Xylem anatomical responses of Larix Gmelinii and Pinus Sylvestris influenced by the climate of Daxing'an mountains in Northeastern China

Wood anatomy and plant hydraulics play a significant role in understanding species-specific responses and their ability to manage rapid environmental changes. This study used the dendro-anatomical approach to assess the anatomical characteristics and their relation to local climate variability in the boreal coniferous tree species Larix gmelinii (Dahurian larch) and Pinus sylvestris var. mongolica (Scots pine) at an altitude range of 660-m to 842- m. We measured the xylem anatomical traits (lumen area (LA), cell wall thickness (CWt), cell counts per ring (CN), ring width (RW), and cell sizes in rings) of both species at four different sites Mangui (MG), Wuerqihan (WEQH), Moredagha (MEDG) and Alihe (ALH) and investigated their relationship with temperature and precipitation of those sites along a latitude gradient. Results showed that all chronologies have strong summer temperature correlations. LA extremes were mostly associated with climatic variation than CWt and RWt. MEDG site species showed an inverse correlation in different growing seasons. The correlation coefficient with temperature indicated significant variations in the May-September months at MG, WEQH, and ALH sites. These results suggest that climatic seasonality changes in the selected sites positively affect hydraulic efficiency (increase in the diameter of the earlywood cells) and the width of the latewood produced in P. sylvestris. In contrast, L. gmelinii showed the opposite response to warm temperatures. It is concluded that xylem anatomical responses of L. gmelinii and P. sylvestris showed varied responses to different climatic factors at different sites. These differences between the two species responses to climate are due to the change of site condition on a large spatial and temporal scale

Unraveling the importance of forest structure and composition driving soil microbial and enzymatic responses in the subtropical forest soils

As the responsive soil properties, soil microbial fractions and enzymatic activities are often recommended for assessing soil environment. Different flora, silvicultural practices, and anthropogenic activities regulate essential ecosystem processes. They could substantially affect biological properties, nutrient budgets, and biogeochemical cycles at local and regional scales. This study examined how different forest compositions influenced by various anthropogenic activities (land use change, over-exploitation, species translocation) affect soil microbial properties and enzymatic activities, as well as the effects of soil chemical properties on these patterns in important sub-tropical forest ecosystems in Southern China. The research was conducted at Lutou forest research station, located in Yueyang, Hunan Province, China. Soil samples were collected at 0–10, 10–20, and 20–40 cm depths from natural broadleaved forest (NBF), coniferous monoculture plantations (CPF), and mixed forest stand. CPF stands are directly affected by human interference and frequent harvesting practices, whereas mixed forest and NBF stands are naturally grown forests with minimal human interference. Enzymes continually play a positive role in preserving soil health. The results showed that the interaction effect of forest type and soil depth significantly influenced urease, sucrase, and protease activity (all p < 0.001); however, no clear patterns were observed. Soil microbial carbon (MBC) and soil microbial nitrogen (MBN) were remarkably higher in 0–10 cm in mixed forest and NBF stand compared to CPF stand. For the upper soil layer, soil organic carbon (SOC) was higher in mixed forest, whereas, for the remaining two layers, it was observed to be highest in NBF. Moreover, the microbial quotient (MBC/SOC) was considerably higher in NBF forest in all soil layers than in mixed forest and CPF stand. Soil organic carbon (SOC) and soil total nitrogen (TN) had a strong positive relationship with MBC compared to MBN. Our study contributes toward an enhanced understanding of soil enzymatic responses and microbial soil dynamics’ biological patterns, controls, and activities in different rural forest ecosystems

The interactive impact of straw mulch and biochar application positively enhanced the growth indexes of maize (Zea mays L.) crop

