Seedling Height Research Articles

Fertigation with Nitrogen and Phosphorus Improve Plant Growth, Root Growth, and Buddability of Containerized Citrus Nursery Plants

ABSTRACT Large-scale multiplication of quality planting material is needed to meet the huge demand of planting material in fruit crops. Little information is available on the effect of fertigation on rootstock growth, budding success, and buddling growth in containerized citrus nursery. The present studies were undertaken to study the effect of eight fertigation treatments viz. control (N0P0), N60, N80, N100, N0P100, N60P100, N80P100, and N100P100 on the growth of rough lemon rootstock and subsequently budded three citrus varieties. Among the treatments, N60P100 significantly improved seedling height, diameter, leaf number, root growth, leaf area in rough lemon, Blood Red orange, Kinnow mandarin, and Daisy mandarin over the control. The stomatal conductance was higher with treatments N60, N80, N60P100, and N80P100. While higher photosynthetic rates were observed with N60P100 and N80P100, N60P100 also improved the budding success in Blood Red, Kinnow, and Daisy. Fertigation treatments increased the nutrient concentration in leaves of all the varieties. The principal component analysis revealed that plant height and diameter were positively correlated with root length, root diameter, root number, photosynthetic rate, stomatal conductance, and chlorophyll content in rough lemon. In all the varieties, the sprout length and diameter showed a positive correlation with leaf area, leaf number, root length, root diameter, fibrous root number, photosynthesis rate, stomatal conductance, and chlorophyll content. Among different treatments, N60P100 was the best treatment in improving the shoot growth, root growth, and physiological parameters of rough lemon rootstock. Besides, it also improved budding success and buddling growth in all three citrus varieties.

BARC Biostimulant 1, a novel Streptomyces rochei C3-based formulation for disease biocontrol and plant growth promotion

Pythium aphanidermatum is a very destructive plant pathogen causing damping-off disease of vegetable seedlings in nurseries. In addition, this plant pathogenic oomycete causes seed, stem and rhizome rot, as well as post-harvest diseases. Currently, the disease management relies heavily on high dosages of chemicals like metalaxyl and copper oxychloride biocides, which are not only expensive, but are hazardous to the ecosystem. In our quest for developing a disease management strategy that is economical and safe, we isolated a strain of an actinobacterium that is highly inhibitory to P. aphanidermatum, the major cause of damping-off disease. Based on morphology and 16S rRNA sequence analysis, we identified this isolate as Streptomyces rochei. Using an LC-MS/MS analysis, the inhibitory principle has been tentatively identified as (4 S)-4,5-dihydro-4-hydroxygeldanamycin.We developed a novel formulation “BARC Biostimulant 1” using split tamarind seeds as a substrate and talcum powder as a carrier and S. rochei as the active ingredient. In P. aphanidermatum-infested soil, seed treatment and drenching resulted in about 50 % improvement in germination in greenhouse assay and protected field experiments. Under open field conditions, the germination improved to the extent of 20 %. In addition to suppression of the disease, the formulation also improved plant growth parameters like weight and height of seedlings, and induced defense responses. We further undertook multi-location replicated field trials to evaluate this purely organic formulation as a biostimulant across four states of India. Seed treatment with BARC Biostimulant 1 at the rate of 5 g/ kg seeds enhanced germination of seedlings by 80 % and enhanced fresh weight by 105 % (average of four locations), indicating a good commercial potential of this formulation.

Effects of Different Potting Mixture on Early Development of <i>Afzelia quanzesis </i>Welw. Species Seedlings

Planting native plant species is becoming increasingly important as the world begins to realise the importance of restoring ecosystems, especially since many valuable species are on the brink of extinction due to human over-exploitation. <i>Afzelia quanzensis</i> Welw. is one of the valuable timber species, highly targeted in uncontrolled selective loggings, hence threatening its existence. This study assessed the effects of different potting mixtures on <i>A. quanzensis</i> early seed germination, which is an essential step for its mass propagation. Four different potting mixtures: T1 (forest soil, agricultural residues, tobacco, and cow manures), T2 (forest soil, tobacco manure), T3 (forest soil and cow manure), and T4 (forest soil and agricultural residues) were utilised. Employing a completely randomised design with each mixture replicated four times, the study monitored growth parameters, such as leaf count and seedling height, over one month. Results from two-way ANOVA with Turkey’s multiple comparisons test showed that forest soil and cow manure (T3) yielded the tallest plants and highest scores of leaf count. The study provides valuable insights for nursery managers and researchers working on the mass propagation of the <i>A. quanzensis</i> tree species for plantations in the region.

