Hordeum jubatum L. is a perennial herb with high ornamental value and strong stress tolerance. Nitrogen deposition and cold stress are key environmental factors that affect stability of ecosystems in cold regions of northeast China. These factors significantly affect plant growth and development. Arbuscular mycorrhizal fungi (AMF) are symbiotic soil fungi that can increase plant resistance and growth. However, research on impacts of nitrogen deposition and cold stress on roots of H. jubatum-AM symbionts remains limited. Root biomass (dry and fresh weight), architecture (length, surface area, volume, forks, number of fourth-order roots, and root fractal dimension), and ultrastructure of H. jubatum were assessed, both in the presence and absence of AMF, under conditions of nitrogen deposition and cold stress. Cold stress inhibited all indicators of root architecture and disrupted root ultrastructure, with greater inhibition shown in the N2 (NH4+/NO3- = 1:1) treatment under cold stress, indicating nitrogen deposition increased sensitivity of H. jubatum to cold stress. Inoculation with AMF significantly reduced damage caused by nitrogen deposition and cold stress on H. jubatum roots compared with the non-inoculation treatment. Our results demonstrate different effects of the interaction of nitrogen deposition and cold stress versus single stress (nitrogen deposition or cold stress) on plant root development and provide a scientific basis for the use of mycorrhizal technology to improve resistance and productivity of cold-tolerant plants in cold regions under stress conditions.

The tsunami in March 2011 heavily damaged the Pinus thunbergii Parlatore erosion-control coastal forests of northeastern Japan. The restoration is in process but has been challenged by waterlogging resulting from soil compaction of artificial growth bases. In this study, a pot experiment was conducted to elucidate the waterlogging responses of two-year-old P. thunbergii seedlings in terms of waterlogging duration. Three waterlogging durations were set (7 days, 17 days, and 32 days, water table at soil surface) during August, followed by a waterlogging-free recovery period (28 days) in September. In this experiment, the responses of both above- and belowground organs during waterlogging and after the release from waterlogging were elucidated, focusing on parameters, such as transpiration and photosynthesis rates, as well as fine root growth and morphology. As a result, we found that under the conditions of our experiment, if the waterlogging duration is within 17 days, P. thunbergii seedlings can recover physiological activity in about a week; however, if the waterlogging duration is over 32 days, recovery after the release from waterlogging largely varied among seedlings. For the seedlings that could recover, recovery took at least 2 weeks, which required new fine root growth. In cases where the damage was irreversible, seedlings showed an overall decline. These results suggest that it is important to manage the waterlogging conditions so that P. thunbergii seedlings can recover without prolonged negative effects.

Imazethapyr, a widely used herbicide, exhibits a long persistence in soils and can cause injury to rotational crops. Here, we discovered that imazethapyr inhibits primary root elongation in Arabidopsis by inhibiting cell division and expansion rather than damaging the organization of root meristem. Integration of transcriptomic and metabolomic analysis revealed that imazethapyr downregulated multiple genes related to cell wall loosening and modification, leading to increased cell wall thickness and inhibited cellular expansion in Arabidopsis roots. Furthermore, imazethapyr upregulated auxin biosynthesis and transport, resulting in enhanced auxin accumulation at root tips. Elevated auxin concentrations triggered apoplast alkalization and the inactivation of wall-loosening enzymes, further suppressing root growth. This research provides new insights into the molecular mechanism underlying imazethapyr phytotoxicity and offers potential strategies for developing crops that are better adapted to soils contaminated with imidazolinone herbicides.

This experiment examined the effects of blending bottom ash produced after combusting dry livestock manure (BACL, 2-4 mm particle) as a soil amendment on the physicochemical properties of the root zone and growth response of creeping bentgrass in sandy soil. The treatments were designed as follows: control [100% sand], 3% BACL (3% BACL + 97% sand), 5% BACL (5% BACL + 95% sand), 7% BACL (7% BACL + 93% sand), and 10% BACL (10% BACL + 90% sand). Although BACL improved the soil physical properties, such as the capillary porosity, total porosity, and hydraulic conductivity, it reduced the cation exchangeable capacity. The BACL treatments increased the pH, EC, Av-P2O5, and Ex-K compared to the control. The turf color index, chlorophyll content, shoot length, clipping yield, and shoot dry weight after the BACL treatments were similar to the control. The growth and nutrient uptake of the roots in the BACL treatment were higher than those of the control. The BACL application amount was positively correlated with the capillary porosity and total porosity of the root zone (p <= 0.01) and with the growth and nutrient levels of the roots (p <= 0.05). These results suggest that applying BACL as a soil amendment enhanced the uptake of phosphorus and potassium in the roots of creeping bentgrass by improving the soil porosity in the root zone and by supplying phosphate and potassium.

