Leaf Growth Research Articles

Effect of soil type on tipping point hydrological requirements for Axonopus compressus grass under extreme drought stress

Critical soil suctions (threshold, tipping point, and permanent wilting) corresponding to initial drought response, near-death stage, and complete mortality, respectively; is essential for formulating irrigation schemes of vegetation grown in compacted soil under drought conditions. The effect of soil types on these critical soil suctions are unexplored and is crucial in understanding the soil-specific plant water functions. This study aims to establish the drought response of Axonopus compressus (grass), based on stomatal conductance (gs) and chlorophyll fluorescence parameters (CI) grown in different soil types. A. compressus were grown in six soil types (2 coarse-grained and 4 fine-grained soils) for 8 weeks, followed by continued drought condition. The gs and CI were monitored along with soil suction and moisture content. Both leaf and root growth were observed to be higher in coarse-grained soils than fine-grained soils, even though the water retention of the coarse-grained soils were comparatively less. Drought stress initiation in plants was captured by ψthreshold from the CI (especially in fine-grained soils) before the gs response. The three critical soil suctions estimated from the correlation between CI and ψ were found to be increasing with higher soil clay fraction. Corresponding plant available water contents (based on v/v volumetric water content) with each of three critical soil suctions were found to be dependent on the relative growth of canopy to root growth that occurred in different soil medias. Especially, plant available water in ‘tipping suction’ was dependent on the soil clay fraction (i.e., higher fraction could restrict root water uptake) and is presented with a simple empirical correlation for A. compressus.

The crosstalk interaction of ethylene, gibberellins, and arbuscular mycorrhiza improves growth in salinized tomato plants by modulating the hormonal balance

Ethylene (ET) and gibberellins (GAs) play key roles in controlling the biotic and abiotic interactions between plants and environment. To gain insights about the role of ET and GAs interactions in the mycorrization and response to salinity of tomato (Solanum lycopersicum L.) plants, the ET-insensitive (Never-ripe, Nr), and the ET-overproducer (Epinastic, Epi) mutants and their wild type cv. Micro-Tom (MT), were inoculated or not with the arbuscular mycorrhizal fungi (AMF) Rhizophagus irregularis and exposed to control (0 mM NaCl) and salinity (100 mM NaCl) conditions, with and without gibberellic acid (10−6 M GA3) application during four weeks. Exogenous GA3 enhanced plant growth irrespective of the genotype, AMF, and salinity conditions, while an additional effect on growth by AMF was only found in the ET-overproducer (Epi) mutant under control and salinity conditions. Epi almost doubled the AMF colonization level under both conditions but was the most affected by salinity and GA3 application compared to MT and Nr. In contrast, Nr registered the lowest AMF colonization level, but GA3 produced a positive effect, particularly under salinity, with the highest leaf growth recovery. Foliar GA3 application increased the endogenous concentration of GA1, GA3, and total GAs, more intensively in AMF-Epi plants, where induced levels of the ET-precursor ACC were also found. Interestingly, GA4 which is associated with AMF colonization, registered the strongest genotype x GA x AMF × salinity interactions. The different growth responses in relation to those interactions are discussed.

Evaluation of the Effect of Soil Water Conditions on the Development and Water Requirements of Adult Oil Palm (Elaeis guineensis Jacq.) in the Northern Region of Colombia

Sustainable water management is a key approach for enhancing the productivity of oil palm trees while addressing the impacts of climate change and variability. Determining the water needs of a crop is crucial for the appropriate application of water. This research was carried out in two plantations in Agustín Codazzi, Colombia, using a completely randomized design. This study involved examining the impacts of five different water conditions (50, 150, 300, 450, and 600 L per day) on the growth and yields of mature oil palm trees (aged 10–17 years), and their water consumption was calculated using the water balance method. The results indicated that the crop was negatively affected by daily water applications of 300, 150, and 50 L per day, showing statistically significant differences (p < 0.05) when compared to the 450 and 600 L per day treatments, particularly in terms of leaf emergence, leaf area index, and yield (tons per hectare). The 50 L per day treatment resulted in the most substantial decrease in yield (around 26%), primarily attributed to a reduction in the number of bunches. The most favorable crop responses were observed with water applications of 450 and 600 L per day, aligning with the crop’s potential evapotranspiration values (ranging between 5.4 and 5.7 mm per day) and yielding crop coefficients of 0.88 and 0.9, respectively. Notably, these values varied between dry and rainy seasons, peaking between December and March.

