Plant Growth Index Research Articles

The Colonization and Effect of Isaria cateinannulata on Buckwheat Sprouts.

The use of entomogenous fungi as endophytes is currently an area of active research. Isaria cateniannulata is an important entomogenous fungus that has been employed for the active control of a range of pests in agricultural and forestry settings, but its direct impact on plants remains to be evaluated. Herein, we assessed the ability of I. cateniannulata to colonize buckwheat, Fagopyrum esculentum and F. tataricum, and its impact on buckwheat defense enzyme activity and physiological indexes. The majority of fungal submerge condia was able to enter into leaves through stomata and veins, and this was followed by conidial attachment, lytic enzyme secretion, conidial deformation, and enhanced defensive enzyme activity within buckwheat, followed by the repair of damaged tissue structures. I. cateniannulata populations on buckwheat leaf surfaces (in CFU/g) reached the minimum values at 24 h after inoculation. At this time, the blast analysis revealed that the sequence identity values were 100%, which was consistent with the sequence of I. cateniannula. The number of I. cateniannulata submerge conidia colonized in the buckwheat leaves gradually rose to peak levels on 7 d post-inoculation, and then gradually declined until 10 d, at which time the buckwheat plant growth index values increased. This study provided novel evidence that I. cateniannulata could be leveraged as an endophytic fungus capable of colonizing buckwheat plants and promoting their growth.

Bacillus velezensis BY6 Promotes Growth of Poplar and Improves Resistance Contributing to the Biocontrol of Armillaria solidipes.

To improve the application of endophyte Bacillus velezensis BY6 from the xylem of poplar, the effect of BY6 on the growth of diseased Populus davidiana × Populus. alba var. pyramidalis Louche (Pdpap poplar) seedlings and the biological control effect on the pathogen Armillaria solidipes were tested using a plant split-root experiment. After applying BY6 to the roots of diseased Pdpap poplar seedlings, the results show that plant growth indicators (dry mass, fresh mass, and plant height) were significantly increased (p < 0.05), and genes related to auxin hormone signal transcription were activated. BY6 indicated a surprising control effect after the inoculation of diseased Pdpap poplar seedlings. Compared to the infected control group, the treated disease index of the diseased Pdpap poplar seedlings in the treatment group were reduced by 49.53% on the 20th day. The relative staining areas of diaminobenzidine (DAB) and Trypan blue decreased by 3.37 and 7.31 times, respectively. The physiological indicators (soluble sugar and protein) and oxidase indicators were significantly increased (p < 0.05). The expression levels of defense genes related to salicylic acid (SA) and jasmonic acid (JA) signaling pathways were significantly increased (p < 0.05). Amazingly, the results indicate that BY6 simultaneously activates induced systemic resistance (ISR) and systemic acquired resistance (SAR) in diseased Pdpap poplar seedlings and promotes growth. The results indicate that BY6 is a promising candidate for developing forest tree biofertilizers and biopesticides.

Effects of Led Light Intensity and Carbon Dioxide Concentration on the Growth of Spinach (Spinacia oleracea L.) in a Plant Factory

This research aimed to investigate the effects of light intensity and the carbon dioxide (CO2) concentration on spinach’s growth during vegetative stage in plant factory (PF). Two experiments were conducted with different CO2 concentration in closed chamber (500 ppm and 800 ppm). In each experiment, plants were hydroponically grown under three light intensities of 115, 140 and 160 µmol.m-2s-1. Growth’s parameters were determined at different growth stages (T30, T37 and T44 respectively to 30, 37 and 44 days after sowing). ANOVA analysis and non-parametric Kruskal analysis of variance were used to evaluate the statistical significance of the treatment effects. The results showed that, before 30 days old, the increase of light intensity was not significantly effected to the growth of plant. During later growing periods (30 days old afterward), the increase of light intensity remarkably boost up yield’s related traits such as leaf number, fresh mass and dry mass under 500ppm CO2 concentration. The combination of light intensity and CO2concentration at 800ppm showed the plant growth indicators increased significantly at the T37 and T44 stages (after 30 days old), especially at the last week of growth period, fresh weight and dry weight of plants were significantly different at the light treatment L2, increased 37% and 57.6%, respectively as compared to light treament only. The results suggested that, during latest growing period, the average light intensity of 140 µmol.m-2s-1combining with elevating CO2 concentration is an alternatively way to enhance spinach growth. The findings of this study could be helpful for growers to improve growing conditions for a better development of spinach in the indoor farming (PF)&#x0D;

