Root Morphological Characteristics Research Articles

Interactions between root and rhizosphere microbes mediate phosphorus acquisition in Pinus tabulaeformis

The Pinus tabulaeformis plantation is a major industrial forest in China. Phosphorus (P) deficiency seriously affected its growth and productivity. Root traits and rhizosphere microorganisms play essential roles in plant P acquisition. However, how root traits interact with microbial communities for P acquisition remains largely unclear. The responses of P. tabulaeformis root morphological characteristics, oxalic acid, soil P fractions and rhizosphere bacterial and fungal communities and potential functions to P addition were investigated using a pot experiment with three P levels (0, 20, and 80 mg P kg−1 soil). Additionally, we constructed a functional synthetic microbial community (SynCom) and verified their behaviors in promoting plant P acquisition and growth. P fertilization significantly increased the soil CaCl2-P, citrate-P, HCl-P and microbial biomass P (MBP) fractions and decreased oxalic acid, bacterial indicator genera in P deficiency and ectomycorrhizal fungi (ECM). Most of the bacterial indicator genera in P deficiency were negatively correlated with citrate-P and HCl-P but were positively correlated with alkaline phosphatase (ALP) and oxalic acid. According to structure equation models, soil total P could directly influence P acquisition efficiency and indirectly through its effects on ECM or by regulating oxalic acid, which regulated bacterial indicator genera in P deficiency and thus affected ALP production. Inoculation with SynCom significantly increased soil available P contents, ALP activities, root P concentrations and superoxide dismutase activities. Under low P conditions, P. tabulaeformis adopted a high carbon cost strategy for P acquisition, specifically moderating root secretion. Rhizosphere bacteria could accelerate soil P mobility and enhance the P absorption ability and systemic resistance of roots to alleviate P stress. This study provided the theoretical basis for the exploitation and utilization of microbial fertilizers, as well as for the cultivation and management of plantation.

Biochar Application Combined with Water-Saving Irrigation Enhances Rice Root Growth and Nitrogen Utilization in Paddy Fields

To improve nitrogen use efficiency (NUE) during rice cultivation, it is essential to comprehend the morphological and physiological traits of rice roots. However, in high-fertility black soil regions of Northeast China, the effects of combining biochar application with water-saving irrigation (WSI) conditions on rice root development and nitrogen utilization are still unknown. To address this knowledge gap, a combination of field experiments and 15N tracer micro-area investigations was conducted in this study. Four treatments were implemented: (i) controlled irrigation without biochar application (CB0); (ii) controlled irrigation with 2.5 t ha−1 biochar application (CB1); (iii) controlled irrigation with 12.5 t ha−1 biochar application (CB2); and (iv) controlled irrigation with 25 t ha–1 biochar application (CB3). Flooded irrigation conditions without biochar treatment (FB0) were used as the control. The primary objective of this research was to identify the mechanisms by which combined WSI conditions and biochar application affect rice root development and nitrogen utilization. Biochar application enhanced rice root morphological and physiological characteristics. Optimal biochar application increased the longest root length (RL), root volume (RV), root fresh weight (RFW), root active absorption area, root bleeding intensity, and root activity (RA) of rice while also optimizing the root–shoot ratio and facilitating nitrogen absorption by roots. These changes in root morphological and physiological characteristics facilitated the absorption of fertilizer-15N and soil nitrogen by rice roots, ultimately leading to improvements in rice yields and NUEs. Notably, the rice yields, NUE, nitrogen agronomic efficiency (NAE), and nitrogen partial factor productivity (NPFP) of CB2 plants were 16.45%, 39.42%, 24.48%, and 16.45% higher than those of FB0 plants, respectively. These results highlight the effectiveness of biochar application as a strategy to ensure food security and enhance NUE under WSI conditions. Furthermore, this study suggests that the recommended optimal application amount of biochar for the black soil area of Northeast China is 12.5 t ha−1.

