Agrosystems, Geosciences & Environment最新文献

The use of conventional tillage practices in crop production systems has led to a significant soil loss in many regions of Iran. Conservation tillage practices can help restore the degraded soils. A 2-year experiment was conducted in an irrigated corn (Zea mays L.) cropping system during the 2014–2016 growing seasons on a silty clay soil with a Mediterranean climatic condition. The experiment was carried out as a split plot based on a randomized complete block design with three replications. The main factor was the tillage system in three levels (conventional tillage, reduced tillage, and no tillage), and the sub-factor was the corn hybrid including KSC704, AS71, BC678, and Simon. Results showed that the surface layer of the soil (0- to 20-cm depth) was more affected by tillage systems, so that conservation tillage systems (reduced and no tillage) improved physical (including soil moisture contents at field capacity and permanent wilting points, the amount of water-dispersible clay, and mean weight diameter of the soil aggregates), chemical (including the amount of soil organic carbon, cation exchange capacity, total nitrogen, phosphorus, potassium, and iron), and biological (including microbial biomass carbon, basal and substrate-induced respiration, metabolic quotient, and the activity of soil extracellular enzymes) properties of the soil. For example, soil organic carbon under no and reduced tillage systems was higher by 28% and 22%, respectively, compared to conventional tillage. In general, the results revealed that tillage practices even in a relatively short-term period can notably affect soil characteristics.

Common bean (Phaseolus vulgaris L.) is an essential legume crop in Ethiopia with the potential to contribute to the agricultural system and food security. Since limited productivity is one of the main problems in the study region, stability analysis is essential to enhance productivity by identifying superior genotypes. Thus, this study was conducted to identify common bean genotypes that perform best and are stable at diverse agroecologies. The experiment was carried out on twenty-five small-seeded genotypes grown at four agroecologies for 2021–2022, using a triple lattice design. Evaluation was conducted on nine quantitative traits related to yield. To analyze the performance and stability of the genotypes, analysis of variance (ANOVA), AMMI (additive main effects and multiplicative interaction), AMMI stability value (ASV) rank, WAASB (weighted average of absolute scores biplot), genotype selection index (GSI), and GGE biplot analysis were used. The ANOVA revealed highly significant (p < 0.001) effects of genotypes, environment, and genotype-by-environment interaction for all traits, except the nonsignificant environmental effect for plant height and hundred seed weight. The result of AMMI indicated that Alemtena and Negele Arsi were stable environments and identified G22, G24, and G21 as stable genotypes. However, the GGE identified the mega-environments and best yielding common bean for each environment. The other statistical model, WAASB, identified Mieso as the most representative and discriminating environment, and GSI considered G11, G21, and G24 as desirable genotypes. Both AMMI and ASV identified G18, G21, and G24 as stable genotypes across the tested areas and are recommended for mega-environment production, and Alemtena as an ideal location for the selection of common bean genotypes, since it shows high representativeness and discrimination ability.

Sorghum [Sorghum bicolor (L.) Moench] is an important crop in Ethiopia, especially in lowland areas where drought stress is a major issue. Despite its tolerance, sorghum is susceptible to water-deficit stress during certain growth stages. To identify drought-tolerant genotypes and traits/mechanisms contributing to drought tolerance, a study evaluated 225 sorghum genotypes and assessed the variability, heritability, and genetic advance of these traits using a simple lattice design under stress and non-stress conditions. The analysis revealed significant differences in all traits under both conditions. Drought had a notable impact on various aspects of plant growth, including flowering, maturity, grain yield, and physiological traits such as chlorophyll content and canopy temperature. The study also found moderate to high genetic variation, genetic advance, and heritability for grain yield per panicle, panicle weight, plant height, panicle length, straw yield, and aboveground biomass under both environments. Additionally, grain yield had a positive correlation with 1000-kernel weight, aboveground biomass, harvest index, and grain yield per panicle under both conditions. These traits therefore deserve more attention in future breeding programs aimed at developing drought-tolerant sorghum varieties. The study underlined that morpho-physiological diversity in the studied material is shaped by genotypes, and it could be utilized for variety development and germplasm conservation programs aimed at improving drought tolerance in sorghum.

The performance of the cover system, used in the reclamation of a mine site, is primarily assessed through hydraulic properties, including volumetric water content, suction, and saturated hydraulic conductivity (k_sat). However, these properties may be influenced by factors such as soil mineralization (which refers to the process by which organic materials are converted into inorganic substances through natural processes), temperature (by the viscosity of water and the activity of microorganisms in the soil), and organic matter content (OMC), which complicate the accurate assessment of cover system performance. To better understand the impact of OMC on hydraulic properties, this study was initiated with two objectives: (i) evaluating the effect of OMC on the water retention curve (WRC) and k_sat of a sandy material amended with peat and (ii) proposing equations to predict the WRC of sand amended with organic matter using the Fredlund and Xing model. This was accomplished through laboratory tests that determined the WRC and k_sat of sand and sand amended with varying concentrations of peat (0%, 1%, 3%, 5%, 7.5%, 10%, 12.5%, and 15%). The investigation results indicate the air entry value (the suction at which the material begins to desaturate) evaluated using the sand mixture WRC did not show any notable variation. The k_sat of the sand mixtures decreases with increasing peat concentration. In terms of prediction, the results obtained for the six mixtures tested in the laboratory showed an excellent agreement between predicted and experimental values, demonstrating the high accuracy with which the WRC s were predicted.

