Seedling Growth Parameters Research Articles

Prospective of Indole-3-Acteic Acid (IAA) and Endophytic Microbe Bacillus subtilis Strain SSA4 in Paddy Seedlings Development and Ascorbate–Glutathione (AsA-GSH) Cycle Regulation to Mitigate NaCl Toxicity

Plant growth promoting endophytes significantly affected plant health. The present study demonstrates effect of endophytic isolate Bacillus subtilis strain SSA4 and exogenous Indole-3-acetic acid (IAA) on paddy seedlings growth parameters, photosynthetic pigments, photosynthesis, leaf gas exchange parameters, respiration, oxidative stress biomarkers and Ascorbate-Glutathione (AsA-GSH) cycle under different NaCl (0-300mM) stresses. The Bacillus subtilis SSA4 was identified by 16S r-RNA gene sequence analyses and NCBI BLASTn tools. The B. subtilis SSA4 tolerated 1100mM NaCl and produced IAA (42.15µgm/L) at 300mM NaCl stress. The paddy genotype (HUR 917) treated with exogenous IAA (21µgm/L) and B. subtilis strain SSA4 egg cell based bioformulation was significantly affected seedlings physiology and biochemistry at lower (150mM) and higher (300mM) NaCl doses. In conclusion, co-inoculation found as effective green tool to mitigating salinity stress in paddy seedlings.

Herbicidal potential of meadow sage (Salvia pratensis L.) against velvetleaf (Abutilon theophrasti Med.) and common corn-cockle (Agrostemma githago L.)

Medicinal and aromatic plants with allelopathic effect are a potential source of natural herbicides. The experiment was conducted in order to assess herbicidal potential of meadow sage (Salvia pratensis L.) on germination and growth of weed species velvetleaf (Abutilon theophrasti Med.) and common corn-cockle (Agrostemma githago L.). Water extracts from S. pratensis dry biomass in different concentrations were evaluated under controlled laboratory conditions in Petri dish bioassay. Herbicidal effect of S. pratensis extracts depended on the extract concentration and weed species. In general, higher concentrations of water extract showed greater negative effect on germination and growth parameters of weed seedlings. A. githago had greater sensitivity to S. pratensis extracts with reductions in germination and seedlings growth up to 100% in treatments with 7.5% and 10% extract concentrations. A. theophrasti germination was not affected by water extracts, however, substantial reductions of root and shoot length as well as fresh weight of seedlings were recorded. S. pratensis proved as promising plant species for further studies.

Mapping the Genomic Regions Controlling Germination Rate and Early Seedling Growth Parameters in Rice.

Seed vigor is the key performance parameter of good quality seed. A panel was prepared by shortlisting genotypes from all the phenotypic groups representing seedling growth parameters from a total of 278 germplasm lines. A wide variation was observed for the traits in the population. The panel was classified into four genetic structure groups. Fixation indices indicated the existence of linkage disequilibrium in the population. A moderate to high level of diversity parameters was assessed using 143 SSR markers. Principal component, coordinate, neighbor-joining tree and cluster analyses showed subpopulations with a fair degree of correspondence with the growth parameters. Marker-trait association analysis detected eight novel QTLs, namely qAGR4.1, qAGR6.1, qAGR6.2 and qAGR8.1 for absolute growth rate (AGR); qRSG6.1, qRSG7.1 and qRSG8.1 for relative shoot growth (RSG); and qRGR11.1 for relative growth rate (RGR), as analyzed by GLM and MLM. The reported QTL for germination rate (GR), qGR4-1, was validated in this population. Additionally, QTLs present on chromosome 6 controlling RSG and AGR at 221 cM and RSG and AGR on chromosome 8 at 27 cM were detected as genetic hotspots for the parameters. The QTLs identified in the study will be useful for improvement of the seed vigor trait in rice.

