Agrosystems, Geosciences & Environment最新文献

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.

With declining of the Ogallala Aquifer in the Central High Plains, cotton (Gossypium hirsutum L.) has emerged as a low-water-demanding alternative to corn (Zea mays). However, cotton harvest leaves minimal cover on the soil surface following harvest due to application of harvest aids. Planting cover crops following cotton harvest is not always viable as it often leaves insufficient time for establishing covers due to cold and dry conditions in the region. Seeding cover crops in standing cotton may be a viable option; however, the effect of harvest aids on these covers remains unknown. This study evaluates the response of cover crops winter pea (Pisum sativum), triticale (Triticosecale rimpaui Wittm), hairy vetch (Vicia villosa), black oats (Avena sativa), crimson clover (Trifolium incarnatum), and rapeseed (Brassica napus L.) to different cotton harvest aids (DFT-6EC and AIM). The crops were grown in pots in climate-controlled chambers and green cover was measured weekly using Canopeo application. The crops were sprayed with harvest aids 42 days after planting. The green cover was reduced in all crops by at least 45% within 2 weeks after spraying for both harvest aids when compared to check pots, with winter pea losing 100% of green cover. The average harvest biomass was reduced by 45% and 52% in pots sprayed with AIM and DFT as compared to check pots, respectively. These results show that cover crops are susceptible to cotton harvest aids and will need adequate time to produce biomass before harvest aid application if interseeded in cotton crops.

Cover cropping is an important management practice that can benefit the cash crop and the environment. Plant species, weather, and cover crop termination influence biomass production and N fixation potential. This study was conducted to determine optimal termination dates for production systems in Arkansas based on growing degree days (GDD) for eight different cover crop species: Austrian winter pea (AWP) (Pisum sativum), balansa clover (Trifolium michelianum), barley (Hordeum vulgare), black-seeded oats (Avena sativa), common vetch (Vicia sativa var. Cahaba), cereal rye (Secale cereale), crimson clover (Trifolium incarnatum), and hairy vetch (Vicia villosa). Field studies were conducted at three research stations in Arkansas to provide differences in climate and rate of GDD accumulation. An area of 0.17 m² was harvested for aboveground biomass and total N uptake randomly within each experimental unit every 2 weeks, starting on February 15. Aboveground biomass accumulation and N content were regressed as a function of GDD for each cover crop treatment. At the Rohwer site, AWP, for example, accumulated an average of 3643 kg ha⁻¹ of biomass and 107 kg N ha⁻¹ at termination, whereas 30 days before termination, the average was 1868 kg ha⁻¹ of biomass and 69 kg N ha⁻¹. The growth rate increased dramatically closer to termination due to warmer temperatures, which allowed for rapid GDD and aboveground biomass accumulation. These results suggest that termination dates can be identified using previous and forecasted weather data.

Soil fertility depletion, particularly nitrogen and phosphorus, is a major constraint to wheat (Triticum aestivum L.) productivity in Ethiopia, influencing crop yields and food security. A field experiment was conducted to determine the optimum nitrogen and phosphorus rates for wheat yield, nutrient uptake, nutrient use efficiency, and economic returns in Wadla District, North Wollo, Ethiopia. The experiment was arranged in a factorial randomized complete block design with three replications. The treatment consisted of 46, 92, 138, and 184 kg ha⁻¹ N levels and 23, 46, 69, and 92 kg ha⁻¹ P₂O₅ levels. Yield and yield component parameters, as well as a plant sample, were collected. The collected data were analyzed using Statistical Application Software in a mixed model. The results showed that the nutrient levels significantly influenced yield, yield components, nutrient uptake, nutrient use efficiency, and economic returns. The maximum biological grain (3840.0 kg ha⁻¹) and biomass (7910 kg ha⁻¹) yields were recorded at 138 kg N ha⁻¹ with 92 kg P₂O₅ ha⁻¹. The highest performance, in terms of economically yield-related parameters, was recorded with the combined application of 138 kg N ha⁻¹ and 69 kg P₂O₅ ha⁻¹, resulting in biomass and grain yields of 7800 and 3770 kg ha⁻¹, respectively. Total nitrogen uptake was high for 138 kg N ha⁻¹ (82.52 kg N ha⁻¹), while phosphorus uptake was high for 69 kg P₂O₅ ha⁻¹ (18.42 kg P ha⁻¹), with uptake efficiency decreasing at higher rates. The nutrient use efficiency parameter also reached its highest values at the lowest to moderate N and P levels. Partial budget analysis indicates that the applications of 138 kg N ha⁻¹ with 69 kg P₂O₅ ha⁻¹ gave the highest net benefit of 258,954.2 ETB ha⁻¹, with a marginal return of 5825.3%. Therefore, the application of 138 kg N ha⁻¹ and 69 kg P₂O₅ ha⁻¹ is recommended for maximizing wheat yield, economic returns, and enhancing nutrient uptake and nutrient efficiency in Wadla and similar agro-ecological areas. Further research should be done on the long-term residual effect of P and nutrient efficiency through regular soil testing and monitoring to enhance nutrient uptake while minimizing environmental footprints.