Stages Of Seedling Development Research Articles

Evaluation of Frost Tolerance in Sugar Beet Cultivars During Early Growth Stages

AbstractLate spring frost is the most hazardous abiotic stress affecting the survival of sugar beet seedlings. Therefore, it is very important to identify frost-tolerant cultivars during the early seedling development stage. In the study, the physiological and morphological responses of ten sugar beet cultivars (Ernestina, Isabella, Orthega, Serenada, Kuno, Taurus, Tuna, Mohican, Rodeo, and Smılodon) to frost stress at different growth stages (V1.1, V2.1, and V3.1) were evaluated. Seedlings were exposed to − 3 °C for 2 h at all stages. Percent damage (%), leaf chlorophyll content (SPAD), leaf surface temperature (°C), electrolyte leakage (%), leaf relative water content (%), and turgidity loss (%) were examined. The results showed that higher damage percentages were observed in earlier growth stages of sugar beet, with recorded values of 29.7% in V1.1, 15.4% in V2.1, and 3.6% in V3.1. A great genotypic variation was observed among the cultivars; electrolyte leakage increased from 15.6% in control to 52.6% in frost stress, and higher electrolyte leakage was obtained from frost-stressed plants. The relative water content of leaves increased only at stage V2.1, although frost decreased turgor loss. Sugar beet showed sensitivity to frost in earlier seedling growth stages, but their tolerance levels increased in later growth stages. The study revealed that electrolyte leakage is a reliable indicator for identifying sugar beet cultivars that exhibit tolerance to frost stress during early development.

Residual phytotoxicity effects of different integrated herbicides management in soils from field-treated plots and post-harvest field

Soil residual phytotoxicity of commonly used herbicides in cotton crop in India were investigated through bioassay. Pendimethalin at 900 g a.i. ha-1, oxyfluorfen at 180 g a.i. ha-1, oxadiargyl at 90 g a.i. ha-1, quizalofop-ethyl at 40 g a.i. ha-1, imazethapyr at 75 g a.i. ha-1, propaquizafop at 50 g a.i. ha-1 and glyphosate at 960 g a.i. ha-1 were applied to field plots of 6.0 x 6.0 m2. Sorghum and cucumber were used in the bioassay and succeeding crops groundnut, green gram & pearl millet to test the residual effect of herbicides in the soil of the treated plots and post-harvest field. Soil, sampled at 30 day after treatment (DAT) for pre emergence herbicide and until 2 weeks (WAT) for post emergence herbicide later, show significant affect the seed germination and seedling development stage of sorghum and cucumber. There was no residual toxicity of pre and post-emergence herbicides as observed through field bioassay after harvesting cotton crop and it was found safe to grow groundnut, green gram and pearl millet as succeeding crop.

Accumulation patterns of flavonoids during multiple development stages of tea seedlings

Accumulation patterns of flavonoids during multiple development stages of tea seedlings

Genetic diversity of barley accessions from East Asian countries in terms of resistance to powdery mildew

Background. Barley is an ancient crop currently cultivated in more than 100 countries. High adaptability makes it possible to cultivate it in environments unfavorable for many other crops. At the same time, fungal diseases can have a negative impact on its grain yield and quality. One of the most harmful is the fungus Blumeria graminis (DC.) Golovin ex Speer f. sp. hordei Marchal. The pathogen can overcome a cultivar’s resistance, resulting in significant harvest losses. There is a need for a constant search for new effective sources of resistance to powdery mildew for barley breeding.Materials and methods. A set of 950 barley accessions from the East Asian center of the crop’s morphogenesis were studied at the adult stage of plant development. They were screened and crossed in the fields of Pushkin and Pavlovsk Laboratories of VIR (St. Petersburg, Russia). Genetic control of barley resistance to B. graminis was analyzed in a climate chamber under artificial infection pressure with the northwestern population of the fungus. Scoring scales were used for screening.Results and conclusions. Weak development of B. graminis during the heading phase was observed on plants of 38 barley accessions from the East Asian center. High resistance at all stages of development was manifested by 20 genotypes that can be used in breeding programs. Resistance genes in 18 selected forms differed in their effectiveness at the seedling stage of development and during the heading phase. Accessions k-3433, k-10931, k-10934, k-11608, k-17545, k-20272, k-20279, k-20354 and k-27867 had one dominant resistance gene each. Accessions k-11608, k-12278, and k-17545 are protected by the identical gene, while the resistance of k-3433 is induced by a gene that differs from the genes present in accessions k-10931 and k-20279.