Biochar enhances the growth and physiological characteristics of Medicago sativa, Amaranthus caudatus and Zea mays in saline soils

Biochar is a promising solution to alleviate the negative impacts of salinity stress on agricultural production. Biochar derived from food waste effect was investigated on three plant species, Medicago sativa, Amaranthus caudatus, and Zea mays, under saline environments. The results showed that biochar improved significantly the height by 30%, fresh weight of shoot by 35% and root by 45% of all three species compared to control (saline soil without biochar adding), as well as enhanced their photosynthetic pigments and enzyme activities in soil. This positive effect varied significantly between the 3 plants highlighting the importance of the plant-biochar interactions. Thus, the application of biochar is a promising solution to enhance the growth, root morphology, and physiological characteristics of plants under salt-induced stress.

Effects of vegetation growth on soil microstructure and hydro-mechanical behaviour

Literature studies are evidencing the counterposed effects of vegetation on soil hydraulic behaviour. Besides, root effects at the microscale are rarely quantified for direct correlations with phenomenological observations due to the complexity of adopting up-scaling factors. This study explores the microstructural causes behind the observed changes in vegetated compacted clayey sand's hydraulic and volume change behaviour. To this aim, laboratory experiments were carried out on compacted samples seeded with Cynodon dactylon. Significant changes in soil water-saturated permeability, water retention and shrinkage upon drying were observed after root growth. Laboratory measurements were complemented with quantification of root morphological features and observations at the microscale at different soil hydraulic states. X-ray scans and mercury intrusion porosimetry allowed covering seven orders of magnitude of pore sizes, shedding light on soil fabric changes at the soil-root interface and the clay aggregate scale. The effects of roots on the soil pore size distribution consisted of multi-physics phenomena: fissure generation, void clogging, and soil aggregation due to roots’ chemical interaction. Furthermore, a good correlation was found between the normalised volume of roots and the micro-pores volume. This new expression was included in a framework to predict soil water retention behaviour considering the aggregated structure and soil-root hydro-chemical interactions.

Adding Agricultural Topsoil and Growing Perennial Ryegrass (Lolium perenne L.) Enhanced the Rehabilitation of Metal/loids Enriched Iron Ore Mine Tailings

AbstractRevegetating iron-ore mine tailings is difficult due to their poor physicochemical and microbial properties. This experiment aimed to improve tailings properties for better plant growth and rhizosphere activities. First, a pot experiment was conducted to assess the influence of topsoil amendment on the remediation of tailings collected from two sites (coded A and B) in Western Australia to promote the growth of perennial ryegrass (Lolium perenne L. cv Ausvic). Each pot was filled with pre-defined ratios of topsoil to mine tailings (0, 10, 20, 30, 50 and 100% w/w). Perennial ryegrass was harvested 60 days after sowing and analysed for plant growth, root morphological characteristics and metal uptake by shoots. Second, a study on biological attributes and an incubation study over 84 days were carried out. The addition of topsoil significantly decreased pH, but EC and total organic carbon (TOC) increased with an increased proportion of topsoil. Total concentrations of As, Co, Cr, Cu, Ni, Pb, Zn, Fe and Mn decreased with an increased ratio of topsoil in growth medium. The highest root dry biomass was observed in the treatments with 30% and 50% topsoil addition to tailings, whereas shoot dry biomass only increased with 50% topsoil. Total root length increased significantly with 50% topsoil addition to site A tailings. A significant increase in microbial biomass carbon (MBC) was found with 50% addition of topsoil compared with the control. Microbial quotient (MBC/TOC) decreased significantly with the addition of topsoil to both types of tailings. Metal contents in perennial ryegrass shoots decreased with the increasing rate of topsoil, but perennial ryegrass was an effective phytoextractor of Cu, Zn and Mn. Further, the incubation study revealed that 50% topsoil application increased cumulative respiration emissions in both A and B tailings after 42 days. Iron ore mine tailings can be improved in terms of physicochemical and biological attributes by adding topsoil. However, further investigation should be carried out to determine the speciation of metal/loids in amended iron ore tailings.

