Control Treatment Research Articles

Effects of Various Salinity and Water Stress Levels on Physiological and Biochemical Traits of Pepper

ABSTRACT Salinity and drought are among the most important abiotic stress factors with vital impacts on plant growth and development. Effects of different salinity and water stress levels on physiological and biochemical traits of pepper were investigated in this study. Five different salinity (S1: 0.3 dS/m; S2: 2.5 dS/m; S3: 5dS/m; S4: 7.5 dS/m; S5: 10 dS/m) and three different irrigation levels (I100: full irrigation; I75: 25% deficit; I50: 50% deficit) were used. Plant water consumption (ET) values decreased in increasing salinity levels. Pepper yield was significantly affected by both salinity and water stress. There was a 62.8% yield loss under salt stress as compared to the control treatment and a 70.1% yield loss under 50% water deficit (I50) as compared to full irrigation (I100). Irrigation water salinity and water deficits caused significant differences in physiological and photosynthetic parameters (plant height, plant fresh and dry weight, leaf area, chlorophyll, and carotenoid content). Salinity and water stress had significant impacts on enzymatic and non-enzymatic contents such as superoxide dismutase (SOD), peroxide (POD), catalase (CAT), proline, malondialdehyde (MDA), total phenolic content (TPC) and total flavonoid content (TFC). It was concluded based on present findings that irrigation waters with a salinity level up to 5 dS/m could be used in pepper cultivation, but water deficits should be avoided.

Quality of Red Clover Forage in Different Organic Production Systems

The aim of this study was to determine the quality of organically grown red clover herbage and silage after being influenced by supplementary mineral fertilization. The experimental treatments were as follows: control treatment without fertilization (group C), treatment where kalimagnesia (Patentkali) was applied (group P), and treatment where potassium sulfate (SOP) was applied (group S). In each year of the experiment, first-cut herbage was harvested at the beginning of flowering and ensiled. The year of the study had a significant (p ≤ 0.05) influence on the analyzed parameters of herbage and silage, excluding the content of calcium (Ca), acetic acid (AA), and ammonia nitrogen (N-NH3). The organic production system exerted a significant (p ≤ 0.05) effect on the concentrations of crude protein (CP), acid detergent lignin (ADL), water-soluble carbohydrates (WSC), minerals (P, K, Ca, Na), lactic acid (LA), ethanol, and N-NH3. The pattern of fermentation was affected by both experimental factors. True protein (TP) content was determined at 70–84% CP in herbage and 53–65% CP in silages. The energy value and the protein value of herbage varied significantly across years of the study and in response to the combined effects of both experimental factors (p ≤ 0.05). Red clover grown in organic production systems supplied high-quality forage.

Delayed treatment of cynomolgus macaques with a FVM04/CA45 monoclonal antibody cocktail provides complete protection against lethal Sudan virus infection.

There are currently no approved vaccines or therapeutics for Sudan virus, a filovirus which is highly related to Ebola virus and causes similar disease and outbreaks. In this study, a cocktail of two potent monoclonal antibodies that effectively neutralize Sudan virus was tested in a nonhuman primate model of Sudan virus disease. Treatment was highly effective, even when initiated as late as 5 days after infection, when clinical signs of infection were already evident. All treated animals showed complete recovery from infection, with little evidence of disease, while all animals that received a control treatment succumbed to infection within 8 days. The study further demonstrated the strong therapeutic potential of the antibody treatment and supported further development for use in Sudan virus outbreaks.

Early life thermal conditioning alters heat-shock protein expression in response to an adult thermal stressor.

