Growth Characteristics Of Seedlings Research Articles

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

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

Re-watering solution facilitates seed germination and seedling growth of Carex schmidtii: Implication for species re-introduction in degraded semi-arid wetlands

Water deficiency threatens the health and function of wetlands in semi-arid areas. Optimum re-watering is an effective method for close-to-natural restoration to mitigate wetland degradation. Although the ecological importance of optimal re-watering as a nature-based solution for promoting wetland plant growth has been widely recognized, the response mechanisms of seed germination and seedling growth to re-watering are still poorly understood despite their decisive impact on plant life history. To fill this gap, this study compared the characteristics of seed germination and seedling growth in Carex schmidtii under initial water content with three levels (30%, 50%, and 70%) and five re-watering treatments (maintained at constant water content and re-watering to 100% on 7th, 14th, 21st, and 28th day). Moreover, the degree of reserve mobilization during four germination stages (seed suckering, sprouting, 20% germination, and seedling growth) was investigated. The results showed that water deficiency and re-watering treatments significantly affected C. schmidtii seed germination, seedling growth, and reserve mobilization. Compared with the other treatments, 50% moisture content and re-watering to 100% on the 14th day (50%-RT3) treatment significantly improved germination traits (germination rate, daily germination rate, germination index, and vigor index) and seedling growth characteristics (shoot length, root length, shoot biomass, root biomass, and total biomass). Furthermore, the degree of mobilization of starch, soluble protein, fat, and soluble sugar accumulation in C. schmidtii seeds under 50%-RT3 was higher than that in the other treatments. The structural equation model showed that the characteristics of seed germination and seedling growth of C. schmidtii were directly related to water deficiency and re-watering treatments, whereas reserve mobilization indirectly affected seed germination and seedling growth. These findings demonstrated that water deficiency and re-watering treatments have a crucial regulatory effect on seed germination and seedling growth of wetland plant species through a dual mechanism. This study provides information for the formulation of an optimum re-watering strategy for wetland vegetation restoration in semi-arid areas of the world.

Germination Indices and Seedling Growth Parameters in Maize under Salinity Stress with Varying Concentrations of Giberellic Acid (GA)

Salinity stress is one of the factors limiting seed emergence and seedling development in sunflower at New halfa scheme in East of Sudan. A study of two factors pots experiment was conducted during winter season of 2019 to evaluate germination indices and seedling growth characters of maize seeds under salinity stress with varying concentrations of synthetic growth regulator namely (GA3). The experiment was laid out according RCBD with three replications. Treatments consisted of five levels of salinity (0, 0.5, 1.0, 1.5 and 2% ) designated as Na0, Na0.5, Na1.0 ,Na1.5 and Na2.0, and four levels of GA3 were (0, 50,75 and 100 p.pm) designated as G0, G50, G75 and G100, respectively,. The studied parameters include germination indices; daily germination (MDG), daily germination speed (DGS), final germination percentage (FGP), mean emergence time (MET), mean Energy of germination (EE), emergence index (EI), coefficient of uniformity of emergence (CUE) and vigour index (SVI). Also, seedling fresh and dry weight, shoot length and root length were measured, and the shoot/root ratio was calculated. The negative effects of salinity stress significantly decreased germination indices and seedlings growth characters in a dose dependent manner. The results showed that, application of GA3 at medium levels concentration (specify those doses) increased all studied parameters. In conclusion, application of high Ga3 levels enhanced all germination indices and seedlings growth characters while high salinity levels reduced these traits of maize seeds. Such result has made the base for further study that should be conducted in different seasons with different growth regulators involving different parameters of other crops.

Genome-wide identification and expression analysis of the cryptochromes reveal the CsCRY1 role under low-light-stress in cucumber.