Phenological description and thermal time requirements for the seedling phase of three Brazilian native forest species

AbstractUnderstanding the phenological stages and thermal requirements of the seedling phase of forest species is crucial for sustainable nursery management. This study proposed an adaptation of a phenological scale based on the basic Biologische Bundesanstalt, Bundessortenamt, and Chemical industry, associated with the thermal requirement to describe the phenological stages during the seedling phase of three forest species: Cybistax antisyphilitica, Libidibia ferrea, and Platycyamus regnellii. The phenological scale of C. antisyphilitica and L. ferrea was defined and described through 22 seedling development stages ranging from dry seed to 20th visible leaf emitted on the main stem (from 00 to 120) and P. regnellii for 12 leaf development stages, from dry seed to 10th visible leaf emitted on the main stem (from 00 to 110). In addition, the duration (days) and thermal time (°C day) were determined for each seedling development stage. C. antisyphilitica needs to accumulate more energy (and days) to finish the seedling phase (1551.9°C day or 261 days) compared to L. ferrea (1127°C day or 175 days) and P. regnellii (1109.7°C day or 193 days). However, the three forest species exhibit similar energy demands throughout most stages of seedling development, except code 09–12 for C. antisyphilitica. This study provides important information for optimizing silvicultural techniques, evaluating the response of temperature on phenological stages, and assessing the impacts of global warming on forest seedling development.

Morphological and biochemical changes with hormone and hydro- priming applications in safflower (Carthamus tinctorius L.) seedlings under salinity stress conditions

In this study, the ameliorative effects of hydro- and hormopriming applications against salt stress of safflower seeds during germination and seedling development stage were investigated. Primed (hydropriming (0, 1, 2 and 3 days) with distilled water and hormopriming for 24 hours (0, 50, 100 and 150 mg L-1 with kinetin) and nonprimed seeds were sown under control (no salt) and salt stress (0, 50, 100 and 150 mM NaCl) conditions. When priming applications under salt stress are compared with the control, germination percentage (GP), seedling lenght (SL), root length (RL), seedling fresh weight (SFW), root fresh weight (RFW), leaf relative water content (RWC), elctrolyte leakeage (EL) parameters reducing the effects of stress, however, it was determined that caused an increase in carotenoid (Car), superoxide dismutase (SOD), total phenolic compounds (TPC) parameters. Besides this, it has an inhibitory effect on the increase in proline (Pro) and malondialdehyde (MDA) content. According to the correlation analysis, significant positive correlation was determined in all parameters. A significant positive correlation was determined for hydropriming GP with SL, RL, SFW, RFW, and for hormopriming with SL, RL, SFW, RFW, total Chl, RWC and GP. According to the PCA analysis, the parameters examined in both applications it is seen that they are divided into four different groups. In conclusion, this study priming applications are compared with each other, it has been determined that hormopriming is more effective in reducing the effects of stress than hydropriming.

First report in South Korea of a bacterial leaf blight of oats caused by Pseudomonas salomonii.