A two-year experiment was carried out at Shenyang Agricultural University’s research field area in China to evaluate the impact of the combined application of straw mulch (0 and 8 t ha−1) and biochar (0, 4, 12, and 36 t ha−1) on the morphological traits and grain development of rainfed maize during 2018 and 2019. The results showed that straw mulch and different biochar application rates significantly impacted the maize growth index. Compared to non-biochar-treated soils, the introduction of straw mulch improved plant height, stem diameter, leaf area index (LAI), leaves, stem, root, and crop growth rate (CGR), and dry weight of rainfed maize crop. The highest plant height, stem diameter, LAI, leaves, stem, root growth rate, CGR, and dry weight of rainfed maize crop were reported when soil was treated with a higher rate of biochar (36 t ha−1). Biochar increased grain filling rate while decreasing grain filling duration in rainfed maize crops. Our results indicate that straw mulch and biochar-based soil management strategies can improve the rainfed maize growth with the environmental benefits of global warming mitigation. However, due to the wide range of biochar properties, the interactions between straw mulch and biochar should be given special consideration in the maize cropping system

Effect of exogenous application of nicotinic acid on morpho-physiological characteristics of Hordeum vulgare L. under water stress

Abiotic stresses, such as high temperature and drought conditions, greatly influence the development of plants and the quality and quantity of products. Barley (Hordeum vulgare L.) crop production is largely impacted by drought, affecting growth, yield, and ultimately the productivity of the crop in hot arid/semi-arid conditions. The current pot experiment was directed to observe the outcome of nicotinic acid (NA) treatments on barley’s physiological, biochemical, and production attributes at two capacity levels, i.e., 100% normal range and withholding water stress. Randomized complete block design (RCBD) was used during the experimentation with the two-factor factorial arrangement. NA was applied exogenously by two different methods, i.e., foliar and soil application (fertigation). NA solution contained various application levels, such as T1 = control, foliar applications (T2 = 0.7368 gL−1, T3 = 1.477 gL−1, T4 = 2.2159 gL−1), and soil applications (T5 = 0.4924 gL−1, T6 = 0.9848 gL−1, and T7 = 1.4773 gL−1). Results depicted that, overall, foliar treatments showed better effects than control and soil treatments. Plant growth was preeminent under T4 treatment, such as plant height (71.07 cm), relative water content (84.0%), leaf water potential (39.73-MPa), leaf area index (36.53 cm2), biological yield (15.10 kgha−1), grain yield (14.40 kgha−1), harvest index (57.70%), catalase (1.54 mmolg−1FW−1), peroxidase (1.90 g−1FWmin−1), and superoxide dismutase (52.60 µgFW−1) were superior under T4 treatment. Soil plant analysis development (54.13 µgcm−2) value was also higher under T4 treatment and lowest under T7 treatment. In conclusion, NA-treated plants were more successful in maintaining growth attributes than non-treated plants; therefore, the NA foliar treatment at the rate of 2.2159 gL−1 is suggested to find economical crop yield under drought conditions. The present study would contribute significantly to improving the drought tolerance potential of barley through exogenous NA supply in water deficit areas

Can bacterial endophytes be used as a promising bio-inoculant for the mitigation of salinity stress in crop plants? : a global meta-analysis of the last decade (2011-2020)

Soil salinity is a major problem affecting crop production worldwide. Lately, there have been great research efforts in increasing the salt tolerance of plants through the inoculation of plant growth-promoting endophytic bacteria. However, their ability to promote plant growth under no-stress and salinity-stress conditions remains largely uncertain. Here, we carried out a global meta-analysis to quantify the plant growth-promoting effects (improvement of morphological attributes, photosynthetic capacity, antioxidative ability, and ion homeostasis) of endophytic bacteria in plants under no-stress and salinity-stress conditions. In addition, we elucidated the underlying mechanisms of growth promotion in salt-sensitive (SS) and salt-tolerant (ST) plants derived from the interaction with endophytic bacteria under no-stress and salinity-stress conditions. Specifically, this work encompassed 42 peer-reviewed articles, a total of 77 experiments, and 24 different bacterial genera. On average, endophytic bacterial inoculation increased morphological parameters. Moreover, the effect of endophytic bacteria on the total dry biomass, number of leaves, root length, shoot length, and germination rate was generally greater under salinity-stress conditions than no-stress conditions. On a physiological level, the relative better performance of the bacterial inoculants under the salinity-stress condition was associated with the increase in total chlorophyll and chlorophyll-b, as well as with the decrease of 1-aminocylopropane-1-carboxylate concentration. Moreover, under the salinity-stress condition, bacterial inoculation conferred a significantly higher increase in root K+ concentration and decrease in leaf Na+ concentration than under the no-stress condition. In SS plants, bacterial inoculation induced a higher increase in chlorophyll-b and superoxide dismutase activity, as well as a higher decrease in abscisic acid content, than in ST plants. Under salinity-stress, endophytic bacterial inoculation increased root K+ concentration in both SS and ST plants but decreased root Na+ concentration only in ST plants. Overall, this meta-analysis suggests that endophytic bacterial inoculation is beneficial under both no salinity-stress and salinity-stress conditions, but the magnitude of benefit is definitely higher under salinity-stress conditions and varies with the salt tolerance level of plants

