Search Results (72)

The premature senescence of red raspberry leaves severely affects plant growth. In this study, the double-season red raspberry cultivar ‘Polka’ was used, with N₁₅₀ (0.10 g N·kg⁻¹) selected as the treatment group (T150) and N₀ (0 g N·kg⁻¹) set as the control (CK). This study systematically investigated the mechanism of premature senescence in red raspberry leaves under different nitrogen application levels by measuring physiological parameters and conducting a combined multi-omics analysis of transcriptomics and metabolomics. Results showed that T150 plants had 8.34 cm greater height and 1.45 cm greater ground diameter than CK. The chlorophyll, carotenoid, soluble protein, and sugar contents in all leaf parts of T150 were significantly higher than those in CK, whereas soluble starch contents were lower. Malondialdehyde (MDA) content and superoxide anion (O₂⁻) generation rate in the lower leaves of T150 were significantly lower than those in CK. Superoxide sismutase (SOD) and peroxidase (POD) activities in the middle and lower functional leaves of T150 were higher than in CK, while catalase (CAT) activity was lower. Transcriptomic analysis identified 4350 significantly differentially expressed genes, including 2062 upregulated and 2288 downregulated genes. Metabolomic analysis identified 135 differential metabolites, out of which 60 were upregulated and 75 were downregulated. Integrated transcriptomic and metabolomic analysis showed enrichment in the phenylpropanoid biosynthesis (ko00940) and flavonoid biosynthesis (ko00941) pathways, with the former acting as an upstream pathway of the latter. A premature senescence pathway was established, and two key metabolites were identified: chlorogenic acid content decreased, and naringenin chalcone content increased in early senescent leaves, suggesting their pivotal roles in the early senescence of red raspberry leaves. Modulating chlorogenic acid and naringenin chalcone levels could delay premature senescence. Optimizing fertilization strategies may thus reduce senescence risk and enhance the productivity, profitability, and sustainability of the red raspberry industry. Full article

Soybean (Glycine max L.) is vulnerable to environmental stresses, such as heavy rainfall and high winds, which promote lodging and reduce plant performance during the monsoon season. To mitigate these issues, we evaluated the effects of plant topping, a practice involving the removal of apical buds, on plant architecture, physiological traits, and grain yield in four soybean cultivars over two growing seasons (2021–2022). Plant topping was performed at the V6-7 stage by cutting 30–35 cm above the ground. Plant topping reduced plant height by up to 23.5% and decreased leaf area index (by 8.0–16.4%), potentially improving light penetration into the lower canopy. Although chlorophyll concentration declined temporarily (297.8 vs. 272.8 mg m⁻² for non-topping vs. topping, respectively), NDVI remained stable, indicating delayed senescence. Chlorophyll fluorescence parameters revealed cultivar-specific stress responses, particularly in Taegwang, which showed elevated ABS/RC, TR₀/RC, and DI₀/CS values under plant topping. Grain yield was generally unaffected, except in Jinpung, which increased by 34% under plant topping in 2021 (2701 kg ha⁻¹ vs. 3621 kg ha⁻¹ for non-topping vs. topping). In conclusion, plant topping may help improve canopy structure and light distribution without compromising yield, potentially reducing lodging risk and offering a cultivar-specific management strategy. Full article

To identify optimal strategies for high-yield and high-efficiency cultivation under a “short-season direct-seeded cotton with once-only irrigation” regime, we conducted two-year field experiments (2022 and 2023) using a split-plot factorial design with three planting densities (30,000 (D1), 45,000 (D2), and 60,000 (D3) plants·ha⁻¹) and three nitrogen application rates (150 (N1), 180 (N2), and 210 (N3) kg·ha⁻¹). Our study systematically examined how these treatment combinations influenced canopy architecture, physiological traits, yield components, and fiber quality. The results showed that increased planting density significantly enhanced plant height, the leaf area index (LAI), and the number of fruiting branches, with the highest density (D3) contributing to a more compact and efficient canopy. Moderate nitrogen input (N2) significantly increased peroxidase (POD) activity, reduced malondialdehyde (MDA) accumulation, delayed functional leaf senescence, and prolonged the canopy’s photosynthetic performance. A significant interaction between planting density and nitrogen application was observed. The D3N2 treatment (high density with moderate nitrogen) consistently achieved the highest fruiting branch count, boll number per plant, and yields of both seed cotton and lint in both years, while maintaining stable fiber quality. This indicates its strong capacity to balance high yield with quality and maintain physiological resilience. By contrast, the D1N1 treatment (low density and low nitrogen) exhibited a loose canopy, premature photosynthetic decline, and the lowest yield. The D3N3 treatment (high density and high nitrogen) promoted vigorous early growth but reduced stress tolerance during later growth stages, leading to yield instability. These findings demonstrate that moderately increasing planting density while maintaining appropriate nitrogen levels can effectively optimize canopy structure, improve stress resilience, and enhance yield under short-season direct-seeded cotton systems with once-only irrigation. This provides both theoretical underpinning and practical guidance for achieving stable and efficient cotton production under such systems. Full article