Sapling recruitment as an indicator of carbon resiliency in forests of the northern USA.

Tree regeneration shapes forest carbon dynamics by determining long-term forest composition and structure, which suggests that threats to natural regeneration may diminish the capacity of forests to replace live tree carbon transferred to the atmosphere or other pools through tree mortality. Yet, the potential implications of tree regeneration patterns for future carbon dynamics have been sparsely studied. We used forest inventory plots to investigate whether the composition of existing tree regeneration is consistent with aboveground carbon stock loss, replacement, or gain for forests across the northeastern and midwestern USA, leveraging a recently developed method to predict the likelihood of sapling recruitment from seedling abundance tallied within six seedling height classes. A comparison of carbon stock predictions from tree and seedling composition suggested that 29% of plots were poised to lose carbon based on seedling composition, 55% were poised for replacement of carbon stocks (<5 Mg ha-1 difference) and 16% were poised to gain carbon. Forests predicted to lose carbon tended to be on steeper slopes, at lower latitudes, and in rolling upland environments. Although plots predicted to gain and lose carbon had similar stand ages, carbon loss plots had greater current carbon stocks. Synthesis and applications. Our results demonstrate the utility of considering tree regeneration through the lens of carbon replacement to develop effective management strategies to secure long-term carbon storage and resilience in the context of global change. Forests poised to lose C due to climate change and other stressors could be prioritized for regeneration strategies that enhance long-term carbon resilience and stewardship.

Isolation, screening, and molecular characterization of indigenous Trichoderma isolates from West Java, Indonesia and their plant growth-promoting capability on rice plants (Oryza sativa L.)

Trichoderma species are widely acknowledged as growth-promoting fungi that have been utilized to enhance the growth and yield of numerous crops. This research examined the capacity of 30 Trichoderma strains, isolated from two organic rice fields in West Java, Indonesia, to enhance the germination, growth, and physiological characteristics of rice plants (Oryza sativa L.). In general, Trichoderma strain TM10 demonstrated the greatest ability to increase seed germination (97.25 %), vigor index (3122.83), and germination speed (59.91 seeds/day). This strain also increased seedling root length and seedling height by 101.62 % and 112.20 %, respectively. Plants treated with TM10 exhibited a notable improvement in root length, plant height, fresh weight, and dry weight compared to control plants, demonstrating increases of 188.68 %, 69.90 %, 157.41 %, and 159.38 %, respectively. Furthermore, the total chlorophyll content and stomatal number in TM10-treated plants exhibited increments of 75.23 % and 75.53 %, respectively. Five selected isolates (TM7, TM10, SB2, SB8, and SB14) were evaluated for their potential to produce plant growth-promoting compounds, including phosphatase enzyme (ranging from 0.54 to 11.14 µg pNP g−1h−1), indole-3-acetic acid (IAA) (ranging from 28.96 to 63.91 µg/mL), ammonia (ranging from 1.96 to 5.79 µg/mL), and hydrogen cyanide (HCN) (ranging from 221.76 to 274.82 ppm). The best strain, namely TM10, was then molecularly identified as Trichoderma yunnanense. This investigation demonstrates that Trichoderma spp. isolated from organic rice fields could be used as a bioinoculant in sustainable rice production.

Combined Effect of Subsurface Water Retention Technology and Arbuscular Mycorrhizal Fungi on Growth, Physiology and Biochemistry of Argan Seedlings under Field Conditions.