Developmental environmental stressors can have instructive effects on an organism's phenotype. This developmental plasticity can prepare organisms for potentially stressful future environments, circumventing detrimental effects on fitness. However, the physiological mechanisms underlying such adaptive plasticity are understudied, especially in vertebrates. We hypothesized that captive male zebra finches (Taeniopygia castanotis) exposed to a mild heat conditioning during development would acquire a persisting thermotolerance, and exhibit increased heat-shock protein (HSP) levels associated with a decrease in oxidative damage when exposed to a high-intensity stressor in adulthood. To test this, we exposed male finches to a prolonged mild heat conditioning (38°C) or control (22°C) treatment as juveniles. Then in a 2 × 2 factorial manner, these finches were exposed to a high heat stressor (42°C) or control (22°C) treatment as adults. Following the adult treatment, we collected testes and liver tissue and measured HSP70, HSP90, and HSP60 protein levels. In the testes, finches exhibited lower levels of HSP90 and HSP60 when exposed to the high heat stressor in adulthood if they were exposed to the mild heat conditioning as juveniles. In the liver, finches exposed to the high heat stressor in adulthood had reduced HSP90 and HSP60 levels, regardless of whether they were conditioned as juveniles. In some cases, elevated testes HSP60 levels were associated with increased liver oxidative damage and diminishment of a condition-dependent trait, indicating potential stress-induced tradeoffs. Our results indicate that a mild conditioning during development can have persisting effects on HSP expression and acquired thermotolerance.

Improving detached tiller culture for doubled haploid production in wheat (T. aestivum L.) by post‐pollination fungicides application and UV radiation treatment

AbstractThis work aims at improving the proven protocol for doubled haploid production in wheat. This procedure has some deficits, for example, microbial infection of ears as well as of the nutrient culture medium. In the present study, the potential effect of sterilization by detached tiller culture fungicides of ears as well as of nutrient medium to control microbial infection, and its effect on the formation of caryopses and embryos (CFF, EFF) was studied. In a further experiment, the UV‐light was used as physical sterilant for the nutrient medium. All of the fungicides and their concentrations studied were found to be effective to control infection on ears except the concentration 0.05% tilt. 0.1% tilt gave the highest CFF (79.5%) followed by 0.1% Bayleton (78.0%). The lowest CFF was recorded in control treatment (48.8%). Among Bavistin treatments, the 0.2% Bavistin gave maximum CFF (68.5%) as well as EFF (29.1%) followed by 0.1% Bavistin (64.9%, 23.7%). The higher concentration of tilt (0.2%) showed detrimental effects on EFF (17.5%). Bavistin in tiller culture nutrient medium reduced infection in medium and was shown to improve CFF and EFF (67.4%, 29.8%).

Full-Length Transcriptome Assembly of Platycladus orientalis Root Integrated with RNA-Seq to Identify Genes in Response to Root Pruning

Platycladus orientalis (P. orientalis) is a common tree used for vegetation restoration in northern China, and its large area propagation helps to improve site conditions. However, under harsh conditions such as poor land, the survival rate of P. orientalis is very low. Numerous studies have shown that root pruning can promote the formation of lateral roots in seedlings, enhancing the roots’ capacity to absorb soil nutrients and water, and thereby improving the survival rate of seedlings. In this study, a one-third root pruning treatment was applied to P. orientalis seedlings, and the whole transcriptome of seedlings subjected to both control (CK) and root pruning treatments was sequenced to analyze their gene expression profiles. This study investigated the regulatory mechanisms of lateral root development in response to root pruning damage at the molecular level. Using nine cells, 15.28 Gb of clean data were obtained, which yielded 101,688 high-quality full-length transcript sequences and 22,955 low-quality full-length transcript sequences after clustering. Redundancy was then removed using CD-HIT, and Illumina RNA-seq sequencing produced 139.26 Gb of clean data. A total of 2025 differentially expressed genes (DEGs) were identified at three time points following root pruning treatment. Enrichment analysis revealed that the peroxidase gene family plays a significant role in lateral root proliferation. Furthermore, the expression levels of the peroxidase gene family were notably upregulated in comparison to the control group. Pathway enrichment analysis identified 22 relevant genes, which appeared to be highly associated with root growth and resilience to stress. Through examining the expression patterns and correlations of these genes, five central genes emerged as key players. The findings of this research suggest that the peroxidase gene family plays a crucial role in the stress response and root development of P. orientalis, providing reference and guidance for root development in other plant species.