Effect of supplemental light, pinching, and number of plants per pot on the growth and flowering of chrysanthemum plant (Dendranthema grandiflora Tzvelev)

This study was conducted in the plastic house - Nursery of the Duhok University - Duhok governorate-Kurdistan region-Iraq from the period 10th Apr. 2021 to 10th Jan. 2022. This study aimed to investigate the effect of supplemental light (light and without light), pinching (pinching and without pinching) and number of plants per pot (2, 3, and 4) plants/pot on the growth and flowering of chrysanthemum (Dendranthema grandiflora Tzvelev) plant. The results showed that supplemental light for one month delayed the flower bud emergence (223.08) days, and flower anthesis (241.58) days compared with the control (without supplemental light) that gave (198.83, 218.44) days for the two characteristics respectively. Further, supplemental light gave the best results for flower length, flower diameter, flower number, and vase life compared to (without supplemental light). Pinching delayed the flower bud emergence and decreased the plant high, growth index, flower diameter, and vase life of cut flower significantly while it significantly increased the flower diameter and vasa life. Increasing the number of plants per pot to 4 plants caused a significant increment in flower number (8.25) compared with 2 plants which gave 5.64 plants/pot. The triple interaction showed significant differences in all characteristics and number of days to flower bud emergence and flower anthesis were the highest mean for the supplemental light with or without the pinch and 2 plants/pot. Also, the best plant height (72.33) cm and growth index (26761) cm3 were recorded without supplemental light, without pinch with 2 plants/pot. However, the maximum vase life of 26.33 days was found from the interaction of supplemental light, pinch, and 2 plants/pot.

Effects of foliar application of humic acid extracts and indole acetic acid on important growth indices of canola (Brassica napus L.)

Vermicompost (VC) is a rich source of HA that improves plant growth and yield indices such as fresh and dry weights, plant height, stem diameter, leaf area, and chlorophyll index value. In this study, the effect of foliar application of HA extracted from different types of VC enriched with bacteria and/or fertilizers, commercial HA (CHA) and indole acetic acid (IAA) on the growth characteristics of canola (Brassica napus) in greenhouse conditions were compared. According to the results, the foliar application of HA extracted from VC had complete superiority over CHA and IAA in most traits except for the leaf number. Furthermore, the highest level of foliar application of HA (600 mg L−1) enriched with Azotobacter chroococcum (21Az) + Pseudomonas fluorescens (Ps 59) (HA-AS) generated the highest height, diameter, leaf area, and chlorophyll index value. Also, the highest stomatal conductance and photosynthesis rate were observed with the application of 600 mg L−1 HA extracted from VC enriched with nitrogen, sulfur, and phosphorus (HA-NSP) compared to the other treatments. Besides, dry and fresh weights and seed yield under HA-NSP and HA-AS treatments were at their highest rate. Among the extracted HAs, the one extracted from the nitrogen enriched VC had the lowest efficiency. Based on the present study, the HA extracted from VC enriched with Azotobacter, Pseudomonas and NSP is recommended to increase canola growth and production.

Soil Organic Nitrogen Components and N−Cycling Enzyme Activities Following Vegetation Restoration of Cropland in Danxia Degraded Region

Soil organic nitrogen (SON) components are a key indicator of soil fertility and plant growth. The Danxia degraded region (DDR) is an ecologically fragile area in southern China, where the “Grain for Green” project has been implemented to prevent further land degradation. However, little is known about the effects of vegetation restoration on SON components in the DDR or the factors that influence them. We compared three vegetation restoration types, namely, grassland, shrubland, and arbor forest, with cropland to determine the relationship between SON components and N−cycling enzyme activities. Vegetation restoration increased the soil amino sugar N and amino acid N and reduced the proportion of non−hydrolyzable N. Compared with forest restoration measures, restoration to grassland was more beneficial to SON levels and N−fixation capacity. Vegetation restoration also increased soil nitrate reductase, denitrifying enzyme, protease, β−1,4−N−acetylglucosaminidase activities, and soil microbial biomass. Vegetation restoration in the DDR changed the SON components through the “mineralization−fixation” of organic matter via amorphous iron and proteases, which, in turn, affected the level of available soil N. Vegetation restoration improved the soil N structure and promoted the intrinsic soil N cycle, providing a scientific basis for soil quality restoration in the DDR.