In March 2020, approximately 20% of leaves in a commercial oat field growing Avena sativa (cv. Samhan) in Jeongeup, Korea (35.3859°, 126.5607°), displayed leaf blight in the seedling stage of development. The lesions observed in 2020 were of a yellow discoloration that spread from the leaf tip downward with minimal brown delineation (Fig. S1A). These symptoms differed from the haloes delineated at the edges by extensive brown necrosis caused by Pseudomonas coronofaciens (Kim 2020a; Fig. S1C). To isolate the causal agent, 3-cm-long pieces of symptomatic leaves from ten different oat plants were disinfected by submersion in 70% ethanol for 5 min followed by immersion in 1% sodium hypochlorite for 5 min and rinsing extensively with sterile distilled water. The air-dried segments were transferred intact to nutrient agar, and only one colony type (yellow-colored, wet, with a shiny convex surface) was observed. After single colony isolation, three isolates from different 2020 field-grown diseased leaves, termed 2007, 2009, and 2011, were selected at random. The isolates produced fluorescent siderophores on King's medium B and triggered a hypersensitive response (HR) when infiltrated into tobacco (cv. Xanthi) leaves (Fig. S1D). Multilocus sequence typing analysis with four housekeeping genes was used for taxonomic identification of these isolates (Maiden et al. 1998). The 16S rRNA sequences were amplified with the 27F/1492R universal primers (Weisburg et al. 1991). The primers for three housekeeping genes were designed using genome sequence of P. coronaficiens X-1 causing halo blight disease in Korea (NZ_CP050260.1, Kim, 2020b). The products obtained had sizes of 640 bp for gltA (using primers F: 5'-CCT GGT AGC CAA GAT GCC GAC-3'; R: 5'-CAA AGA TCA CGG TGA ACA TGC TGG-3'), 710 bp for gyrB (with primers F: 5'-TCG GCA GCC GAG GTC ATC ATG AC-3'; R: 5'-TTG TCT TTG GTC TGC GAG CTG AA-3'), and 870 bp for rpoD ( with primers F: 5'-GTG AAG GCG AAA TCG AAA TCG-3'; R: 5'-CCG ATG TTG CCT TCC TGG ATC AG-3'). The concatenated sequences (2,353 bp/2,376 bp) had 99% identity with the gene sequences from P. salomonii type strain (AY091528.1, NZ_FNOX01000003, LC486864.1, LC486849.1), but lesser identity (90%) with P. coronafaciens (Fig. S2). Pathogenicity of the Korean isolates was confirmed by fulfilling Koch's postulates using leaves of 2 week-old greenhouse-grown 'Samhan' seedlings. Plants (n=50) were sprayed with 108 cfu/ml bacterial suspensions in water or with sterile water as controls. The plants were incubated for a week at 23 °C in 100% relative humidity under a 10 h light/14 h dark photoperiod. Five days after bacterial inoculation, yellow discoloration appeared at the leaf tips which progressed downward with time (Fig. S1B). Three bacterial isolates extracted from yellowed, inoculated leaves had 16S rRNA gene sequences identical to that of P. salomonii Korean isolates, 2007, 2009 and 2011, and they caused the anticipated symptoms when inoculated into oat leaves. These findings indicate that P. salomonii should be added to the potential pathogens of oats grown in Korea. Understanding whether spring weather conditions (warmth and humidity) boost this oat disease will help devise disease alert systems for farmers (Anderson 2004; Chakraborty 2005).

Early selection for drought tolerance in popcorn based on gene effects estimated in seedlings.

Low rainfall rates are becoming increasingly frequent because of climate change, causing droughts and threatening world food security. For popcorn, drought is the most limiting abiotic factor for plant's growth and development. Thus, the water deficit directly impacts for crop productivity. Based on knowledge of the genetic basis of traits involved in stages of popcorn germination and seedling development under water stress, genotypes with potential for adaptation to adverse growing conditions can be selected early. Therefore, data on genetic effects and combining ability of 10 popcorn parents were compiled to propose breeding strategies for the development of cultivars with greater adaptation to water stress in the early stages. Forty-five diallel hybrids were evaluated under two different water regimes, that is, water stress and full irrigation. This corresponded to a water retention capacity of 25% and 70% of the germination paper. The plants were watered daily as needed for seven days. A range of factors were evaluated, that is, germination traits including the germination speed index and germination on the seventh day; shoot traits including length and dry weight; and root system including length, dry weight, root-to-shoot ratio, maximum root number, root network area, specific and root network length, and root volume. Breeding for drought adaption in the early stages of popcorn development can be successful when hybrids are used, because of the genetic effects of dominance (ϕs). These control the traits evaluated at the seedling stage. The combinations L61 x P2 and L71 x P3 were recommended, in view of the more successful performance estimated for traits related to the shoot and root system.