Consequences of Hydro-Priming Cola parchycarpa K. Schum. and Cola rostrata K. Schum. Seeds

Hydro-priming is an important seed treatment technique for rapid seed germination. Cola species exhibits long and uneven germination. Hence this study was aimed at investigating the effect of hydro-priming durations on the germination and seedling growth of Cola parchycarpa and Cola rostrata. Five treatments (hydro-priming durations of 0 hour, 24 hours, 48 hours, 72 hours and 96 hours) were used and the experiment was laid out in a completely randomized design (CRD) with 6 replicates each. In C. parchycarpa, mean seed germination time of 40.50 days was observed only at 0 hour while there was no germination at 24, 48, 72 and 96 h of hydro-priming. In C. rostrata, there was a significant increase in the germination time as the hydro-priming duration increased from 0 h (13.83 d) to 48 h (45.00 d) with decreased germination percentage, while at 72 and 96 h of hydro-priming, germination failed to occur. There was no significant difference at P<0.05 in the seedling growth parameters of C. rostrata at the different hydro-priming durations. Hydropriming of C. parchycarpa and C. rostrata seeds before planting is not recommended for these two Cola species as it result in embryo death of the seeds.

Endophytic Bacteria Isolated from Tea Leaves (Camellia sinensis var. assamica) Enhanced Plant-Growth-Promoting Activity

Tea (Camellia sinensis var. assamica) is a traditional and economically important non-alcoholic beverage-producing plant grown in large plantations in the northern region of Thailand and has a diverse community of endophytic bacteria. In this study, a total of 70 bacterial isolates were isolated from healthy asymptomatic samples of tea leaves from five different tea gardens in Chiang Mai, Thailand. Based on 16S rDNA sequence analysis, these bacterial isolates were taxonomically grouped into 11 different genera, namely Bacillus, Curtobacterium, Enterobacter Microbacterium, Moraxella, Neobacillus, Priestia, Pseudarthrobacter, Pseudomonas, Sporosarcina, and Staphylococcus. All these isolates were evaluated for their potential to produce indole-3-acetic acid (IAA), siderophores, and cellulolytic enzymes while having phosphate-solubilizing and tannin tolerance capacity. Most isolated bacterial endophytes belonged to the Bacillus genus and exhibited multiple plant-growth-promoting abilities. All bacterial endophytes could produce varied concentrations of the indole-related compounds, and the strain Curtobacterium citreum P-5.19 had the highest production of IAA at 367.59 µg/mL, followed by Pseudarthrobacter enclensis P-3.12 at 266.97 µg/mL. Seventy-eight percent (78%) of the total isolates solubilized inorganic phosphate, while 77%, 65%, and 52% were positive for extracellular proteases, cellulases, and pectinases, respectively. Remarkably, 80% of the isolates were capable of growth on nutrient agar supplemented with 1% (w/v) tannic acid. C. citreum P-5.19 and P. enclensis P-3.12 were selected for evaluation of plant growth promotion, and it was found that both bacterial endophytes enhanced seed germination rate and improved seedling growth parameters such as fresh and/or dry weight, root length, and shoot lengths of sunflower and tomato seeds. The selected bacterial endophytes isolated from tea leaves in this study could be used in bioformulation for plant growth promotion and advancing sustainable agricultural practices contributing to the decreased use of chemical inputs. This is the first report of an endophytic bacterium, Pseudarthrobacter enclensis, being isolated from C. sinensis.

Improving salt tolerance of bean (Phaseolus vulgaris L.) with hydrogen sulfide

The current study examined the H2S applications on growth, biochemical and physiological parameters of bean seedlings under saline conditions. The findings of the study indicated that salt stress decreased plant growth and development, photosynthetic activity, and mineral and hormone content [excluding abscisic acid (ABA)] in bean seedlings. Plant and root fresh mass and dry mass with H2S applications increased as compared to the control treatment at the same salinity level. Both salinity and H2S treatments significantly affected the net assimilation rate, stomatal conductance, transpiration rate, and intercellular CO2 content of bean seedlings. Significant increases occurred in H2O2, malondialdehyde (MDA), proline, sucrose content, enzyme activity, and ABA content with salt stress. However, H2S applications inhibited the effects of salinity on plant growth, photosynthetic activity, and mineral content in beans. H2S applications reduced H2O2, MDA, proline, sucrose content, enzyme activity, and ABA content in beans. As a result, exogenous H2S applications could mitigate the negative impacts of salinity in beans.