Low-light-stress is a common meteorological disaster that can result in slender seedlings. The photoreceptors play a crucial role in perceiving and regulating plants' tolerance to low-light-stress. However, the low-light-stress tolerance of cucumber has not been effectively evaluated, and the functions of these photoreceptor genes in cucumber, particularly under low-light-stress conditions, are not clear. Herein, we evaluated the growth characteristics of cucumber seedlings under various LED light treatment. The low-light-stress tolerant cucumber CR and intolerant cucumber CR were used as plant materials for gene expression analysis, and then the function of CsCRY1 was analyzed. The results revealed that light treatment below 40 μmol m-2 s-1 can quickly and effectively induce low-light-stress response. Then, cucumber CR exhibited remarkable tolerance to low-light-stress was screened. Moreover, a total of 11 photoreceptor genes were identified and evaluated. Among them, the cryptochrome 1 (CRY1) had the highest expression level and was only induced in the low-light sensitive cucumber CS. The transcript CsaV3_3G047490.1 is predicted to encode a previously unknown CsCRY1 protein, which lacks 70 amino acids at its C-terminus due to alternative 5' splice sites within the final intron of the CsCRY1 gene. CRY1 is a crucial photoreceptor that plays pivotal roles in regulating plants' tolerance to low-light stress. In this study, we discovered that alternative splicing of CsCRY1 generates multiple transcripts encoding distinct CsCRY1 protein variants, providing valuable insights for future exploration and utilization of CsCRY1 in cucumber.

Effects of humic acid water-soluble fertilizer on growth and physiological characteristics of Bupleurum chinense seedlings

The effects of humic acid water-soluble fertilizer on the growth and physiological characteristics of Bupleurum chinense seedlings(Zhongchai No.1) were studied by using a single factor experiment design. When the seedling age was 60 days, the humic acid water-soluble fertilizer was diluted 1 200 times(T1), 1 500 times(T2), 1 800 times(T3), and 2 100 times(T4) for seedling treatment, respectively, and water was used as the control(CK). The effects of different treatments on growth indexes, biomass accumulation, root activity, antioxidant enzyme activity, membrane lipid peroxidation, and photosynthetic characteristics of B. chinense seedlings were analyzed after 30 days. The results showed that compared with CK, stem height, leaf number, root diameter, and root length of the B. chinense seedlings under T3 treatment were significantly increased by 36.82%, 37.03%, 42.78%, and 22.38%, respectively. Root fresh weight, leaf fresh weight, root dry weight, and leaf dry weight under T3 treatment were significantly increased by 90.36%, 98.68%, 123.84%, and 104.38%, respectively. In addition, humic acid water-soluble fertilizer also enhanced TTC reducing activity of the root of B. chinense seedlings, inhibited malonaldehyde(MDA) content, increased superoxide dismutase(SOD), peroxidase(POD), and catalase(CAT) enzyme activities, improved chlorophyll content, and enhanced P_n, G_s, T_r, and other photosynthetic parameters. In conclusion, the application of humic acid water-soluble fertilizer diluted 1 800 times can significantly promote the growth of B. chinense seedlings, enhance root vitality, improve seedling stress resistance, and enhance photosynthesis. The results of this study can provide a theoretical basis for fertilization of B. chinense seedlings.

The stress history of soil bacteria under organic farming enhances the growth of wheat seedlings.

The effects of stress factors associated with climate change and agricultural management practices on microorganisms are often studied separately, and it remains to be determined how these factors impact the soil microbiome and, subsequently, plant growth characteristics. The aim of this study was to understand how the historical climate and agriculture to which soil microbes have been exposed can influence the growth characteristics of wheat seedlings and their associated bacterial communities. We collected soil from organic and conventional fields with different histories of climate conditions to extract microbes to inoculate wheat seeds under agar-based cultivation conditions. Within a growth period of 8 days, we monitored germination rates and time as well as seedling above-ground biomass and their associated bacterial communities. The results showed a positive interaction between conventional farming practices and an ambient climate for faster and higher germination rates. We demonstrate that soil microbial extracts from organic farming with experience of the future climate significantly enhanced above-ground biomass along with the diversity of bacterial communities associated with seedlings than other treatments. Such findings support the idea that organic agricultural practices not only mitigate the adverse effects of climate change but also promote the diversity of seedling-associated bacteria.

Effects of the seedling tray overlapping for seed emergence mode on emergence characteristics and growth of rice seedlings.