In Vitro Seed Germination and Seedling Development of Dracula felix (Luer) Luer—An Orchid Native to Ecuador

Effects of daily temperature fluctuations that mimic on-site environmental conditions were tested on seed germination and development in Dracula felix, a native epiphytic orchid from the neotropics. Mature seeds collected from a native population lost their viability from 60% to 37.78% and 0% after 8 and 16 weeks., respectively, under 22 ± 2 °C. Seed viability was completely lost when seeds were maintained at −10 °C in the dark. Less than 50% germination was observed in D. felix seed across all treatments. Seed germinated regardless of the light or temperature treatment. However, significant improvement in germination was observed at 17/22 °C compared to constant temperature treatments. Early seedling development stages were observed only on 1/2XMS and VW media at 17 °C or 17 °C/22 °C under a 12 h light photoperiod. Neither germination nor seedling development were improved by any fungal strain tested using standard symbiotic germination protocols. Information obtained from this study is critical to ensure the ex-situ conservation of this and other rare Dracula species under current and future climate change scenarios.

Developmental dynamics of crassulacean acid metabolism (CAM) in Opuntia ficus-indica.

The relative contributions of C3 photosynthesis and crassulacean acid metabolism (CAM) during the earliest stages of development were investigated to assess how much each might contribute to cactus pear (Opuntia ficus-indica) productivity. The developmental progression of C3 photosynthesis and CAM was assessed in seedlings and daughter cladodes of mature plants by titratable acidity, δ13C isotopic values and diel gas exchange measurements. Nocturnal acidification was observed in seedling cladodes and cotyledons at the earliest stages of development and became highly significant by 75 days of development. Seedling cotyledons showed mean δ13C values of -21.4 and -17.1 ‰ at 30 and 100 days of age, respectively. Seedling cladodes showed mean δ13C values of -19.4 and -14.5 ‰ at 30 and 100 days of age, respectively. These values are typical of CAM plants. Net CO2 assimilation was negative, then occurred in both the day and the night, with nighttime fixation becoming predominant once the primary cladode reached 5 cm in size. Emergent daughter cladodes growing on mature plants showed nocturnal titratable acidity at the earliest stages of development, which became significant when daughter cladodes were >2.5-5 cm in height. Emergent daughter cladodes showed mean δ13C values of -14.5 to -15.6 ‰, typical of CAM plants. CO2 assimilation studies revealed that net CO2 uptake was negative in daughter cladodes <12 cm in length, but then exhibited net positive CO2 assimilation in both the day and the night, with net nocturnal CO2 assimilation predominating once the daughter cladode grew larger. Developing O. ficus-indica primary and daughter cladodes begin as respiring sink tissues that transition directly to performing CAM once net positive CO2 fixation is observed. Overall, these results demonstrate that CAM is the primary form of photosynthetic carbon assimilation for O. ficus-indica even at the earliest stages of seedling or daughter cladode development.

Maize seedling information extraction from UAV images based on semi-automatic sample generation and Mask R-CNN model

