Changes in Metal Distribution, Vegetative Growth, Reactive Oxygen and Nutrient Absorption of Tagetes patula under Soil Cadmium Stress

Phytoremediation with hyperaccumulator plants has been recognized as a potential way for the clearing of cadmium (Cd)-contaminated soil. In this study, hyperaccumulator Tagetes patula was treated with seven concentrations of Cd, ranging from 0 to 300 mg kg−1. The Cd enrichment and nutrient contents in different organs during different growth phases were investigated. Under Cd concentrations ≤75 mg kg-1, the morphological growth of T. patula did not change significantly regardless of growth stage. However, when Cd concentration exceeded 150 mg kg−1, the morphological growth was remarkedly inhibited. The root/shoot ratio remained unchanged except for at 300 mg kg−1. In addition, Cd negatively influenced the flowering process at the concentration of 300 mg kg−1. Cd content increased significantly in Cd-treated plants. Nitrogen absorption was increased under Cd treatments, and phosphorus content was also increased under concentration ≤150 mg·kg−1. However, the potassium content in the flower was decreased under 300 mg kg−1. Furthermore, the contents of H2O2, O2− and malondialdehyde were increased during the seedling phase, especially when Cd concentration was ≥150 mg kg−1. In summary, T. patula showed a strong ability to tolerate Cd, and such ability might be explained by nutrient absorption and reactive oxygen clearness.

Root Morphology, Allometric Relations and Rhizosheath of Ancient and Modern Tetraploid Wheats (Triticum durum Desf.) in Response to Inoculation with Trichoderma harzianum T-22

Early root traits and allometrics of wheat are important for competition and use of resources. They are under-utilized in research and un-explored in many ancient wheats. This is especially true for the rhizosheath emerging from root-soil interactions. We investigated root morphology, root/shoot relations and the amount of rhizosheath of four tetrapoid wheat seedlings (30 days after emergence): the italian landrace Saragolle Lucana and modern varieties Creso, Simeto and Ciclope, and tested the hypothesis that inoculation with Trichoderma harzianum T-22 (T-22) enhances rhizosheath formation and affects wheat varieties differently. Overall growth of non-inoculated plants showed different patterns in wheat varieties, with Saragolle and Ciclope at the two extremes: Saragolle invests in shoot rather than root mass, and in the occupation of space with highest (p < 0.05) shoot height to the uppermost internode (5.02 cm) and length-to-mass shoot (97.8 cm g−1) and root (more than 140 m g−1) ratios. This may be interpreted as maximizing competition for light but also as a compensation for low shoot efficiency due to the lowest (p < 0.05) recorded values of optically-measured chlorophyll content index (22.8). Ciclope invests in biomass with highest shoot (0.06 g) and root (0.04 g) mass and a thicker root system (average diameter 0.34 mm vs. 0.29 in Saragolle) as well as a highest root/shoot ratio (0.95 g g−1 vs. 0.54 in Saragolle). Rhizosheath mass ranged between 22.14 times that of shoot mass in Ciclope and 43.40 in Saragolle (different for p < 0.05). Inoculation with Trichoderma increased the amount of rhizosheath from 9.4% in Ciclope to 36.1% in Simeto and modified root architecture in this variety more than in others. Ours are the first data on roots and seedling shoot traits of Saragolle Lucana and of Trichoderma inoculation effects on rhizosheath. This opens to new unreported interpretations of effects of Trichoderma inoculation on improving plant growth.

The Response of Antioxidant System of Drought-Stressed Green Pea (Pisum sativum L.) Affected by Watering and Foliar Spray with Silica Nanoparticles