Influence of ionic cerium and cerium oxide nanoparticles on Zea mays seedlings grown with and without cadmium

Cerium (Ce4+) and cerium oxide nanoparticles (CeO2-NPs) have diversified reported effects on plants. Once dispersed in the environment their fate is not well understood, especially in co-existence with other pollutants like cadmium (Cd). The effect of co-application of Ce and Cd are reported in various studies, but the role of Ce source (ionic or bulk) and nanoparticle size is still unknown in cereal plants like maize (Zea mays). To better understand the synergistic effects of Ce and Cd, 500 mg kg−1 Ce coming from ionic (Ce4+ as CeSO4) and CeO2 nano sources (10 nm, 50 nm, and 100 nm) alone and in combination with 0.5 mg Cd kg−1 sand were applied to maize seedlings. Growth, physiology, root structure, anatomy, and ionic homeostasis in maize were measured. The results revealed that Ce4+ resulted in overall decrease in seedling growth, biomass and resulted in higher heavy metal (in control sets) and Cd (in Cd spiked sets) uptake in maize seedlings' root and shoot. The effects of CeO2-NPs were found to be dependent on particle size; in fact, under Cd-0 (non-Cd spiked sets) CeO2-100 nm showed beneficial effects compared to the control. While under co-application with Cd, CeO2-50 nm showed net beneficial effects on maize seedling growth parameters. The Ce alone, and in combination with Cd, altered the root suberin barrier formation. Both ionic and nano Ce sources alone and in co-existence with Cd behaved differently for tissue elemental concentrations (Ce, Cd, micronutrients like B, Mn, Ni, Cu, Zn, Mo, Fe and elements Co, Si) suggesting a strong influence of Cd–Ce coexistence on the element's uptake and translocation in maize.

Synergistic effect of Pseudomonas azotoformans and Trichoderma gamsii in management of Fusarium crown rot of wheat

Fusarium crown rot is the major soil-borne disease of wheat and occurs throughout cereal producing areas of the world including Algeria. This study evaluated 10 bacterial and fungal strains, originating from Algeria as potential biological control agents against three soil-borne phytopathogens responsible for Fusarium crown rot of wheat (Fusarium pseudograminearum ON687723, F. graminearum ON685926 and F. equisti MK361175). All benificial microbial strains tested inhibited the pathogens mycelial growth in vitro. Isolate P58 (Pseudomonas azotoformans NR_113600) was the most effective antagonist against all the test pathogens in direct confrontation assay, and exhibited average of 70% growth inhibition of Fusarium spp. Isolate T2 (Trichoderma gamsii MK361138) proved suppression efficacy in the range of 61.87 to 71.64% toward plant pathogens. Under greenhouse conditions, wheat seeds treated with isolate P58 and T2 separately reduced the severity of crown rot disease significantly and improved the growth parameters of wheat seedlings as compared to control. The combined use of Pseudomonas azotoformans and Trichoderma gamsii increased the effectiveness of the antagonists and promoted wheat growth. Thus, it can be concluded that these strains can be utilized as a biocontrol agent for management of soilborne cereal pathogens.

Effect of Soil Mixtures Based on a Gneiss-Derived Soil and Two Forest Floor Types on Growth and Nutritional Status of Castanea sativa Mill. Seedlings

Aiming at the production of robust chestnut plants suitable for the establishment of plantations or for their use in afforestation of forest ecosystems, we studied the effect of soil mixtures on growth, physiological characteristics, and nutritional status of chestnut seedlings. In a complete randomized-block design pot experiment, the soil used was derived from gneiss weathering (GN) and the treatments included GN and GN with fertilization (GN-FER) as well as mixtures of GN with forest floor (FF) from chestnuts (GN-CFF) and from evergreen broad-leaved trees (GN-EFF). Both types of forest floor and fertilization had similar positive effect on seedlings growth and photosynthetic parameters. The most significant effects on soil nutrients were found in GN-CFF and GN-EFF treatments, except for extractable phosphorus (P) and exchangeable potassium (K), whose highest concentrations were observed in GN-FER. Leaf analysis showed that the concentrations of almost all nutrients in all treatments were within the adequacy limits, with the exception of nitrogen (N) in GN, copper (Cu) in GN-EFF, and K in all treatments. Both types of forest floor satisfied the nutritional needs of chestnut seedlings to a large extent and their incorporation in this type of soil combined with limited addition mainly of K and to a lesser degree of P could enhance adequacy of these nutrients in soil and plants. Thus, forest floor application may be an appropriate alternative to integrated nutrient management for robust chestnut seedlings production with significant forestry and environmental impacts.