Rhizosphere Ventilation Effects on Root Development and Bacterial Diversity of Peanut in Compacted Soil

Soil compaction is one of the crucial factors that restrains the root respiration, energy metabolism and growth of peanut (Arachis hypogaea L.) due to hypoxia, which can be alleviated by ventilation. We therefore carried out a pot experiment with three treatments: no ventilation control (CK), (2) ventilation volumes at 1.2 (T1), and 1.5 (T2) times of the standard ventilation volume (2.02 L/pot). Compared to no-ventilation in compacted soil, ventilation T1 significantly increased total root length, root surface area, root volume and tips at the peanut anthesis stage (62 days after sowing), while T2 showed a negative impact on the above-mentioned root morphological characteristics. At the podding stage (S2, 95 days after sowing), both ventilation treatments improved root morphology, especially under T1. Compared to CK, both ventilation T1 and T2 decreased the activities of enzymes involving the anaerobic respiration, including root lactate dehydrogenase, pyruvate decarboxylase and alcohol dehydrogenase. The activities of antioxidant enzymes of root superoxide dismutase, peroxidase and catalase also decreased at S1, while superoxide dismutase and peroxidase significantly increased under T1 at S2. The ventilation of compacted soil changed soil nitrogen-fixing bacterial communities, with highest bacterial alpha diversity indices under T1. The Pearson correlation analyses indicated a positive relationship between the relative abundance of Bradyrhizobiaceae and root activity, and between unclassified_family of Rhizobiales and the root surface area, while Enterobacteriaceae had a negative impact on the root nodule number. The Pearson correlation test showed that the root surface, tips and activity positively correlated with root superoxide dismutase and peroxidase activities. These results demonstrate that soil ventilation could enhance plant root growth, the diversity and function of soil nitrogen-fixing bacterial communities. The generated results from this present study could serve as important evidence in alleviating soil hypoxia caused by compaction.

Changes in the Root Architecture of Oil Palm Seedlings in Response to Nitrogen Starvation

Oil palm (Elaeis guineensis) is a widely cultivated crop known for its high oil yield. It is cultivated extensively across tropical regions, notably in Southeast Asia, Africa, and Latin America. It plays a vital role in global vegetable oil supply, meeting approximately 35% of the world’s demand. However, the expansion of oil palm plantations often involves the utilization of degraded soils where nutrient availability, particularly nitrogen, is limited, posing challenges to plant growth and productivity. Roots are crucial in responding to nitrogen deficiency by adjusting their growth and distribution; however, research on root system distribution patterns in oil palm still needs to be completed. This study analyzes the root system architecture using RhizoVision Explorer, a 2D root image processing software while assessing its relationship with nitrogen availability across two commercial cultivars: Deli × La Mé of African oil palm (Elaeis guineensis) and the interspecific hybrid O×G Coari × La Mé. Our findings reveal significant associations between eight root traits in oil palm seedlings and treatments with and without nitrogen availability. Notably, total root morphology (length, surface area, and volume), rotation angle, solidity, and hole characteristics decreased under nitrogen deprivation, whereas surface angle frequency increased. We highlight the variability of these traits across cultivars, suggesting genetic dependence and potential utility in breeding programs. Moreover, interactions observed in primary root morphology and hole size indicate greater differences between control and nitrogen-treated groups in C × LM than in D × LM cultivars. On the other hand, cultivar differences, regardless of nitrogen availability, influenced lateral root morphology, while nitrogen availability, irrespective of cultivar, affected inclined angle frequency. Significant differences were observed in growth and development parameters such as root and shoot biomass, root-to-shoot ratio, and leaf emission numbers between nitrogen-optimal and nitrogen-starved conditions. Nitrogen significantly affects root architecture and plant growth in oil palm, particularly in the C × LM cultivar during the nursery stage.

Effects of Funneliformis mosseae on Growth and Photosynthetic Characteristics of Camellia oleifera under Different Nitrogen Forms