Sub-surface drip fertigation of nitrogen coupled with crop residue incorporation enhanced the growth and yield of maize in an alluvial soils

A two-year field experiment was conducted at ICAR-Indian Agricultural Research Institute, New Delhi, to standardize the N-fertigation schedule and crop residue management in sub-surface drip fertigated (SSDF) maize [Pusa HQPM 1’ improved: double bio-fortified]. The experiment was laid-out in a split-plot design with 3 replications. There were 8 main-plot treatments comprising different N sub-surface drip fertigation levels (0, 50, 75, 100% RDN) with one conventional cultivation of maize, where RDN (150 kg/ha) was applied as per recommendation. Under sub-surface fertigation of N, each dose of N was divided into 3-and 4-splits, for fertigation. Sub-plot treatments included greengram residue (3 t/ha) and no greengram residue incorporation. P and K (60 kg P2 O5 /ha and 40 kg K2 O/ha respectively) fertilizers were supplied equally in all the plots by SSDF. Results revealed that plant height at various stages statistically varied with levels and splits of SSDF-N and crop residue incorporation. The highest plant height and leaf area were recorded with 100% RDN-4S which remained at par with 100% RDN-3S and 75% RDN-4S. Conventional maize cultivation was inferior to ‘RDN100’ and 75%, however on par with 50% RDN. The nitrogen uptake was found significantly superior in 100 and 75%RDN over conventional and control treatments. Similarly, the grain yield of maize was highest under 100% ‘RDN-4’ &3 S, and 75% RDN-4S, which were at par with one another. Overall, it could be concluded that sub-surface fertigation of N not only improved the growth and yield of maize but also helped in 25–50% saving of valuable fertilizer.

Effect of casein bioactive peptides on performance, nutrient digestibility, enzyme activity and intestinal microbial population in broiler chickens.

This experiment was carried out to investigate the effect of bioactive peptides derived from casein on performance, nutrient digestibility, enzyme activity and intestinal microbial population in broiler chickens. In this study, 350 1-day-old male Ross 308 broiler chicks were distributed among 35 pens in a completely randomized design with seven treatments, five replicates and 10 chicks in each replicate. The experimental treatments included: basal diet without any additives (control), basal diet + Avilamycin antibiotic, basal diet + 200, 400, 600, 800 and 1000 mg of peptides per kg of diet. Results showed no significant effects of the experimental treatments on weight gain and feed conversion ratio during the starter period, but there was a significant improvement in weight gain in grower, finisher and whole periods in chicks fed with diet containing 1000 mg/kg peptides (p < 0.05). Adding peptides improved intestinal morphology (in duodenum and ileum) (p < 0.05). Supplementation of casein peptides significantly reduced thiobarbituric acid reactive substances concentration in breast and thigh meat. The activity of amylase, lipase and protease enzymes improved in treatments containing 800 and 1000 mg peptides in comparison to the control treatment. The use of casein-peptides increased intestinal Lactobacillus and decreased Coliform populations.

In vitro response of sugarcane (Saccharum spp. Hybrid) plantlets to flooding stress

Flooding caused by climate change puts the productivity of sugarcane cultivation at risk. The objective of this study was to evaluate the effect of in vitro flooding stress on sugarcane plantlets. Sugarcane plantlets were grown in test tubes containing Murashige and Skoog semi-solid medium without growth regulators as a control treatment and two stress levels using a double layer with sterile distilled water to simulate hypoxia and anoxia. After 15 d of culture, the number of new shoots, plantlet height, number of leaves, number of roots, root length, stomatal density, percentage of closed stomata and percentage of dry matter were evaluated. In addition, biochemical variables such as chlorophylls, carotenoids, phosphoenolpyruvate (PEP), Rubisco, total proteins (TP), proline (Pr), glycine-betaine (GB), phenols, antioxidant capacity and lipid peroxidation were determined in all treatments. Results showed a higher number of new shoots, leaves and percentage of closed stomata in the flooded plantlets, while plantlet height, number of roots, stomatal density, and dry matter were higher in the control treatment. Regarding, chlorophyll, carotenoid, PEP and Rubisco contents decreased in the flooded treatments, while TP and phenol contents were higher in the partially submerged treatment. Antioxidant capacity and lipid peroxidation increased in the fully submerged treatment. Pr and GB contents did not show changes in any of the evaluated treatments. Stress induced by excess water in a double layer in vitro is an alternative method to determining physiological and biochemical mechanisms of tolerance to hypoxia and anoxia caused by flooding for breeding programs in sugarcane.

