Few studies have investigated summer cover crops as a replacement for bare fallow in semi-arid temperate regions, and summer cover crop impacts on soil biological function, water balances and ...subsequent winter crop yields in these regions remain largely unknown.
The 4-year field study aimed to determine the consequences of replacing a summer fallow with a summer growing cover crop on soil function, water balances and subsequent winter cash crop yields in a semi-arid region (486 mm mean annual rainfall) of the Australian southern cropping zone.
A canola (Brassica napus)-wheat (Triticum aestivum L.) rotation with summer fallow was compared to the same rotation with either i) a single species (buckwheat, Fagopyrum esculentum L.) summer cover crop; ii) a four-species mixed brassica + cereal summer cover crop or iii) a cropping sequence with a temporary legume intercrop in the wheat phase of the rotation. Cover crop biomass production, soil water to a depth of 90 cm at cash crop sowing, crop yields and soil functional indices were quantified.
Cover crops produced 500–700 kg biomass ha−1 in the 2020 and 2021 seasons and 1000–2400 kg biomass ha−1 in 2022. The four-species mixed cover crop significantly lowered soil water (around 30 mm; P < 0.05) at the time of sowing the cash crop compared to the control and resulted in 15% reduction (P = 0.12) in canola seed yield in 2020, but no significant effect of cover crops of soil water and mineral N at sowing, or cash crop yields, were observed in subsequent seasons. In 2021 the temporary vetch intercrop produced > 1000 kg ha−1 biomass over 9 weeks, and led to a (non-significant) 10% wheat yield reduction. There was no significant effect of cover crop or temporary intercrop treatments on soil functions in the 2020 or 2021 seasons, but activities of several soil enzymes (leucine aminopeptidase, arylsulfatase and B-glucosidase; P < 0.05) and water-soluble carbon (P = 0.059) were significantly higher in the summer cover crop plots compared to control and intercrop plots in March 2022 following termination of the cover crops. These changes coincided with a significant increase in saturated hydraulic conductivity in the four-species cover crop plots in March 2022 compared to control plots.
The study did not provide any compelling evidence for benefits of summer cover crops over fallow in the short term (3–4 years). The relatively low cover crop biomass production over the 4-year study suggests summer cover crops are unlikely to substantially improve soil carbon levels in temperate, semi-arid cropping systems.
•The impact of summer cover crops was investigated in a temperate semi-arid environment.•Cover crops reduced (P = 0.12) cash crop yields in one of three seasons.•Cover crops only had an effect on soil function parameters in 1 of the 3 seasons.•Low cover crop biomass production may limit long-term soil C effects.
Tribolium castaneum (Herbst) is a harmful pest of stored grain and flour-based products in tropical and subtropical region. In the present study, rhizome of Drynaria quercifolia (J. Smith) was ...evaluated for pesticidal and pest repellency activities against T. castaneum, using surface film method and filter paper disc method, respectively. In addition, activity of the isolated compound 3,4-dihydroxybenzoic acid was evaluated against the pest.
Chloroform soluble fraction of ethanol extract of rhizome of D. quercifolia showed significant pesticidal activity at doses 0.88 to 1.77 mg/cm(2) and significant pest repellency activity at doses 0.94 to 0.23 mg/cm(2). No pesticidal and pest repellency activity was found for petroleum ether, ethyl acetate and methanol soluble fractions of ethanol extract as well as for 3,4-dihydroxybenzoic acid.
Considering our findings it can be concluded that chloroform soluble fraction of rhizome of D. quercifolia is useful in controlling T. castaneum of stored grain and flour-based products.
Two peatland micro-relief forms (microforms) – hummocks and hollows – differ by their hydrological characteristics (water table level, i.e. oxic-anoxic conditions) and vegetation communities. We ...studied the CH4 and CO2 production potential and the localization of methanogenic pathways in both hummocks and hollows at depths of 15, 50, 100, 150 and 200cm in a laboratory incubation experiment. For this purpose, we measured CH4 and CO2 production rates, peat elemental composition, as well as δ13C values of gases and solids; the specific inhibitor of methanogenesis BES (2-bromo-ethane sulfonate, 1mM) was aimed to preferentially block the acetoclastic pathway.
