Seedling Root Length Research Articles

Ascorbate-glutathione cycle and thioredoxin system are involved in nitric oxide alleviating excess nitrate stress in tomato seedlings

ABSTRACT Nitric oxide (NO) plays an important role in plant growth, development, and stress responses. The exogenous NO donor sodium nitroprusside (SNP) increased the plant height, root length, and biomass of tomato seedlings under nitrate stress, especially 100 μM SNP. The reactive oxygen species (ROS) and malondialdehyde (MDA) contents were decreased, while the antioxidant enzyme activities, ascorbate and glutathione contents, and expression of SlTrxh, SlNTRB, SlTpx were increased in tomato after SNP and nitrate stress treatment, compared with nitrate stress. The tomato plants showed shorter root length, more MDA and ROS contents after the NADPH-dependent thioredoxin reductase (NTR) inhibitor Auranofin (ANF) was added, suggesting that ANF inhibited the alleviating effect of NO under nitrate stress. The NO and S-nitrosothiol (SNO) contents and the SlNR transcript levels were decreased and the expression of SlGLB, SlGSNOR was increased after NO and nitrate stress treatment. The S-nitrosylated level in tomato roots was increased after nitrate stress. The SlMDHAR, SlTrxh, and SlNTRB protein were S-nitrosylated after NO and nitrate stress treatment. These results suggested that key enzymes in ascorbate-glutathione cycle and Trx system played an important role in alleviating the effect of NO in tomato seedlings under nitrate stress involving the S-nitrosylation modification.

Determination of Physiochemical Characteristics Associated with Various Degrees of Cadmium Tolerance in Barley Accessions

Soil contamination by heavy metals such as cadmium (Cd), which is present as a result of agricultural and industrial practices, is a critical problem in many countries around the world. High Cd concentrations in crops during the seedling stage can have a negative impact on performance and growth. The aim of the present study, which involved 59 barley accessions, was to investigate the effects of different Cd concentrations (125, 250, and 500 µM) on the responses of the barley accessions and to identify the biomarker parameters that would aid in the early growth stage selection of the best-performing accession. Barley accessions differed significantly in their morphological and physiochemical characteristics. Compared to the untreated plants, treatments with Cd lowered germination percentages by 1.75–64.28%, 1.67–46.62%, and 1.66–61.90% for concentrations of 125, 250, and 500 μM, respectively. The average of all genotypes showed significant reductions in root length, shoot length, and fresh weight of seedlings, ranging from 37.08% to 77.88%, 18.70% to 44.10%, and 7.69% to 35.87%, respectively. In comparison to untreated plants, the average seed water absorption (WU) increased across all accessions by 42.21% and 20.74%, respectively, under Cd-125 and Cd-250 stress conditions. In contrast, all biochemical measurements increased when Cd concentrations were elevated, with the exception of guaiacol peroxidase (GPA) and catalase (CAT). Across all genotypes, the mean of proline (PC) and sugar (SSC) contents showed the largest increases (123% for PC and 98.63% for SSC) under the Cd-500 stress condition. Three barley accessions: Acsad-14, ABN, and Arabi Aswad, were found to be the most tolerant accessions under all cadmium exposure, whereas the performance of the other tested accessions: Black-Kalar, Bujayl 1-Shaqlawa, and Black-Chiman was inferior. The OMIC analysis identified the biomarker parameters for differentiating the high, moderate, and low tolerant groups as the WU for Cd-125 stress, GPA, WU, CAT, total phenolic content for Cd-250 stress, and all physiochemical traits, with the exception of the CAT feature for Cd-500 treatment. The majority of trait pairings showed significant correlations. Hence, Acsad-14, ABN, and Arabi Aswad barley accessions that had great performance under cadmium conditions can be candidates for selection in a breeding program to improve the growth of plants and output in lands infected by cadmium. It can be concluded that seed water uptake, guaiacol peroxidase, and proline content were biomarker traits that would aid in the early growth stage selection of the best-performing accession under Cd stress conditions.