The argan (Argania spinosa L. Skeels) ecosystem is severely degrading in arid and semi-arid lands due to climate change, particularly in terms of density loss and reforestation failure. Thus, it is important to adopt innovative effective sustainable practices to optimize the densification and reforestation success of the argan tree. The purpose of the present research was to investigate the combined effect of subsurface water retention technology (SWRT) and the use of native arbuscular mycorrhizal fungi (AMF) on edaphic, growth, physiological and biochemical parameters of field-grown argan seedlings in the Essaouira region, Morocco. In this experiment, one-year-old argan seedlings were transplanted in the absence and presence of biodegradable plastic and AMF. Our findings revealed that the application of SWRT enhanced soil profile moisture up to 640% at 40 cm depth compared to the control. The combination of this technology with AMF also improved soil fertility. Furthermore, the application of SWRT, with or without AMF, significantly enhanced argan seedling height (208 and 168%, respectively), stomatal conductance (54 and 33%, respectively), and chlorophyll fluorescence (21 and 20%, respectively). Similarly, the combined application of SWRT and AMF significantly improved protein and sugar content (36 and 57%, respectively), as well as antioxidant enzyme activities (peroxidase and polyphenol oxidase) and chlorophyll pigments content compared to the control. However, this treatment reduced malondialdehyde and H2O2 content in the argan leaves. As a summary, SWRT technology combined with AMF may be used as a valuable strategy to promote the success of argan reforestation and to limit soil erosion and desertification in arid and semi-arid climates.

Environmental conditions differently shape leaf, seed and seedling trait composition between and within elevations of tropical montane forests

The composition of plant functional traits varies in response to environmental conditions due to processes of community assembly and species sorting. However, there is a lack of understanding of how plant trait composition responds to environmental conditions at different spatial scales and across the plant life cycle. We investigated the trait composition of leaves (specific leaf area), seeds (seed mass) and seedlings (initial seedling height) across elevations and within elevations in relation to soil and light conditions in a tropical montane forest in southern Ecuador. We surveyed traits and communities of adult trees, seeds and seedlings on nine plots at three elevations (1000–3000 m a.s.l.) and calculated community‐weighted mean trait values to analyse trait variation across and within elevations. In addition, we measured two environmental factors (soil C/N ratio and canopy openness) to quantify local‐scale variation in environmental conditions within elevations. We found that community‐weighted means of specific leaf area, seed mass and initial seedling height decreased consistently with increasing elevation. Within elevations, mean trait values of trees, seeds and seedlings responded differently to local‐scale environmental conditions. Specific leaf area decreased with increasing soil C/N ratio, and initial seedling height decreased with increasing canopy openness. Seed mass was associated neither with soil nor with light conditions. Our findings show that broad‐scale and local‐scale processes differently shape the composition of leaf, seed and seedling traits in tropical forests, indicating a scale‐dependence in trait–environment associations. Furthermore, plant traits corresponding to different life stages were related differently to environmental conditions within elevations. Community assembly processes may therefore lead to differences in species sorting at early and late plant life stages.

Genetic Parameters Estimated in the Early Growth of Dimorphandra mollis Benth. Progenies

The extractivism of Dimorphandra mollis Benth., which is a native tree from the Brazilian Cerrado biome, popularly known as fava d’anta, combined with the reduction in native vegetation area in the country over the years may result in a decrease in the specie’s natural populations. The objective of this study was to estimate the quantitative genetic parameters in nursery, hardening, and field phases, based on a progeny test. The experimental design adopted was randomized blocks (six blocks for the nursery and hardening phases, and four blocks for the field phase with 5 plants/plot and 72 mother trees), with evaluations of the collar diameter and seedling height at 30, 90, 150, 480, and 570 days after sowing, between the production and planting phases. Among the coefficients of variance, the phenotypic and additive ones showed the highest values. Heritabilities for height ranged from moderate to high (0.15 to 0.43), indicating good genetic control of the traits, high potential for selection, and possibility of genetic gains. The genetic divergence of the progenies resulted in division into five groups, confirming the existence of genetic variability among the evaluated progenies and the potential for conservation and breeding programs.