Over 50 years of a field experiment on cropping systems in Bałcyny, Poland: Assessing pesticide residues in soil and crops from the perspective of their field application history

Many agricultural problems can be illustrated and solved through long-term field experiments. Since 1967, an experiment has been conducted in Bałcyny, Poland, to compare continuous cropping with growing crops in crop rotation. The experiment also provides information on the history of chemical crop protection, which may have influenced soil and crop contamination with pesticide residues. In this study, fields of winter rye in continuous cropping (CCrye) and a 5–6-field crop rotation (CRrye) were used as an example to investigate the occurrence of pesticides in soil and grain in the context of previous use of chemical crop protection products. Two levels of crop protection were also examined: herbicide (since the 1972/73 growing season) and fungicide (since 1982/83) application (HF) and control treatment (CT; no herbicides since 1972/73, no fungicides since 1982/83). Insecticides were used only when absolutely necessary. Between 1967 and 2019, 58 different active substances were applied to the fields selected for this study. Soil and grain samples collected in 2019 after rye harvest were analyzed for the presence of 441 and 496 different substances, respectively. Only DDT and its metabolites were detected in soil, even though DDT was not applied to the fields after 1967. The concentration of ΣDDT (sum of all metabolites and isomers) ranged from 038 to 130 µg kg–1 soil and exceeded the limit set in Poland (120 µg kg–1) under CRrye-HF treatment. In winter rye grain, no pesticide residues were found. The results show that long-term rational use of less persistent pesticides does not lead to contamination of the soil or the test cereal grain, but DDT continues to threaten the environment five decades after its probable last use. The study points to the value of comprehensive long-term recording for providing a retrospective assessment of pesticide exposure. Long-term field experiments facilitate this approach.

Exogenous melatonin delays yellowing in postharvest broccoli by regulation of ABA and carotenoid metabolite

Yellowing is the first visible sign of floret senescence and quality deterioration in broccoli, mainly caused by chlorophyll degradation and carotenoid accumulation. In this study, the impacts of melatonin (MLT) treatment on anabolism, catabolism and storage of carotenoid in postharvest broccoli associated with ABA regulation were investigated at transcript and metabolic levels. Results showed that MLT treatment effectively repressed yellowing and senescence along with a decrease in respiration rate and ethylene emission, enhancing endogenous MLT and abscisic acid (ABA) levels. A total of 925 metabolites were differentially expressed between the control and MLT treatment, which were mainly classified into amino acids, sugars, lipids, flavonoids and others. Specific analysis revealed that MLT treatment decreased sugars, lipids, flavonoids, and aromatic amino acids, but increased aliphatic amino acids. Meanwhile, MLT treatment suppressed the expression levels of genes related to carotenoid anabolism (BoPSY, BoPDS, BoZDS, BoCRTISO, BoLCYB, BoVDE, and BoZEP) and storage (BoOR), but the genes involved in carotenoid catabolism (BoNCED2, BoNCED6, BoCCD1 and BoCCD7) were up-regulated, which could collectively result in a decrease in the levels of β-carotene and lutein and an increase in ABA level. Moreover, correlation analysis indicated that lutein content was positively correlated with BoVDE, BoPDS and BoZDS, and negatively correlated with ABA level. Thus, MLT treatment slowed down the yellowing of broccoli during storage, which might be ascribed to inhibiting the anabolism and storage of carotenoid and promoting carotenoid catabolism and ABA biosynthesis.