Optimizing Fertilization Strategies to Promote Leaf-Use Ginkgo Productivity and Ecosystem Economic Benefits: An Integrated Evaluation of a Field Trial in Southern China

Field experiments were conducted on a four-year-old leaf-use ginkgo plantation in southern China to assess the impact of nine different fertilization strategies with varying N-P2O5-K2O rates at three growth phases (FBD: March for bud development; FLG: May for leaf growth; FLS: July for leaf strengthening) on leaf-use ginkgo (Ginkgo biloba L.) leaf productivity and ecological economic benefits (EEBs). The results indicated that regardless of timing and rate, fertilizer application led to an increase in leaf area and thickness, resulting in higher ginkgo leaf yield. The highest fresh (215.14 g tree−1) and dry (78.83 g tree−1) yields were observed with 3 g N + 2.5 g P2O5 + 1.5 g K2O tree−1 in FLG. FLS was found to mitigate the decline in SPAD values of leaves during late summer. Furthermore, fertilized ginkgo trees exhibited higher flavonoid concentrations in leaves, enhancing profitability. However, higher fertilizer rates were associated with elevated greenhouse gas emissions, nitrogen losses and ecological costs. Despite these drawbacks, all fertilization treatments resulted in increased net economic income. Specifically, compared to no fertilization, FBD, FLG and FLS treatments boosted net income by 3.5~26.6%, 11.6~60.5% and 5.8~35.4%, respectively. Using the entropy weight TOPSIS method, it was concluded that optimizing the N, P and K fertilization rate and timing (applying 3–2.5–1.5 g tree−1 of N-P2O5-K2O in May) is a beneficial approach to maximize EEBs and industrial benefits in leaf-use ginkgo plantations in southern China. This study provides valuable insights into suitable fertilization patterns and management for leaf-use ginkgo plantations in southern China.

Crop water stress index characterizes maize productivity under water and salt stress by using growth stage-specific non-water stress baselines

ContextThe use of non-destructive, continuous, and rapid canopy temperature (Tc) indices for crop stress diagnosis is of significant importance for improving crop water productivity (WP). However, the comprehensive applicability of the crop water stress index (CWSI), grounded in Tc, in diagnosing both single and combined water and salt stress, as well as characterizing physiological and growth traits, remains inadequately explored. ObjectiveWe aim to investigate the ability of CWSI to diagnose single and combined water and salt stress and to test whether a non-water stress baseline (NWSB) with or without growth stage and genotype differences influences CWSI to characterise maize leaf physiological and growth traits. MethodsHere, we measured the Tc using infrared radiation thermometers of two maize genotypes (XY335 and ZD958) under both single and combined water and salt stress over two growing seasons, compared the differences of NWSB in three growth stages, and established CWSI. Our analysis involved scrutinizing the differences in characterizing crop physiology and growth traits between CWSI calculated using NWSB with and without growth stage differentiations. ResultsOur findings indicated that Tc is modulated by an interplay of soil water content, VPD, and soil salinity. The NWSB exhibited variations with both growth stage (pslope < 0.001) and genotype (pslope or pintercept < 0.01). The CWSI can diagnose single and combined water and salt stress suffered by maize. Under no stress, and single and combined water and salt stress, CWSI was significantly correlated with stomatal conductance (R2 ≥ 0.31, p < 0.1) and net photosynthetic rate (R2 ≥ 0.38, p < 0.1), rather than with hydraulic traits. The mean CWSI across the entire growth period closely correlated with leaf area index (LAI), canopy photosynthetically active radiation interception, biomass, yield, and evapotranspiration across varying treatments (R2 ≥ 0.54, p < 0.1). Contrary to CWSI derived from NWSB without growth stage variations, utilizing CWSI with growth stage distinctions better characterized physiological traits, while the former was more suitable for delineating yield and WP. ImplicationsThis research underscores the efficacy of CWSI for stress diagnosis and the evaluation of gas exchange and productivity in maize under both single and combined soil water-salt stress. This investigation significantly propels forward the implementation of crop-centric irrigation strategies aimed at optimizing water utilization efficiency.