ContextThe emergence rate and growth of maize seedlings are crucial for variety selection and farm managers; however, the complex planting environment and seedling morphological differences pose great challenges for seedling detection. ObjectiveThis study aims to rapidly quickly and accurately extract maize seedling information in the field environment based on UAV images with reduced labor cost. MethodsIn this paper, we proposed an automatic identification method for maize seedlings adapted to complex scenarios (different varieties and different seedling development stages) by fine-tuning the Mask R-CNN model. Aiming at the difficulty of obtaining the training data required by the deep learning algorithm, this paper proposes a semi-automatic labeling method for the deep learning sample data of maize seedlings. At last, we proposed a method to identify the locations of disrupted monopoly and extract seedling information such as coverage and seedling area uniformity, the mapping covers the whole experimental field. Results and conclusionsThis paper includes a discussion on the effect of real flight data and resampling data on model detection results. Indeed, the results show that the identification precision of the real flight data under the same resolution is lower than that of the resampled data. The detection precision of the model decreased as the spatial resolution decreased. To ensure AP@ 0.5IOU above 0.8, the minimum image spatial resolution is 2.1 cm. We finally selected a model which had the training data with a spatial resolution of 0.8 cm in 2019 and the average precision AP@0.5IOU was 0.887, the average accuracy of emergence rate monitoring in 2019 was 98.87 % and migration to 2020 is 95.70 %, 2021 is 98.77 %. SignificanceThis work can quickly and effectively extract maize seedlings, and provide accurate seedling information, which can provide support for timely supplementation and subsequent seed selection.

Identification of the Function of the Pathogenesis-Related Protein GmPR1L in the Resistance of Soybean to Cercospora sojina Hara.

Pathogenesis-related proteins, often used as molecular markers of disease resistance in plants, can enable plants to obtain systemic resistance. In this study, a gene encoding a pathogenesis-related protein was identified via RNA-seq sequencing analysis performed at different stages of soybean seedling development. Because the gene sequence showed the highest similarity with PR1L sequence in soybean, the gene was named GmPR1-9-like (GmPR1L). GmPR1L was either overexpressed or silenced in soybean seedlings through Agrobacterium-mediated transformation to examine the resistance of soybean to infection caused by Cercospora sojina Hara. The results revealed that GmPR1L-overexpressing soybean plants had a smaller lesion area and improved resistance to C. sojina infection, whereas GmPR1L-silenced plants had low resistance to C. sojina infection. Fluorescent real-time PCR indicated that overexpression of GmPR1L induced the expression of genes such as WRKY, PR9, and PR14, which are more likely to be co-expressed during C. sojina infection. Furthermore, the activities of SOD, POD, CAT, and PAL were significantly increased in GmPR1L-overexpressing soybean plants after seven days of infection. The resistance of the GmPR1L-overexpressing lines OEA1 and OEA2 to C. sojina infection was significantly increased from a neutral level in wild-type plants to a moderate level. These findings predominantly reveal the positive role of GmPR1L in inducing resistance to C. sojina infection in soybean, which may facilitate the production of improved disease-resistant soybean cultivars in the future.

Responses of tree seedlings to understory filtering by the recalcitrant fern layer in a subtropical forest.

The recalcitrant understory fern layer is an important ecological filter for seedling regeneration, yet how the fern layer influences seedling regeneration dynamics remains unclear. Here we transplanted 576 seedlings of four dominant tree species, Castanopsis fargesii, Lithocarpus glaber, Schima superba and Hovenia acerba, to the treatments of Diplopterygium glaucum retention and removal under an evergreen broad-leaved forest in eastern China. We monitored the survival, growth and biomass data of these seedlings for 28 months, and then used generalized linear mixed models to evaluate the treatment effects on seedling survival, growth, biomass and root-shoot ratio. Our results showed that fern retention significantly inhibited the seedling establishment of all four species. During the seedling development stage, the seedling relative growth rate of L. glaber decreased under fern retention, which was not the case for the other three species. Root-shootratio of C. fargesii and L. glaber increased significantly under fern retention. Our findings provide new evidence of the filtering effect of a recalcitrant fern understory. Notably, we observed that the response of tree seedlings to the recalcitrant fern understory was more sensitive in the establishment stage. Finally, our work highlights that the filtering effect of the recalcitrant fern understory changes depending on the regeneration stages, and that shade-tolerant species, C. fargesii and L. glaber were even more affected by fern disturbed habitats, suggesting that effective management should attempt to curb forest fern outbreaks, thus unblocking forest recruitment.