Seed Priming with Exogenous Amino Acids Improves Germination Rates and Enhances Photosynthetic Pigments of Onion Seedlings (Allium cepa L.)

As a biostimulant, amino acids play crucial roles in enhancing plant growth and development. These roles, combined with the ability to be approved for organic usage, make amino acids a good choice for sustainable farming systems. This work investigates the effect of onion seed priming with different exogenous amino acids, specifically the impact of seed priming in enhancing a diverse range of morpho-physiological responses of onion seedlings. Here, we primed onion seeds (Cultivar Giza 6) with ten exogenous amino acids. Based on the growth parameters of onion seedlings, data showed that glutamine significantly improved the most studied parameters. Germination percentage (GP) ranged from 85% in Methionine (Met) to 98.5% in Proline (Pro) and Tryptophan (Try), with 10% over the control treatment. Glutamine (Glu) enhanced the vigor index (VI) of onion, giving the seeds a high ability to produce normal seedlings. The most extended root system (≥3.3 cm) was obtained from Glu, Glycine (Gly), Pro, and Try treatments. The maximum shoot length was obtained from treatments (Glu and Try) with more than 60% over control. Priming onion seeds with amino acids (AAs) increased chlorophyll contents compared with non-primed seeds. Glutamine and Threonine (Thr) had the highest results (122 and 127 μg/g fresh weight, respectively), while the Glu treatment registered the highest Carotene contents with 50% over the control treatment. Furthermore, the data illustrate that the principal component analysis-1 (PCA1) indicates 67.2% variability, and PCA2 indicates 14.8% variability. Strong positive correlations were observed between germination percentage, root length, shoot length, dry matter, chlorophyll a, and carotene. The study concluded that the primed onion seeds by glutamine, proline, and tryptophan had the best germination rates.

Genotype-Dependent Jasmonic Acid Effect on Pinus sylvestris L. Growth and Induced Systemic Resistance Indicators.

Due to temperature changes, forests are expected to encounter more stress than before, both in terms of biotic factors, such as increased insect attacks, and abiotic factors, such as more frequent droughts. Priming trees to respond to these changes faster and more effectively would be beneficial. Induced systemic resistance (ISR) is a mechanism that is turned on when plants encounter unfavorable conditions. Certain elicitors, such as jasmonic acid (JA) are known to induce plants' metabolic response. However, even though studies on ISR in herbaceous species are common and varied ISR elicitors can be used in agriculture, the same cannot be said about trees and forestry enterprises. We aimed to investigate whether JA used in different concentrations could induce metabolic changes (total phenol content, total flavonoid content, photosynthesis pigment content, antioxidant enzyme activity) in Pinus sylvestris seedlings and how this varies between different pine half-sib families (genotypes). After six weeks with a single application of JA, pine seedlings in several pine genetic families exhibited increased antioxidant enzyme activity, total phenol content and carotenoid content that correlated positively with JA concentrations used. Results from other genetic families were varied, but in many cases, there was a significant response to JA, with a noticeable increase as compared to the unaffected group. The impact on chlorophyll content and flavonoids was less noticeable overall. A positive effect on seedling growth parameters was not observed in any of the test cases. We conclude that JA can induce systemic resistance after a single application exogenously in P. sylvestris seedlings and recommend that the use of JA needs to be optimized by selecting appropriate concentrations.