Unveiling intra-population functional variability patterns in a European beech (Fagus sylvatica L.) population from the southern range edge: drought resistance, post-drought recovery and phenotypic plasticity.

Understanding covariation patterns of drought resistance, post-drought recovery and phenotypic plasticity, and their variability at the intra-population level are crucial for predicting forest vulnerability to increasing aridity. This knowledge is particularly urgent at the trailing range edge since, in these areas, tree species are proximal to their ecological niche boundaries. While this proximity increases their susceptibility, these populations are recognized as valuable genetic reservoirs against environmental stressors. The conservation of this genetic variability is critical for the adaptive capacity of the species in the current context of climate change. Here we examined intra-population patterns of stem basal growth, gas exchange and other leaf functional traits in response to an experimental drought in seedlings of 16 open-pollinated families within a marginal population of European beech (Fagus sylvatica L.) from its southern range edge. We found a high degree of intra-population variation in leaf functional traits, photosynthetic performance, growth patterns and phenotypic plasticity in response to water availability. Low phenotypic plasticity was associated with higher resistance to drought. Both drought resistance and post-drought recovery of photosynthetic performance varied between maternal lines. However, drought resistance and post-drought recovery exhibited independent variation. We also found intra-population variation in stomatal sensitivity to soil drying, but it was not associated with either drought resistance or post-drought recovery. We conclude that an inverse relationship between phenotypic plasticity and drought resistance is not necessarily a sign of maladaptive plasticity, but rather it may reflect stability of functional performance and hence adaptation to withstand drought. The independent variation found between drought resistance and post-drought recovery should facilitate to some extent microevolution and adaption to increasing aridity. The observed variability in stomatal sensitivity to soil drying was consistent with previous findings at other scales (e.g., inter-specific variation, inter-population variation) that challenge the iso-anisohydric concept as a reliable surrogate of drought tolerance.

Influence of Water and Fertilizer Reduction on Respiratory Metabolism in Sugar Beet Taproot (Beta vulgaris L.).

Inner Mongolia, a major region in China for growing sugar beet, faces challenges caused by unscientific water and fertilizer management. This mismanagement restricts the improvement of sugar beet yield and quality and exacerbates water waste and environmental pollution. This study aims to evaluate the effects of reduced water and fertilizer on the growth and physiological metabolism of sugar beet taproot. Field experiments were conducted in Ulanqab, Inner Mongolia, in 2022 and 2023, using a split-plot design with three levels each of fertilization and irrigation. The study analyzed the effects of reduced water and fertilizer treatments on fresh taproot weight, respiration rate, energy metabolism, respiratory enzyme activity, and gene expression in sugar beet taproot. It was found that a 10% reduction in fertilizer significantly increased the beet taproot fresh weight. Further research revealed that during the rapid leaf growth phase and the taproot and sugar growth period, a 10% reduction in fertilizer upregulated HK and IDH gene expression and downregulated G6PDH gene expression in the beet taproot. This increased HK and IDH activities, decreased G6PDH activity, enhanced the activity of the EMP-TCA pathway, and inhibited the PPP. Taproot weight was positively correlated with the respiration rate, ATP content, EC, and ATPase, HK, and IDH activities, thereby increasing the taproot growth rate and taproot fresh weight, with an average increase of 4.0% over two years. These findings introduce a novel method for optimizing fertilizer use, particularly beneficial in water-scarce regions. Implementing this strategy could help farmers in western Inner Mongolia and similar areas improve crop yield and sustainability. This study offers new insights into resource-efficient agricultural practices, highlighting the importance of customized fertilization strategies tailored to local environmental conditions.