Seedling mode plays a crucial role in the rice production process, as it significantly affects the growth and development of seedlings. Among the various seedling modes, the seedling tray overlapping for seed emergence mode (STOSE mode) has been demonstrated to be effective in enhancing seedling quality. However, the impact of this mode on the germination and growth of seeds with varying plumpness remains uncertain. To investigate the effect of the STOSE mode on seedling emergence characteristics, growth uniformity, and nutrient uptake of seeds with varying plumpness levels, we conducted a study using super early rice Zhongzao 39 (ZZ39) as the test material. The seeds were categorized into three groups: plumped, mixed, and unplumped. The results indicated that the STOSE mode significantly improved the seedling rate for all types of seeds in comparison to the seedling tray nonoverlapping for seed emergence mode (TSR mode). Notably, the unplumped seeds exhibited the most pronounced enhancement effect. The soluble sugar content of the seeds increased significantly after 2 days of sowing under the STOSE mode, whereas the starch content exhibited a significant decrease. Furthermore, the STOSE mode outperformed the TSR mode in several aspects including seedling growth uniformity, aboveground dry matter mass, root traits, and nutrient uptake. Overall, the STOSE mode not only promoted the germination and growth of plumped and mixed seeds but also had a more pronounced impact on unplumped seeds.

Hidrocondicionamento e substratos afetam a emergência e a produção de mudas de Calendula officinalis L.

ABSTRACT: In order to establish protocols that can contribute to the propagation of medicinal plants, this study evaluated the effect of hydropriming and substrates on the emergence and production of Calendula officinalis L. seedlings. Seeds were submitted or not to hydropriming for 24 hours, and subsequent sowing in four substrates: S1) 100% Dystroferric Red Latosol - DRL, S2) DRL + coarse sand (1:1 v/v), S3) DRL + Tropstrato® commercial substrate (1:1 v/v) and S4) 100% Tropstrato®, and kept in greenhouse with 50% shading. Higher emergence percentage in substrates with the presence of DRL was observed. Seed hydropriming impaired seedling emergence, but contributed to root growth, biomass production and seedling quality. The 100% Tropstrato® substrate favored higher dry mass production and seedling quality. Positive linear correlation (≥ 0.70) was observed between shoot and root growth characteristics with biomass production and Dickson’s quality index. Principal component analysis explained 78.95% of the experimental variance, excluding the first count and the shoot/root ratio with low representativeness. In the cluster analysis of Euclidean distances, seedlings with the greatest similarity were those produced with 100% DRL and DRL + Tropstrato® with and without hydropriming, respectively. Dystroferric Red Latosol is recommended pure or combined with Tropstrato® for the production of C. officinalis L seedlings, and the hydropriming impaired seedling emergence characteristics.

Effect of prechilling and nano-selenium on seed germination of Dorema ammoniacum

The aim of this research was to investigate the effectiveness of nano-selenium (nano-Se) on germination properties of vasha (Dorema ammoniacum), an endangered medicinal plant in Iran. The experiment was conducted in a completely randomised two-factor, experiment with five concentrations (0, 5, 10, 20, and 40 mg L –1) of nano-Se and seed prechilling treatment (4°C). All the germination characteristics, including percentage germination, mean germination and vigour indices were improved by nano-Se treatments (p <; 0.05). Among the treatments, the combination of prechilling and 20 mg L –1 nano-Se conditioning was the best treatment, both in improving germination and the growth characteristics of seedlings. It can be concluded that pretreatment of seeds with nano-Se and prechilling can be used for promoting germination of D. ammoniacum seeds.