Potential application of melatonin in reducing boron toxicity in rice seedlings through improved growth, cell wall composition, proline, and defense mechanisms

Melatonin (MT) has been demonstrated to provide defense against both biotic and abiotic stressors. Boron toxicity (BT) can significantly limit the growth and production of plants. However, few studies have been conducted on whether MT is effective in attenuating B toxicity in different plants. In order to evaluate the efficacy of exogenous MT treatment in reducing the negative impact of BT on rice seedlings, this study examined the influence of MT on growth, antioxidant capacity, cell wall composition, and proline metabolism in rice seedlings under hydroponics. Four treatments were established: MT (50 μM), MT + BT (50 μM MT + 800 μM B), BT (800 μM), and CK (control) in a completely randomized design. The results indicate that BT had a significant detrimental effect on the shoot length, root length, and root and shoot fresh weights of rice seedlings by 11.96%, 27.77%, 25.69%, and 18.67%, respectively as compared to the control treatment. However, exogenous MT application increased these parameters and reduced B accumulation in aboveground parts (14.05%) of the plant. Exogenous MT also increased the endogenous melatonin content and antioxidant enzyme activities (64.45%, 71.61%, 237.64%, and 55.42% increase in superoxide dismutase, ascorbate peroxidase, and peroxidase activities, respectively), while decreasing reactive oxygen species levels and oxidized forms of glutathione and ascorbic acid. Additionally, MT enhanced the biosynthesis of proline by decreasing proline dehydrogenase (ProDH) and increasing the GSH (glutathione) and ASA (ascorbic acid) contents. Exogenous MT also increased cell wall components that can increase B adsorption to the cell wall. Overall, these findings suggest that MT application can be a potential solution for strengthening the stress tolerance of rice seedlings, particularly under conditions of B toxicity. In regions where soil contains high levels of boron, the use of MT could enhance rice crop yields and quality.

Growth Response of Cocoa (Theobroma cacao L.) Seedlings on Various Planting Media Administration

Growth response of cocoa (Theobroma cacao L.) seedlings on various planting media administration. This research aimed to determine the growth response of cocoa seedling plants with the application of various compost media. The purpose of this research was to provide information regarding the type of compost combination that was suitable for the growth of cocoa seedlings. This research was conducted in Sugihwaras Village, Wonomulyo Subdistrict, Polewali Mandar Regency, West Sulawesi, Indonesia from October 2020 to January 2021. The analytical method used in this research was the Randomized Block Design (RBD) with 8 treatments: 1) 1:1:1 (Soil + Cow Manure + Sand), 2) 2:1:1 (Soil + Cow Manure + Sand), 3) 1:1:1 ( Soil + Tofu Dregs + Sand ), 4) 2:1:1 (Soil + Tofu Dregs + Sand), 5) 1:1:1 (Soil + Vermicompost + Sand), 6) 1:1:1 (Vermicompost + Cow Manure + Tofu Dregs), 7) 2:1:1 (Soil + Vermicompost + Cow Manure), 8) 2:1:1 (Soil + Cow Manure + Tofu Dregs). Each treatment was repeated three times, so that the number of samples was 72 plants. This study indicated that the treatment of Soil + Cow Manure + Sand media with a ratio of 2:1:1 gave the best effect on the plant height, plant weight, and root length of cocoa seedlings.

Ozone Processing of Corn Grains: Effect on Seed Vigor and Surface Disinfection

ABSTRACT Ozone treatment of corn seeds with respect to determination on changes in germination ability, germination under salt stress, seedling growth, seedling root length, conductivity and inactivation of endogenous microflora was studied. Corn seeds immersed in water treated by fixed ozone dose of 12.5 g/m3 for 1 (1O3), 3 (2O3) and 5 min (3O3) at room temperature. Ozone treatment provided full germination (100%) of the corn seeds on the 2nd day; whereas 66.6% of the control seeds germinated on the 8th days after planting. Ozone treated seedling were significantly taller and stronger than the control samples with significantly longer seedling root. Germination under 100 mM salt stress for ozone treated seeds was significantly higher than that of the control samples. Electrical conductivity of the seeds was significantly affected by the measurement time rather than ozone treatments. Ozone treatments provided significant inactivation on total aerobic mesophilic bacteria and total mold and yeast of the endogenous bacteria revealing maximum of 5.31 and 6.15 log reductions, respectively. It was concluded that ozone treatment at 12.5 g/m3 for 5 min can be utilized to treat corn seeds as these treatment parameters provided maximum inactivation on endogenous microflora with improvement of vigor and stronger seedling formation.