Impact of allelochemicals from shade trees bark on the performance of cocoa seedlings

AbstractShade trees are important in cocoa agroforestry systems; however, they release allelochemicals from various parts that affect understory plants. Unfortunately, information on allelochemicals produced by shade tree bark in cocoa plantation remain scarce. This study investigates the effect of allelochemicals from bark of shade trees on cocoa seedlings growth. The experiment was a 4 × 11 factorial study, and the treatments were four different concentrations from each of the 11 tree species. The treatments were laid out in a completely randomized design with four replicates. Data were collected at 30, 60, 90, 120, and 150 days after treatment applications. The tree species alone and bark extract concentrations alone significantly impacted plant height from 90 to 150 days after application. Albizia ferruginea (Guill. &amp; Perr.) Benth, Celtis mildbraedii Engl., and Triplochiton scleroxylon K. Schum produced the highest cocoa seedling heights. All concentrations also influenced stem diameter of cocoa seedlings. Albizia ferruginea enhanced stem diameter significantly among tree species and the control. Tree species and bark extract concentrations interacted to increase fresh root weights and dry plant biomass. Albizia ferruginea consistently increased dry plant biomass, while C. mildbraedii produced the highest enhancement for fresh roots. All concentrations enhanced plant biomass, with the 75 mg mL−1 concentration consistently producing the highest plant fresh and dry weights. Albizia ferruginea and C. mildbraedii can be potential tree species in the cocoa agroforestry when 2‐month‐old cocoa seedlings are to be transplanted on the field. Bark extract of 75 mg mL−1 concentration can be used as a growth stimulant on cocoa seedlings.

Exploring genotypic variations in cotton associated with growth and nitrogen use efficiency

Low nitrogen (N) is a major limitation of cotton sustainability and productivity. N-efficient genotype cultivation can enhance productivity under the economical N usage. This study was conducted to characterize 15 cotton genotypes for N use efficiency (NUE) under differential N (0.0125 and 0.125 g kg−1 of sand) supply. All studied traits significantly responded to genotypes and N treatments. Under low N conditions, plants experienced reduced seedling height, root weight, shoot weight and total biomass (TDM) production, chlorophyll content, photosynthetic efficiency, NPK content, and N uptake efficiency (NUpE). Thus, intercellular CO2 concentration, photosynthetic N use efficiency (PNUE), and NUtE enhanced in low N supply, although these changes varied in magnitude. Based on variations in TDM production (14.6–33.1%) and NUtE (3.3–20.4%), GH-Uhad, FH-Anmol, FH-Super, GH-Haadi, and SLH-Chandani were categorized as efficient and responsive (ER), while J-7, CIM-343, FH-155, FH-492, FH-444 found as inefficient and non-responsive. The efficient and non-responsive group contained FH-142, GH-Baghdadi, and FH-490 whereas FH-152 and Cyto-179 were classified as inefficient and responsive. The scoring method provided further insight into genotypic NUE related to biomass distribution, photosynthetic rate (Pn), NUpE, and NUtE under low N. The highest cumulative score (15-18) of ER genotypes for these attributes indicated selected traits orchestrated to determine the NUE. Moreover, agronomical and NUE-related traits were positively associated with Pn, suggesting that photosynthesis is a primary manipulator of plant growth which coordinates biomass production and NUE. Overall, cultivars exhibited greater genotypic variation for NUE, providing a scientific basis to evaluate the existing germplasm and proposing that cultivation of N-efficient genotypes can decrease N application and help cotton breeding for sustainable production.