In-Vitro Management of Erwinia amylovora caused by Fire Blight of Apple with Synthetic Chemicals

Apple (Malus pomila L) belongs to family Rosacea and it is an edible fruit; mostly utilized by different age groups. Apple trees are grown worldwide. It is considered an important fruit in the temperate region of Balochistan, Pakistan. Fire blight is caused by the pathogen Erwinia amylovora the most damaging disease of apple and other pomes orchards in the world. The aim of the present study was conducted to record the incidence of the disease and management through the use of chemicals. For this purpose, survey was conducted for disease samples from the various districts of Balochistan Viz., Quetta, Ziarat, Killa Saifullah and Kalat. Among all the districts Ziarat was found to be most severe by pathogen with 20% incidence followed by Quetta having 18.67%, Kalat14.31% and Killa Saifullah 13.44% incidence, and different chemicals, i.e. Streptomycin, Tetracycline, Gentamicin, Kasugomycin, Oxytetracycline at different doses were tested against the pathogen and all the chemicals shown great effectiveness against Erwiana amylorora In-vitro conditions. The maximum inhibition zone made by chemical streptomycin with value 15.50 and minimum value of tetracycline with 10.90.and there was no inhibition zone observed in control treatment. All the data was statistically analyzed

Effect of Insecticide Exposure Across Multiple Generations of the Earthworm Eisenia andrei.

The toxicity of neonicotinoids and many of their replacement insecticides to nontarget soil invertebrates such as earthworms has previously been established. However, the long-term effects of these substances on these organisms are largely unknown. In the field of soil ecotoxicology, lumbricid earthworms such as Eisenia andrei are used extensively due to the availability of standardized test methods and their adaptability to laboratory culture and testing. Multigenerational studies have gained popularity and attention in recent years, with a shift toward the use of long-term assays and lower concentrations of test chemicals. The use of exposure concentrations that include those measured in a monitoring program carried out by the Government of Ontario presents a realistic exposure scenario that may not show significant effects in contemporary, shorter term studies. We used current standardized test methods as a basis for the development of multigenerational studies on E. andrei. The effects of exposure to a single application of the insecticides thiamethoxam and cyantraniliprole on the survival and reproduction of E. andrei were observed over three (thiamethoxam) or two (cyantraniliprole) generations using consecutive reproduction tests. No significant impacts on adult survival were reported in any generation for either insecticide, whereas reproduction decreased between the first and second generations in the thiamethoxam test, with median effective concentration (EC50) values of 0.022 mg/kg dry weight reported for the first generation compared with 0.002 mg/kg dry weight in the second generation. For cyantraniliprole, an EC50 of 0.064 was determined for the first generation compared with 0.016 mg/kg dry weight in the second generation. A third generation was completed for the thiamethoxam test, and a significant decrease in reproduction was observed in all treatments and controls compared with previous generations. No significant difference between thiamethoxam treatments and the control treatment was reported for the third generation. Collectively, these data indicate that exposure of oligochaetes to these two insecticides at concentrations representative of field conditions may result in long-term stresses. Environ Toxicol Chem 2024;00:1-13. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Fruit Position, Light Exposure and Fruit Surface Temperature Affect Colour Expression in a Dark-Red Apple Cultivar