The impact of biochar application on plant performance under drought stress necessitates a comprehensive understanding of biochar-soil interaction, root growth, and plant physiological processes. Therefore, pot experiments were conducted to assess the effects of biochar on plant responses to drought stress at the seedling stage. Two contrasting maize genotypes (drought-sensitive KN5585 vs. -tolerant Mo17) were subjected to biochar application under drought stress conditions. The results indicated that biochar application decreased soil exchangeable Na+ and Ca2+ contents while increased soil exchangeable K+ content (2.7-fold) and electrical conductivity (4.0-fold), resulting in an elevated leaf sap K+ concentration in both maize genotypes. The elevated K+ concentration with biochar application increased root apoplastic pH in the drought-sensitive KN5585, but not in the drought-tolerant Mo17, which stimulated the activation of H+-ATPase and H+ efflux in KN5585 roots. Apoplast alkalinization of the drought-sensitive KN5585 resulting from biochar application further inhibited root growth by 30.7%, contributing to an improvement in water potential, a reduction in levels of O2-, H2O2, T-AOC, SOD, and POD, as well as the down-regulation of genes associated with drought resistance in KN5585 roots. In contrast, biochar application increased leaf sap osmolality and provided osmotic protection for the drought-tolerant Mo17, which was associated with trehalose accumulation in Mo17 roots. Biochar application improved sucrose utilization and circadian rhythm of Mo17 roots, and increased fresh weight under drought stress. This study suggests that biochar application has the potential to enhance plant drought tolerance, which is achieved through the inhibition of root growth in sensitive plants and the enhancement of osmotic protection in tolerant plants, respectively. Biochar application decreased soil exchangeable Na+ and Ca2+, but increased soil exchangeable K+ and electrical conductivity.Biochar increased apoplastic pH, but reduced root growth, stress damage and stress response during drought for the drought-sensitive KN5585.Biochar improved osmotic protection, trehalose accumulation, and fresh weight during drought for the drought-tolerant Mo17.

The global agricultural productivity has been significantly impaired due to the extensive use of heavy metal. Cadmium (Cd) is now recognized as a significant soil and environmental contaminant that is primarily spread by human activity. This study investigates the possible impact of melatonin (ME) in mitigating the toxicity caused by Cd in pepper (Capsicum annuum L.) seedlings. There were three groups of plants used in the experiment: control (CK) plants, Cd-stressed plants and ME-pretreated + Cd-stressed plants. The concentration of ME and Cd was 1 mu M and 0.1 mM, respectively, and applied as root application. The results described that Cd treatment remarkably reduced growth parameters, impaired pigment concentration, hindered gas exchange traits. In contrast, ME supplementation significantly recovered these parameters by increase in growth and biomass production of pepper seedlings under Cd toxicity. In addition, ME application considerably increased osmolyte production and protein level in pepper leaves and roots. Furthermore, ME positively upregulated the antioxidant enzymes activity and effectively decreased the oxidative damage in pepper leaves and roots. The enhanced antioxidant enzymes activity performed a significant role in the reduction of H2O2 and MDA concentration in plants under Cd stress. The findings indicated that the application of ME to plants effectively alleviates the stress caused by Cd exposure. Moreover, ME demonstrates significant efficacy in mitigating the adverse impacts of Cd on pepper plants.

This study aimed to investigate the influence of chemical and structural characteristics of biochar on the development of rice plants grown in fragile sandy soil. An experiment was carried out in pots with the application of four doses (0 ton ha-1; 10 ton ha-1; 20 ton ha-1; 30 ton ha-1) of eucalyptus biochar from four artisanal sources (B1, B2, B3, and B4). Fresh root mass increased by 0.56% with the application of biochar B4 and decreased with the application of biochars B1, B2, and B3 (23.3%; 18.3%; 19.9%). The fresh mass of sheath and leaves decreased by an average of 23.6% and 27%, respectively, with the application of all biochars. Root dry mass increased by 7.8% with the application of biochar B4 and decreased with the application of B1, B2, and B3. The sheath dry mass and leaf dry mass decreased by an average of 20.2% and 25.1%, respectively, with the application of all biochars. The nutrient content, specifically P, K, and N, increased with the application of B1, B2, and B3. The application of biochar B4 (30 ton ha-1) lessened the damage to the photosynthetic apparatus and promoted physiological recovery. The beneficial effect of biochar B4 occurred at a dose of 30 ton ha-1 in the reaction centers, increasing photochemical efficiency in photosystem II. Root development was stimulated by the application of biochar B4, increasing root area by 55% (10 ton ha-1) and 56% (20 ton ha-1 and 30 ton ha-1). The total length increased by 48% with the application of biochar B4 and by 27% with biochar B2 (30 ton ha-1). The length of thick roots and the total root volume were less affected by the treatments, with increases of approximately 11% and 7%, respectively. Although most treatments did not result in higher biomass production compared to the control, there was a notable increase in nutrient content in the aboveground portion, particularly with the application of biochar B2. Furthermore, improvements in photosynthetic parameters and root morphology were observed, particularly when biochar B4 was applied. Overall, the findings of this study indicate that biochars B2 and B4, at rates of 20 and 30 ton ha-1, respectively, hold promise for enhancing cultivation in vulnerable Planosols in the Rio de Janeiro region of Brazil. However, to fully understand the effects on soil properties in different crops and the economic implications of implementing biochar in agriculture, further long-term and large-scale research is necessary.