Cucumber mosaic virus Is Unable to Self-Assemble in Tobacco Plants When Transmitted by Seed

Cucumber mosaic virus (CMV), which has great impact on agronomic production worldwide, is both aphid and seed transmitted. Although the mechanisms of aphid transmission have been widely studied, those underlying the ability of CMV to survive and remain infectious during the passage from one generation to the next through the seeds are still to be clarified. Moreover, the viral determinants of seed transmission rate are poorly understood. Three viral genotypes produced from same RNA 1 and 2 components of CMV-Fny but differing in RNA 3 (the wild type CMV-Fny, a pseudorecombinant CMV-Fny/CMV-S and a chimeric CMV previously obtained by our group, named F, FS and CS, respectively) were propagated in Nicotiana tabacum cv Xanthi plants in order to assess differences in tobacco seed transmission rate and persistence through plant generations in the absence of aphid transmission. Seed-growth tests revealed CMV infection in the embryos, but not in the integuments. Seedlings from seed-growth tests showed the presence of all considered viruses but at different rates: from 4% (F, FS) to 16% (CS). Electron microscopy revealed absence (CS) of viral particles or virions without the typical central hole (F and FS). In agreement, structural characteristics of purified CMV particles, assessed by circular dichroism spectroscopy, showed anomalous spectra of nucleic acids rather than the expected nucleoproteins. These alterations resulted in no seed transmission beyond the first plant generation. Altogether, the results show for the first time that correct virion assembly is needed for seed infection from the mother plant but not to seedling invasion from the seed. We propose that incorrect virion formation, self-assembly and architecture stability might be explained if during the first stages of germination and seedling development some tobacco seed factors target viral regions responsible for protein-RNA interactions.

Nanopriming-mediated memory imprints reduce salt toxicity in wheat seedlings by modulating physiobiochemical attributes

BackgroundAround the globe, salinity is one of the serious environmental stresses which negatively affect rapid seed germination, uniform seedling establishment and plant developments restricting sustainable agricultural productivity. In recent years, the concepts of sustainable agriculture and cleaner production strategy have emphasized the introduction of greener agrochemicals using biocompatible and natural sources to maximize crop yield with minimum ecotoxicological effects. Over the last decade, the emergence of nanotechnology as a forefront of interdisciplinary science has introduced nanomaterials as fast-acting plant growth-promoting agents.ResultsHerein, we report the preparation of nanocomposite using chitosan and green tea (CS-GTE NC) as an ecofriendly nanopriming agent to elicit salt stress tolerance through priming imprints. The CS-GTE NC-primed (0.02, 0.04 and 0.06%), hydroprimed and non-primed (control) wheat seeds were germinated under normal and salt stress (150 mM NaCl) conditions. The seedlings developed from aforesaid seeds were used for physiological, biochemical and germination studies. The priming treatments increased protein contents (10–12%), photosynthetic pigments (Chl a (4–6%), Chl b (34–36%), Total Chl (7–14%) and upregulated the machinery of antioxidants (CAT (26–42%), POD (22–43%)) in wheat seedlings under stress conditions. It also reduced MDA contents (65–75%) and regulated ROS production resulting in improved membrane stability. The priming-mediated alterations in biochemical attributes resulted in improved final germination (20–22%), vigor (4–11%) and germination index (6–13%) under both conditions. It reduced mean germination time significantly, establishing the stress-insulating role of the nanocomposite. The improvement of germination parameters validated the stimulation of priming memory in composite-treated seeds.ConclusionPre-treatment of seeds with nanocomposite enables them to counter salinity at the seedling development stage by means of priming memory warranting sustainable plant growth and high crop productivity.

Evaluation of efficacy of Phyto-synthesized iron oxide nanoparticles in contributing drought resilience in wheat (Triticum aestivum L.)