Microplastics in soil affect the growth and physiological characteristics of Chinese fir and Phoebe bournei seedlings

Pot experiments were conducted using Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) and Phoebe bournei (Hemsl.) Yang) to investigate whether soil microplastics adversely affect the nurturing and renewal of plantations. Microplastics composed of polyethylene and polypropylene with a size of 48 μm were used. The treatments included a control group (without microplastics) and groups treated with microplastic concentrations of 1% and 2% (w/w). The effects of microplastics on the growth, photosynthetic pigments in leaves, antioxidant systems, and osmotic regulation substances of the seedlings were analysed by measuring the seedling height, ground-line diameter growth, chlorophyll (chlorophyll a, chlorophyll b, and total chlorophyll) contents, antioxidant enzyme (superoxide dismutase, peroxidase, catalase) activities, and malondialdehyde, soluble sugar, and soluble protein levels. The results indicated that treatment with 1% polyethylene microplastics increased the chlorophyll a, total chlorophyll, and soluble protein contents in the leaves of both types of seedlings while inhibiting superoxide dismutase and peroxidase activities in P. bournei seedlings. Treatment with 2% polyethylene or polypropylene microplastics suppressed the chlorophyll a, chlorophyll b, and total chlorophyll contents; superoxide dismutase, peroxidase, and catalase activities; and soluble sugar and soluble protein levels in the leaves of both types of seedlings, resulting in reduced growth in terms of height and ground-line diameter. The physiological effects of polyethylene microplastics were more evident than those of polypropylene at the same concentration. The results demonstrated that microplastics can affect photosynthesis, the antioxidant system, and osmotic regulation in Chinese fir and P. bournei seedlings, thereby inhibiting their normal growth and development. Exposure to 1% (w/w) microplastics triggered stress responses in seedlings, whereas 2% (w/w) microplastics impeded seedling growth.

Effect of Persistent Salt Stress on the Physiology and Anatomy of Hybrid Walnut (Juglans major × Juglans regia) Seedlings.

Soil salinization has become one of the major problems that threaten the ecological environment. The aim of this study is to explore the mechanism of salt tolerance of hybrid walnuts (Juglans major × Juglans regia) under long-term salt stress through the dynamic changes of growth, physiological and biochemical characteristics, and anatomical structure. Our findings indicate that (1) salt stress inhibited seedling height and ground diameter increase, and (2) with increasing salt concentration, relative water content (RWC) decreased, and proline (Pro) and soluble sugar (SS) content increased. The Pro content reached a maximum of 549.64 μg/g on the 42nd day. The increase in superoxide dismutase (SOD) activity (46.80-117.16%), ascorbate peroxidase (APX) activity, total flavonoid content (TFC), and total phenol content (TPC) under salt stress reduced the accumulation of malondialdehyde (MDA). (3) Increasing salt concentration led to increases and subsequent decreases in the thickness of palisade tissues, spongy tissues, leaves, and leaf vascular bundle diameter. Upper and lower skin thickness, root periderm thickness, root diameter, root cortex thickness, and root vascular bundle diameter showed different patterns of change at varying stress concentrations and durations. Overall, the study concluded that salt stress enhanced the antireactive oxygen system, increased levels of osmotic regulators, and low salt concentrations promoted leaf and root anatomy, but that under long-term exposure to high salt levels, leaf anatomy was severely damaged. For the first time, this study combined the anatomical structure of the vegetative organ of hybrid walnut with physiology and biochemistry, which is of great significance for addressing the challenge of walnut salt stress and expanding the planting area.

Strengths of fertilizer and litter effects on seedling recruitment and growth of grassland species differ depending on functional groups and seed size.