Overstorey leaf production and emergence of sassafras saplings in a southwest Missouri oak woodland: An analysis based upon long-term effects of fire

Overstorey leaf production and emergence of sassafras saplings in a southwest Missouri oak woodland: An analysis based upon long-term effects of fire

Sustainable cottonseed protein bioplastics: Physical and chemical reinforcement, and plant seedling growth application

Petroleum-based plastic containers for plant seedling growth are expensive to recycle and have negative environmental impacts when discarded. In this work, a novel family of sustainable and biodegradable plastic films and containers were fabricated by simply casting and mold-curing methods, which demonstrated outstanding performance promoting crop seed germination and plant seedling growth. Concentrate cottonseed protein (CPC) was used as polymeric matrix, pulp fiber (PF) as a physical reinforcement, tannic acid (TA) as a chemical modifying agent, with their addition contents ranging from 0 ∼ 30 % (PF) and 0 ∼ 10 % (TA), respectively. Evaluations of the composite CPC/PF and CPC/TA films regarding their structure, morphology, tensile properties, and water resistance show that the physical and chemical reinforcement resulted in good interfacial compatibility, mechanical strength, and water resistance. Moreover, the newly prepared bioplastics were biodegradable in soil in three weeks, and did not harm crop seed germination and growth. More importantly, the protein derived biocontainers/pot (CPC/PF30 and CPC/TA10) can provide excellent growth conditions for plant root and leaf growth such as chili peppers because of their low toxicity and 100 % germination rate. More importantly, the healthy growing environment was closely related to the presence of nutritious elements/ions that the plant needed. Specifically, the biodegradation of the bioplastics during plant seedling test released nitrogen-containing ions like NH4+ (0.25 wt% for CPC/TA10 versus 0.17 wt% for polyethylene), and retained in soil, playing a decisive role in seedling growth. Therefore, the cottonseed protein bioplastics reinforced by pulp fiber and tannic acid are beneficial to crop seedling growth, holding great potential for being used as plantable pots/containers in agriculture and horticulture applications.

Biogenic synthesis of hollow carbon dots using cigarette ash for photocatalytic and sensing applications

In this research article, the synthesis of hollow carbon dots (HCDs) from cigarette ash (CA) as a precursor using simple pyrolysis method is presented. The unique hollow nature of synthesized HCDs was confirmed by high-resolution transmission electron microscopy and nitrogen physisorption techniques. HCDs, with a size of ∼ 9 nm, exhibit specific surface area of 12.1 m2/g and stimulated pore diameter of 2.1 nm. HCDs demonstrated remarkable degradation efficiency by eradicating 91 % of rose Bengal dye within 120 min under UV irradiation at pH = 5.00 and display selective and sensitive detection of Fe3+ with a detection limit of around 1.1 µM. Ecological effect of HCDs on sprouted seeds of chickpea (Cicer arietinum) and wheat (Triticum aestivum) revealed their capacity to positively influence multiple aspects of plant development. Introduction of HCDs into growth medium (water) appeared to stimulate shoot, root, and leaf growth, suggesting a potential role for HCDs in enhancing overall plant health and productivity. These findings enabled HCDs derived from CA as promising candidate for sensitive metal ions detection, environmental remediation, and plant growth enhancement. It is the first time to upcycle CA into distinctive HCDs, serving as a potent tool for detecting and breaking down environmental contaminants.