BIOTESTING OF SOIL CONDITIONS AT THE TERRITORIES ADJACENT TO AIRPORTS

The development of civil aviation is accompanied by a constant increase in man-made load on the environment. The application of methods of bioindication and biotesting of anthropogenic and technogenic influences on the ecosystem components is one of the possible options for monitoring the state of the environment at territories subject to technogenic stress due to the activities of environmentally hazardous enterprises. To study the level of man-made impact of airport activities on the state of the soil (namely, phytotoxicity), at the territory adjacent to the airport "Kyiv" named after I. Sikorskyi International Airport from the upper and lower levels at different distances from the airport runway (from 5 m to 2 km) soil samples were taken using the envelope method. As a control (conditionally clean soil), a soil sample collected at the territory of Holosiiv Park (soil type: dark gray forest soils) was used. In total, six soil samples were analyzed. On the third day of germination the growth characteristics of Allium cepa seedlings were determined. Test parameters that were used to determine the phytotoxic effect: the percentage of seed germination, namely the energy of its germination, the length of the root and the length of the stem. The analysis of the obtained data on the germination of Allium cepa seeds showed that the lowest germination was recorded for the soil samples that were taken at a distance of 5 and 1500 m from the runway, which indicates an increased level of phytotoxic impact due to the activities of the airport.
 The greatest phytotoxic effect for the stem of Allium cepa seedlings was observed for the soil sample located at a distance of 5 m from the ZPS. For soil samples taken at a distance of 5 m to 1000 m, i.e. with distance from the runway of the airport, a decrease in the level of phytotoxicity of the soil is observed. Only when approaching the highway (at a distance of 1,000 m to 2,000 m) there was observed an increase in phytotoxicity of the soil again.
 Among the investigated samples of meristem tissues, the presence of mitotic activity of cells was observed in the meristems of root tip samples of onion seedlings germinated on soil samples that were taken at a distance of 5 m, 1500 m and 2000 m from the airport. The determined mitotic indices (MI) for these soil samples are as following: for a soil sample taken at a distance of 5 m, it was 2.9 %; for a soil sample taken at a distance of 1500 m was 2.6 %; for a soil sample taken at a distance of 2000 m was 2.6 %. The research results confirm the need for constant monitoring of the soil condition at these technogenically loaded territories, in order to increase the level of environmental safety of these territories.

Effect of Spraying with Triacontanol and Adding Humic acid on the Chemical Content of Pear Seedlings Pyrus Cimmunis L. Cv. Le-Conte

This study was conducted at the research station of the College of Agriculture, Anbar University in 2022 to investigate the effect of foliar application of triacontanol at concentrations of 0, 25, 50, and 100 mg L−1, symbolized by T0, T1, T2, and T3, respectively, and the addition of humic acid to the soil at concentrations of 0, 25, and 50 mg L−1, symbolized by H0, H1, and H2, respectively, on some chemical growth characteristics of Le-conte pear seedlings. The results showed significant differences among the treatments, where the addition of the growth regulator triacontanol at treatment T3 (100 mg L−1) resulted in a significant superiority in the carbohydrate content the leaves (6.18%), nitrogen content the branches (2.207%), nitrogen content the leaves (1.937%), carbohydrate content the branches (13.378%), phosphorus content in the branches (0.367%), and phosphorus content the leaves (0.347%). On the other hand, the effect of humic acid showed significant superiority at treatment H2 (50 mg L−1) in the carbohydrate content the leaves (5.49%), nitrogen content the branches (2.160%), nitrogen content the leaves (1.908%), carbohydrate content the branches (12.858%), phosphorus content the branches (0.341%), and phosphorus content the leaves (0.338%). the results showed that the interaction between the study factors was significant, with superiority of the treatment T3H2 in all the studied characteristics.

Effect of Adding Organic Fertilizer and Humic Acid on some Vegetative and Root Growth Characteristics of Fig Seedlings, Diyala Black Cultivar

This study was conducted at the research station of the College of Agriculture - University of Anbar during the 2022 growing season. To study the effect of adding organic fertilizer (poultry waste) at levels (0, 0.5, 1 kg seedlings−1), which is symbolized by (A0, A1, A2) respectively, and humic acid in levels (0,250,500 ml L−1), which is symbolized by (B0, B1, B2) respectively, in some characters of vegetative, root and chemical growth of fig seedlings of Aswad Diyala cultivar. The results showed that the addition of organic fertilizer at level of 1 kg seedlings-1 outperformed and led to a significant increase in plant height (36.89 cm), main root length (27.83 cm), leaf content of total chlorophyll (63.10 mg 100 g−1 fresh weight), leaf content of nitrogen (2.080%), leaf content of phosphorus (0.450%), leaf content of potassium (3.389%), leaves content of carbohydrates (35.88%). The study showed the significant superiority of humic acid at level B2 (500 ml L−1) on the rate of increase in plant height (31.22 cm), main root length (27.16 cm), leaf content of total chlorophyll (58.00 mg 100g−1 fresh weight), leaf nitrogen content (2.053%) The leaf content of phosphorous (0.444%), the leaf content of potassium (3.379%), the leaves content of carbohydrate (35.87%). Also, the two-way interactions between the study factors had a significant effect on most of the studied traits.