Morpho-physiological growth performance and phytoremediation capabilities of selected xerophyte grass species toward Cr and Pb stress

Being sessile organisms, plants cannot escape unwanted changes in the environment. The rapid human population explosion caused significant environmental problems. Heavy metals produced through various sources can cause severe damage to living organisms. The study was planned to evaluate four grass species’ morpho-physiological growth characteristics and phytoremediation capabilities under chromium (Cr) and lead stress (Pb) in the arid climate. Typha angustifolia, Tragus roxburghii, Aeluropus logopoides, and Cenchrus ciliaris grass species were used for the study. One-year-old stubbles from the Cholistan desert were used for the experiment. Cr treatments in the form of K2Cr2O7 were applied at 0, 20, 40, and 80 mg L–1, whereas Pb was applied as PbCl2 at 0, 50, 200, and 500 mg L–1 as control, low, moderate and high-stress, respectively. After 6 weeks of heavy metals treatments, plants were harvested and analyzed for growth performance and phytoremediation capabilities. Results depicted that, regarding morphological attributes, T. angustifolia performed better, followed by C. ciliaris; no clear pattern was observed for T. roxburghii and A. logopoides. The CO2 assimilation rate (Co2d) and water use efficiency (WUE) increased as the heavy metal stress increased in all species under both metals. In contrast, total chlorophyll content was higher under low stress. Other physiological parameters, such as relative humidity (RHd), net photosynthetic rate (A), transpiration rate (E), stomatal conductance (Gs), leaf internal CO2 concentration (Ci) and membrane stability index (MSI) gradually decreased as the Cr, and Pb stress levels increased among all the species. Moreover, Cr and Pb absorption contents of T. angustifolia were higher than the other three species at each stress level. Overall, T. angustifolia thrived against heavy metals stress and showed higher biomass, maximum photosynthetic measurements, WUE and higher metal absorption among all the selected species. Results concluded that although all the selected species behaved fine under stress conditions, T. angustifolia performance was better; thus, it can be used to remediate the soil near industrial estates

Floods wreak havoc in Pakistan : a deadly reality of climate change exposing frailty of global response efforts

Given recent unprecedented anthropogenic activities, dynamic shifts in atmospheric balance are rapidly becoming the new normal, triggering climatic upheavals of varying intensity worldwide. It is almost certain that some of the recent extreme weather events, such as the Australian bush and Amazon forest fires, the Russian and Canadian heat waves, the African droughts, and the change. Another important reason to grasp the reality of climate change is the declining biodiversity of insects, including pollinators and predators, which could limit crop productivity worldwide (Raven and Wagner, 2021). Yet both the frequency and magnitude of these catastrophic events around the world suggest that they are occurring more rapidly than most climate models predict. Global warming is currently causing unrivaled glacial retreat and rapid melting of the glaciers in many parts of the world. Pakistan is home to 7253 glaciers, the largest number outside the Arctic polar region, and is one of the countries most affected by climate change due to the accelerated melting of these glaciers. According to recent reports on the glacial hydrology of the Himalaya-Karakoram range, a population of nearly one billion people could be affected by devastating climate change-induced snowmelt and flooding events (Azam et al., 2021)