Wheat is the majorly cultivated staple crop worldwide. The world witnesses a great percentage of yield loss of wheat due to drought stress. The present study aimed at evaluating the efficacy of phytosynthesized iron oxide nanoparticles (FeONPs) in contributing to drought resilience in wheat (Triticum aestivum L.) under rain-fed conditions. FeONPs were biosynthesized by using leaf extract of Prosopis cineraria as a reducing and capping agent. The synthesized nanoparticles were characterized to evaluate the structural and biochemical aspects. The FeONPs were found to be irregularly spherical in shape with a mean size of 42.6 nm. The concentration of nanoparticles in the sample was found to be 164.01 mg l−1. An experimental setup was laid out in a randomized-plot design with 3 replications for Rabi season 2020–2021. Five dosages of nanoparticles were prepared as 12.5, 25, 50, 75 and 100 ppm from the stock solution. The wheat crop varieties grown in the field were subjected to a total of 3 treatments; Nanopriming, foliar application of FeONPs at seedling development stage (20 DAS), and tillering stage (30 DAS). Plants that were not treated with NPs were considered as control. No irrigation regime was followed as the effect of NPs on the crop was to be assessed under rain-fed conditions only. Plant growth parameters were recorded. The obtained results revealed that the application of FeONPs positively affected all the morphological and yield attributes in the wheat crop. The highest concentrations used were found to be most effective and showed a significantly pronounced effect as compared to the control at p ≤ 0.05. The study concluded that the FeONPs can contribute to drought resilience in wheat.

Abiyotik stres koşullarında yetiştirilen Gypsophila pilulifera (Caryophyllaceae) tohumlarının in vitro çimlenme ve vejetatif büyüme özellikleri

Gypsophila pilulifera Boiss. &amp; Heldr. is an economically important critically endangered (CR) endemic species of Turkey. This species is a Mediterranean element and type sample is located in square C3 (Antalya). Plants are much more sensitive to abiotic stress factors, especially during germination and seedling development stages. In this study, in vitro germination and seedling growth properties of G. pilulifera Boiss. &amp; Heldr. (Caryophyllaceae) were investigated under salt and drought stress. The seeds were cultured in hormone-free MS media containing increasing doses of NaCl (50, 100, 150, 200 mM) and PEG 6000 (5%, 10%, 15% and 20%). Germinated seeds were counted every three days for the first week and every day for the second week. The root and hypocotyl length, number of leaves, fresh weight and vigor index of the plants were determined at the end of 21 days. A negative correlation was determined between increased salt and drought stress and all vegetative growth parameters. Although germination was obtained on MS medium with the highest level of drought (20%), there was no germination on MS medium containing 200 mM NaCl. As a result, it was determined that the plant was more sensitive to salinity stress than drought and high salt concentrations inhibited the germination by 100%.

Characterization of Current Fusarium oxysporum f. sp. vasinfectum Isolates from Cotton in the San Joaquin Valley of California and Lower Valley El Paso, Texas.

Fusarium oxysporum f. sp. vasinfectum race 4 is a causal agent of Fusarium wilt of cotton (Gossypium spp.). This study aimed to characterize the existing distribution and frequency of current field populations of F. oxysporum f. sp. vasinfectum race 4 genotypes in the San Joaquin Valley (SJV) of California and Lower Valley El Paso, TX and examine representative isolates for aggressiveness during different stages of seedling development. A survey was conducted from 2017 to 2019 across 13 locations in the SJV and one location in El Paso, TX during 2018. From the SJV, isolates identified as the F. oxysporum f. sp. vasinfectum race 4 T genotype were dispersed across the SJV, whereas isolates identified as the F. oxysporum f. sp. vasinfectum race 4 N genotype were most frequently isolated from cotton fields in the northern county of Merced. The F. oxysporum f. sp. vasinfectum race 4 isolates from the Texas location were identified as the MT genotype. A selection of representative isolates was evaluated using three inoculation assays (rolled-towel, F. oxysporum f. sp. vasinfectum-infested oat seed, and root-dip inoculation) to test the isolates' abilities to produce symptoms during seedling stages of cotton development. All isolates tested were capable of producing symptoms on cotton; however, isolate aggressiveness varied within and across inoculation assays. In all assays, higher levels of disease development were observed in the moderately susceptible Pima (Gossypium barbadense L.) cultivars (DP-340 or PHY-830) when compared with the moderately tolerant Upland (G. hirsutum L.) cultivar (FM-2334). However, no correlation was found among the different response variables for the rolled-towel assay when compared with the root-dip and infested oat seed assays. These results suggest that different genes are involved in the resistance response during the early seedling development stage measured in the rolled-towel assay compared with the later seedling development stages measured during the root-dip inoculation and infested oat seed assays, revealing the complexity of the Fusarium wilt disease and host-plant resistance mechanisms.