VALORIZATION OF TOMATO PLANT WASTES AND OPTIMIZATION OF GROWTH CONDITIONS FOR INDOLE-3-ACETIC ACID PRODUCTION BY Streptomyces plicatus STRAIN PT2

This study focused on the production of the phytohormone indole-3-acetic acid (IAA) using tomato plant tissues as feedstock and on highlighting its growth promotion effect on tomato seedlings. Twelve actinobacterial strains were screened for IAA production under standard growth conditions and the strain Streptomyces plicatus PT2 was selected as a promising producer. The establishment of growth conditions to increase IAA production by S. plicatus PT2 was conducted using Plackett-Burman mathematical design with seven variables. The variables L-tryptophan quantity and tomato roots-extract rate were the two significant variables influencing IAA production. The most impacting variables were optimized using the surface methodology (RSM) formulated according to the Central Composite Design (CCD). The optimized broth supplemented with 4 mg L-1 of L-tryptophan and 25% of tomato roots-extract significantly improved the IAA production from 96.3 µg mL-1 within 120h to a maximum of 110.29 µg mL-1 within 96h. The in-planta application of the produced IAA and a chemical IAA showed a significant increase in the dry weight, the shoot and root lengths of tomato seedlings. This is the first study showing the production of IAA using Streptomyces plicatus strain PT2 by exploring tomato plant tissues and its plant-growth promotion efficacy compared to a chemical marketed one. These results support a reasonable approach for the valorization of abundant worldwide tomato plant wastes in the phytohormones production bioprocesses.

Physiological and Biochemical Properties of Cotton Seedlings in Response to Cu2+ Stress

Copper(II) (Cu2+) is essential for plant growth and development. However, high concentrations are extremely toxic to plants. We investigated the tolerance mechanism of cotton under Cu2+ stress in a hybrid cotton variety (Zhongmian 63) and two parent lines with different Cu2+ concentrations (0, 0.2, 50, and 100 μM). The stem height, root length, and leaf area of cotton seedlings had decreased growth rates in response to increasing Cu2+ concentrations. Increasing Cu2+ concentration promoted Cu2+ accumulation in all three cotton genotypes' roots, stems, and leaves. However, compared with the parent lines, the roots of Zhongmian 63 were richer in Cu2+ and had the least amount of Cu2+ transported to the shoots. Moreover, excess Cu2+ also induced changes in cellular redox homeostasis, causing accumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Conversely, antioxidant enzyme activity increased, while photosynthetic pigment content decreased. Our findings indicated that the hybrid cotton variety fared well under Cu2+ stress. This creates a theoretical foundation for the further analysis of the molecular mechanism of cotton resistance to copper and suggests the potential of the large-scale planting of Zhongmian 63 in copper-contaminated soils.

Response of Cocoa (Theobroma cacao L.) Seedling Growth on Various Growing Media and Organic Plant Supplements

Cocoa (Theobroma Cacao L.) as a plantation crop which success is determined by healthy and quality seedlings. The use of planting media with a mixture of manure and plant organic supplements may result in healthy soil because it contains soil microorganisms that are beneficial and may support the growth of cocoa seedlings. Purpose of this study was to determine the initial growth response of cocoa seedlings on various growing media and dosages of an organic plant supplement as liquid organic fertilizer. The research was conducted in February–September 2022 in a nursery located in Kradenan, Purwoharjo, Banyuwangi Regency and in Agricultural Laboratory of University of Jember, Bondowoso Campus, Bondowoso Regency. Study was carried out in a 4 x 4 factorial using a randomized block design with three replications. The first factor was planting media which consisted of four levels of treatment, namely soil + chicken manure, soil + goat manure, soil + cow manure, and soil + rabbit manure. The second factor was dose of organic plant supplement which consisted of 4 levels, namely the control treatment of 0, 50, 100, and 150 mL polybag-1. Data were analyzed using analysis of variance and follow-up tests using Duncan’s multiple range test at 5% level. Variables observed included seedling height, number of leaves, stem diameter, leaf length, leaf width, number of roots, root length, fresh weight, and dry weight of seedlings. The results showed that there was an interaction effect on all parameters except seedling height, number of leaves, and number of roots. The conclusion of the study showed that there was an effect of interaction treatment with the best treatment combination planting media using cow manure and organic plant supplement dose of 50 mL polybag-1.