The way in which alternate wetting and drying irrigation (AWD), as a water-saving practice promoted in rice (Oryza sativa L.) production systems, could enhance the productivity and water use efficiency (WUE) attracts broad attention. This study selected six mid-season indica rice varieties to investigate the impacts of AWD and conventional irrigation (CI) on grain yield, WUE, grain filling, and root traits. A two-year field experiment demonstrated that grain yields and WUE were significantly increased with varietal improvements. With the improvement of varieties, the maximum grain filling rate and mean grain filling rate for both apical superior and basal inferior spikelets were progressively enhanced during the grain filling stage. Compared to CI, AWD significantly enhanced grain yield and WUE. Flag leaf photosynthetic rate and root characteristics, including root weight, root length, root absorbing surface area, root oxidation activity, and zeatin (Z) + zeatin riboside (ZR) contents in panicles, roots, and root bleeding, were superior under AWD across early, mid, and late grain filling stages. Correlation and path analysis showed that improved grain filling in basal inferior spikelets was attributed to delayed root senescence during the grain filling stage under AWD. These results indicated that AWD would be a better irrigation regime to improve yield and WUE by optimizing grain filling and root growth for modern varieties. Full article

Melatonin is found in all classes of living organisms. In particular, in plants melatonin acts as an antioxidant that helps plants deal with both biotic and abiotic stress. In plants, melatonin improves seed germination, fruit ripening, photosynthesis, biomass production, circadian rhythm, membrane integrity, root development, leaf senescence, osmoregulation, and stress modulation. Melatonin concentrations vary enormously in different plants, different plant growth stages, different plant organs, and both the season and time of day that a plant is harvested. In addition, melatonin promotes root growth and development, prevents leaf senescence, promotes flowering and fruit ripening, promotes lateral root formation, stimulates gene expression of enzymes involved in photosynthesis, and protects plants from phytopathogen attack. Moreover, melatonin produced by soil bacteria can affect plant tolerance and health; in turn, melatonin synthesized by plants can influence the soil and rhizosphere microbiome. Finally, very recent literature indicates that melatonin can directly and positively affect the functioning of other soil bacteria. Full article

This study examines the effects of drought timing on height growth and seasonal leaf phenology in pedunculate oak (Quercus robur L.) seedlings. Drought represents a significant threat to long-lived tree species, impacting growth, phenology, and recovery potential. This research aims to assess whether the timing of drought stress influences height growth and leaf phenology while also investigating possible compensatory mechanisms. The experiment involved five groups of seedlings: four exposed to drought at different periods during the 2022 and 2023 growing seasons, and one regularly irrigated control group. The key monitored parameters included height growth, spring flushing, autumn leaf senescence, and photosynthesis. Preliminary results revealed that late-spring and summer drought had a significant negative impact on height growth and delayed autumn senescence, whereas mid-spring drought allowed for compensatory growth. Spring leaf phenology remained largely unaffected by drought treatments. None of the drought-stressed plants showed increased photosynthesis during the recovery phase compared to the control. These findings highlight the critical role of drought timing in determining growth and phenological outcomes. Relatively late-season droughts were particularly detrimental, limiting recovery and resource allocation, while early-season droughts provided better opportunities for compensation. Further research on drought recovery mechanisms and nutrient interactions is needed to refine forestry management strategies under climate change. Full article