Drought stress is a significant environmental factor affecting sesame (Sesamum indicum L.) yield and quality. This study was conducted as a split-plot factorial experiment in a randomized complete block design with three replications at two experimental sites: Zabol and Iranshahr in two arid locations in southeastern Iran, Sistan and Baluchestan province, Iran. The main plot factor was drought stress, with three irrigation levels: a1 (regional irrigation), a2 (irrigation cessation at 50% flowering stage), and a3 (irrigation cessation at 50% podding stage). The subplot factors were sesame cultivars (Halil, Dashtestan, and Darab) and four zeolite application rates (0, 3, 6, and 9 tons/ha mixed with the soil before sowing). The studied traits included plant height, number of capsules per plant, number of seeds per capsule, 1000-seed weight, seed yield, biological yield, harvest index, and antioxidant enzymes. The highest plant height (111.38 cm) was observed for the Dashtestan cultivar in Zabol under non-stress conditions with 9 tons/ha zeolite application. The highest number of capsules (42.1) and biological yield (3.92 tons/ha) were obtained from Zabol under non-stress conditions with 9 tons/ha zeolite application and the Darab cultivar. The highest number of seeds per capsule (69.96), 1000-seed weight (3.63 g), and seed yield (1.53 tons/ha) were obtained from Iranshahr under non-stress conditions with 9 tons/ha zeolite application and the Halil cultivar. Additionally, the highest activities of catalase, ascorbate peroxidase, guaiacol peroxidase, and polyphenol oxidase were obtained under severe stress conditions (irrigation cessation at 50% flowering stage) without zeolite application in Iranshahr with the Halil cultivar. The highest oil percentage was obtained under non-stress conditions with 9 tons/ha zeolite application and the Darab cultivar in Iranshahr. Zeolite application, particularly at 9 tons/ha, significantly improved seed yield, oil content, and antioxidant enzyme activities under moderate drought (p < 0.05). Among cultivars, Halil demonstrated superior performance under stress conditions, showing higher catalase and peroxidase activity. These findings highlight the potential of using zeolite and drought-tolerant cultivars to enhance sesame productivity in water-limited environments.

Ammonia (NH₃) volatilization reduces fertilizer use efficiency and increases environmental nitrogen (N) loss when urea ammonium-nitrate (UAN) is surface-applied. Volatilization is driven by localized pH increases resulting from the rapid hydrolysis of large quantities of urea. We hypothesized that nozzles that concentrate UAN in narrow bands would produce greater volatilization than nozzles that broadcast UAN widely. The effect of three nozzle types (dribble band, three-hole streamer, and flat fan) was evaluated in field trials conducted in 2012 and 2013 in Elora, ON, Canada. UAN was surface applied at 168 kg N ha⁻¹ (2012) or 112 kg N ha⁻¹ (2013) onto bare soil multiple times each season. In 2013, UAN was also applied with or without a urease inhibitor (UI) as an additional treatment. Volatilization was measured for 20–34 days after UAN application using the Dosi-Tube method. In 2012, volatilization was overall low (mean = 12.9 kg N ha⁻¹), and nozzle type did not affect volatilization. In 2013, a year with greater overall volatilization even with UI use (mean = 36.3 kg N ha⁻¹), flat fan nozzles reduced NH₃ volatilization relative to dribble bands by 22% (p = 0.048). Volatilization from the three-hole streamer nozzle was not different from either nozzle type. The magnitude of the nozzle type effect on volatilization varied across application dates in 2013, likely due to weather variation during the measurement period. The findings suggest that UAN application methods that reduce urea concentration in the soil solution can lead to modest but inconsistent reductions in volatilization.

Water mint (Mentha aquatica L.) is a medicinal plant with significant therapeutic potential for treating a wide range of diseases. Due to its ability to grow in various geological environments, this study aimed to determine the morphological and phytochemical variability of water mint populations in Northern Iran. Identical and equally sized rhizomes of ten water mint populations were collected from their natural habitats and then cultivated at an experimental farm site in Mazandaran province. The root and stem diameters of most populations were not significantly different. The leaf size varied between populations, with three (Marzonabad, Lafoor, and Hassanabad) exhibiting smaller leaves than the others. The populations with smaller leaf sizes demonstrated a higher leaf number. The highest antioxidant potential was observed in Hassanabad (40 m) and Kia-kola (10 m), with the lowest IC50, while the maximum essentical oil (EO) percentage was found in Balamarznak (250 m). The gas chromatography and gas chromatography/mass spectrometry identified 30 components of EOs, and the main compounds were 1,8-cineol (10.7–27.5%), menthofuran (1.4–17.7%), trans-caryophyllene (1.7–15%), germacrene D, and viridifloro (0–8.08%). Four chemotypes of water mint were distinguished based on biochemical features. Principal component analysis and heat map analysis revealed that leaf size and 1,8-cineol exhibit the minimum variability. However, smart and sensitive morphological traits with the maximum variability were root weight, shoot weight, and the number of leaves and branches. In general, water mint populations with the highest antioxidant capacity and EO content can be obtained within the altitudinal gradient range of 250–300 m.