Paecilomyces variotii extracts promote growth and alleviate nutrient deficiency symptoms in apple

It is essential to find environment-friendly agrochemicals to cope with the problems of nutrient imbalance, fruit quality decline, and physiological disorders during apple fruit production, which is beneficial for improving the quality and yield of apple. A natural extract from Paecilomyces variotii (ZNC), an endophytic fungus, has been used widely to enhance crop performance. However, an understanding of the mechanism underlying ZNC-triggered growth and alleviation of nutrient deficiency-associated symptoms in apples remains elusive. Here, the photosynthesis, leaf growth, and fruit quality were enhanced by adding ZNC. In addition, ZNC relieved nutrient deficiency-related symptoms promoted the differentiation of root morphology and vitality, and reduced the accumulation of osmoprotectants and reactive oxygen species, thereby promoting growth under normal and nutrient-deficient conditions. Finally, genome-wide RNA sequencing reveals the ZNC-regulated mechanisms involved in hormone and metal ion pathways. Our study reveals the role of ZNC in promoting growth and improving the quality of apple, providing a new direction for reducing the use of chemical fertilizers and pesticides.

Stable early heading in photoperiod-insensitive rice varieties results from an extremely short photoperiod-sensitive phase and weak temperature sensitivity

The transition from vegetative to reproductive growth in rice (Oryza sativa) is mainly regulated by photoperiod and temperature; however, it remains unclear how photoperiod-insensitive (photo-In) early heading rice varieties make this transition. Vegetative growth consists of a basic vegetative phase (BVP) and a photoperiod-sensitive phase (PSP). A certain duration of the BVP is required prior to the PSP, which varies according to daylength conditions. PSP duration is conventionally used as a parameter of photoperiod sensitivity, but this is not applicable to photo-In rice varieties. Here, we aimed to characterize the PSP in photo-In rice varieties. We examined four photo-In varieties and photoperiod-sensitive (photo-Se) varieties grown in four controlled environments, evaluating the lengths of their growth phases based on the turning point of the interval of leaf emergence and panicle initiation (PI). The photo-In varieties had an extremely short PSP, regardless of daylength, compared with the photo-Se varieties. Low temperature uniformly prolonged all growth stages in the photo-In varieties but led to a much longer PSP in the photo-Se varieties. The photo-In varieties, each carrying a non-functional allele of Ghd7, lost the ability to suppress PI, resulting in early heading. Hemi-knockout plants at the Ghd7 locus demonstrated the earlier heading than the wild-type plant due to shortening of PSP. Our results suggest that the photo-In varieties begin PI immediately after the end of the BVP, but their flowering is not a temperature-dependent process.

The underlying mechanisms by which boron mitigates copper toxicity in Citrus sinensis leaves revealed by integrated analysis of transcriptome, metabolome and physiology.

Both copper (Cu) excess and boron (B) deficiency are often observed in some citrus orchard soils. The molecular mechanisms by which B alleviates excessive Cu in citrus are poorly understood. Seedlings of sweet orange (Citrus sinensis (L.) Osbeck cv. Xuegan) were treated with 0.5 (Cu0.5) or 350 (Cu350 or Cu excess) μM CuCl2 and 2.5 (B2.5) or 25 (B25) μM HBO3 for 24wk. Thereafter, this study examined the effects of Cu and B treatments on gene expression levels revealed by RNA-Seq, metabolite profiles revealed by a widely targeted metabolome, and related physiological parameters in leaves. Cu350 upregulated 564 genes and 170 metabolites, and downregulated 598 genes and 58 metabolites in leaves of 2.5μM B-treated seedlings (LB2.5), but it only upregulated 281 genes and 100 metabolites, and downregulated 136 genes and 40 metabolites in leaves of 25μM B-treated seedlings (LB25). Cu350 decreased the concentrations of sucrose and total soluble sugars and increased the concentrations of starch, glucose, fructose and total nonstructural carbohydrates in LB2.5, but it only increased the glucose concentration in LB25. Further analysis demonstrated that B addition reduced the oxidative damage and alterations in primary and secondary metabolisms caused by Cu350, and alleviated the impairment of Cu350 to photosynthesis and cell wall metabolism, thus improving leaf growth. LB2.5 exhibited some adaptive responses to Cu350 to meet the increasing need for the dissipation of excessive excitation energy (EEE) and the detoxification of reactive oxygen species (reactive aldehydes) and Cu. Cu350 increased photorespiration, xanthophyll cycle-dependent thermal dissipation, nonstructural carbohydrate accumulation, and secondary metabolite biosynthesis and abundances; and upregulated tryptophan metabolism and related metabolite abundances, some antioxidant-related gene expression, and some antioxidant abundances. Additionally, this study identified some metabolic pathways, metabolites and genes that might lead to Cu tolerance in leaves.