Effect of Simulated Drought and Rainfall Fluctuation on Seedling Growth of Two Savannah Trees Species in Sudan: An Experimental Exploration

Climate change scenarios project that several regions, especially in dryland areas of sub-Saharan Africa, will undergo increasing aridity and, subsequently, expanding land degradation. The study aims to investigate the effect of two drying treatments on establishing and growing Hashab (Acacia senegal) and Boabab (Adansonia digitata) in nursery conditions. Through a 2×2 factorial experiment, seedlings grown in a mixture of silt and sand soil (2:3) were treated by irrigation intervals of one or two liters every three days for 14 weeks to simulate rainfall fluctuation patterns. Seedling germination rate, leaf number, stem height, and diameter were measured weekly; taproot length, shoot, and root dry weights were also assessed. The results showed that neither drying treatment significantly affected A. senegal and A. digitata seedling growth parameters. However, an interaction effect was found in the height and diameter for A. senegal and shoot dry weight for A. digitata. The study concluded that A. senegal and A. digitata seem tolerant to drying treatment. Therefore, the two species are recommended for afforestation programs in areas with relatively harsher conditions. Also, exposing the seedlings of these studied species to similar, extended periods of simulated drought (e.g., 6 – 12 months) is recommended for future studies.

EFFECTIVENESS OF COMPARATIVE GOAT MANURE FERTILIZER ON THE GROWTH OF COFFEE SEEDS FROM ARABICA VARIETIES (Coffea arabica L)

Seed quality is determined by good seedling techniques, one of which is the use of planting media. Where the planting media can use soil media with animal waste. The purpose of this study to determine the effectiveness of goat manure seedling media on the growth of Arabica coffee seedlings and to obtain the best comparison of goat manure seedling media on the accretion of Arabica coffee seedlings. This research method used a completely randomized design consisting of one factor and four treatments, namely soil 1:0 (M0), soil + goat manure 1:1 (M1), soil + goat manure 1:2 (M2), and soil + goat Manure 1:3 (M3). Variables observed: percentage, plant height, number of leaves. The data obtained were analyzed using the ANOVA if significantly continued with DMRT at the 5% level. The results showed the effectiveness of goat manure seedling media on the growth of arabica coffee seedlings, with a growth percentage of 97%. The best comparison of goat manure seedling media on the growth parameters of arabica coffee seedlings in the M3 treatment with a mixture of soil and goat manure ratio (1:3), the average plant height (14.19 cm), and the number of leaves (7.0 strands).

Effect of different growth media on biometric parameter of brinjal and chilli seedlings under shade net house

The study was undertaken for two consecutive years (2017 and 2018) to evaluate the effect of different growth media on various growing parameters and incidence of insect pest on brinjal and chilli seedlings. Seedlings were grown in protray using six types of growing media. The highest germination percentage (71.11), plant height (11.05 cm), number of leaves (5.81) and percentage healthy seedlings (89.82) were observed with vermiculite + perlite + vermi- compost (1:1:2) during both the years in brinjal. Similarly in chilli, highest germination percentage (66.33), plant height (9.81 cm), number of leaves (5.62) and percentage healthy seedlings (87.61) were observed with vermiculite + perlite + vermi-compost (1:1:2). There was significantly low incidence of whitefly in brinjal (1.49 whitefly/leaf) and chilli (1.65 whitefly/ leaf) seedling grown in media with vermiculite + perlite + vermi-compost (1:1:2). Hence, vermiculite + perlite + vermi-compost (1:1:2) was found as optimum growth media for growing of chilli and brinjal seedlings. The findings of this study recommend the use of vermiculite + perlite + vermi-compost (1:1:2) as growth media for raising nursery by farmers as it had significant positively effect on plant growth parameters of seedlings that lead to increase production of chilli and brinjal.

Effects of Early Drought Stress on Germination and Seedling Growth Parameters of Kırik Bread Wheat (Triticum aestivum L.)