Increased water limitations due to climate change will pose severe challenges to forest ecosystems in Europe. We investigated the response of potted saplings of Fagus sylvatica L., one of the major European tree species, to a spring and a summer water-withholding period with control–control (C-C), control–drought (C-D), drought–control (D-C) and drought–drought (D-D) treatments. We focused on recovery capacity and phenological and growth traits and questioned the extent to which an earlier drought influenced the response to a second drought in the same growing season. To examine the impact of the level of drought stress, a distinction was made between saplings with less or more than half of their leaves desiccated due to the spring drought (D<50 and D>50). The timing of the drought influenced the immediate post-drought response: saplings severely affected by the spring drought (D>50) resprouted, whereas saplings severely affected by the summer drought (C-D and D<50-D) did not. The spring treatment influenced the onset of visual symptoms in the summer drought, with saplings less affected in the spring drought (D<50-D) developing symptoms three days later than the saplings not subjected to drought in the spring (C-D), whereas severely affected saplings (D>50-D) had not yet display symptoms seventeen days after the first visual symptoms in the spring control saplings (C-D). The timing of autumnal leaf senescence displayed the legacies of the spring treatment. The saplings heavily affected by the spring drought showed a slower decrease in relative chlorophyll content and delayed leaf senescence (D>50-C and D>50-D), which may enable the repair of damaged tissues. The saplings that were less affected by the spring drought (D<50-C) showed earlier autumnal leaf senescence, which is likely an acclimation response. Interestingly, a larger diameter increment in autumn for all of the saplings that experienced the summer drought (C-D, D<50-D and D>50-D) may indicate the recovery of hydraulic capacity by new xylem growth. Our results underline the plasticity of young F. sylvatica saplings in response to (repeated) drought. Full article

Tropical trees that remain evergreen and exhibit leaf litterfall that is gradual over time coexist with trees that are seasonally deciduous and exhibit pulsed litterfall. The manner in which these trees acquire, store, and contribute nutrients to the biogeochemical cycle may differ. Green and senesced leaves from deciduous Ficus prolixa trees were compared with those from Ficus tinctoria on the island of Guam. The results enabled stoichiometry and resorption calculations. F. prolixa’s young green leaf nitrogen (N) and potassium (K) concentrations were double, and the phosphorus (P) concentration was triple, those of F. tinctoria. Concentrations converged as the leaves aged such that no differences in concentration occurred for senesced leaves, indicating that nutrient resorption proficiency did not differ between the two species. In contrast, the resorption efficiency was greater for F. prolixa than F. tinctoria for all three nutrients. The N:P values of 6–11 and K:P values of 5–7 were greater for young F. tinctoria leaves than young F. prolixa leaves. The N:K values were 1.1–1.6 and did not differ between the two species. No differences in pairwise stoichiometry occurred for senesced leaves for any of the nutrients. These Guam results conformed to global trends indicating that seasonally deciduous plants are more acquisitive and exhibit greater nutrient resorption efficiency. The differences in how these two native trees influence the community food web and nutrient cycling lies mostly in the volume and synchronicity of pulsed F. prolixa litter inputs, and not in differences in litter quality. These novel findings inform strategic foresight about sustaining ecosystem health in Guam’s heavily threatened forests. Full article

Current agriculture intensifies crop cultivation to meet food demand, leading to unsustainable use of chemical fertilizers. This study investigates a few physiological and agronomic responses of common wheat following the inoculation with plant growth-promoting bacteria to reduce nitrogen inputs. A field trial was conducted in 2022–2023, in Legnago (Verona, Italy) on Triticum aestivum var. LG-Auriga comparing full (180 kg ha⁻¹) and reduced (130 kg ha⁻¹) N doses, both with and without foliar application at end tillering of the N-fixing bacterium Methylobacterium symbioticum. Biofertilization did not improve shoot growth, while it seldom increased the root length density in the arable layer. It delayed leaf senescence, prolonged photosynthetic activity, and amplified stomatal conductance and PSII efficiency under the reduced N dose. Appreciable ACC-deaminase activity of such bacterium disclosed augmented nitrogen retrieval and reduced ethylene production, explaining the ameliorated stay-green. Yield and test weight were unaffected by biofertilization, while both glutenin-to-gliadin and HMW-to-LMW ratios increased together with dough tenacity. It is concluded that Methylobacterium symbioticum can amplify nitrogen metabolism at a reduced nitrogen dose, offering a viable approach to reduce chemical fertilization under suboptimal growing conditions for achieving a more sustainable agriculture. Further research over multiple growing seasons and soil types is necessary to corroborate these preliminary observations. Full article