Effects of Different Salt Concentrations on Germination and Seedling Growth of Some Sweet Sorghum [Sorghum bicolor var. saccharatum (L.) Mohlenbr.] Cultivars

This study was carried out to determine the effects of different salt concentrations on germination and seedling growth of sweet sorghum [Sorghum bicolor var. saccharatum (L.) Mohlenbr.] cultivars. The research was carried out under laboratory conditions and sweet sorghum cultivars Ulusoy, Sorge, Biomarlı, Erdurmuş, and Gülşeker were used as plant material. Five different sweet sorghum cultivars and four different salt (NaCl) concentrations (0-, 100-, 200-, and 300 mM) were the subjects of the laboratory experiments which was set up in randomized plots in a factorial design with 4 replications. In the study, germination parameters such as germination percentage (GP), mean germination time (MGT), germination index (GI), coefficient of uniformity of germination (CUG) and germination speed (GS), and seedling growth parameters such as root and shoot fresh weight, root and shoot dry weight, root and shoot length, lateral root number and lateral root length were investigated. As a result of the research, it was determined that the germination and seedling growth parameters (excluding MGT) decreased as salt concentration increased. This decrease in germination characteristics was significant at 100 mM salt dose according to the average values of the cultivars, and it was observed that the cultivars were more sensitive to salt stress in the seedling development stage than the germination stage. In the study, it was determined that there were significant differences between sweet sorghum genotypes under salt-stressed conditions during germination and seedling stages. In this sense, Ulusoy and Erdurmuş sweet sorghum cultivars were prominent in terms of salt tolerance. It is important to use salt tolerant cultivars considering the genotypic differences in sweet sorghum cultivation in salt-affected areas.

Impacts of nano-TiO2 on the initial development stages of barley seedlings under salinity

The most important development period in cereal plants is the initial stage, that is, seed germination and early seedling development. Even if the barley is thought to be a partially salt-tolerant plant, it may be severely affected when exposed to salinity at initial developmental periods. Pre-treatment and preparation of seeds before sowing have an important in agriculture. Nano-seed priming treatment is a new approach used to increase germination, emergence and seedling growth recently. In this study, the effects of nano-TiO2 (0, 100, 200 mg L-1 n-TiO2) pre-application and ongoing/combination application under salinity (0, 100, 200, 300 mM NaCl) on germination and early seedling growth of barley plants were investigated. Root lengths (RL, mm), germination rates (GR, %), radicle emerging (RE, %), number of coleoptiles (CN) were measured depending on the day (1, 2, 3 days). At the end of the third day, seedling fresh and dry weights (FW,DW mg) were measured. The relative growth index (RGI) of root and mean germination time (MGT) were calculated. It was determined that the application of 100 mg L-1 n-TiO2 increased root length and RGI compared to control groups. It was observed that the application of 100 mg L-1 n-TiO2 significantly increased the germination percentage, biomass and root length especially in 100 mM salt conditions. Also, 100 mg L-1 n-TiO2 increased the RE too in 100 mM salt conditions (1st day). In this study, it was determined that 300 mM NaCl was inhibitory dose, and also germination remained below 20% in 200 mM NaCl in all groups