Modulation of cell differentiation and growth underlies the shift from bud protection to light capture in cauline leaves.

Plant organs have evolved into diverse shapes for specialized functions despite emerging as simple protrusions at the shoot apex. Cauline leaves serve as photosynthetic organs and protective structures for emerging floral buds. However, the growth patterns underlying this dual function remain unknown. Here, we investigate the developmental dynamics shaping Arabidopsis (Arabidopsis thaliana) cauline leaves underlying their functional diversification from other laminar organs. We show that cauline leaves display a significant delay in overall elongation compared to rosette leaves. Using live imaging, we reveal that their functional divergence hinges on early modulation of the timing of cell differentiation and cellular growth rates. In contrast to rosette leaves and sepals, cell differentiation is delayed in cauline leaves, fostering extended proliferation, prolonged morphogenetic activity, and growth redistribution within the organ. Notably, cauline leaf growth is transiently suppressed during the early stages, keeping the leaf small and unfolded during the initiation of the first flowers. Our findings highlight the unique developmental timing of cauline leaves, underlying their shift from an early protective role to a later photosynthetic function.

Effects of atmospheric CO2 concentration on transpiration and leaf elongation responses to drought in Triticum aestivum, Lolium perenne and Festuca arundinacea.

Leaf elongation is vital for Poaceae species' productivity, influenced by atmospheric CO2 concentration ([CO2]) and climate-induced water availability changes. Although [CO2] mitigates the effects of drought on reducing transpiration per unit leaf area, it also increases total leaf area and water use. These complex interactions associated with leaf growth pose challenges in anticipating climate change effects. This study aims to assess [CO2] effects on leaf growth response to drought in perennial ryegrass (Lolium perenne), tall fescue (Festuca arundinacea) and wheat (Triticum aestivum). Plants were cultivated in growth chambers with [CO2] at 200 or 800ppm. At leaf six to seven unfolding, half of the plants were subjected to severe drought treatment. Leaf elongation rate (LER) was measured daily, whereas plant transpiration was continuously recorded gravimetrically. Additionally, water-soluble carbohydrate (WSC) content along with water and osmotic potentials in the leaf growing zone were measured at drought onset, mid-drought and leaf growth cessation. Elevated [CO2] mitigated drought impacts on LER and delayed growth cessation across species. A positive correlation between LER and soil relative water content (SRWC) was observed. At the same SRWC, perennial grasses exhibited a higher LER with elevated [CO2], likely due to enhanced stomatal regulation. Despite stomatal closure and WSC accumulation, CO2 did not influence nighttime water potential or osmotic potential. The marked increase in leaf area across species resulted in similar (wheat and tall fescue) or higher (ryegrass) total water use by the experiment's end, under both watered and unwatered conditions. In conclusion, elevated [CO2] mitigates the adverse effects of drought on leaf elongation in three Poaceae species, due to its impact on plant transpiration. Overall, these findings provide valuable insights into CO2 and drought interactions that may help anticipate plant responses to climate change.

Optimizing leaf nutrient status, growth, and yield parameters in high-density apple orchards (cv. Super chief) via integrated drip irrigation and fertigation techniques