Effects of Light Intensity on Seedling Emergence and Early Growth of Liquidambar formosana Hance

Liquidambar formosana Hance is a common deciduous broad-leaved tree known for its fast growth rate and adaptability. However, excessive logging has substantially reduced the area of natural forest patches of L. formosana, and seedling regeneration is essential for the long-term continuation of L. formosana populations. To explore the effects of light intensity on the seedling emergence and early growth of L. formosana, a controlled experiment was conducted under three light-intensity treatments (20%, 60%, and 100% of full sunlight, i.e., the photosynthetic photon flux densities (PPFDs) were 223.93 ± 7.54, 670.94 ± 30.14, and 1119.61 ± 23.19 μmol·m−2·s−1, respectively). The seedling emergence percentage, mean germination time, germination synchrony, vitality index, survival percentage, emergence index, morphological characteristics, and biomass allocation under different light intensities were analyzed. The seedling vitality index and survival percentage significantly differed among the treatments and were the lowest under 20% light intensity. With increased light intensity, the seedling mean germination time and germination synchrony increased and then decreased, and the opposite was true for the emergence index. With the increased light intensity, the seedling height, stem diameter, and root length significantly increased. The total, root, stem, and leaf biomasses reached maximum values under full sunlight. With the increased light intensity, the leaf biomass ratio increased, whereas the root biomass, stem biomass, and root–shoot ratios decreased. Our results indicated that the poor light environment under the canopy is not conducive to the survival and growth of L. formosana seedlings and may be among the primary reasons for low seedling establishment.

Effects of Multi-Walled Carbon Nanotubes and Nano-Silica on Root Development, Leaf Photosynthesis, Active Oxygen and Nitrogen Metabolism in Maize.

Carbon nanotubes (MWCNTs) and nano-silica (nano-SiO2) are widely used in the field of life science because of their special physical and chemical properties. In this study, the effects of different concentrations of MWCNTs (0 mg·L-1, 200 mg·L-1, 400 mg·L-1, 800 mg·L-1 and 1200 mg·L-1) and nano-SiO2 (0 mg·L-1, 150 mg·L-1, 800 mg·L-1, 1500 mg·L-1 and 2500 mg·L-1) on maize seedling growth and relative mechanisms were explored. The main results are as follows: MWCNTs and nano-SiO2 can promote the growth of maize seedlings, and promote plant height, root length, the dry and fresh weight of seedlings, root-shoot ratio and so on. The ability to accumulate dry matter increased, the relative water content of leaves increased, the electrical conductivity of leaves decreased, the stability of cell membranes improved and the water metabolism ability of maize seedlings increased. The treatment of MWCNTs with 800 mg·L-1 and nano-SiO2 with 1500 mg·L-1 had the best effect on seedling growth. MWCNTs and nano-SiO2 can promote the development of root morphology, increase root length, root surface area, average diameter, root volume and total root tip number and improve root activity, so as to improve the absorption capacity of roots to water and nutrition. After MWCNT and nano-SiO2 treatment, compared with the control, the contents of O2·- and H2O2 decreased, and the damage of reactive oxygen free radicals to cells decreased. MWCNTs and nano-SiO2 can promote the clearance of reactive oxygen species and maintain the complete structure of cells, so as to slow down plant aging. The promoting effect of MWCNTs treated with 800 mg·L-1 and nano-SiO2 treated with 1500 mg·L-1 had the best effect. After treatment with MWCNTs and nano-SiO2, the activities of key photosynthesis enzymes PEPC, Rubisco, NADP-ME, NADP-MDH and PPDK of maize seedlings increased, which promoted the opening of stomata, improved the fixation efficiency of CO2, improved the photosynthetic process of maize plants and promoted plant growth. The promoting effect was the best when the concentration of MWCNTs was 800 mg·L-1 and the concentration of nano-SiO2 was 1500 mg·L-1. MWCNTs and nano-SiO2 can increase the activities of the enzymes GS, GOGAT, GAD and GDH related to nitrogen metabolism in maize leaves and roots, and can increase the content of pyruvate, so as to promote the synthesis of carbohydrates and the utilization of nitrogen and promote plant growth.