Sol-Gel-Derived Functional Coatings for Pre-Sowing Seed Treatment

The superatomic structure of film-forming sols obtained by the acid hydrolysis of tetraethoxysilane (TEOS) in an aqueous medium (free of organic solvents) was studied using the SAXS method. The formation of nanoparticles (NPs) was confirmed in alcohol-free silica sols with both a low (1 vol. %) content of TEOS and a high (10 vol. %) content of TEOS, hydrolyzed in an aqueous-alcoholic medium. A trimodal size distribution was revealed for the resulting NPs, with radii ranging from less than 1 nm to ~11 nm. The volume fraction of NPs tends to grow with increases in TEOS concentration, as well as with the introduction of magnetic NPs of iron oxides into silica sols. The synthesized silica sols and suspensions based on silica sols with FexOy NPs were used for the pre-sowing treatment of white and cauliflower cabbage seeds in order to provide a functional coating on their surfaces, thereby improving seed germination, stimulating their growth in the early stages of development, and suppressing the effect of phytopathogens. The effect of the pre-sowing seed treatment in sol-gel compositions on seed germination and the growth characteristics of plant seedlings is analyzed, including the influence of iron-oxide magnetic NPs’ compositions and concentrations in silica sols.

Effects of indole butyric acid and coconut liquid endosperm on rooting of Crateva adansonii stem

Indole butyric acid (IBA) and coconut liquid endosperm (CLE), two rooting agents, were tested in three concentrations to see how they affected the rooting of Crateva adansonii DC stem cuttings. 300 mg/L, 200 mg/L, and 100 mg/L (IBA) of rooting material and 100%, 80%, and 60% of CLE were the concentrations that were assessed. This was done in three replications using completely randomized design (CRD). The setup, which lasted six months, was on exhibit in the Botanic Garden at the Department of Plant Science and Biotechnology, University of Nigeria, Nsukka. While control stem cuttings took the longest to start and finish bud break on the stem cuttings, higher concentrations of the rooting chemical substances, 300 mg/L IBA and 100 percent CLE respectively, influenced the shortest times (initial and final). The results showed that the control had the fewest buds that sprouted into leaves, whereas 300 mg/L IBA and 100 percent CLE had the highest percentage of buds that turned into leaves on the stem cuttings. Regardless of the treatment concentrations utilized, a thin callus formed on the stem cuttings. Observations on rooting revealed that not all callused stem cuttings subsequently took root. IBA and CLE were applied to stem cuttings in various concentrations, and the results were seedlings with lateral and feeding roots. The maximum percentage of rooting response was seen in stem cuttings treated with 300 mg/L IBA and 100 percent CLE, respectively, while the control did not root. The findings of measuring the aerial and sub aerial growth characteristics of seedlings revealed that 300 mg/L IBA and 100 percent CLE had a greater impact on the development of higher values of the growth parameters examined than cuttings treated with lower concentrations of the two rooting agents. Based on the findings of this study, it is possible to draw the conclusion that C. adansonii can be multiplied vegetatively by using rooting agents to help stem cuttings take root. It is recommended that more research be done using rooting medium with a higher concentration and rooting agents like auxins at different concentrations.