Agricultural grasslands play an important role in conserving the biodiversity of the European cultural landscape. Both, litter cover and soil nutrient availability, change with grassland management, but it is not well-studied how seedling recruitment and growth of multiple grassland species are influenced by their single or combined effects. Therefore, we studied the effects of nitrogen fertilization (100 kg N per year and ha) and litter cover (250 gdw per m2) on seedling recruitment and growth of 75 temperate grassland species (16 graminoid species, 51 forb species, 8 legume species) in a full factorial microcosm experiment. Overall, fertilizer reduced seedling emergence, while litter cover increased it even when combined with fertilization. Fertilization increased seedling height and biomass, and the combination of fertilizer and litter resulted in even stronger responses. Litter cover alone did not influence seedling biomass or seedling height. While the overall direction of treatment effects was similar across functional groups, their strengths were mostly weaker in graminoids than in non-legume forbs and legumes. Positive litter effects on seedling emergence were stronger in large-seeded species. Positive fertilization effects on seedling growth were stronger in small-seeded species, while their seedling biomass was negatively affected by litter cover. In summary, our results show for multiple grassland species that the combination of litter cover and fertilization modulates their single effects. The varying sensitivity of how grassland species representing different functional groups and seed sizes respond with their seedling emergence and growth to litter cover and nitrogen fertilization indicates that the consequences of land-use change on grassland diversity and composition already start to manifest in the earliest stages of the plant life cycle.

Effects of growing media, and cultivar on developments and quality of mango rootstock.

In a successful mango plant establishment, the choice of a strong and healthy rootstock is crucial for subsequent propagation. An experiment was conducted during the 2023 mango seedling growing season at the Sokoine University of Agriculture horticultural sections in Morogoro, Tanzania. The study aimed to evaluate the influence of different growing media and cultivars on the growth and development of quality-certified mango rootstock plants. Ripe local mango fruits were collected from neighbouring farms and sown in polyethylene bags containing a mixture of forest soil, sand, farmyard manure, and sawdust. The experiment followed a randomized complete block design with three replications. Data collected included days to 50% germination, seedling mortality, seedling height, stem girth, and chlorophyll content (measured using the SPAD Unit). Results indicated that using sindano cultivars as rootstock significantly reduced days to germination and increased germination percentage (89.5%) while minimizing seedling mortality (2). Additionally, forest soil contributed to maximum seedling height (43.95 cm), stem diameter (0.52 cm), and chlorophyll content (40.05). The interaction between cultivar and growing media significantly influenced various mango seedling growth parameters. Bongwa cultivars planted in growing media composed of forest soil alone or combined with farmyard manure and sand produced high-quality, certifiable mango rootstock plants.

Impact of Humic Acid Addition and Ginger Rhizome Extract Spraying on Apricot Seedlings, Cv. Hamawi

During the growing season of 2021, the study was carried out in the lath house of the Department of Horticulture and Landscaping at the College of Agriculture at the University of Anbar, to investigate the impact of humic acid (H) addition at values of (0, 4, 8 ml L-1) and misting a ginger rhizome extract (Z) solution at (0, 5, 10 g L-1) concentrations On a few apricot seedling growth traits and chemical composition, cultivar Hamawi. The outcomes showed a considerable impact of humic acid addition on all attributes investigated, particularly the high level (H2, which exhibited the attributes with the highest values (seedlings height 30.57 cm, length of branches 18.6 cm, the stem diameter is 2.7 mm, number of leaves is 132.8 leaf seedlings-1, the percentage of dry matter of leaves is 51.86%, the leaf area 2065.02 cm2 seedlings-1, chlorophyll content of leaves 11.21 mg g-1 fresh weight, leaves content of total carbohydrates 13.76%). Spraying ginger rhizome extract was used as treatment (Z2), and it had the most notable effects on the characteristics (The rate of increase in seedling height, rate of increase in stem diameter, rate of increase in number of leaves, percentage of leaf dry matter, leaf area, content of leaves from chlorophyll, content of leaves from total carbohydrates) which were (26.58 cm, 2.6 mm, 126.7 seedling leaf-1, 50.79%, 1804.03 cm2 seedling-1, 11.13 mg g-1 fresh weight, and 12.95%) respectively.