Nitrogen fertilizer increases agricultural yields but increases economic costs and causes a series of environmental problems. Arbuscular mycorrhizal fungi (AMF) have the potential to be used as biological fertilizer. However, the influence of nitrogen form on plant growth responsiveness to AMF inoculation is poorly understood. In this study, we investigated the effects of Funneliformis mosseae on growth, root morphology and photosynthetic characteristics of Camellia oleifera under different nitrogen forms during three harvest periods and clarified the most suitable nitrogen form for C. oleifera–AMF symbiosis. The results showed that urea, ammonium and nitrate nitrogen promoted plant growth and photosynthetic capacity, among which urea treatment had the highest value in all three harvests. No significant difference in plant growth parameters was observed between ammonium and nitrate nitrogen treatments in the first two harvests, while the plant height was significantly lower under ammonium nitrogen treatment than nitrate nitrogen treatment in the third harvest. Inoculation with F. mosseae in the presence of indigenous AMF could promote AMF colonization and plant growth at all three harvest times. Inoculation with F. mosseae significantly increased gas exchange parameters, the maximum photochemical efficiency (Fv/Fm) and the actual photochemical efficiency (ΦPSII). Inoculation with AMF increased the photochemical quenching coefficient (qP) better under urea treatment and improved the non-photochemical quenching coefficient (qN) better under ammonium nitrogen treatment. Principal component analysis showed that urea is the most beneficial nitrogen fertilizer for C. oleifera–AMF symbiosis. The results of this study provide a theoretical basis for the combination use of AMF and nitrogen fertilizer in agroforestry.

Evaluation of Fine Root Morphology and Rhizosphere Environmental Characteristics of the Dioecious Idesia polycarpa Maxim

To explore the differences in the fine root characteristics and rhizosphere environment of male and female Idesia polycarpa Maxim at different stages, 7-year-old male and female I. polycarpa were used as plant materials. The fine root characteristics were measured with a root scanner, and rhizosphere soil was collected at the flowering stage (May), fruit accumulation stage (July), and fruit maturity stage (October). In addition, this study analyzed the soil nutrient characteristics of these conditions at different stages. At the same time, Illumine high-throughput sequencing technology and gas chromatography–tandem mass spectrometry (GC–MS) technology were used to analyze the rhizosphere microbes and metabolites of male and female plants at different stages. The results showed that the total root length, surface area, total volume, root tip number, and total average diameter of the fine root of female plants were larger than those of male plants, and the difference reached its maximum in the fruit material accumulation stage. Total carbon (TC) and total nitrogen (TN) content in the rhizosphere soil of male and female plants significantly differed over multiple stages, while available soil nitrogen and potassium content significantly differed during fruit ripening. The rhizosphere microbial composition of male and female plants was similar, and the dominant bacteria in the rhizosphere soil of each stage were Proteobacteria, Acidobacteria, Ascomycota, and Mortierellomycota. The relative abundance of Bacillus, Arthrobacter, Volutella, and Neocosmospora in rhizosphere soil at different stages differed between male and female plants. Combined with the OPLS-DA model and database retrieval, 29 significantly different metabolites, most of which were carbohydrates, were detected in the rhizosphere soil of male and female plants. Moreover, there were more significant metabolites in the rhizosphere soil at the flowering stage than in the fruit ripening stage. Through RDA analysis, available potassium (AK), Pedomicrobium, Chaetomium, and Glucose 1 had the greatest influence on fine root traits of I. polycarpa. The results indicated that the fine root traits were negatively correlated with AK and rhizosphere metabolites. Moreover, positive correlations were found with rhizosphere microorganism traits. The above results laid a foundation for the field management of I. polycarpa and the screening and application of rhizosphere growth-promoting bacteria resources.

Evaluation of Morpho-Physiological Traits of Oat (Avena sativa L.) under Drought Stress

The increase in intensity and frequency of drought due to global climate change has increased the urgency of developing crop cultivars suitable for dry environments. Drought tolerance is a complex trait that involves numerous physiological, biochemical, and morphological responses. A better understanding of those mechanisms is critical to develop drought tolerant cultivars. In this study, we aimed to understand the morphophysiological changes at the shoot and root levels in response to drought stress of ten oat genotypes with diverse root morphological characteristics. Twenty-one-day old plants were subjected to drought stress in a greenhouse by withholding water for two weeks. Several characteristics including chlorophyll content, relative water content (RWC), stomatal conductance, stomata number, shoot dry weight (SDW), root dry weight (RDW), root-to-shoot biomass ratio (RSR), root length, root area, and root volume were measured on well-watered, and drought-stressed plants. Grain yield was evaluated by continuing the drought treatment with a drying and rewatering cycle every 15 days until physiological maturity. The water regime had a significant impact on all traits evaluated. A significant interaction between genotype and water treatment was observed for RWC, chlorophyll content, stomatal conductance, stomata number, and grain yield but not for root traits, suggesting that the root system of all genotypes responded similarly to drought stress. Hayden, the cultivar with the lowest reduction in grain yield from the drought treatment, was among the genotypes with the lowest reduction in RWC and chlorophyll content but with a sharp decrease in stomata number, thus indicating that regulating the plant water status and maintaining the photosynthesis level are important for oat plants to maintain grain yield under drought stress. The size of the root system was not correlated with grain yield under drought, but the RWC and grain yield were significantly correlated under drought, thus suggesting that maintaining the RWC is an important characteristic for oat plants to maintain yield under drought stress.