Abiotic stress caused by drought impairs plant growth and reduces yields. This study aimed to investigate the impact of silica nanoparticles (SiO2 NPs) through the adverse effects of drought on the growth, oxidative stress, and antioxidative response of pea ‘Respect’. Pea plants were grown in a greenhouse before being watered (100 ± 1 mL per pot) or foliar sprayed (ca. 14 ± 0.5 mL plant−1) with suspensions containing SiO2 NPs (0, 12.5 ppm, 25 ppm, and 50 ppm) and were exposed to drought stress for 10 days. Drought stress was created by maintaining 30% of the soil moisture while the control was 80%. The growth parameters of pea grown under drought stress conditions were improved by spraying or watering plants with SiO2 NPs (12.5, 25, and 50 ppm). At drought stress, peas treated with SiO2 NPs (50 ppm) increased their relative water content by 29%, specific leaf area by 17%, and decreased root/shoot ratio by 4% as compared to plant non-treated with SiO2 NPs. In addition, spraying or watering of SiO2 NPs increased peas tolerance to drought by increasing the activity of antioxidant enzymes at least three times including catalase, ascorbate peroxidase, glutathione reductase, and superoxide dismutase, as well as reducing hydrogen peroxide and lipid peroxidation in plant tissue. It was observed the increase in total phenolic compounds and non-enzymatic antioxidant activity (DPPH, ABTS, FRAP) in peas treated with SiO2 NPs under drought stress. The physiological response of peas to drought and the effects of SiO2 NPs studied in this experiment based on the use of the concentration of 50 ppm nanoparticles can protect peas from the damaging effects of drought and could help reduce global food shortages.

EVALUATION OF FUNGICIDES AGAINST PHYTOPHTHORA AND FUSARIUM (root rot spp.) OF CITRUS ROOTSTOCKS SEEDLINGS

Citrus is one of the most important fruit crop in the world and is usually grown through grafting technique. Rootstock is one of the significant part in grafted plants and has crutial effect on production, including yield, fruit quality, tree size, tolerance to salts and diseases, and scion compatibility. Citrus is susceptible to several fungal pathogens causing incalculable losses to the crop. Among all soil-borne fungal pathogens, Phytophthora and Fusarium cause the most severe damage to the nursery or orchards plants. This research was planned to evaluate the effectiveness of fungicides as soil drenching and root dipping to control Phytophthora and Fusarium attacking citrus rootstock seedlings at the nursery stage. Different physiological and morphological parameters were studied in the infected plants and data were compared with that of control. The data were recorded and compared concerning rootstock seed and seeding response using standard measures and statistical analysis. The results showed that plants inoculated with Phytophthora and Fusarium root rot spp.when treated with Aliette and Ridomil Gold showed maximum root shoot ratio, fresh dry weight ratio, photosynthetic rate, stomatal conductance, water potential and transpiration rate as compared to untreated plants. The results also depicted that plants treated with Aliette and Ridomil Gold through soil drenching have maximum root shoot ratio, fresh dry weight ratio, photosynthetic rate, stomatal conductance and transpiration rate as compared to root dipped plants. Keywords: Fungal diseases, pathogens, root rot, nursery plants.

Assessment of Antifungal Efficacy and Release Behavior of Fungicide-Loaded Chitosan-Carrageenan Nanoparticles against Phytopathogenic Fungi

Biopolymeric Chitosan-Carrageenan nanocomposites 66.6–231.82 nm in size containing the chemical fungicide mancozeb (nano CSCRG-M) were synthesized following a green chemistry approach. The physicochemical study of nanoparticles (NPs) was accomplished using a particle size analyzer, SEM and FTIR. TEM exhibited clover leaf-shaped nanoparticles (248.23 nm) with mancozeb on the inside and entrapped outside. Differential scanning calorimetry and TGA thermogravimetry exhibited the thermal behaviour of the nanoform. Nano CSCRG-1.5 at 1.5 ppm exhibited 83.1% inhibition against Alternaria solani in an in vitro study and performed as well as mancozeb (84.6%). Complete inhibition was exhibited in Sclerotinia sclerotiorum at 1.0 and 1.5 ppm with the nanoformulation. The in vivo disease control efficacy of mancozeb-loaded nanoparticles against A. solani in pathogenized plants was found to be relatively higher (79.4 ± 1.7) than that of commercial fungicide (76 ± 1.1%) in pot conditions. Nanomancozeb showed superior efficacy for plant growth parameters, such as germination percentage, root–shoot ratio and dry biomass. The nanoformulation showed higher cell viability compared to mancozeb in Vero cell cultures at 0.25 and 0.50 mg/mL in the resazurin assay. CSCRG-0.5 showed slow-release behavior up to 10 h. Thus, these green nano-based approaches may help combat soil and water pollution caused by harmful chemical pesticides.