Seedling development of Schizolobium parahyba var. amazonicum inoculated with Rhizoglomus clarum in different doses of phosphorus

This work aimed to evaluate the growth and phosphorus uptake of Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby (pinho-cuiabano) seedlings inoculated with Rhizoglomus clarum (T.H.Nicolson &amp; N.C.Schenck) Sieverd., G.A.Silva &amp; Oehl at different doses of phosphorus. The treatments consisted of five levels of phosphorus (0, 25, 50, 100 and 200 mg dm-³) and inoculation or not with R. clarum. After 45 days of seedling inoculation, we analyzed: height, root fresh and dry matter, shoot fresh and dry matter, number of leaves, survival, stem diameter, root volume, Dickson quality index, mycorrhizal colonization, relative water content, leaf tissue density, phosphorus content, efficiency of phosphorus uptake and efficiency of phosphorus utilization. Inoculation with R. clarum and the lowest doses of phosphorus resulted in lower seedling mortality rates. R. clarum did not increase the phosphorus content, efficiency of phosphorus uptake, efficiency of phosphorus utilization, relative water content and the Dickson quality index of the seedlings, but it was efficient in increasing the shoot fresh and dry matter as well as leaf tissue density. Inoculation with R. clarum and phosphate fertilization had a significant joint effect on seedling height and root fresh matter. Thus, it can be concluded that R. clarum may represent an important sustainable technology for the production of pinho-cuiabano seedlings, increasing seedling growth, even at low levels of phosphate fertilization.

The Effects of NPK Fertilizer and Coconut Husk Ash as Ameliorant on Growth and Photosynthetic Rate of Oil Palm Seedlings in Peat Media

This study aimed to investigate the effects of NPK fertilizer and coconut husk ash as an ameliorant on growth and photosynthetic levels of oil palm seedlings in peat soil growth media. A Completely Randomized Design (CRD) was used with two factors, NPK 12:12:17:2+TE including control, 30 g, 60 g, and 90 g per plant. Coconut husk ash includes control, 40 g, 80 g, and 120 g per plant. The data were statistically analyzed using ANOVA, and any observed significant difference led to Duncan's test at p&lt;0.05. The combination of 90 g of fertilizer dose and 80 g of coconut husk ash produced the tallest plant height of 104.53 cm. The highest increase in stem girth was 6.01 cm. The photosynthetic rate was 39.11 μmol CO2 m-2 s-1, and the highest stomatal conductance was 0.21 H2O m-2 s-1. The highest internal CO2 and Water Use Efficiency was 177 μmol CO2 mol-1 and 16.15, respectively, while the best transpiration rate was 2.94 mM H2O m-2s-1. Additionally, the photosynthetic rate positively correlated with seedling height and stem diameter, with a R2 0.25 and 0.44 coefficient, respectively. Stomatal conductance was positively correlated with stem diameter, namely R2 0.04. Meanwhile, transpiration rate was negatively correlated with seedling height (R2 17%) and seedling stem diameter (R2 6.9%). Intracellular CO2 was negatively correlated with plant height but positively correlated with stem diameter. The results of this study are expected to be used in increased growth and photosynthesis.

Polystyrene microplastics enhanced the toxicity of cadmium to rice seedlings: Evidence from rice growth, physiology, and element metabolism

Microplastics (MPs) and cadmium (Cd) are toxic to rice; however, the effects and mechanisms of their combined exposure are unclear. The combined exposure effects of polystyrene microplastics (PS-MPs) with different particle sizes (1–10 μm, 50–150 μm) and concentrations (50, 500 mg·L−1) and Cd on rice were explored. PS-MPs combined with Cd amplifies the inhibition of each individual exposure on the height and biomass of rice seedlings, and they showed antagonistic effects. PS-MPs reduced the content of chlorophyll and increased the content of carotenoid rice seedlings significantly. High concentrations of PS-MPs enhanced the inhibition of Cd on chlorophyll content. Cd, PS-MPs single and combined exposures significantly altered the antioxidant enzyme (POD, CAT, SOD) activities in rice seedlings. Under PS-MPs exposure, overall, the MDA content in shoots and roots exhibited opposite trends, with a decrease in the former and an increase in the latter. In comparison with Cd treatment, the combined exposures' shoot and root MDA content was reduced. Cd and PS-MPs showed “low concentration antagonism, high concentration synergism” on the composite physiological indexes of rice seedlings. PS-MPs significantly increased the Cd accumulation in shoots. PS-MPs promoted the root absorption of Cd at 50 mg·L−1 while inhibited at 500 mg·L−1. Cd and PS-MPs treatments interfered with the balance of microelements (Mn, Zn, Fe, Cu, B, Mo) and macroelements (S, P, K, Mg, Ca) in rice seedlings; Mn was significantly inhibited. PS-MPs can enhance of Cd's toxicity to rice seedlings. The combined toxic effects of the two contaminants appear to be antagonistic or synergistic, relying on the particle size and concentration of the PS-MPs. Our findings offer information to help people understanding the combined toxicity of Cd and MPs on crops.