Effect of Seed Source on Seed Vigour and Field Performance of the Sorghum [Sorghum bicolor. (L.) Moench] Cultivar Taba

A set of laboratory tests and field experiments were conductedfor two consecutive seasons (2009/10 and 2010/11) to investigate theeffect of seed source on seed quality attributes of the sorghum cultivarTabat. Simple correlation coefficients were calculated to determine thedegree of association between the different vigour tests and seedlingemergence under field conditions. Seeds were obtained from fourlocations: two rainfed (Damazin and Habeela) and two irrigated (KhashmEl Girba and El Gezira). Data were collected on initial seed moisturecontent, 1000-seed weight, germination percentage, rate of germination,seedling shoot length, seedling root length, seedling shoot to root lengthratio, seedling fresh weight, seedling dry weight, plant height, number ofleaves per plant, leaf area per plant and plant fresh and dry weight. Theresults indicated that, under laboratory conditions, seed source hadsignificant effect on seedling root length and fresh weight in the firstseason, on germination percentage and rate of germination in the secondseason and on seed moisture content and 1000 seed weight in bothseasons. Significant differences were found in seedling shoot length andplant height under field conditions. Seeds from Habeela and Damazinperformed well with regard to germination percentage, rate ofgermination and field seedling emergence. Also, seeds from the rainfedareas produced taller plants than those from irrigated areas (Khashm ElGirba and El Gezira). The results also showed that field seedlingemergence was positively correlated with the estimate, under laboratory

Bacillus amyloliquefaciens FG14 as a potential biocontrol strain against rusty root rot of Panax ginseng, and its impact on the rhizosphere microbial community

Rusty root rot is the most destructive disease in ginseng production. The bacterial strain FG14 isolated from the rhizosphere of Panax ginseng was characterised as Bacillus amyloliquefaciens. The inhibition rates of the FG14 bacterial suspension against the mycelial growth, spore production and spore germination of Ilyonectria robusta which causes ginseng rusty root rot were all more than 90% at a concentration of 108 cfu/mL. The sterile fermentation broth of strain FG14 also had significant inhibitory ability. The results of plantgrowth promotion showed that the fresh weight and root length of ginseng seedlings treated with 3 × 108 cfu/mL FG14 bacterial suspension were 4.49 times and 2.12 times greater than the seedlings treated with I. robusta. The soil enzyme activities of urease, phosphatase, invertase, and catalase of strain FG14 and the expression of seven lipopeptide biosynthesis genes were up-regulated, and antifungal metabolite production was stable. The diversity and abundance of bacterial and fungal communities in rhizosphere soil changed during different growth stages of ginseng after inoculation with strain FG14. The relative abundance of the Ilyonectria genus was significantly lower than the water control at the leaf spreading stage of P. ginseng. These results indicate the great potential of B. amyloliquefaciens FG14 for use as a biological agent for the green control of ginseng rusty root rot.

Genome-wide identification of BcGRF genes in flowering Chinese cabbage and preliminary functional analysis of BcGRF8 in nitrogen metabolism.