The Effect of Temperature and Relative Humidity Inside The Shade Netting on The Growth of Pepper Fruiting Branch Cuttings

Pepper (Piper nigrum L.) has many benefits, especially in its seeds, commonly used as a food flavoring. Pepper effectively increases appetite, increases the digestive glands' activity, and accelerates fatty substances' digestion. In general, pepper production per unit area in Indonesia is low. The average is below 1 ton of dry pepper per hectare. This low productivity is mainly due to inadequate cultivation techniques, such as improper fertilization and inadequate care. The development of pepper cultivation is still running slowly due to the many obstacles faced by farmers. This productivity could be increased if farmers could apply good and correct cultivation techniques. Generally, pepper cultivation in Indonesia uses standards. This technique is expensive and requires intensive maintenance. The pepper seeds commonly planted by farmers come from running shoots. The experimental design used was the split-plot design with shade netting as the first factor and the administration of husk charcoal as the second factor. Other factors observed were climatic factors, including temperature and relative humidity, bird bud burst time, sprouting time, and root-shoot ratio. The results indicated that the shade netting and husk charcoal treatment on the planting medium significantly affected bird bud burst time, sprouting time, and root-shoot ratio. This study aimed to investigate the effect of climate on the growth of pepper cuttings. The results indicated that the best bird bud burst time occurred in treatment n0 (100%), a0 (1:1) 34.67 days, and not significantly different from n0 (100%) a2 (0: 1) 35.00 days. The best sprouting time occurred in treatment n0 (100%) a2 (0: 1) 32.00 days, not significantly different from n0 (100%) a0 (1: 1) 32.50 days. The root-shoot ratio was significantly different in treatment n0 (100%) a1 (1; 0) 5.28 g.

An ABA Functional Analogue B2 Enhanced Salt Tolerance by Inducing the Root Elongation and Reducing Peroxidation Damage in Maize Seedlings

Salt stress negatively affects maize growth and yield. Application of plant growth regulator is an effective way to improve crop salt tolerance, therefore reducing yield loss by salt stress. Here, we used a novel plant growth regulator B2, which is a functional analogue of ABA. With the aim to determine whether B2 alleviates salt stress on maize, we studied its function under hydroponic conditions. When the second leaf was fully developed, it was pretreated with 100 µM ABA, 0.01 µM B2, 0.1 µM B2, and 1 µM B2, independently. After 5 days treatment, NaCl was added into the nutrient solution for salt stress. Our results showed that B2 could enhance salt tolerance in maize, especially when the concentration was 1.0 µMol·L−1. Exogenous application of B2 significantly enhanced root growth, and the root/shoot ratio increased by 7.6% after 6 days treatment under salt stress. Compared with control, the ABA level also decreased by 31% after 6 days, which might have resulted in the root development. What is more, B2 maintained higher photosynthetic capacity in maize leaves under salt stress conditions and increased the activity of antioxidant enzymes and decreased the generation rate of reactive oxygen species by 16.48%. On the other hand, B2 can enhance its water absorption ability by increasing the expression of aquaporin genes ZmPIP1-1 and ZmPIP1-5. In conclusion, the novel plant growth regulator B2 can effectively improve the salt tolerance in maize.

Physiological Response and Proteomics Analysis of Reaumuria soongorica Under Salt Stress

