crop antioxidant capacity as evaluated by the activity of plant extracts to scavenge the 2,2-diphenyl-1-picrylhydrazyl (DPPH), and on the maximum quantum yield of photosystem II (Fv/Fm). Mean comparisons showed that elevated CO₂ increased certain traits such as shoot dry weight (ShDW) (34.1%), root dry weight (RDW) (50.8%), leaf area (LA) (12.5%), grain weight (GW) (64.1%), and yield-related traits and combination of significant indices (CSI) (72.5%). In comparison, Proline (−19.3%), Malondialdehyde (MDA) (−34.4%) levels, and antioxidant enzyme activities, including ascorbate peroxidase (APX) (−39.1%), peroxidase (POX) (−26.1%), and catalase (CAT), (−34.4%) decreased. Water stress negatively affected ShDW (−40.2%), GW (−43.7%), RDW (−28.5%), and LA (−28.8%), while it positively affected DPPH (36.0%), APX (54.8%), CAT (85.1%), and MDA (101%). Six-row barley genotypes (Goharan and Mehr) had the highest yield under normal humidity and elevated CO₂ concentrations, while under water stress conditions, their yield decreased more than two-row genotypes (Behrokh and M9316). Principal component analysis and heatmapping revealed that two-row barley genotypes exhibited the highest stress resistance under elevated CO₂ concentrations, with the highest levels of secondary metabolites.

The experiment was completed to evaluate the responses of forage yield and silage quality of dual-purpose corn hybrids to urea fertigation. For this purpose, two studies were conducted each as a split plot experiment based on a randomized complete block design with three replications at two locations in research farms of College ...