Growth-regulating factors (GRFs) are a unique family of transcription factors with well-characterized functions in plant growth and development. However, few studies have evaluated their roles in the absorption and assimilation of nitrate. In this study, we characterized the GRF family genes of flowering Chinese cabbage (Brassica campestris), an important vegetable crop in South China. Using bioinformatics methods, we identified BcGRF genes and analyzed their evolutionary relationships, conserved motifs, and sequence characteristics. Through genome-wide analysis, we identified 17 BcGRF genes distributed on seven chromosomes. A phylogenetic analysis revealed that the BcGRF genes could be categorized into five subfamilies. RT-qPCR analysis showed that BcGRF1, 8, 10, and 17 expression clearly increased in response to nitrogen (N) deficiency, particularly at 8 h after treatment. BcGRF8 expression was the most sensitive to N deficiency and was significantly correlated with the expression patterns of most key genes related to N metabolism. Using yeast one-hybrid and dual-luciferase assays, we discovered that BcGRF8 strongly enhances the driving activity of the BcNRT1.1 gene promoter. Next, we investigated the molecular mechanism by which BcGRF8 participates in nitrate assimilation and N signaling pathways by expressing it in Arabidopsis. BcGRF8 was localized in the cell nucleus and BcGRF8 overexpression significantly increased the shoot and root fresh weights, seedling root length, and lateral root number in Arabidopsis. In addition, BcGRF8 overexpression considerably reduced the nitrate contents under both nitrate-poor and -rich conditions in Arabidopsis. Finally, we found that BcGRF8 broadly regulates genes related to N uptake, utilization, and signaling. Our results demonstrate that BcGRF8 substantially accelerates plant growth and nitrate assimilation under both nitrate-poor and -rich conditions by increasing the number of lateral roots and the expression of genes involved in N uptake and assimilation, providing a basis for crop improvement.

Effect of Pre-sowing Seed Treatments and Synthetic Polymer Coating on Seed Quality and Storability in Redgram (Cajanus cajan. L.)

Successful agriculture depends on high-quality seed, which is a fundamental and important ingredient. Under unfavourable environmental conditions like drought, pre-sowing seed treatment such as seed coating and seed priming could boost the seed germination and seedling vigour. The coating agents often include plant growth regulators, micro-fertilizers, pesticides, and insecticides. The present investigation was carried out to assess the impact of seed treatment and polymer coating on seed quality parameters of pigeon pea cv PRG 176 during 2018 to 2021 at Seed Research and Technology Centre, Rajendranagar, Hyderabad. The trail was laid out in randomized block design with four replications. Freshly harvested redgram variety Ujwala Seeds were treated for Seed hardening with ZnSO4 @100ppm + Seed coating with Polymer 3ml/kg + Bavistin 2g/kg + Imidacloprid 1ml/kg + Pseudomonas fluorescens 10 g/kg + Rhizobium in different combinations. The treated seeds were shade dried, packed in gunny bags, and stored at room temperature to assess the impact of various treatments on seed quality metrics under ambient storage conditions. The results of bimonthly observations on seed quality parameters showed that there were substantial differences between the treatments for the characters under study. The T7 treatment recorded highest germination percentage (98 and 70.67), speed of emergence (12.1 and 10.1), electrical conductivity (0.169 and 0.292), seedling shoot length (14.9 and 8.65cm), seedling root length (14.5 and 8.52cm), seedling length (29.4 and 17.17cm), seedling fresh weight (5.55 and 2.5g), seedling dry weight (0.40 and 0.21g), seed vigour index-I (2881 and 1213), seed Vigour Index-II (53.9 and 14.84) over other treatments under study at initiation of studies (2MAS) and at 28 months of storage period respectively. The current study's findings showed that T7 treatment greatly outperformed all other treatments for all characters, maintaining an optimal germination percentage (70.67%) even up to 28 months of storage under ambient storage conditions.

Influence of 2,4-dichloro Phenoxy Acetic Acid on Seeds Germination and Early Growth of Mesquite (Prosopis juliflora Swarz) DC Seedlings

This study was conducted to evaluate the effect of 2,4-dichloro phenoxy acidic acid (2,4-D) on seed germination and the early growth of mesquite (Prosopis juliflora) seedlings. The three sizes of mesquite at the flowering stage (small, medium, and large) were treated with 2,4-D at different rates (0, 6×103, 12×103, 18×103 and 24×103 mg a.i. / L) dissolved in two solvents (diesel or water), the application method basal bark treatment was used in the two different seasons. The results showed that: the three factors (2,4-D rates, tree sizes, and solvent types) significantly decreased germination percentage with the increase of 2,4-D rate dissolved in diesel with all sizes of trees, while the emergence percentage, radical length, and shoot height were significantly decreased as 2,4-D rate increase dissolved in diesel or water. In the winter season, the root length of seedlings raised from seeds collected from the three tree sizes treated with 2,4-D dissolved in water was significantly decreased as a 2,4-D rate increased, while in the rainy season, the root length was affected with 2,4-D dissolved in diesel. In addition, the effect of 2,4-D rates and solvent types was evaluated for all parameters, the results found that: 2,4-D dissolved in diesel significantly decreased germination percent than the corresponding rates dissolved in water. Emergence percentage and shoot height and radical length were significantly decreased with 2,4-D dissolved in diesel or water compared to their control. In the winter season, the root length is affected by 2,4-D dissolved in water, while in the rainy season affected by 2,4-D dissolved in diesel.