Soil salinity can severely restrict plant growth. Yet Reaumuria soongorica can tolerate salinity well. However, large-scale proteomic studies of this plant’s salinity response have yet to reported. Here, R. soongorica seedlings (4 months old) were used in an experiment where NaCl solutions simulated levels of soil salinity stress. The fresh weight, root/shoot ratio, leaf relative conductivity, proline content, and total leaf area of R. soongorica under CK (0 mM NaCl), low (200 mM NaCl), and high (500 mM NaCl) salt stress were determined. The results showed that the proline content of leaves was negatively correlated with salt concentration. With greater salinity, the plant fresh weight, root/shoot ratio, and total leaf area increased initially but then decreased, and vice-versa for the relative electrical conductivity of leaves. Using iTRAQ proteomic sequencing, 47, 177, 136 differentially expressed proteins (DEPs) were identified in low-salt vs. CK, high-salt vs. control, and high-salt vs. low-salt comparisons, respectively. A total of 72 DEPs were further screened from the groups, of which, 34 DEPs increased and 38 DEPs decreased in abundance. These DEPs are mainly involved in translation, ribosomal structure, and biogenesis. Finally, 21 key DEPs (SCORE value ≥ 60 point) were identified as potential targets for salt tolerance of R. soongolica. By comparing the protein structure of treated vs. CK leaves under salt stress, we revealed the key candidate genes underpinning R. soongolica’s salt tolerance ability. This works provides fresh insight into its physiological adaptation strategy and molecular regulatory network, and a molecular basis enhancing breeding, under salt stress conditions.

Characterization of Maize Hybrids (Zea mays L.) for Detecting Salt Tolerance Based on Morpho-Physiological Characteristics, Ion Accumulation and Genetic Variability at Early Vegetative Stage

Increasing soil salinity due to global warming severely restricts crop growth and yield. To select and recommend salt-tolerant cultivars, extensive genotypic screening and examination of plants’ morpho-physiological responses to salt stress are required. In this study, 18 prescreened maize hybrid cultivars were examined at the early growth stage under a hydroponic system using multivariate analysis to demonstrate the genotypic and phenotypic variations of the selected cultivars under salt stress. The seedlings of all maize cultivars were evaluated with two salt levels: control (without NaCl) and salt stress (12 dS m−1 simulated with NaCl) for 28 d. A total of 18 morpho-physiological and ion accumulation traits were dissected using multivariate analysis, and salt tolerance index (STI) values of the examined traits were evaluated for grouping of cultivars into salt-tolerant and -sensitive groups. Salt stress significantly declined all measured traits except root–shoot ratio (RSR), while the cultivars responded differently. The cultivars were grouped into three clusters and the cultivars in Cluster-1 such as Prabhat, UniGreen NK41, Bisco 51, UniGreen UB100, Bharati 981 and Star Beej 7Star exhibited salt tolerance to a greater extent, accounting for higher STI in comparison to other cultivars grouped in Cluster-2 and Cluster-3. The high heritability (h2bs, >60%) and genetic advance (GAM, >20%) were recorded in 13 measured traits, indicating considerable genetic variations present in these traits. Therefore, using multivariate analysis based on the measured traits, six hybrid maize cultivars were selected as salt-tolerant and some traits such as Total Fresh Weight (TFW), Total Dry Weight (TDW), Total Na+, Total K+ contents and K+–Na+ Ratio could be effectively used for the selection criteria evaluating salt-tolerant maize genotypes at the early seedling stage.

Evaluating Positive and Negative Effects of Seven Biogenic Metal-based Nanoparticles on Seed Germination and Seedling of Nano-primed Wheat and Flax Seeds

Seed germination is the first and the most susceptible stage in plant’s growing phases, so could be considered as an index to evaluate the effect of newly developed materials like nanoparticles (NPs), providing useful information for researchers. In our experiments, germination tests have been carried out in Petri plates, containing wet filter paper and nano-primed seeds. We had biosynthesized seven nanoparticles in our previous researches, including calcinated and non-calcinated zinc oxide, zinc, magnesium oxide, silver, copper and iron nanoparticles. The effect of these biogenic nanoparticles and their counterpart metallic salts including zinc acetate, magnesium sulphate, silver nitrate, copper sulphate and iron (III) chloride was studied on two popularly grown plants, wheat and flax, in laboratory condition to obtain preliminary information for future field experiments. Germination percentage, shoot length, root length, seedlings length, root-shoot ratio, seedling vigor index (SVI), shoot length stress tolerance index (SLSI) and root length stress tolerance index (RLSI) were calculated at 2nd and 7th days of the experiment. According to the results, the response of the plants to metal containing nanoparticles and metal salts mainly depend on type of the metal, plant species, concentration of the NP suspension or salt solution, condition of the exposure and the stage of growth.