The cumulative CH4 production of all depths was almost one fold higher in hollows than in hummocks, with no differences in CO2. With depth, CO2 and CH4 production decreased, and the relative contribution of the hydrogenotrophic pathway of methanogenesis increased. The highest methanogenic activity among all depths and both microforms was measured at 15cm of hollows (91%) at which the highest relative contribution of acetoclastic vs. hydrogenotrophic pathway (92 and 8%, respectively) was detected. For hummocks, the CH4 production was the highest at 50cm (82%), where relative contribution of acetoclastic methanogenesis comprised 89%. The addition of 1mM BES was not selective and inhibited both methanogenic pathways in the soil. Thus, BES was less efficient in partitioning the pathways compared with the δ13C signature. We conclude that the peat microforms – dry hummocks and wet hollows – play an important role for CH4 but not for CO2 production when the effects of living vegetation are excluded.
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•Micro-relief significantly affected CH4 but not CO2 production in surface peat soil.•Soil of 10–50cm depth produced up to 90% of the CH4 and 50% of the CO2.•Hollows' topsoil showed the highest relative contribution of acetoclastic pathway (92%).•The contribution of hydrogenotrophic pathway of methanogenesis increased with depth.
Vehicle detection is used for detecting vehicles on roads, highways, parking, or any other place. It plays a key function in the control and management of traffic. In the Intelligent Transportation ...System (ITS), nighttime identification and recognition of moving vehicles are the most challenging and important processes. The quantity of vehicles on the road has grown significantly in recent years, and as a result, road accidents are constantly occurring. Accidents are more likely to happen at night, according to statistics. The whole vehicle body remains invisible at night due to the absence of illumination. Visibility at night is the major issue for safe driving. The appearance of vehicle headlights at night conditions plays a key role. When driving at nighttime, drivers usually turn on high-intensity headlights, resulting in annoyance for drivers driving from the opposite direction. For oncoming vehicles, these high-intensity lights generate glare and induce temporary blindness. For this reason, most accidents happen at nighttime. In solving this problem, nighttime vehicle detection is of great significance. The main focus of this review paper is to examine, present, and summarize the various proposed methods and techniques, and future directions so that new methods of vehicle detection can be developed which are to circumvent accidents during the night and keep distance between the moving vehicles. Hopefully, this review paper will be helpful for future research and consideration either for developing improved algorithms or guidance or both.
•Elevated CO2 stimulated biomass, grain yield and root length of wheat in both upper and deeper soil layers.•Biomass, grain yield and water use were positively associated with root length in deeper, ...but not upper soil layer.•CO2 fertilisation effect on biomass and grain yield was of similar magnitude under both irrigated and rainfed conditions.•The CO2 effect on water use was dependent on cultivars and irrigation regimes.•The ‘CO2 fertilisation effect’ did not differ between the two studied cultivars.
This study investigated crop water use of wheat grown in a dryland Mediterranean-type environment under elevated atmospheric CO2 concentrations (CO2). Two related cultivars, contrasting in agronomic features (cvs. Scout and Yitpi; Scout has good early vigour and high transpiration efficiency), were grown under ambient CO2 (aCO2, ∼400 μmol mol−1) and elevated CO2 (eCO2, ∼550 μmol mol−1) in the Australian Grains Free Air CO2 Enrichment (AGFACE) facility for two growing seasons. Each year, an irrigation treatment (rainfed versus irrigated) was imposed within the CO2-treatments. Normalised difference vegetation index (as surrogate for canopy cover) and root length in the upper (0 cm–32 cm) and deeper (33 cm–64 cm) soil layers were measured at stem-elongation and anthesis.