This study aimed to evaluate the effects of fruit position, light exposure and fruit surface temperature (FST) on apple fruit colour development and fruit quality at harvest, including sunburn damage severity. This was achieved by undertaking two experiments in a high-density planting of the dark-red apple ANABP 01 in Tatura, Australia. In the 2020–2021 growing season an experiment was conducted to draw relationships between fruit position and fruit quality parameters. Here, sample fruit position and level of light exposure were respectively determined using a static LiDAR system and a portable quantum photosynthetically active radiation (PAR) sensor. At harvest the sample fruit were analysed for percentage red colour coverage, objective colour parameters (L*, a*, b*, hue angle and chroma), sunburn damage, fruit diameter (FD), soluble solids concentration (SSC), flesh firmness (FF) and starch pattern index (SPI). A second experiment was conducted in the 2021–2022 growing season and focused on how fruit shading, light exposure and the removal of ultraviolet (UV) radiation affected the FST, colour development and harvest fruit quality. Five treatments were distributed among sample fruit: fully shaded with aluminium umbrellas, shaded for one month and then exposed to sunlight until harvest, exposed for one month and then shaded until harvest, covered with a longpass UV filter and a control treatment. The development of colour in this dark-red apple cultivar was highly responsive to aspects of fruit position, and the intensity and quality of light exposure. The best-coloured fruit were exposed to higher quantities of PAR, exposed to both PAR and UV radiation simultaneously and located higher in the tree canopy. Fruit that were fully exposed to PAR and achieved better colour development also displayed higher FST and sunburn damage severity.

Dynamic physiological response of tef to contrasting water availabilities

Global climate change is leading to increased frequency of extreme climatic events, higher temperatures and water scarcity. Tef (Eragrostis tef (Zucc.) Trotter) is an underutilized C4 cereal crop that harbors a rich gene pool for stress resilience and nutritional quality. Despite gaining increasing attention as an “opportunity” crop, physiological responses and adaptive mechanisms of tef to drought stress have not been sufficiently investigated. This study was aimed to characterize the dynamic physiological responses of tef to drought. Six selected tef genotypes were subjected to high-throughput whole-plant functional phenotyping to assess multiple physiological responses to contrasting water regimes. Drought stress led to a substantial reduction in total, shoot and root dry weights, by 59%, 62% and 44%, respectively (averaged across genotypes), and an increase of 50% in the root-to-shoot ratio, relative to control treatment. Drought treatment induced also significant reductions in stomatal conductance, transpiration, osmotic potential and water-use efficiency, increased chlorophyll content and delayed heading. Tef genotypes exhibited diverse water-use strategies under drought: water-conserving (isohydric) or non-conserving (anisohydric), or an intermediate strategy, as well as variation in drought-recovery rate. Genotype RTC-290b exhibited outstanding multifaceted drought-adaptive performance, including high water-use efficiency coupled with high productivity under drought and control treatments, high chlorophyll and transpiration under drought, and faster drought recovery rate. This study provides a first insight into the dynamic functional physiological responses of tef to water deficiency and the variation between genotypes in drought-adaptive strategies. These results may serve as a baseline for further studies and for the development of drought-resistant tef varieties.

Dynamic physiological response of tef to contrasting water availabilities

Global climate change is leading to increased frequency of extreme climatic events, higher temperatures and water scarcity. Tef (Eragrostis tef (Zucc.) Trotter) is an underutilized C4 cereal crop that harbors a rich gene pool for stress resilience and nutritional quality. Despite gaining increasing attention as an “opportunity” crop, physiological responses and adaptive mechanisms of tef to drought stress have not been sufficiently investigated. This study was aimed to characterize the dynamic physiological responses of tef to drought. Six selected tef genotypes were subjected to high-throughput whole-plant functional phenotyping to assess multiple physiological responses to contrasting water regimes. Drought stress led to a substantial reduction in total, shoot and root dry weights, by 59%, 62% and 44%, respectively (averaged across genotypes), and an increase of 50% in the root-to-shoot ratio, relative to control treatment. Drought treatment induced also significant reductions in stomatal conductance, transpiration, osmotic potential and water-use efficiency, increased chlorophyll content and delayed heading. Tef genotypes exhibited diverse water-use strategies under drought: water-conserving (isohydric) or non-conserving (anisohydric), or an intermediate strategy, as well as variation in drought-recovery rate. Genotype RTC-290b exhibited outstanding multifaceted drought-adaptive performance, including high water-use efficiency coupled with high productivity under drought and control treatments, high chlorophyll and transpiration under drought, and faster drought recovery rate. This study provides a first insight into the dynamic functional physiological responses of tef to water deficiency and the variation between genotypes in drought-adaptive strategies. These results may serve as a baseline for further studies and for the development of drought-resistant tef varieties.