The objective of this research was to assess the feasibility of remote sensing (RS) technology, specifically an unmanned aerial system (UAS), to estimate Bambara groundnut canopy state variables including leaf area index (LAI), canopy chlorophyll content (CCC), aboveground biomass (AGB), and fractional vegetation cover (FVC). RS and ground data were acquired during Malaysia’s 2018/2019 Bambara groundnut growing season at six phenological stages; vegetative, flowering, podding, podfilling, maturity, and senescence. Five vegetation indices (VIs) were determined from the RS data, resulting in single-stage VIs and cumulative VIs (∑VIs). Pearson’s correlation was used to investigate the relationship between canopy state variables and single stage VIs and ∑VIs over several stages. Linear parametric and non-linear non-parametric machine learning (ML) regressions including CatBoost Regressor (CBR), Random Forest Regressor (RFR), AdaBoost Regressor (ABR), Huber Regressor (HR), Multiple Linear Regressor (MLR), Theil-Sen Regressor (TSR), Partial Least Squares Regressor (PLSR), and Ridge Regressor (RR) were used to estimate canopy state variables using VIs/∑VIs as input. The best single-stage correlations between canopy state variables and VIs were observed at flowering (r > 0.50 in most cases). Moreover, ∑VIs acquired from vegetative to senescence stage had the strongest correlation with all measured canopy state variables (r > 0.70 in most cases). In estimating AGB, MLR achieved the best testing performance (R² = 0.77, RMSE = 0.30). For CCC, RFR excelled with R² of 0.85 and RMSE of 2.88. Most models performed well in FVC estimation with testing R² of 0.98–0.99 and low RMSE. For LAI, MLR stood out in testing with R² of 0.74, and RMSE of 0.63. Results demonstrate the UAS-based RS technology potential for estimating Bambara groundnut canopy variables. Full article

Leaf senescence is essential for the growth and development of deciduous trees in the next season. Larix gmelinii, a deciduous coniferous tree, exhibits its most distinctive feature by turning yellow in the autumn and eventually shedding its leaves, resulting in significant changes in its appearance during the fall. Lysine acetylation plays an important role in diverse cellular processes; however, limited knowledge is available regarding acetylations in the needle senescence of L. gmelinii. In this study, the proteomics and acetylated modification omics of two phenotypic leaves, yellow and green (senescent and non-senescent) needles, were analyzed before autumn defoliation. In total, 5022 proteins and 4469 unique acetylation sites in 2414 lysine acylated proteins were identified, and this resulted in the discovery of 1335 differentially expressed proteins (DEPs) and 605 differentially expressed acetylated proteins (DAPs) in yellow versus green needles. There are significant differences between the proteome and acetylome; only 269 proteins were found to be DEP and DAP, of which 136 proteins were consistently expressed in both the DEP and DAP, 91 proteins were upregulated, and 45 proteins were down-regulated. The DEPs participate in the metabolism of starch and sucrose, while the DAPs are involved in glycolysis and the tricarboxylic acid cycle. Among them, DEPs underwent significant changes in glycolysis and citric acid cycling. Most of the enzymes involved in glycolysis and the citrate cycle were acetylated. DAPs were down-regulated in glycolysis and up-regulated in the citrate cycle. In all, the results of this study reveal the important role of lysine acetylation in the senescence of L. gmelinii needles and provide a new perspective for understanding the molecular mechanism of leaf senescence and tree seasonal growth. Full article

Shaping the canopy architecture and delaying leaf senescence in maize are pivotal strategies for extending the crop’s photosynthetic period and improving yield. The application of plant growth regulators (PGRs) is a critical cultivation measure, with the timing of application being of paramount importance. To explore the effects of PGR application time on maize canopy structure, leaf senescence characteristics and yield, a comparative two-year field study was undertaken during the 2019–2020 growing seasons at the Gongzhuling Experimental Station of the Jilin Academy of Agricultural Sciences, utilizing a PGR containing ethephon as the active ingredient. The experiment was structured with two plant densities of 60,000 and 90,000 plants ha⁻¹, and three distinct PGR application protocols: T10 (application of PGR at the 10th leaf stage), T15 (application at the 15th leaf stage), and CK (control group sprayed with water). The result indicated that the yield increased by 5.62% following T15 treatment compared to the CK under high density (90,000 plants ha⁻¹). Furthermore, the kernel per ear and the 1000-kernel weight increased by 3.93% and 5.62% respectively, while the abortion rate decreased. Correlation analysis showed that yield and yield components were correlated with plant morphology, physiology, and aging characteristics under 90,000 plants ha⁻¹. Pollen density was also positively correlated with the top leaf area and the top leaf angle (p < 0.01). Furthermore, relative green leaf area at maturity (RGLAM) showed positive correlations with chlorophyll b, superoxide dismutase activity (SOD), peroxidase activity (POD), catalase activity (CAT), and soluble protein content (p < 0.01), while displaying a negative correlation with malondialdehyde content (MDA) (p < 0.01). Spraying plant growth regulators at the 15-leaf stage under high density can effectively enhance the top canopy structure of the maize and reduce the upper leaf area and angle, increase pollen density, and boost the number of grains. Furthermore, it delayed the senescence of leaves, prolonged the functional period of the leaves, increased kernel weight, optimized light resource utilization, and ultimately enhanced the maize yield. Full article