Overexpression of ZmDUF1644 from Zoysia matrella enhances salt tolerance in Arabidopsis thaliana

The DUF1644 family is a highly conserved and functionally unknown protein family and it has been demonstrated that it significantly improved the salt tolerance of rice (non-halophytes). However, little is understood about the function of the DUF1644 gene in halophytes. This study aimed to investigate whether the DUF1644 gene has a similar function in non-halophytes as in halophytic species. The functions of ZmDUF1644 transferred from the halophytic Zoysia matrella into non-halophytic Arabidopsis thaliana were investigated under salt stress (150 mM NaCl). Phylogenetic analysis clustered ZmDUF1644 and OsSDIP361 in the same group, which function as salt-tolerant genes in rice. The obtained results exhibited that the ZmDUF1644 gene significantly alleviated the adverse effects of salt stress on transgenic Arabidopsis thaliana seedlings. The maximum root length, fresh weight, and photosynthetic pigment content of the transgenic seedlings were obviously better than that of the wild type. The relative electrolyte leakage rate, Na+ content, and Na+/K+ ratios were relatively lower in the transgenic line than in the wild type under salt stress. Moreover, the expression of AtSOS2 gene was also significantly higher than that of wild-type under salt stress. The study concluded that the ZmDUF1644 gene was significantly overexpressed in salt-stressed Arabidopsis thaliana, enhancing its salt tolerance. It is the first report on the functions of ZmDUF1644 from halophytic Zoysia matrella which has a similar function in glycophytic species or non-halophytic species.

Foliar application of 6-benzyladenine after pollination improves hybrid rice seed vigor through modulating antioxidant system

Application of plant growth regulators emerges as one of the most reliable methods to enhance crop productivity and quality. However, knowledge is limited in seed quality of hybrid rice subjected to exogenous 6-Benzyladenine (6-BA) application during seed development. A 2-year experiment was conducted to investigate the effects of 6-BA treatment after pollination on seed vigor and its underlying regulatory mechanisms. Results showed that 6-BA treatment increased germination potential (GP) and vigor index (VI) of hybrid rice irrespective of cultivar and year, particularly with 50 mg/L. Consistently, seedling quality including seedling height, root length and dry weight was significantly enhanced under 6-BA treatment with 50 mg/L. Based on the results above, 50 mg/L was considered as the optimal concentration. Additionally, 6-BA treatment with 50 mg/L increased catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) activities, and it strongly induced the expression of OsAPX1 and OsCSD3 related to antioxidant enzyme activity at the early stage of seed emergence. Therefore, spraying 6-BA with 50 mg/L after pollination could be recommended as an agronomic practice for hybrid rice seed production with high seed vigor.

Cold Plasma Treatment for Astragalus membranaceus Seed Germination and Seedling Growth Improvement

Background: Astragalus membranaceus seeds have dormant properties that not only limit germination but also negatively affect the growth of seedlings. We investigated the enhancing effect of cold plasma treatment on seed germination and the positive effect on seedling growth of Astragalus membranaceus by treating its seeds with cold plasma at different power levels. Method: The Astragalus membranaceus seeds were treated with cold plasma at power levels of 40, 60, 80, 100, 120, 140, 160, 180, 200, 220 and 240 W for 15 seconds with helium gas and seeds without any treatment were used as control. Results: The Astragalus membranaceus seeds were treated with cold plasma, which not only improved seed germination, but also had a positive effect on seedling growth, with the best results for the 80 W power cold plasma treatment. The 80 W power cold plasma treatment increased the germination rate, germination index and vigor index of Astragalus membranaceus seeds by 26.8%, 12.4% and 39.8%, respectively; increased root length, CAT activity and SOD activity of Astragalus membranaceus seedlings by 24.5%, 99.7% and 7.1%, respectively and decreased the relative conductivity and MDA content of Astragalus membranaceus seedlings by 6.6% and 17.6%, respectively; compared with that of the control group.