Host defense alteration in Caenorhabditis elegans after evolution under ionizing radiation

BackgroundAdaptation to a stressor can lead to costs on other traits. These costs play an unavoidable role on fitness and influence the evolutionary trajectory of a population. Host defense seems highly subject to these costs, possibly because its maintenance is energetically costly but essential to the survival. When assessing the ecological risk related to pollution, it is therefore relevant to consider these costs to evaluate the evolutionary consequences of stressors on populations. However, to the best of our knowledge, the effects of evolution in irradiate environment on host defense have never been studied. Using an experimental evolution approach, we analyzed fitness across 20 transfers (about 20 generations) in Caenorhabditis elegans populations exposed to 0, 1.4, and 50.0 mGy.h− 1 of 137Cs gamma radiation. Then, populations from transfer 17 were placed in the same environmental conditions without irradiation (i.e., common garden) for about 10 generations before being exposed to the bacterial parasite Serratia marcescens and their survival was estimated to study host defense. Finally, we studied the presence of an evolutionary trade-off between fitness of irradiated populations and host defense.ResultsWe found a lower fitness in both irradiated treatments compared to the control ones, but fitness increased over time in the 50.0 mGy.h− 1, suggesting a local adaptation of the populations. Then, the survival rate of C. elegans to S. marcescens was lower for common garden populations that had previously evolved under both irradiation treatments, indicating that evolution in gamma-irradiated environment had a cost on host defense of C. elegans. Furthermore, we showed a trade-off between standardized fitness at the end of the multigenerational experiment and survival of C. elegans to S. marcescens in the control treatment, but a positive correlation between the two traits for the two irradiated treatments. These results indicate that among irradiated populations, those most sensitive to ionizing radiation are also the most susceptible to the pathogen. On the other hand, other irradiated populations appear to have evolved cross-resistance to both stress factors.ConclusionsOur study shows that adaptation to an environmental stressor can be associated with an evolutionary cost when a new stressor appears, even several generations after the end of the first stressor. Among irradiated populations, we observed an evolution of resistance to ionizing radiation, which also appeared to provide an advantage against the pathogen. On the other hand, some of the irradiated populations seemed to accumulate sensitivities to stressors. This work provides a new argument to show the importance of considering evolutionary changes in ecotoxicology and for ecological risk assessment.

Host defense alteration in Caenorhabditis elegans after evolution under ionizing radiation

BackgroundAdaptation to a stressor can lead to costs on other traits. These costs play an unavoidable role on fitness and influence the evolutionary trajectory of a population. Host defense seems highly subject to these costs, possibly because its maintenance is energetically costly but essential to the survival. When assessing the ecological risk related to pollution, it is therefore relevant to consider these costs to evaluate the evolutionary consequences of stressors on populations. However, to the best of our knowledge, the effects of evolution in irradiate environment on host defense have never been studied. Using an experimental evolution approach, we analyzed fitness across 20 transfers (about 20 generations) in Caenorhabditis elegans populations exposed to 0, 1.4, and 50.0 mGy.h− 1 of 137Cs gamma radiation. Then, populations from transfer 17 were placed in the same environmental conditions without irradiation (i.e., common garden) for about 10 generations before being exposed to the bacterial parasite Serratia marcescens and their survival was estimated to study host defense. Finally, we studied the presence of an evolutionary trade-off between fitness of irradiated populations and host defense.ResultsWe found a lower fitness in both irradiated treatments compared to the control ones, but fitness increased over time in the 50.0 mGy.h− 1, suggesting a local adaptation of the populations. Then, the survival rate of C. elegans to S. marcescens was lower for common garden populations that had previously evolved under both irradiation treatments, indicating that evolution in gamma-irradiated environment had a cost on host defense of C. elegans. Furthermore, we showed a trade-off between standardized fitness at the end of the multigenerational experiment and survival of C. elegans to S. marcescens in the control treatment, but a positive correlation between the two traits for the two irradiated treatments. These results indicate that among irradiated populations, those most sensitive to ionizing radiation are also the most susceptible to the pathogen. On the other hand, other irradiated populations appear to have evolved cross-resistance to both stress factors.ConclusionsOur study shows that adaptation to an environmental stressor can be associated with an evolutionary cost when a new stressor appears, even several generations after the end of the first stressor. Among irradiated populations, we observed an evolution of resistance to ionizing radiation, which also appeared to provide an advantage against the pathogen. On the other hand, some of the irradiated populations seemed to accumulate sensitivities to stressors. This work provides a new argument to show the importance of considering evolutionary changes in ecotoxicology and for ecological risk assessment.