Silicon improves the effect of phosphate-solubilizing bacterium and arbuscular mycorrhizal fungus on phosphorus concentration of salinity-stressed alfalfa (Medicago sativa L.)

Under salinity stress, the availability of soil nutrients to plants is reduced, leading to disruption of nutrition and the balance of plant nutrients, including phosphorus (P). The use of phosphate-solubilizing microorganisms (PSM) and silicon (Si) in alleviating salinity stress and improving the uptake of P by plants has become a global solution. However, there is limited information on the effect of phosphate-solubilizing bacteria and arbuscular mycorrhizal fungi in the combination with Si on improving the absorption of P by plants including legumes under salinity stress. In this study, the plant growth-promoting potential of an effective phosphate-solubilizing bacterial strain (R115), Microbacterium shaanxiense, and an arbuscular mycorrhizal fungus, Claroideoglomus etunicatum, alone or in the combination with Si to alleviate salinity stress in alfalfa inoculated with its rhizobial symbiosis, Ensifer meliloti N44, and improve the absorption of P by this plant was investigated by a pot-experiment in a completely randomized design with factorial arrangement in three repetitions. Experimental treatments included: Si factor at two levels of 0 and 4 mM Si from potassium silicate source, bacterial strain R115 factor at two levels of B0 (control), and strain R115 (B1), mycorrhizal fungus factor at two levels of F0 (control) and mycorrhizal fungus (F1), and salinity (saline water) factor at three levels of 0, 5, and 15 dS m−1. Salinity stress reduced plant biomass, the content of chlorophyll, the concentration of N, P and K of plant and increased the concentration of Na in shoot tissue and the activity of antioxidant enzymes (catalase and superoxide dismutase) in alfalfa plant. However, the use of PSM (M. shaanxiense R115 and C. etunicatum) and Si improved the morphological and physiological characteristics of the plant, reduced the plant Na concentration, and increased the concentration of N, P, and K of alfalfa plants. The highest improvement in plant growth indices (shoot P concentration) was recorded in plants inoculated with PSM in the presence of Si. The results of this study showed that Si fertilization can be suggested as a sustainable strategy for improving the plant growth promoting effects of PSM on the growth of alfalfa (e.g., increased shoot P concentration) and encouraging ecological adaptability of this plant under saline water irrigation.

Long-term nitrogen enrichment accelerates soil respiration by boosting microbial biomass in coastal wetlands

Coastal wetlands are essential in terrestrial carbon balance because they act as natural “blue carbon” sinks, influenced by anthropogenic nitrogen (N) enrichment. N enrichment alters soil environment and plant growth, impacting carbon loss through soil respiration (Rsoil). However, the responses of Rsoil to N enrichment remain elusive in coastal wetlands, hindering the estimation of carbon fluxes. To bridge this knowledge gap, we used an 8-year field N fertilization platform in the coastal wetlands of the Yellow River Delta, China, to measure Rsoil composed of heterotrophic respiration and autotrophic respiration, and multiple indicators of soil properties, microbial activities, and plant growth. We found long-term N enrichment increased Rsoil by 26.6 ± 1.2% (mean ± standard deviation) and quadrupled microbial biomass carbon, accounting for 26.9 ± 1.2% of the increase in heterotrophic respiration. In addition, N enrichment boosted plant growth, increasing the above-ground biomass by 28.7 ± 6.9% while inducing a cooling effect that partly offsets the increase in autotrophic respiration. In particular, N enrichment elevated soil temperature sensitivity of Rsoil with the increase of N levels, suggesting that the nutrient-related control of Rsoil responds to warming. The study indicates that N enrichment stimulates Rsoil in coastal wetlands by boosting microbial biomass carbon through interactions between soil environmental conditions and plant growth. These results have implications for predicting the carbon cycle with anthropogenic N enrichment.