Nutrients and water are important ecophysiological components for apples' development and productivity. The combination of high-density plantation, drip irrigation, and weekly fertigation not only conserves irrigation water, but also reduces cultivation costs compared to conventional methods. Leaf nutrient analysis provides insight into nutrient levels and assists in determining irrigation and fertigation schedules. We conducted the current research over two years (2021–22 and 2022–23) to evaluate different drip-fertigation effects on leaf nutrient status, vegetative growth, and yield of high-density apples. The experimental study employed a factorial randomised block design, replicating 16 different treatment combinations three times each. Each replication consisted of three plants, and the treatments included four irrigation levels (100 %, 80 %, 60 %, and control) and four fertigation levels (absolute control, 100 %, 75 %, and 50 % of the recommended NPK dosage). Analysis of the leaves indicated that IR1 (Drip irrigation at 100 % ETc) showed notably higher levels of nitrogen at (3.06 %), phosphorus at (0.48 %) and potassium at (2.07 %) compared to other treatments. Regarding fertigation levels, FN1 [100 % (AD) NPK] showed the highest nitrogen (3.12 %), phosphorus (0.50 %), and potassium (2.09 %) content. Parameters related to vegetative growth, including tree height, plant spread in both east-west (EW) and north-south (NS) directions, trunk girth, annual extension growth, and leaf area showed significant increases with higher irrigation and fertigation levels, surpassing conventional irrigation (IR4) by 6.17 percent, 7.78 percent (EW), 8.62 percent (NS), 10.49 percent, 4.53 percent and 1.96 percent, respectively. Among fertigation, FN1- 100 % AD (NPK) registered a maximum increase in growth parameters. Our analysis demonstrated that combining irrigation and fertigation improved leaf nutrient status and vegetative growth characteristics, which are critical determinants of fruit yield.

Effect of simulated extreme rainfall on the vegetative phenology of perennial and annual herbaceous plants from a Brazilian dry forest.

Detecting changes in the phenological responses of herbaceous species as a function of predicted climate change is important for forecasting future scenarios for the functioning of dry tropical forests, especially when predicting an increase in the frequency and intensity of extreme droughts. Because of the sensitivity of plants to water availability, our study hypothesizes that if years become drier or wetter, herbaceous plants will synchronously change the onset, duration, and intensity of their vegetative phenophases. We used a historical series of 60 years of precipitation observations for the Caatinga vegetation to define daily average of precipitation for rainy (Twet), median (Tcontrol), and dry (Tdry) years. We simulated past average daily rainfall (Twet, Tcontrol, and Tdry) while growing two herbaceous perennials and two herbaceous annuals. We monitored plant growth and measured the activity (absence or presence) and intensity of vegetative phenophases. We used circular statistical analysis to assess differences between treatments. Our results revealed that leaf production was seasonal but relatively uniform for perennial species and highly seasonal (wet season) for annual species. Simulated dry years induced lower leaf emergence concentrated over a few months in annual species, but this effect was more strongly significant in one of the two perennial species. Both annual and perennial species can experience delayed and less intense leaf abscission during the rainy season in years with below-average precipitation. In contrast, large voluminous rains in years with above-average precipitation can accelerate and intensify the process of leaf renewal. If future precipitation reductions occur, the changes in phenological response indicate that the cover of annual and perennial herbaceous species in this study will likely decrease, altering the landscape and functioning of dry tropical forests. However, the potential trade-offs observed may help populations of these species to persist during years of severe drought in the Caatinga.

Plasticity of leaf functional traits and growth responses to disturbance among cutting cultivars of Cryptomeria japonica in southern Japan

ABSTRACT Cryptomeria japonica (Thunb. ex L. f.) D. Don is the most major plantation species in Japan, and cultivars have been developed and planted under variable environmental conditions across the country. Productivity of clonal plantations is influenced by the ability of the genotype to acclimate to edaphic- and geographic-scale variation in environmental conditions and disturbance regimes. Because all individuals are genetically identical in a clonal plantation, the trait differences among individuals represent phenotypic plasticity. Here, we investigated how phenotypic plasticity and response to disturbance vary among cutting cultivars of C. japonica. We compared tree height, leaf morphology, nitrogen content, and frequency/intensity of growth-release observed in tree rings after thinning and disturbance among six cutting cultivars in 45-year-old provenance trials in south-western Japan. Nitrogen use efficiency was higher in the site where maximum tree height (H max) was taller, while shoot mass per area (SMA) was larger in the site where H max was shorter. Cultivars that grew well had high leaf nitrogen content (N G) and showed more efficient nitrogen use with high nitrogen-resorption efficiency (NRE). Yabukuguri, an intermediate-growth cultivar, was characterized by large SMA and greater plasticity in SMA and tree height in response to topographical and regional variation, as well as greater intensity of growth-release in tree-ring series indicating growth resilience following disturbance. Our results provide guidelines for selecting cultivars with high acclimation potential and resilience to environmental perturbation, which is important for sustaining plantation forests in uncertain environmental conditions expected by future climate change.