Climatological and social fallacies about COVID‑19 pandemic

Coronavirus disease (COVID-19) has emerged as a major global challenge since 2019. With the fast rise in the infected cases and deaths worldwide, many environmental and climate-related myths and fallacies spreaded fast. These fallacies include virus cannot spread in hot and humid conditions, cold weather can inhibit the virus, drinking hot water and sunlight can help cure the COVID-19, ultraviolet (UV) disinfectant lamps and UV rays from sunlight can kill the virus, use of hairdryers and hot showers for virus prevention, etc. Social norms and mindset of the people in the world towards a pandemic are quite similar. The primary purpose of this article is to enlighten the readers regarding these climatological misconceptions and social fallacies, helping spread proper knowledge and manage the outbreak of this deadly pandemic

Annual growth progression, nutrient transformation, and carbon storage in tissues of Cunninghamia lanceolata monoculture in relation to soil quality indicators influenced by intraspecific competition intensity

Purpose: Nutrient distribution among tree tissues influence the growth, yield, and persistence of trees. One of the factors which can affect the nutrient concentrations can be stand density because competition for growth space and below-ground resources play a significant role in the productivity of plantation forests. Methods: This study analyzed the impact of planting density and soil quality indicators on the annual growth process, nutrient uptake, nutrient use efficiency, and carbon storage in mid-aged Chinese fir (Cunninghamia lanceolata) stands established at low, intermediate, and high-density. Stem density was 1450 trees hm2 (2.36 x 2.36 m spacing), 2460 trees hm2 (1.83 x 1.83 m spacing), and 3950 trees hm2 (1.44 x 1.44 m spacing) in low-, intermediate-, and high-density stands, respectively. Results: Stand density (R2 = 0.812) was the primal factor responsible for altering nutrients dynamics in tree components, while soil quality (R2 = 0.572) indicators play a secondary role. Across the years, the diameter and volume annual growth increment were more significant in the low-density, whereas height growth increment was more prominent in the intermediate-density. The highest carbon storage (33.78 t hm−2) was observed in the intermediate-density stand. Plant nutrient concentrations and nutrient use efficiency varied significantly among different densities (p<0.05). Significant associations of soil properties with biomass, height, and diameter were observed in intermediate-density. Conclusions: These patterns were co-regulated by planting density, tree growth rate, and soil nutrient status and reflected the plant tissue’s nutrient status, which could provide valuable information for sustainable nutrient management practices in tree plantations for maximizing productivity, yield, and long-term sustainability

Non-targeted metabolomics reveal the impact of phenanthrene stress on root exudates of ten urban greening tree species

Different root exudations can modify the bioavailability of persistent organic pollutants (POPs). Among these exudations, the low molecular weight organic acids play an imperative role in this process. The study was conducted to analyze the effect of phenanthrene (PHE) stress on root exudation variations and changes in its chemical composition in ten urban greening tree species, namely Loropetalum chinense, Gardenia ellis, Photinia fraseri, Ligustrum japonicum, Rhododendron simsii, Osmanthus fragrans, Gardenia jasminoides, Buxus sinica, Camellia sasanqua, and Euonymus japonicas. The experiment was carried out in three PHE concentration treatments (0 mg kg−1 (CK), 200 mg kg−1 (PHEL), 2000 mg kg−1 (PHEH)). The root exudates were collected and analyzed by GC-MS method. In total, 673 compounds were identified either with high or low abundance among all species and treatments. Compounds identified in CK, PHEL, and PHEH were 240, 180, and 256, respectively. The results illustrated that carbohydrates, phenols, and esters were the dominant compounds, accounted for more than 92%. Principal component analysis depicted that tree species grown in PHEH showed obvious alteration in compounds of root exudation, whereas little difference was noticed between PHEL and CK. Phenols (80%) were the most abundant, while nitriles contributed a small portion. Moreover, among all species, R. simsii released the maximum number of compounds, and L. japonicum released the least number of compounds accounting for 89 and 46, respectively. The results achieved here to illustrate that plant type, and PHE stress can significantly change the concentrations and species of root exudates. This study provides the scientific reference for understanding the phenanthrene responsive changes in root exudates and phytoremediation of polycyclic aromatic hydrocarbons (PAHs), as well as a screening of urban greening tree species