Effects of planting date and spraying with organic fertilizers on vegetative growth indices of dill plant (Anethum graveolens L.)

Effects of planting date and spraying with organic fertilizers on vegetative growth indices of dill plant (Anethum graveolens L.)

Exogenous Ca2+ priming can improve peanut photosynthetic carbon fixation and pod yield under early sowing scenarios in the field.

Harnessing cold-resilient and calcium-enriched peanut production technology are crucial for high-yielding peanut cultivation in high-latitude areas. However, there is limited field data about how exogenous calcium (Ca2+) application would improve peanut growth resilience during exposure to chilling stress at early sowing (ES). To help address this problem, a two-year field study was conducted to assess the effects of exogenous foliar Ca2+ application on photosynthetic carbon fixation and pod yield in peanuts under different sowing scenarios. We measured plant growth indexes, leaf photosynthetic gas exchange, photosystems activities, and yield in peanuts. It was indicated that ES chilling stress at the peanut seedling stage led to the reduction of Pn, gs, Tr, Ls, WUE, respectively, and the excessive accumulation of non-structural carbohydrates in leaves, which eventually induced a chilling-dependent feedback inhibition of photosynthesis due mainly to weaken growth/sink demand. While exogenous Ca2+ foliar application improved the export of nonstructural carbohydrates, and photosynthetic capacity, meanwhile activated cyclic electron flow, thereby enhancing growth and biomass accumulation in peanut seedlings undergoing ES chilling stress. Furthermore, ES combined with exogenous Ca2+ application can significantly enhance plant chilling resistance and peanut yield ultimately in the field. In summary, the above results demonstrated that exogenous foliar Ca2+ application restored the ES-linked feedback inhibition of photosynthesis, enhancing the growth/sink demand and the yield of peanuts.

Leaf water content contributes to global leaf trait relationships

Leaf functional traits are important indicators of plant growth and ecosystem dynamics. Despite a wealth of knowledge about leaf trait relationships, a mechanistic understanding of how biotic and abiotic factors quantitatively influence leaf trait variation and scaling is still incomplete. We propose that leaf water content (LWC) inherently affects other leaf traits, although its role has been largely neglected. Here, we present a modification of a previously validated model based on metabolic theory and use an extensive global leaf trait dataset to test it. Analyses show that mass-based photosynthetic capacity and specific leaf area increase nonlinearly with LWC, as predicted by the model. When the effects of temperature and LWC are controlled, the numerical values for the leaf area-mass scaling exponents converge onto 1.0 across plant functional groups, ecosystem types, and latitudinal zones. The data also indicate that leaf water mass is a better predictor of whole-leaf photosynthesis and leaf area than whole-leaf nitrogen and phosphorus masses. Our findings highlight a comprehensive theory that can quantitatively predict some global patterns from the leaf economics spectrum.

Entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae play roles of maize (Zea mays) growth promoter

Beauveria bassiana and Metarhizium anisopliae are two of the most important and widely used entomopathogenic fungi (EPFs) to control insect pests. Recent studies have revealed their function in promoting plant growth after artificial inoculation. To better assess fungal colonization and growth-promoting effects of B. bassiana and M. anisopliae on crops, maize Zea mays seedlings were treated separately with 13 B. bassiana and 73 M. anisopliae as rhizosphere fungi in a hydroponic cultural system. Plant growth indexes, including plant height, root length, fresh weight, etc., were traced recorded for 35 days to prove the growth promoting efficiency of the EPFs inoculation. Fungal recovery rate (FRR) verified that both B. bassiana and M. anisopliae could endophytically colonize in maize tissues. The recovery rates of B. bassiana in stems and leaves were 100% on the 7th day, but dropped to 11.1% in the stems and 22.2% in the leaves on the 28th day. Meanwhile, B. bassiana was not detected in the roots until the 28th day, reaching a recovery rate of 33.3%. M. anisopliae strains were isolated from the plant roots, stems and leaves throughout the tracing period with high recovery rates. The systematical colonization of B. bassiana and M. anisopliae in different tissues were further corroborated by PCR amplification of fungus-specified DNA band, which showed a higher detection sensitivity of 100% positive reaction. Fungal density comparing to the initial value in the hydroponic solution, dropped to be well below 1% on the 21st day. Thus, the two selected entomopathogenic fungal strains successfully established endophytic colonization rather than rhizospheric colonization in maize, and significantly promoted its growth in a hydroponic cultural system. Entomopathogenic fungi have great application potential in eco-agricultural fields including biopesticides and biofertilizers.