The Growth Response of Christi Thorn Seedlings to the Dates and Concentrations of (Ticamine Max) and the Liquid Organic Fertilizer (Vevter)

The study was carried out during the growing season (2022) in order to demonstrate the importance of application dates (every 15 and 30 days) and foliar spraying with three concentrations of Ticamine Max (0, 2 and 4 ml. L-1) and the addition of three levels of liquid organic fertilizer (Vevter) (0, 2 and 4 ml. L-1). In improving some growth characteristics of Christi thorn seedlings. The study was designed in a factorial experiment using the Randomized Completely Block Design (R.C.B.D). With three factors, with three replications, and with four seedlings per experimental unit, thus the number of seedlings used in the experiment is (2 x 3 x 3 x 3 x 4 = 216 seedlings). The most important results obtained indicated the significant superiority of the foliar spray at a concentration of 4 ml. L-1 of the amino fertilizer and the addition of liquid organic fertilizer at a concentration of 4 ml. L-1 in all studied traits (increase in height of seedlings, number of leaves, area of leaf, leaf area of seedlings, and concentration of carbohydrates in leaves), while there were no significant differences for the studied traits between the dates of addition.

Effects of exogenous melatonin on growth and physiological characteristics of Agropyron mongolicum seedlings under drought stress.

To clarify the alleviation effect of exogenous melatonin (MT) on Agropyron mongolicum under drought stress, we examined the response of A. mongolicum 'Yanchi' seedlings to simulated drought stress with polyethylene glycol 6000 (PEG-6000), by investigating the effects of exogenous addition of different concentrations (0, 1, 10, 50, 100, 150 and 200 mg·L-1) of MT on seedlings growth and physiological characteristics under drought stress. The results showed that drought stress significantly inhibited the growth of A. mongolicum seedlings, and that exogenous addition of different concentrations of MT could alleviate the growth inhibition caused by drought stress, with the strongest mitigation effect observed at MT concentration of 100 mg·L-1. Compared with the drought stress treatment alone, exogenous addition of 100 mg·L-1 MT under drought stress increased plant height, aboveground dry weight, and leaf relative water content by 58.2%, 121.2% and 48.1%. The contents of chlorophyll a, chlorophyll b, carotenoids increased by 48.7%, 80.8% and 38.3%, superoxide dismutase, peroxidase and root activity increased by 12.6%, 33.9% and 39.1%, and the contents of ascorbic acid and glutathione increased by 19.5% and 18.3%, respectively. The contents of proline, soluble sugar and soluble protein were increased by 16.2%, 32.6% and 14.3%, while that of malondialdehyde, hydrogen peroxide and superoxide anion radical were decreased by 45.8%, 65.8% and 30.8%, respectively. In summary, exogenous addition of 100 mg·L-1 MT could improve drought tolerance of A. mongolicum seedlings by promoting growth, enhancing antioxidant capacity, increasing the content of osmoregulation substances, inhibiting the excessive production of reactive oxygen, and reducing membrane peroxide level.

Elucidating growth and biochemical characteristics of rice seedlings under stress from chromium VI salt and nanoparticles.

Plants are usually provoked by a variety of heavy metal (HM) stressors that have adverse effects on their growth and other biochemical characterizations. Among the HMs, chromium has been considered the most toxic for both plants and animals. The present study was conducted to compare the phytotoxic effects of increasing chromium (VI) salt and nanoparticles (NPs) concentrations on various growth indexes of rice (Oryza sativa L. var. swat 1) seedlings grown in a hydroponic system. The 7-day rice seedlings were exposed to Cr (VI) salt and NPs hydroponic suspensions which were adjusted to the concentration of 0, 50, 100, 150, 200 and 250 mg/L. Both the Cr (VI) salt and NPs with lower concentrations (up to 100mg/L) exerted minimum inhibitory effects on the growth performance of rice seedlings. However, a significant decrease in shoot and root length and their fresh and dry weight was recorded at higher doses of Cr (VI) salt (200 mg/L) and NPs (250 mg/L). The stress induced by Cr (VI) salt has drastically affected the roots, whereas, Cr (VI) NPs significantly affected the shoot tissues. Photosynthetic pigments decreased significantly in a dose-dependent manner, and the reduction was more pronounced in rice seedlings exposed to Cr (VI) NPs compared to Cr (VI) salt. Cr (VI) NPs enhanced the membrane permeability in shoots and roots as compared to that of Cr (VI) salt, which resulted in higher concentration of reactive oxygen species (ROS) and increased lipid peroxidation. The activities of antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) increased significantly in shoot/root tissue following exposure to higher doses of Cr (VI) salt (200 mg/L) and NPs stress (250 mg/L), while minor changes in CAT and APX activities were observed in root and shoot tissues after exposure to higher concentration of Cr (VI) NP. Furthermore, the increasing concentrations of Cr (VI) NPs increased the length of stomatal guard cells. Conclusively, Cr (VI) salt and NPs in higher concentrations have higher potential to damage the growth and induce oxidative stress in rice plants.