Seasonal Dynamics in Mycorrhizal Colonization and Fine Root Features of the White Poplar (Populus alba L.) in Natural Temperate Riverside Forests with Two Contrasting Soils

Fine roots are the most dynamic and physiologically active components of belowground tree organs. However, much remains unknown regarding the changes in fine root morphological characteristics during mycorrhizal colonization, especially in natural sites. The aim of this study was to analyze seasonal heterogeneity in fine roots and the mycorrhizal colonization of mature white poplar (Populus alba L.) trees under different soil conditions. Two floodplain forests were selected in Central Europe (Poland), which differed in soil moisture and structure. Fine roots were sampled during one growing season from the upper soil layer. Poplars were characterized by dual mycorrhizal colonization on one root system. It was, therefore, possible to investigate the contribution of two mycorrhizal types (arbuscular mycorrhiza—AM; and ectomycorrhiza—ECM) in response to different habitat conditions. The season was shown to be significant for all fine root features, as well as the degree of mycorrhizal colonization. Roots were better adapted to a drier habitat with a greater proportion of sand, mainly due to a reduction in the fine root diameter (FRD), while other root characteristics did not differ significantly. The degree of mycorrhizal colonization (RLC) and the proportion of arbuscular mycorrhizal structures (AM) were significantly and negatively correlated with the soil water content. A mutual competition between arbuscular mycorrhizas and ectomycorrhizas for poplar roots was also observed, particularly with respect to the season, site, and soil moisture. Changing environmental conditions (especially soil moisture) contribute not only to the morphological and functional changes of fine roots but also to changes in the proportion of arbuscular mycorrhiza and ectomycorrhiza. Understanding the mechanisms of adaptation of tree roots to changing environmental conditions is especially important in the context of climate change.

Water management, planting slope indicators, and economic benefit analysis for Panax notoginseng production decision under shaded and rain-shelter cultivation: A three-year sloping fields experiment

Panax notoginseng cultivation planting conditions are harsh and require high soil moisture and slope of cultivated land, plus it takes 3–7 years from planting to harvesting. At present, the continuous crop barrier of Panax notoginseng has not been solved, which makes the arable land suitable for planting significantly reduced. And yet, there is almost no report on the impact of coupling water and slope on the growth of Panax notoginseng. Therefore, this study aims to explore the effects of different irrigation levels and slopes on soil water content (SWC) in the root zone, soil nutrient content, root characteristics, yield, water use efficiency (WUE), partial fertilizer productivity (PFP) and economic benefits of Panax notoginseng. During 2018–2020, a field experiment was conducted in the Panax notoginseng growing seasons with three irrigation levels (I1: 70–75% θFC, I2: 75–80% θFC, I3: 80–85% θFC) and three slopes (S1: 2.43°, S2: 6.38°, S3: 16.38°). The results evidenced that soil water and nutrient content increased with increasing irrigation and decreased with increasing slope. The yield of Panax notoginseng, root morphological characteristics, WUE, PFP, and economic benefits showed a trend of increasing first and then decreasing with the increase of irrigation amount and slope, which increased with the increase of planting years. These parameters reached their maximum at the irrigation I2 (75–80% θFC) and slope S2 (6.38°) treatments. Thus, based on the results of this study, medium irrigation I2 (75–80% θFC) and slope S2 (6.38°) should be considered as the best slope and water management strategy to obtain both high Panax notoginseng yield and economic benefits. Through establishing a multi-objective optimization model with binary quadratic regression analysis. It was indicated that Panax notoginseng yield, WUE, PFP, and economic benefits simultaneously reached ≥ 98% of their maximum values when irrigation interval was 152–193 mm and slope interval was 5.4–9°. In summary, the results obtained in this study have important practical significance for the water management of Panax notoginseng cultivation in slope farmland in Yunnan Province, China.