Silicon enhances the drought resistance of peach seedlings by regulating hormone, amino acid, and sugar metabolism

BackgroundDrought is one of the main concerns worldwide and restricts the development of agriculture. Silicon improves the drought resistance of plants, but the underlying mechanism remains unclear.ResultsWe sequenced the transcriptomes of both control and silicon-treated peach seedlings under drought stress to identify genes or gene networks that could be managed to increase the drought tolerance of peach seedlings. Peach (Prunus persica) seedlings were used to analyse the effects of silicon on plant growth and physiological indexes related to drought resistance under drought stress. The results showed that silicon addition improved the water use efficiency, antioxidant capacity, and net photosynthetic rate, inhibition of stomatal closure, promoted the development of roots, and further regulated the synthesis of hormones, amino acids and sugars in peach seedlings. A comparative transcriptome analysis identified a total of 2275 genes that respond to silicon under drought stress. These genes were mainly involved in ion transport, hormone and signal transduction, biosynthetic and metabolic processes, stress and defence responses and other processes. We analysed the effects of silicon on the modulation of stress-related hormonal crosstalk and amino acid and sugar metabolism. The results showed that silicon promotes zeatin, gibberellin, and auxin biosynthesis, inhibits the synthesis of abscisic acid, then promote lateral root development and inhibit stomatal closure, and regulates the signal transduction of auxin, cytokinin, gibberellin and salicylic acid. Silicon also regulates the metabolism of various amino acids and promotes the accumulation of sucrose and glucose to improve drought resistance of peach seedlings.ConclusionsSilicon enhanced the drought resistance of peach seedlings by regulating stress-related hormone synthesis and signal transduction, and regulating amino acid and sugar metabolism.

Recycling of Faecal Sludge: Nitrogen, Carbon and Organic Matter Transformation during Co-Composting of Faecal Sludge with Different Bulking Agents.

This study investigated the effect of locally available bulking agents on the faecal sludge (FS) composting process and quality of the final FS compost. Dewatered FS was mixed with sawdust, coffee husk and brewery waste, and composted on a pilot scale. The evolution of physical and chemical characteristics of the composting materials was monitored weekly. Results indicate that bulking agents have a statistically significant effect (p < 0.0001) on the evolution of composting temperatures, pH, electrical conductivity, nitrogen forms, organic matter mineralisation, total organic carbon, maturity indices, quality of the final compost and composting periods during FS composting. Our results suggest reliable maturity indices for mature and stable FS compost. From the resource recovery perspective, this study suggests sawdust as a suitable bulking agent for co-composting with FS—as it significantly reduced the organic matter losses and nitrogen losses (to 2.2%), and improved the plant growth index, thus improving the agronomic values of the final compost as a soil conditioner. FS co-composting can be considered a sustainable and decentralised treatment option for FS and other organic wastes in the rural and peri-urban communities, especially, where there is a strong practice of reusing organic waste in agriculture.

Influence of ‘Lactobacillus serum’ on the growth of Amaranthus hybridus and some soil chemical properties under screen house conditions