Fruit Position, Light Exposure and Fruit Surface Temperature Affect Colour Expression in a Dark-Red Apple Cultivar

This study aimed to evaluate the effects of fruit position, light exposure and fruit surface temperature (FST) on apple fruit colour development and fruit quality at harvest, including sunburn damage severity. This was achieved by undertaking two experiments in a high-density planting of the dark-red apple ANABP 01 in Tatura, Australia. In the 2020–2021 growing season an experiment was conducted to draw relationships between fruit position and fruit quality parameters. Here, sample fruit position and level of light exposure were respectively determined using a static LiDAR system and a portable quantum photosynthetically active radiation (PAR) sensor. At harvest the sample fruit were analysed for percentage red colour coverage, objective colour parameters (L*, a*, b*, hue angle and chroma), sunburn damage, fruit diameter (FD), soluble solids concentration (SSC), flesh firmness (FF) and starch pattern index (SPI). A second experiment was conducted in the 2021–2022 growing season and focused on how fruit shading, light exposure and the removal of ultraviolet (UV) radiation affected the FST, colour development and harvest fruit quality. Five treatments were distributed among sample fruit: fully shaded with aluminium umbrellas, shaded for one month and then exposed to sunlight until harvest, exposed for one month and then shaded until harvest, covered with a longpass UV filter and a control treatment. The development of colour in this dark-red apple cultivar was highly responsive to aspects of fruit position, and the intensity and quality of light exposure. The best-coloured fruit were exposed to higher quantities of PAR, exposed to both PAR and UV radiation simultaneously and located higher in the tree canopy. Fruit that were fully exposed to PAR and achieved better colour development also displayed higher FST and sunburn damage severity.

Do we need post-tree thinning management? Prescribed fire and goat browsing to control woody encroacher species in an Ethiopian savanna

Worldwide, bush encroachment threatens rangeland ecosystem services, including plant biodiversity and forage for livestock. Various control methods for encroaching woody species and restoring herbaceous vegetation exist but have rarely been explored experimentally. We assessed the impact of post-tree thinning management on tree mortality, the herbaceous community, and overall rangeland condition in Borana, an Ethiopian savanna ecosystem. At two 1.4 ha areas of encroached mono-specific Vachellia drepanolobium (whistling thorn) stands, we set up twenty-four 20 × 10 m experimental plots with four post-tree-thinning treatments (goat browsing only (1), prescribed fire (2), fire and goat browsing (3), and control (4) (i.e., no management after tree cutting), with three replications in a complete block design. Over two growing periods, we monitored resulting tree mortality, coppicing, seedling mortality and recruitment, as well as herbaceous layer attributes (diversity, biomass) and overall rangeland condition. All three post-tree thinning management scenarios significantly enhanced tree mortalities, reduced seedling recruitment and increased the abundance of the dominant desirable grass species. Prescribed fire and fire and goat-browsing treatments resulted in significantly greater grass and forb species richness, forb diversity, and biomass, as well as the overall rangeland condition compared to goat browsing only and the control treatment. However, grass species diversity did not respond to treatments. Post-tree management significantly increased tree mortality, reduced seedling recruitment, and increased the abundance of desirable grass species. Our findings strongly suggest that post-thinning management, particularly prescribed fire or a combination of fire and browsing, is highly effective in suppressing woody encroachment and improving biomass and overall rangeland condition.