Bu çalışma, polietilen glikolün (PEG-6000) çimlenme ve fide parametreleri üzerindeki etkilerini değerlendirmek ve Kirık buğdayı (Triticum aestivum L.) mutasyon ıslah programlarında kullanılabilecek optimal dozu belirlemek amacıyla yapılmıştır. Bu çalışmada 11 farklı PEG-6000 uygulama dozu [0 (kontrol), -1, -2, -3, -4, -5, -6, -7, -8, -9 ve -10 bar] tesadüf deneme desenine göre yapılmıştır. Çimlenme oranı (GP), ortalama çimlenme zamanı (MGT), kök (RL) ve sürgün uzunluğu (SL) ölçülmüştür. Varyans analizi, farklı PEG-6000 konsantrasyonunun GP, MGT, RL ve SL parametrelerinde önemli olduğunu (P <0.01) göstermiştir. En yüksek GP, RL ve SL kontrol konsantrasyonunda elde edilirken; en yüksek MGT, -10 bar konsantrasyonda gözlenmiştir. PEG-6000 konsantrasyonu arttıkça çimlenme oranı, kök uzunluğu ve sürgün uzunluğu önemli ölçüde azalırken, ortalama çimlenme zamanı uzamıştır. Elde edilen verilere dayanarak, -10 bar'lık bir konsantrasyonda etkili bir seleksiyonun gerçekleştirilebileceği sonucuna varılmış ve bu ozmotik potansiyel, çimlenme döneminde kuraklığa dayanıklı çeşidin seçiminde kullanılabileceği sonucuna varılmıştır.

Seed priming with antioxidants improves physiological parameters in sunflower cv. Co-2 under unfavourable germination conditions

The results of studying the effects of sunflower seed priming with 4 different antioxidants at 2 different concentrations under three unfavourable germination are presented in this paper. The goal of the study was to determine the impact of antioxidants on the physiological performance of sunflower seeds under favourable and different unfavourable germination conditions. The findings showed that seed germination was more stressed at 40°C and 100% RH. The effect of stress was minimized by seed priming with Butylated hydroxy toluene 0.1% followed by Butylated hydhydroxy toluene 2 % by recording 7 and 4 per cent higher germination over control. The seedling growth parameters viz., root and shoot length, seedling dry matter production and vigour indices were influenced negatively by NaCl 0.1 % stress condition. Under unfavourable germination conditions, seed priming with Butylated Hydroxytoluene (BHT) at 0.1 per cent, followed by a- Tocopherol at 0.5 per cent, and Ascorbic acid at 1.0 per cent, was observed to improve seedling growth characteristics.

Preparation of Seaweed Nanopowder Particles Using Planetary Ball Milling and Their Effects on Some Secondary Metabolites in Date Palm (Phoenix dactylifera L.) Seedlings.

Due to their distinctive physicochemical characteristics, nanoparticles have recently emerged as pioneering materials in agricultural research. In this work, nanopowders (NP) of seaweed (Turbinaria triquetra) were prepared using the planetary ball milling procedure. The prepared nanopowders from marine seaweed were characterized by particle size, zeta potential, UV-vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). When the seaweed nanopowder of Turbinaria triquetra was subjected to FT-IR analysis, it revealed the presence of different functional groups, including alkane, carboxylic acids, alcohol, alkenes and aromatics. Moreover, the methanol extract was used to identify the polyphenolic components in seaweed (NP) using high performance liquid chromatography (HPLC) and the extract revealed the presence of a number of important compounds such as daidzein and quercetin. Moreover, the pot experiment was carried out in order to evaluate the effects of prepared seaweed (NP) as an enhancer for the growth of date palm (Phoenix dactylifera L.). The date palm seedlings received four NP doses, bi-distilled water was applied as the control and doses of 25, 50 or 100 mg L-1 of seaweed liquid NP were used (referred to as T1, T2, T3 and T4, respectively). Foliar application of liquid NP was applied two times per week within a period of 30 days. Leaf area, number of branches, dry weight, chlorophylls, total soluble sugars and some other secondary metabolites were determined. Our results indicated that the foliar application of liquid NP at T3 enhanced the growth parameters of the date palm seedlings. Additionally, liquid NP at T3 and T4 significantly increased the photosynthetic pigments. The total phenolic, flavonoid and antioxidant activities were stimulated by NP foliar application. Moreover, the data showed that the T3 and T4 doses enhanced the activity of the antioxidant enzymes (CAT, POX or PPO) compared to other treatments. Therefore, the preparation of seaweed NP using the planetary ball milling method could produce an eco-friendly and cost- effective material for sustainable agriculture and could be an interesting way to create a nanofertilizer that mitigates plant growth.