Effects of Water and Nitrogen Regulation on Cotton Growth and Hydraulic Lift under Dry Topsoil Conditions

Dry topsoil and relatively moist subsoil can occur in specific areas and times, limiting plant growth but creating conditions for hydraulic lift (HL). There is a lack of a rational water and nitrogen (N) strategy to improve cotton growth and maintain HL. This study investigated the effects of three topsoil water conditions (W0.6: 60–70%, W0.5: 50–60%, and W0.4: 40–50% of field capacity) and three N rates (N120-120, N240-240, and N360-360 kg N ha−1) plus one control treatment on cotton growth and HL under dry topsoil conditions in 2020 and 2021. The results showed that plant height and leaf area increased with increasing N rate, but the differences among topsoil water conditions were relatively small, except for leaf area in 2021. The HL water amount of all treatments increased gradually and then continued to decline during the observation period. There was a trend that the drier the topsoil or the more N applied, the greater the amount of HL water. Additionally, topsoil water conditions and N rate significantly affected the total HL water amount and root morphological characteristics (root length, surface area, and volume). Seed and lint cotton yield tended to decrease with increasing topsoil dryness at N240 or N360, except for lint yield in 2021, or with decreasing N rate, especially under W0.6. As topsoil became drier, the total evapotranspiration (ET) decreased, while with the increase in N rate, ET showed small differences. Water use efficiency increased with a higher N rate, while N partial factor productivity (PFPN) did the opposite. Furthermore, the PFPN under W0.4 was significantly lower than that under W0.6 at N240 or N120. These findings could be useful for promoting the utilization of deep water and achieving sustainable agricultural development.

Nutrient uptake strategy selection by first-order roots of Juglans mandshurica under shading and phosphorus limitation

We investigated root growth of 1-year-old Juglans mandshurica seedlings under different light environments and varying doses of phosphorus fertilizer, to understand the relationship between root resource acquisition strategies and the variations of light and phosphorus availability. There were four shading intensities (full light, 65% full light, 35% full light, and 20% full light) along with three doses of phosphate fertilizer (0 (CK), 200% soil background available phosphorus, and 500% soil background available phosphorus). We measured in root morphology characteristics, architectural characteristics, and mycorrhizal colonization rates of first-order roots. The results showed that average diameter, average root length, and mycorrhizal colonization rates of first-order roots gradually decreased, and the specific root length, specific surface area, branching ratio and branching intensity showed a trend of first increasing and then decreasing with the increases of shading degree. As the phosphorus content decreased, the first-order root diameter gradually became thinner, and the mycorrhizal infection rate gradually increased. Root morphology and architecture of J. mandshurica would undergo adaptive changes under shade, adapting to the shading environment by expanding specific root length, specific surface area, branching ratio and branching intensity. Under phosphorus limitation, root system of J. mandshurica would increase phosphorus absorption through symbiosis with mycorrhizal fungi. When J. mandshurica was artificially regenerate in forest land with a light transmittance of 35%, root morphology and architecture would adapt to the shading environment. The symbiosis between J. mandshurica and mycorrhizal fungi would be enhanced under phosphorus limitation, which could improve phosphorus absorption of roots.

Transcriptome Analyses Reveal Distinct Defense Strategies in Chili Plants under Soilborne Disease Intervention

Chili (Capsicum annuum L.) is highly susceptible to soilborne diseases, thereby presenting a significant threat that results in considerable yield losses in chili production. The exploration of genes conferring resistance and the underlying defense mechanisms presents a promising strategy for bolstering plant disease control. In this study, we selected two distinct cultivars, the disease-sensitive ‘Hailan 99’ and the disease-tolerant ‘Sanxiaqing’, to elucidate the molecular basis of their responses to soilborne disease intervention. We conducted a comprehensive analysis of root morphological characteristics and transcriptome profiles under stress conditions. Our findings revealed that, when subjected to soilborne disease intervention, these two cultivars exhibited contrasting root system characteristics and responses, reflecting diverse defense strategies. The disease-resistant cultivar demonstrated superior adaptability, possibly owing to its capacity for swift recognition of pathogen effectors, activation of defense responses, and effective containment of infection at localized sites, thus impeding disease progression. Noteworthy genes such as T459_04053, implicated in effector recognition; MSTRG.26158, MSTRG.30886, and T459_22510, associated with secondary metabolite biosynthesis; and T459_05615, partaking in the autophagy pathway, along with other differentially expressed genes linked to effector recognition, immune activation, and modulation of cell death processes, offer valuable insights into enhancing soilborne disease resistance in chili. Furthermore, these findings contribute to an enhanced understanding of the molecular mechanisms underlying soilborne disease resistance in diverse plant crops.