Germination of Lolium perenne and Medicago Species under the Conditions of Drought and Silicon Application as Well as Variable pH and Medicago sativa Root Extracts

Drought and allelopathic conditions impact the germination of seeds of grass and legume species used in mixtures on grassland. This study evaluated the effects of drought and Medicago sativa root extracts at different pH levels on the germination and characteristics of seedlings of Lolium perenne and selected Medicago species. Two experiments were carried out: the first explored the effects of drought induced by PEG solutions (0.0, -0.3, and -0.6 MPa) under silicon (Si) application; the second studied the influence of Medicago sativa root extracts (12 and 24 g/100 mL H2O) and variable pH solutions (control, 5.0, and 6.5) on seed germination. Germination was carried out on Petri dishes for individual species and in two-species mixtures. The drought conditions did not affect the germination capacity of seeds, but it increased the dry weight of the seedlings of the tested species. The application of silicon decreased the root length of the seedlings of all species, independent of the germination conditions. The higher concentration of M. sativa root extract combined with the studied pH solutions had an inhibitive impact on the germination capacity of L. perenne. Our findings revealed that the lower concentration of M. sativa root extract had a beneficial effect on the morphological features (length of roots and leaves, fresh and dry weight) of the seedlings when germination was carried out separately for both species. In the mixture, the effect was especially marked for L. perenne (only in terms of the root length and fresh weight of seedlings). The applied root extracts in combination with the acidic pH conditions limited the germination capacity and growth of the seedlings of L. perenne the most when germination was performed separately. It was concluded from this study that silicon application did not improve the germination capacity of seeds under drought conditions, whereas the germination of L. perenne seeds in a mixture with M. sativa mitigated the negative allelopathic effects of M. sativa root extracts on the seed germination capacity and morphological features of seedlings of L. perenne.

Phytotoxicity of Quillaja lancifolia Leaf Saponins and Their Bioherbicide Potential.

Weeds are major threats to the integrity of agricultural and natural environments due to their invasive and competing potential. Bioherbicides are substances based on natural compounds that are biodegradable and often have low residual effects. Plant species able to produce and release phytotoxic compounds may represent effective bioherbicide sources. Leaves of Quillaja lancifolia D.Don (formerly Q. brasiliensis (A.St.-Hil. & Tul.) Mart.) produce water-soluble specialized metabolites of the saponin class that could be evaluated for phytotoxic activity and potential as natural herbicides. This study was conducted to examine the impacts of Q. lancifolia total saponins aqueous extract (AE) at 4 and 10% (w/v) and of two combined reverse-phase chromatography purified saponin fractions (QB) at 1 and 2% (w/v) on morpho-physiological parameters of Lactuca sativa (lettuce) and Echinochloa crus-galli (barnyardgrass) in pre- and post-emergence bioassays. QB was only tested in pre-emergence assays. In pre-emergence bioassays, the germination rate and germination kinetics were determined. Post-emergence evaluations included effects on seedling morphology, root and shoot length, dry mass, and chlorophyll content. Osmotic potential and pH analyses ruled out roles for these factors in the observed responses. AE had a high inhibitory impact on the germination of both lettuce and barnyardgrass. QB at 1% and 2% (w/v) significantly decreased the growth of lettuce seedlings germinated in its presence by more than 10-fold. Phytotoxic effects on the post-emergence growth of lettuce, especially at the highest concentration tested of AE (10% w/v), was also observed. The presence of quillaic acid-based triterpene saponins in AE and QB was confirmed using different analytical methods. Therefore, both saponin-enriched fraction and aqueous extracts of Q. lancifolia inhibited tested plant growth and development. The water solubility of saponins and the availability of a sustainable source of these molecules from the leaves of cultivated young Q. lancifolia plants make them attractive candidates for use as bioherbicides.