Effect of Populus nigra spring and autumn leaves extract on Capsicum annuum infected with pepper mild mottle virus

Capsicum annuum is one of the main vegetable crops for the local market and exportation in Egypt. In this concern, pepper mild mottle virus (PMMoV) infection caused a significant decrease in Capsicum sp. leading to large economic losses. An isolate of PMMoV was obtained from naturally infected pepper plants, exhibiting different patterns of mottling, leaf distortion, yellowing, and stunting of leaves. The virus was identified. The molecular detection of PMMoV was done using RT-PCR with specific primers designed for coat protein genes. An RT-PCR product (474) bp of the coat protein gene of (PMMoV) was cloned. The target of the investigation was the effect of spring and autumn ethanol extracts of Populus nigra leaves on C. annuum seedling growth and infected C. annuum with (PMMoV) under greenhouse conditions. The experimental data showed that treated spring leaf extract of P. nigra enhanced infected C. annuum seedling growth parameters and fruit quality compared to uninfected seedlings. P. nigra spring leaf extract containing some allo-chemicals had a negative effect on uninfected seedlings. P. nigra autumn leaf extract significantly improved the growth and fruit quality of infected C. annuum seedlings compared to the control.

Exogenous melatonin improves seed germination and seedling growth in greengram under drought stress

Drought stress diminishes seedling germination and vigor by reducing water uptake, inhibiting plant growth and development. Most of the pulse growing areas are under rainfed ecosystems, which significantly reduces crop yield. Melatonin, a growth-regulating compound, is widely used to mitigate the negative effects of abiotic stresses in pulses. With this background, a laboratory experiment was conducted to standardize the optimum melatonin concentration for seed treatment and foliar application in greengram, to minimize the ill effects of drought stress. The experiment was arranged in a completely randomized design (CRD) with three replications for each treatment. The treatments consisted of soaking seeds with different melatonin concentrations, viz., 20, 40, 60, 80 and 100 μM. Seeds were sown in a perti dishes and the drought stress was imposed using poly ethylene glycol 6000 (PEG 6000) @ - 0.4 MPa, and plates were maintained at room temperature (24-30 °C). After the seedlings emerged, various seedling growth parameters like germination percentage, shoot length, root length, vigor index, promptness index, germination stress tolerance index, fresh and dry weight of the seedlings, plant height stress index and root length stress index were recorded. The experimental results showed that drought stress significantly reduced germination percentage and other growth-related parameters in greengram seedlings compared to the melatonin treatments. Among the melatonin treatments, seeds treated with @ 100 μM concentration recorded the highest germination percentage (99.67 %), promptness index (98.80), vigour index (1631.68), shoot and root length (8.9 cm and 7.5 cm), fresh and dry weight of the seedlings (3.249 and 0.147 mg seedling-1) under PEG induced drought stress condition.

IDENTIFICATION OF CHANGES IN THE METABOLIC PROCESSES OF GERMINATION AND GROWTH OF MAIZE SEEDLINGS UNDER THE INFLUENCE OF HEAT STRESS AND THE USE OF REGLALG

Laboratory experiments were carried out to determine the effect of pretreatment of seeds of two hybrids of maize (Zea mays L.) with Reglalg and subsequent exposure to heat stress (HS) of 50°C for 30 min on seed germination, seedling growth and assessment of translocation of endosperm reserve substances for these processes. The results showed a positive effect of Reglalg on seed germination and seedling growth parameters, which were affected by HS conditions. The use of Reglalg to treat the seeds of maize hybrids before expose to HS, had a beneficial effect on the formation of seedling biomass due to an increase in the mass of endosperm translocated from seeds to these processes under the conditions of stress. Also, the use of Reglalg in seed pretreatment favored the decrease in endosperm mass consumed for cellular metabolism respiration under HS.