Effects of Different Nitrogen Application Rates on Root Growth and Distribution of Fine Root Length across Diameter Classes of Wolfberry (Lycium barbarum L.)

The optimized cultivation process of wolfberry (Lycium barbarum L.) to maintain a consistently high and stable yield relies on the prolonged use of significant amounts of nitrogen fertilizers. However, this practice leads to increased production costs and various issues, such as soil pollution and compaction. To address these concerns, a three-year field trial was conducted involving different nitrogen application rates: N1 (20% nitrogen (N) reduction, 540 kg·hm−2), N2 (medium N, 675 kg·hm−2), and N3 (20% nitrogen increase, 810 kg·hm−2). The results showed that the inter-annual growth and development of wolfberry roots had two rapid growth peaks. In comparison with the N3 treatment, the root morphological characteristics index increased significantly under the N1 and N2 treatments. Among the different diameter classes, the most significant increase in fine root length, with an average diameter between 0.4 and 0.8 mm, occurred under the N1, N2, and N3 treatments, accounting for 50.6%, 50.92%, and 47.72% of the total annual growth of root length increments, respectively. Concerning the distribution of fine roots, the active layer depth extended under the N2 treatment suggesting that medium nitrogen application favored the longitudinal extension of fine roots. Leaf nitrogen content and the chlorophyll meter values (SPAD values) in the upper part of the plant, at the tip of shoots/branches, were the most sensitive indicators to changes in nitrogen application rates. These values increased significantly with higher nitrogen application amounts. Similarly, the contents of total sugar, betaine, and β-carotene increased with increasing nitrogen application rates, while the contents of Lycium barbarum polysaccharides (LBPs) and total flavonoids decreased. Finally, based on a comprehensive principal component evaluation, the rankings for root growth and plant development under various nitrogen application treatments were as follows: N2 (1.891) > N1 (0.002) > N3 (−1.894). The results showed that both the aboveground and belowground growth and development of wolfberry plants were most optimized under the N2 treatment. These findings provide a foundational reference for constructing good root morphology of wolfberry through cultivation practices such as nitrogen fertilizer management.

Impact of Excess Magnesium Salt Supply on Rice Yield, Physiological Response, and Grain Mineral Content

Magnesium nutrition in plants has remained largely unexplored compared to other essential elements. Although the impact of magnesium deficiency on plants has been reported from numerous studies, the responses of plants to excess magnesium salt levels have received less attention. Using five different magnesium levels (0, 500, 1000, 1500, and 2000 ppm) and two magnesium sources (MgSO4 and MgCl2), this study evaluated the effect of excess magnesium salts on rice production and associated physiological processes on a hybrid rice cultivar ‘XP 753’. Rice morphological and physiological parameters, including plant growth, biomass, root morphological features, tissue and grain mineral concentrations, membrane injury (MI), chlorophyll, malondialdehyde (MDA) concentrations, proline concentrations, as well as gas exchange parameters, were evaluated. A dose-dependent reduction in above- and below-ground shoot and root morphological features was observed under the application of magnesium salts on the soil substrate. Analysis of physiological parameters demonstrated that an inhibition in plant growth, biomass, and yield was due to the decrease in total chlorophyll content, net photosynthesis rate, and membrane stability in rice. Furthermore, this study showed that the application of magnesium salts to soil interfered with the uptake and translocation of minerals and significantly increased reactive oxygen species (ROS), malondialdehyde (MDA), and proline levels, indicating the toxic effects of excess magnesium salts on rice plants.