The potentials of lactic acid bacteria serum, termed as ‘Lactobacillus (LB) serum’, in enhancing soil nutrient availability and supplies for the growth of Amaranthus hybridus and some chemical properties of soil were investigated at the screen house of the Department of Soil Science, University of Benin. Three application rates of the serum were adopted, consisting of 3 mL (3,000 L.ha-1), 5 mL (5,000 L.ha-1), and 0 ml (0 L.ha-1), and represented as treatment. Amaranthus hybridus was transplanted into pots containing 2 kg of 2 mm sieved air-dried soil. Each treatment was replicated seven times to give a total of 21 pots that were laid out in a Completely Randomized Design (CRD). The treatments were applied twice a week starting from the 2nd week after transplanting. The plant growth indices measured were number of leaves, plant height and plant biomass. The results showed that serum positively influenced the number of leaves and plant biomass (4.333 kg to 4.830 kg) compared to the control (3.901 kg). However, the highest value of the plant biomass was found in the 3 mL (3,000 L.ha-1) treated pots, while the microbial colonies of bacteria in soil after serum application were sustained when compared with the control but at a reduced population for Bacillus subtilis. The application of LB. serum slightly improved the soil total organic carbon (320.0 g.kg-1 to 352.0 g.kg-1) and nitrogen (3.102 g.kg-1 to 3.325 g.kg-1) as against, 64.00 g.kg-1, and 0.639 g.kg-1 in the control respectively.

The Potential of Centong Cactus (Opuntia cochenillifera) as a Remediation Agent for Sidoarjo Mud Polluted Soil with Indicators of Fe Content Reduction and Plant Growth

Iron (Fe) is one of the heavy metals with high levels in Sidoarjo mud and is toxic to cultivated plants. This study aims to measure the potential of Centong Cactus (Opuntia cochenillifera) as a candidate for soil remediation agent in Sidoarjo Mud contaminated land by using soil Fe uptake and plant growth as indicators. This research was carried out for 3 months from December to March 2022 in the yard of Gebang Village, Sidoarjo District. This study used the correlational regression method to determine the relationship between 0-30% content of Sidoarjo mud with Fe content and various plant growth parameters. The data were statistically processed using regression at the 95% confidence level to determine the significance of the effect and the correlation between the mud content and the decrease in soil Fe content and plant growth. The results showed that there was an increase in soil Fe uptake by plants and a decrease in plant growth with an increase in silt content in the soil of the growing media. O. Cochenillifera has the potential as a candidate for phytoremediation agents that can be applied to areas exposed to Sidoarjo mud, especially for its use to reduce Fe metal levels.

Basic Cognition of Melatonin Regulation of Plant Growth under Salt Stress: A Meta-Analysis.

Salt stress severely restricts the growth of plants and threatens the development of agriculture throughout the world. Worldwide studies have shown that exogenous melatonin (MT) can effectively improve the growth of plants under salt stress. Through a meta-analysis of 549 observations, this study first explored the effects of salt stress characteristics and MT application characteristics on MT regulated plant growth under salt stress. The results show that MT has a wide range of regulatory effects on plant growth indicators under salt stress, of which the regulatory effect on root indexes is the strongest, and this regulatory effect is not species-specific. The intensity of salt stress did not affect the positive effect of MT on plant growth, but the application effect of MT in soil was stronger than that in rooting medium. This meta-analysis also revealed that the foliar application of a concentration between 100–200 μM is the best condition for MT to enhance plant growth under salt stress. The results can inspire scientific research and practical production, while seeking the maximum improvement in plant salt tolerance under salt stress.

Individual and combined effects of land use and weeds on Cry1Ab/c protein expression and yield of transgenic cry1Ab/c rice

ABSTRACT Considering the anticipated commercial exploitation of insect-resistant transgenic rice and that the planting area of cultivated rice overlaps with wild rice, simulating an escape of transgenic rice from farmlands and exploring its fitness after entering semi-natural or natural ecosystems through uncontrolled seed dispersal or gene flow are critical to understand the resulting potential long-term environmental risks. The expression of foreign Cry1Ab/c protein and vegetative and reproductive fitness of insect-resistant transgenic rice Huahui1 (HH1) and its parental-line Minghui63 (MH63) were studied under four treatments combining land use and weed competition: farmland and uncultivated land under weed control (F-NW and U-NW, respectively), and farmland and uncultivated land without weed control (F-W and U-W, respectively). The expression of Cry1Ab/c was significantly lower in U-NW, F-W, and U-W than that in the control treatment, F-NW. Except for plant height, key vegetative (tiller number and biomass) and reproductive (grain number and grain weight per plant) growth indices of transgenic HH1 were significantly lower than those of the parental-line MH63 in F-NW and U-NW, indicating a significant fitness cost. In F-W and U-W, vegetative growth indices (plant height, tiller number, and biomass) were similar in HH1 and MH63; however, key reproductive indices including seed-set rate were significantly higher in HH1 than in MH63, indicating significant fitness benefits. Although these results support large-scale cultivation of insect-resistant transgenic rice in China, the ecological risk involved is high in farmland or uncultivated land without weed control (F-W and U-W).