Elevated CO2 stimulated root length of wheat in both upper and deeper soil layers, and this stimulation was modified by cultivars and irrigation regimes. Across cultivars and all treatments, water use, biomass and grain yield were positively associated with root length in the deeper soil layer but not with root length in the upper soil layer. The ‘CO2 fertilisation effect’ on biomass and grain yield was of similar magnitude under both irrigated and rainfed conditions. Although eCO2 did not increase canopy cover in these experiments, the CO2 effect on water use depended on cultivars and irrigation regimes. Despite greater eCO2-induced stimulation of tillers and spikes, the cv. Scout did not receive more biomass or grain yield benefit from the ‘CO2 fertilisation effect’ compared to cv. Yitpi.
Background and aims Increasing atmospheric carbon dioxide concentration (CO.sub.2) stimulates the leaf-level (intrinsic) water use efficiency (iWUE), which may mitigate the adverse effects of drought ...by lowering water use in plants. This study investigated the interactive effect of CO.sub.2 and soil type on growth, yield and water use of canola (Brassica napus L.) in a dryland environment. Methods Two canola cultivars (vigorous hybrid cv. 'Hyola 50' and non-hybrid cv. 'Thumper') were grown in large intact soil cores containing either a sandy Calcarosol or clay Vertosol under current ambient (aCO.sub.2) and future elevated CO.sub.2 (eCO.sub.2), ~550 mumol mol.sup.-1). Net assimilation rates (A.sub.net), stomatal conductance (g.sub.s) and leaf area were measured throughout the growing season. Seed yield and yield components were recorded at final harvest. Water use was monitored by lysimeter balances. Results Elevated CO.sub.2-stimulation of iWUE was greater than the effect on leaf area, therefore, water use was lower under eCO.sub.2 than aCO.sub.2, but this was further modified by soil type and cultivar. The dynamics of water use throughout the growing season were different between the studied cultivars and in line with their leaf development. The effect of eCO.sub.2 on seed yield was dependent on cultivar; the non-hybrid cultivar benefitted more from increased CO.sub.2. Although textural differences between soil types influenced the water use under eCO.sub.2, this did not affect the 'CO.sub.2 fertilisation effect' on the studied canola cultivars. Conclusion Elevated CO.sub.2-induced water savings observed in the present study is a potential mechanism of ameliorating drought effects in high CO.sub.2 environment. Better understanding of genotypic variability in response to water use dynamics with traits affecting assimilate supply and use can help breeders to improve crop germplasm for future climates.
Background and aims Legume N.sub.2 fixation is highly sensitive to drought. Elevated CO.sub.2 (eCO.sub.2) decreases stomatal conductance (g.sub.s) and improves water use efficiency (WUE), which may ...result in soil water conservation and allow N.sub.2 fixation to continue longer under drought. Using a Free-Air CO.sub.2 Enrichment (FACE) approach, this study aimed to elucidate whether eCO.sub.2 improves N.sub.2 fixation of Pisum sativum L. under drought. Methods In a FACE system, plants were grown in ambient CO.sub.2 (~400 ppm) or eCO.sub.2 (~550 ppm) and subjected to either terminal drought or well-watered treatments. Measurements were taken of photosynthesis, soil water dynamics, water soluble carbohydrates (WSC), amino acids (AA) and N.sub.2 fixation. Results Lower g.sub.s under eCO.sub.2 increased water use efficiency at leaf and plant level, and this translated to slower soil water depletion during drought. Elevated CO.sub.2 increased WSC and decreased total AA concentrations in nodules, and increased nodule activity under drought. N.sub.2 fixation was stimulated (+51%) by eCO.sub.2 in proportion to biomass changes. Under eCO.sub.2 a greater proportion of plant total N was derived from fixed N.sub.2 and a smaller proportion from soil N uptake compared to aCO.sub.2. Conclusion This study suggests that eCO.sub.2 increased WUE and this resulted in slower soil water depletion, allowing pea plants to maintain greater nodule activity under drought and resulting in appreciable increases in N.sub.2 fixation. Our results suggest that growth under eCO.sub.2 can mitigate drought effects on N.sub.2 fixation and reduce dependency on soil N resources especially in water-limited agro-ecosystems.
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