Effect of P-Dipping on Growth of NERICA 4 Rice in Different Soil Types at Initial Growth Stages

Phosphorus (P) deficiency resulting from P fixation is a major constraint limiting sustainable rice cultivation in sub-Saharan Africa. Soil texture also affects P availability and use efficiency. In a factorial experiment, we evaluated the combined effect of soil texture (sand, clay loam, and clay) and P treatments P-dipping (Pdip) and two other broadcasted P fertilizer levels (Brod1 and Brod2) on the growth of NERICA 4 rice in the initial growth stages. Across all soil textures and P treatments, total plant biomass ranged from 1.06 to 4.63 g pot−1. The Pdip treatment significantly increased shoot and root biomass relative to control from 1.27 to 1.98 and 0.23 to 0.38 g pot−1, respectively. Mean photosynthetic rate values under Pdip (20.1 μmol m−2 s−1), Brod2 (19.5 μmol m−2 s−1), and Brod1 (19.3 μmol m−2 s−1) treatments showed significant 42%, 37%, and 36% increases over control, regardless of soil texture. In a striking contrast, P-dipping significantly promoted growth of root length under clay soil, but without a commensurate increase in shoot P uptake. Contrary to our hypothesis, the interactive effect of soil texture and P-dipping influenced NERICA 4 shoot and root physiological and morphological characteristics under clay loam soil texture as opposed to clay.

Soil Water Deficit Reduced Root Hydraulic Conductivity of Common Reed (Phragmites australis).

Alterations in root hydraulics in response to varying moisture conditions remain a subject of debate. In our investigation, we subjected common reeds (Phragmites australis) to a 45-day treatment with four distinct soil moisture levels. The findings unveiled that, in response to drought stress, the total root length, surface area, volume, and average diameter exhibited varying degrees of reduction. Anatomically, drought caused a reduction in root diameter (RD), cortex thickness (CT), vessel diameter (VD), and root cross-sectional area (RCA). A decrease in soil moisture significantly reduced both whole- and single-root hydraulic conductivity (Lpwr, Lpsr). The total length, surface area, volume, and average diameter of the reed root system were significantly correlated with Lpwr, while RD, CT, and RCA were significantly correlated with Lpsr. A decrease in soil moisture content significantly influenced root morphological and anatomical characteristics, which, in turn, altered Lpr, and the transcriptome results suggest that this may be associated with the variation in the expression of abscisic acid (ABA) and aquaporins (AQPs) genes. Our initial findings address a gap in our understanding of reed hydraulics, offering fresh theoretical insights into how herbaceous plants respond to external stressors.

Effect of sodium hydrosulfide on physicochemical characteristics and melatonin mediated stress mitigation in bitter gourd (Momordica charantia L.) grown under lead stress

Lead (Pb) is a toxic heavy metal that contaminates soil and water resources after its discharge from different industries. This research study was held to check the consequence of Pb stress and NaHS growth regulator on physicochemical features of Mamodica charantia. A pot experiment was conducted to determine the effect of NaHS (1 Mm and 1.5 Mm) for the screening of M. charantia exposed to severe Pb (500 ppm,1000 ppm and 2000 ppm) stress. Our results depicted that maximum growth of plants was recorded at 1.5 mM concentration, while inhibition was observed in the plants of M. charantia at highest concentration of lead chloride (2000 ppm). Significant positive change in agronomical structures of bitter melon like leaf, root, shoot, branches, root length and shoot length recorded at high concentration of NaHS growth regulator (1.5 mM). In case of lead stress study, plants show reduction in growth and development due to production of ROS species. ROS species reduced the concentration of divalent cations such Zn2+, Mn2+, Mg2+, Ca2+, and Fe2+ by restricting the flow of water. Leaves of M. charantia had lessen carotenoid and chlorophylls and enhanced activity of chlorophyllase in leaves. Biological content of antioxidants (CAT and POD), Protein and Proline were found maximum in NaHS treated plants while minimum in stressed plants. Nutrient content of root and shoot (K, Na and Ca) and morphological characteristics also behaved differently on different concentration of NaHS and Pb stress. Here, we concluded that the application of NaHS under the exposure to Pb stress significantly improved physiological and biochemical structures of M. charantia.