Heme is involved in the exogenous ALA-promoted growth and antioxidant defense system of cucumber seedlings under salt stress

A biosynthetic precursor of tetrapyrrol, 5-aminolevulinic acid (ALA), is widely used in agricultural production, as an exogenous regulatory substance that effectively regulates plant growth. Previous studies have shown that heme and chlorophyll accumulate in plants under salt stress, when treated with exogenous ALA. In this study, we explored the regulatory role of heme in plants, by spraying 25 mg L–1 ALA onto the leaves of cucumber seedlings treated with heme synthesis inhibitor (2,2'-dipyridyl, DPD) and heme scavenger (hemopexin, Hx), under 50 mmol L–1 NaCl stress. The results showed that NaCl alone and DPD + Hx treatments to cucumber seedlings subjected to salt stress adversely affected their growth, by decreasing biomass accumulation, root activity, and root morphology. In addition, these treatments induced an increase in membrane lipid oxidation, as well as enhancement of anti-oxidase activities, proline content, and glutamate betaine. However, exogenous ALA application increased the plant growth and root architecture indices under NaCl stress, owing to a lack of heme in the seedlings. In addition, cucumber seedlings treated with DPD and Hx showed inhibition of growth under salt stress, but exogenous ALA effectively improved cucumber seedling growth as well as the physiological characteristics; moreover, the regulation of ALA in plants was weakened when heme synthesis was inhibited. Heme biosynthesis and metabolism genes, HEMH and HO1, which are involved in the ALA metabolic pathway, were upregulated under salinity conditions, when ferrochelatase activity was inhibited. Application of exogenous ALA increased the heme content in the leaves. Thus, exogenous ALA may supplement the substrates for heme synthesis. These results indicated that heme plays a vital role in the response of plants to salinity stress. In conclusion, heme is involved in ALA-mediated alleviation of damage caused to cucumber seedlings and acts as a positive regulator of plant adaption.

The Influence of Some Secondary Tillage Implement and Mixing Organic Residues on Some Physical Properties of Soil at the Beginning and End of the Oat (Triticum aestivum L.) Growing Season

The study was conducted in one of the fields affiliated to the Agricultural Research Station at the University of Basra, Karmat Ali site. The agricultural field experiment was carried out by dividing the field land according to the Randomized Complete Block Design (RCBD) in a one-time split plots design, where the main plots represent smoothing machines and sub-plots, the levels of organic residues and three replicators. The soil was plowed with a moldboard plow at a depth of 25-30 cm, and the organic residues were mixed with the soil by use of secondary tillage equipment. While the area of the experimental unit was (150 * 250) cm2, a distance of 2m was left between the experimental sectors and units to ensure that there was no overlap between the treatments. Seeds of oats were planted for all experimental units after the implementation of the treatments and at a seeding rate according to the recommendation followed in the region. Soil characteristics are measured for depths (0-15, 15-30) cm and for two periods (beginning and end of the plant growing season), and plant growth and yield indicators are measured at the end of the growing season. The aim of the research is to study the effect of adding levels of manure residues mixed with the surface layer in different ways on soil characteristics at the beginning and end of the oat crop growing season. The results of the experiment indicate the superiority of the spring cultivator and the percentage of adding organic residues (40 tons. Ha-1) over the rest of the machines and fertilization treatments by achieving the lowest apparent density at the beginning and end of the oats growing season, which amounted to 0.992 and 1.113 Mg m-3, respectively. In addition, they have achieved the highest the percentage of total porosity was 62.56 and 57.97 %, respectively. It also gave the highest weighted average diameter, which reached 0.859 and 0.688 mm, respectively. In addition, it gave the lowest soil penetration resistance, which reached 0.887 and 1.130 MPa, respectively.