Drought-tolerant (DT) maize (Zea mays L.) hybrids have demonstrated better performance than non-DT hybrids when drought events are present. The objective of this study was to assess the performance of three DT maize hybrids for whole-plant dry matter (DM) and grain yield and forage nutritive value under conventional or Kura clover (Trifolium ambiguum M. Bieb.) perennial groundcover (PGC) cropping systems. This study was conducted for 3 years at two locations, Arlington and Lancaster, WI. Three DT and one non-DT maize hybrid were no-till sown into killed Kura clover (conventional) and living Kura clover that was suppressed with herbicides (PGC). Whole-plant maize, as for silage, was harvested at 50% kernel milk line, and grain was harvested at physiological maturity. Whole-plant biomass was analyzed for forage nutritive value. There was no cropping system × maize hybrid interaction for any of the measured yield or nutritive value parameters. Maize hybrids in the Kura clover PGC system yielded 3.0 Mg ha⁻¹ less whole-plant DM and 1.5 Mg ha⁻¹ less grain than in the conventional system, but whole-plant forage digestibility was slightly greater with the PGC system. DT hybrids yielded slightly less than the non-DT hybrid over both production systems. The DT hybrids demonstrated no advantage relative to a non-DT maize hybrid in a Kura clover PCG system.

Drought stress severely limits corn production, particularly in arid and semi-arid regions, where erratic climate continues to increase the frequency of water scarcity. Super sweet corn (Zea mays L. var. saccharata) is especially vulnerable due to its reduced starch reserves caused by mutations in the shrunken-2 (sh2) gene, which encodes the large subunit of ADP-glucose pyrophosphorylase (AGPase), a key enzyme in starch biosynthesis. This study aimed to evaluate the expression of the sh2 gene under water-limited conditions in two super sweet corn inbred lines recently incorporated into breeding programs: a drought-tolerant line (MCH87002/19-1) and a drought-sensitive line (MCH87004/23-1). The experiment was conducted in 2020 at the Khorasan Razavi Agricultural and Natural Resources Research and Education Center under controlled greenhouse conditions in Mashhad, Iran. Real-time polymerase chain reaction revealed that water-limited stress significantly downregulated sh2 expression in the drought-tolerant line (0.63-fold; p = 0.023), indicating a potential energy-saving strategy under stress. This downregulation was associated with reduced AGPase activity and limited starch biosynthesis. Conversely, sh2 expression in the drought-sensitive line remained unchanged (0.97-fold; p = 0.892), suggesting a lack of transcriptional response to water-limited conditions. These findings highlight the potential of sh2 as a molecular marker for breeding drought-resilient super sweet corn. Integrating sh2 expression profiles into breeding programs could facilitate the development of genotypes that balance sugar content and stress adaptation, contributing to sweet corn productivity in semi-arid environments.

The demand for medium-grain rice (Oryza sativa L.) in the United States is increasing; therefore, developing high-yielding, high-grain quality, and abiotic stress-tolerant medium-grain rice is crucial to meet the rising demand. In this study, medium-grain rice mutants were developed by irradiating long-grain Presidio rice cultivar. The long-grain Presidio and its 76 sixth-generation (M₆) medium-grain mutants were genetically characterized using single-nucleotide polymorphisms (SNPs) associated with 10 traits related to grain quality, grain filling, and abiotic stress tolerance-. Out of the 76 M₆ Presidio mutants genotyped, 57 mutants homozygous for the medium-grain allele (GG) of GS3 were selected for further analysis. All mutants and the wild-type Presidio had the OsISA1 allele (Ex17GG) for low chalkiness. The In1T/G, Ex6A/C, and Ex10C/T SNPs of the Wx locus subdivided the mutants into low- and intermediate-amylose classes. Ex10C/T SNP was used to categorize into either soft or hard gel with weak or strong pasting viscosity. The Ex8C/T SNP of SSIIa classified the mutants into two groups (low and intermediate) based on their gelatinization temperatures. Five promising medium-grain Presidio mutants (TIL21271-7-2, TIL21271-7-4, TIL21271-7-5, TIL21271-7-6, and TIL21271-7-8) with high grain filling rate allele of GFR1 and favorable alleles for qSCT1 and OsLPTL159 (cold tolerance), TT1 (heat tolerance), qAG1 and qAG3 (anaerobic germination tolerance), and qDTY1.1, qDTY3.2, and qDTY12.1 (drought tolerance) were identified. This study demonstrates the high potential of mutation breeding in developing mutants with favorable alleles on genes for grain yield, quality, and stress tolerance.