Contrasting light capture strategies between shade-tolerant and -intolerant tree seedlings responding to solar canopy spectral composition

Forest regeneration is a crucial ecological process for promote self-reproduction and restoration, which is essential for maintaining complex community structure and preserving biological resources. Although sunlight have been considered as the main driver of forest regeneration, how light quality shapes functional traits of seedlings is poorly understood in the forest understorey, where spectral compositions of solar radiation change dramatically. We investigated the responses of 15 typical functional traits of Pinus koraiensis and Quercus mongolica to five filter treatments that differed in the spectral transmittance: (a) 95 % of solar radiation was transmitted (280–700 nm); (b) ultraviolet (UV)-B radiation was attenuated (>315 nm); (c) all UV radiation was attenuated (>400 nm); (d) all UV radiation and blue light was attenuated (>500 nm); (e) all UV radiation, blue-green light was attenuated (>580 nm). Our results showed that functional traits responded to UV-B radiation (contrasting treatment [a] vs. [b]) with species-dependence, but consistently showed a positive response to blue light (contrasting treatment [c] vs. [d]). UV-B radiation decreased the relative growth rate (RGR) and leaf area ratio (LAR) of P. koraiensis seedlings by 48 % and 42 %, respectively; however, it increased seedling height, total leaf area (TLA), and above-ground biomass of Q. mongolica. Blue light consistently increased LAR and RGR of two species. Furthermore, Q. mongolica was more plastic in morphological traits (including plant height and TLA) and root/shoot ratio than P. koraiensis to the single spectral region (UV-B, UV-A, blue, and green light), but opposite in physiological and biochemical traits (such as chlorophyll and anthocyanidin). These suggest that two studied species have evolved different light capture strategies in the understorey: Q. mongolica seedlings tended to adjust morphology and biomass allocation to enhance light interception capacity, while P. koraiensis seedlings preferred to adjust physiological and biochemical traits to enhance light utilization efficiency. A better understanding how canopy spectral compositions affect seedling regeneration may provide a new insight for future forest management (i.e. the appropriate gap creation or tree species combination).

Different Phenotypic, Photosynthetic, and Physiological Responses to Flooding between Q. nuttallii and Q. palustris.

Flooding stress is an increasingly serious problem in wetlands, often affecting large areas of crops and timber production areas. The current study aimed to explore the species differences in responses to flooding stress between Q. nuttallii and Q. palustris in an outdoor environment. All the tested plants survived after a 60-day flooding treatment that left 5 cm of water above the soil surface. This suggests that the two species are flood-tolerant, so they can be applied in the construction of riparian protection forests and wetland restoration. Compared with control conditions, flooding treatment significantly decreased seedling height and diameter and the Pn, Gs, Tr, Fv/Fm, ABS/CSm, TR0/CSm, ET0/CSm, RE0/CSm, IAA, and GA3 content and significantly increased the content of MDA, H2O2, soluble sugars, SOD, POD, ADH, ABA, and JA. Under control conditions, Q. nuttallii showed significantly greater growth and photosynthetic capability than Q. palustris. In contrast, Q. palustris exhibited less inhibition of growth and photosynthesis, oxidative stress levels, and antioxidant enzyme activities than Q. nuttallii under flooding conditions. The findings indicate that Q. palustris has better defense mechanisms against the damage caused by flooding stress than Q. nuttallii. Q. nuttallii was more sensitive and responsive to flooding than Q. palustris.