Cultural and environmental factors can place creeping bentgrass (Agrostis stolonifera) under extreme stress during the summer months. This stress, coupled with the growth adaptation of creeping bentgrass, can result in shallow, poorly rooted stands of turf. To enhance root zone oxygen and rooting of creeping bentgrass, golf courses use methods such as core and solid-tine aerification, and sand topdressing. An additional method of delivering oxygen to the soil could be irrigation with nanobubble-oxygenated water. The properties of nanobubbles (NBs) allow for high gas dissolution rates in water. Irrigating with NB-oxygenated water sources may promote increased rooting of creeping bentgrass putting greens during high-temperature periods and lead to a more resilient playing surface. The objectives of this study include comparing the effects of irrigation with NB-oxygenated water sources with untreated water sources on creeping bentgrass putting green root zone and plant health characteristics using field and controlled environment experiments. Treatments included NB-oxygenated potable water and irrigation pond water, and untreated potable and irrigation pond water. In the field, NB-oxygenated water did not enhance plant health characteristics of creeping bentgrass. In 1 year, NB oxygenated water increased the daily mean partial pressure of soil oxygen from 17.48 kPa to 18.21 kPa but soil oxygen was unaffected in the other 2 years of the trial. Subsurface irrigation with NB-oxygenated water did not affect measured plant health characteristics in the greenhouse. NB-oxygenation of irrigation water remains an excellent means of efficiently oxygenating large volumes of water. However, plant health benefits from NB-oxygenated irrigation water were not observed in this research.

Oat (Avena nuda L.) is a globally important cereal crop grown for its nutritious grains and is considered as moderately salt-tolerant. Studying salinity tolerant mechanisms of oats could assist breeders in increasing oat production and their economic income in salt-affected areas, as the total amount of saline land in the world is still increasing. The present study was carried out to better understand the salt tolerance mechanism of the naked oat line Bayou1. A soil experiment was conducted on 17 days-old Bayou1 seedlings treated with varying concentrations of NaCl for a period of 12 days. Bayou1 plants grew optimally when treated with 50 mM NaCl, demonstrating their salinity tolerance. Reduced water uptake, decreased Ca2+, Mg2+, K+, and guaiacol peroxidase activity, as well as increased Na+ concentration in leaves, all contributed to a reduction in shoot growth. However, the damage to ionic homeostasis caused by increased Na+ concentrations and decreased K+ concentrations in the roots of Bayou1 did not inhibit its root growth, indicating that the main salt-tolerant mechanism in Bayou1 existed in its roots. Further, a hydroponic experiment found that increasing Na+ concentration in root cell sap enhanced root growth, while maintaining the integrity of root cell membranes. The accumulated Na+ may have facilitated the root growth of Bayou1 exposed to NaCl by effectively adjusting cellular osmotic potential, thereby ensuring root cell turgor and expansion.

In this study, we analysed how the tree growth in stem and roots reacts to thinning, focusing on the consequences for mechanical stability of the root-soil plate quantified by field mechanical bending tests. In order to disentangle the role of the biomechanical control of growth (thigmomorphogenesis) from other factors, half of the studied trees were guyed to remove mechanical stimulation due to the wind of living cells. Surprisingly, our results show a decrease in the root-soil plate mechanical performances for a given stem biomass after thinning. This decrease was however explained by boosted biomass allocation to the stem at the expense of the root system. Further, relationship between the initial stiffness and the strength (overturning moment) of the root-soil plate was modified by thinning. It is suggested that at this development stage (poles), as stem break is the weakest point of tree resistance to wind loads, the biomechanical control of growth strengthens preferentially the stem and not the anchorage. Further developments should study the diversity of behaviours between development stages and between species for a unified theory on the role of the thigmomorphogenetic syndrome in tree resistance to wind risk, with synergies and trade-offs with other processes and functions.