Salt Stress Responses in Early Seedling Growth Characteristics of Blackgram [Vigna mungo (L.) Hepper] Genotypes

In view of increasing salinity and intrusion of salt water into the cultivable land area under coastal saline region, germination and crop establishment is a major problem that influence on decrease in the production and productivity of blackgram. Hence, screening of 101 genotypes under different salt concentrations for growth characters paves way to identify the saline resistant genotypes. The upshot of saline stress on seedling growth characters of 101 genotypes which are collected from different eco geographical regions subjected to Half strength Hoagland and Arnon’s solution (T1), Half strength Hoagland Arnon’s solution +NaCl treatment @100mM, 150mM, 200mM and 250mM concentration @7th, 10th, 13th, 16th days (T2) respectively and Half strength Hoagland and Arnon’s solution (control) (T3) during January 2022. Highly significant variation exhibited among the various genotypes for different seedling growth characters viz., leaf area per plant, total number of leaves per plant, dry weight of leaves per plant, dry weight of shoot per plant, dry weight of roots per plant and dry weight of the whole plant. Salinity has the adverse effect on the growth characters. Among the genotypes studied, AUB-08-33(G81) and CBG-09-08(G18) showed maximum mean values under different NaCl concentrations (T2), recommended as donor parent for hybridization as well as candidate genotype in crop improvement for saline soil.

Performance evaluation of pre-sowing seed treatments using bio-agents in transplanted aromatic rice under organic conditions

In order to minimize the effect of lower productivity issues in terms of organic rice cultivation particularly for the small and marginal farmers of the state of Assam, the present research was undertaken with an objective of improving early seedling growth characteristics in organic rice cultivation using user friendly bio-formulations in the form of seed treatment. Locally prepared five organic bio-formulations particularly Organic-Metajal, Organic-Trichojal, Organic-Beauverijal, Azospirillum spp. and BIO Phos liquid PSB formulation were used as seed treatment on a high yielding aromatic rice variety "Keteki Joha" in order to evaluate the early seedling growth characters in addition to estimating the enzymatic activity by alpha amylase and lipid peroxidation under laboratory conditions. Among all the bio-agents, Org-Trichojal(T3) was found to be most effective in terms of achieving highest percentage of early vigour and seedling growth. Seed treatment with Org-Metajal (T2) and Org-Trichojal (T3)showed higher activity of alpha-amylase and lowest activity for peroxidise which had also reflected the better performance in germination and vigour indicators. While on the other hand, bio-formulations including Org-Metajal (T2).Organic-Beauverijal, Azospirillum spp. and BIO Phos were also found to be effective in improving growth as compared to the control.

Response of Seedling Growth Characteristics to Seed Size and Cotyledon Damage in Quercus wutaishanica

The successful establishment of seedlings is very important for plant regeneration, but it is vulnerable to many factors at this stage. Cotyledon damage will directly affect the health of seedlings, thus affecting the regeneration of the plant population. However, little is known about the effects of different cotyledon loss degrees of large and small seeds on seedling growth. We investigated the effects of 1/4 (light excision), 1/2 (moderate excision), and complete excision of cotyledons (heavy excision) on the growth characteristics of seedlings germinating from different sizes of seeds. The results showed that (1) shoot height, basal stem diameter, number of leaves, leaf area per plant, specific leaf area, and biomass were significantly higher in large-seeded seedlings than in small-seeded seedlings; (2) slight cotyledon excision had no effect on the biomass of large-seeded seedlings but significantly reduced the biomass of small-seeded seedlings. Our study highlights that large-seeded seedlings are more tolerant than small-seeded seedlings in the early seedling recruitment, suggesting that large-seeded seedlings have a strong fitness for recruitment in young populations of Q. wutaishanica.