Metabolomics and histopathological analysis of two tomato cultivars after co-infection with soil-borne pathogens (Southern root-knot nematode and Fusarium wilt fungus)

Southern root-knot nematode (Meloidogyne incognita) and Fusarium wilt fungus (Fusarium oxysporum) are one of the most predominant pathogens responsible for substantial agricultural yield reduction of tomato. The current study planned to assess the effects of M. incognita (Mi) and F. oxysporum (Fo) and their co-infection on two tomato cultivars, Zhongza 09 (ZZ09) and Gailing Maofen 802 (GLM802). The present study examined the effects of co-infection on leaf morphology, chlorophyll content, leaf area, and histopathology. The present study used metabolomics to evaluate plant-pathogen interactions. The outcomes of the current study revealed that chlorophyll content and leaf area decreased more in GLM802 during co-infection. In co-infection (Fo + Mi), the chlorophyll content reduction in ZZ09 was 11%, while in GLM802 the reduction reached up to 31% as compared to control. Moreover, the reduction in leaf are in ZZ09 was 31%, however, in the GLM802 reduction was observed 54% as compared to control plants. Similarly, GLM802 stems exhibited larger brown patches on their vascular bundles than ZZ09 stems. The rate of browning of GLM802 stems was 247% more than ZZ09, during co-infection. Moreover, GLM802 roots exhibited a higher abundance of hyphae and larger galls than ZZ09 roots. In metabolic studies, glutathione, succinic acid, and 2-isopropylmalic acid decreased, whereas spermine and fumaric acid increased in GLM802 co-infected stems. It indicates that GLM802 is weakly resistant; therefore, F. oxysporum and other pathogens readily damage tissue. In the co-infected stem of ZZ09, L-asparagine and shikimic acid increased, but pipecolic acid, L-saccharine, and 2-isopropylmalic acid declined. L-asparagine was crucial in preserving the stability of nitrogen metabolism, chlorophyll synthesis, and leaf growth in ZZ09. Shikimic acid's substantial accumulation could explain the limited extent of browning observed in the vascular bundles of ZZ09. Thus, the present study provides insight into M. incognita and F. oxysporum co-infection in two tomato cultivars, which may aid breeding efforts to generate commercially viable resistant cultivars. However, further research on the relationship between M. incognita and F. oxysporum in different host plants is required in the future.

Effect of Soil Fertility on the Growth Characteristics of Two Young Trees of the Neem Family

To select tree species suitable for growth under Chinese ephedra forests, this study set up three soil fertility treatments: pure sandy soil, V (sand): V (fertilizer) = 3:1, and V (sand): V (fertilizer) = 1:1, to investigate the effects of different soil fertility levels on the growth characteristics of two tree species, Azadirachta indica A. Juss (neem) and Melia azedarach (chinaberry). The results show that: (1) Under low light conditions and pure sandy soil, the height and basal diameter of neem significantly increased, while chinaberry showed a significant increase in height and basal diameter under the V (sand): V (fertilizer) = 1:1 condition. (2) Under the V (sand): V (fertilizer) = 1:1 condition, both neem and chinaberry exhibited maximum leaf growth characteristics, while there was a decreasing trend under the V (sand): V (fertilizer) = 3:1 condition. These results indicate that neem is more suitable for growth in pure sandy soil and is more tolerant to poor soil conditions, while chinaberry thrives under the V (sand): V (fertilizer) = 1:1 condition. This preliminary selection provides a theoretical basis for the initial screening of tree species for coastal defense forests.