Phenology is considered an indicator of environmental changes, with direct implications in the length of the growing season; therefore, it offers essential information for a better understanding of the tree–environment relationships that could lead to the right decisions for forests’ sustainable use and conservation. A better understanding of how European beech (Fagus sylvatica) phenology responds to predicted climate change effects is important for forest management. This study aimed to assess bud burst and senescence among and within beech populations located along a steep elevational gradient. Phenological observations were carried out on 150 beech individuals along an altitudinal transect in the south-eastern Carpathian Mountains, from 550 to 1450 m, in five study sites in two consecutive years. The start of the bud burst, of senescence, and the duration of the growing season varied inversely proportionally to the elevational gradient in both monitored years. Individuals located at the highest altitude need 28 more days to start the growing season than those at the lowest altitude. There is an average difference of 14 days at the start of the growing season in the same beech populations between the two consecutive years. The first stage of senescence (yellowing of leaves) lasted longer in 2021 (21–32 days) than in 2022 (18–25 days), with a difference of 16%–28%, proportional to the increase in altitude. The association of field phenological data with meteorological data indicates that the start of the growing season occurs when the thermal threshold of 10 °C is exceeded, with an accumulation of a least 60 GDD (growing degree days) with a threshold of 0 °C in the last 7 days as a complementary condition. The appearance of the first stage of senescence, the yellowing of the leaves, was also influenced by the temperature and the accumulation of at least 72 SDD (senescence degree days) with a threshold of 0 °C in the last 7 days. Our results confirm that the temperature is the triggering meteorological factor for the onset of bud burst and leaf senescence in European beech. Full article

Macrochloa tenacissima (M. tenacissima), or esparto, is a perennial tussock grass that coexists with Pinus halepensis (P. halepensis) in semi-arid Mediterranean woodlands. This research was carried out to explore diurnal transpiration at leaf level in esparto grass under different levels of pine–esparto competition and in contrasting environmental soil water conditions. The measurement period spanned from the summer of 2020 to the spring of 2021. The relationship between transpiration and competition was conducted in open and closed P. halepensis stands, and the type of leaf (green, senescent) and the maturity of the esparto grass were taken into account. We observed a higher control of transpiration in green leaves, and the correlations between the transpiration and pine competition were noted exclusively in this type of leaf. Our results demonstrated a significant impact of pine competitors (closed stands) on the transpiration of esparto grass, particularly during seasons characterized by scenarios of high water demand: the summer drought period and the commencement of the growing and flowering period (spring). Furthermore, our findings revealed a greater response to transpiration in mature bushes compared to young ones under severe water stress, indicating a higher adaptation to drought by esparto as it ages. Although our results confirmed that PAR increased transpiration in all seasons and in both stands, which is attributable to the heliophilia of esparto grass, the site effects on transpiration could also be attributable to competition for water, especially during periods of drought. These results may have important implications for the dynamics and management of these semi-arid mixed woodlands, as well as the planning of reforestation programs aimed at restoring esparto grass formations. Full article

Fungal endophytes are harboured in the leaves of every individual plant host and contribute to plant health, leaf senescence, and early decomposition. In grasslands, fungal endophytes and their hosts often coexist with large herbivores. However, the influence of grazing by large herbivores on foliar fungal endophyte communities remains largely unexplored. We conducted a long-term (18 yr) grazing experiment to explore the effects of grazing on the community composition and diversity of the foliar fungal endophytes of two perennial grassland species (i.e., Artemisia capillaris and Stipa bungeana) across one growing season. Grazing significantly increased the mean fungal alpha diversity of A. capillaris in the early season. In contrast, grazing significantly reduced the mean fungal alpha diversity of endophytic fungi of S. bungeana in the late season. Grazing, growing season, and their interactions concurrently structured the community composition of the foliar fungal endophytes of both plant species. However, growing season consistently outperformed grazing and environmental factors in shaping the community composition and diversity of both plant species. Overall, our findings demonstrate that the foliar endophytic fungal community diversity and composition differed in response to grazing between A. capillaris and S. bungeana during one growing season. The focus on this difference will enhance our understanding of grazing’s impact on ecological systems and improve land management practices in grazing regions. This variation in the effects of leaf nutrients and plant community characteristics on foliar endophytic fungal community diversity and composition may have a pronounced impact on plant health and plant–fungal interactions. Full article