Intervarietal Differences Research Articles

Climate data integration into wheat performance evaluation reveals large inter-varietal responses

Abstract There is an urgent need to adapt crop breeding strategies to boost resilience in the face of a growing food demand and a changing climate. Achieving this requires an understanding of how weather and climate variability impacts crop growth and development. Using the United Kingdom (UK) as an example, we evaluate changes in the UK agroclimate and analyse how these have influenced domestic wheat production. Here we quantify spatial and temporal variability and changes in weather and climate across growing seasons over the last four decades (1981-2020). Drawing on variety trial data, we then use statistical modelling to explore the interaction between genotype and agroclimate variation. 
We show that changes in the UK agroclimate present both risks, and opportunities for wheat growers, depending on location. From 1981-2020, in Wales, the West Midlands, large parts of the North West, and Northern Ireland, there was an overall increase in frost risk in early spring of 0.15 additional frost days per year, whilst in the East early frost risk decreased by up to 0.29 days per year. Meanwhile, over the period 1987-2020, surface incoming shortwave radiation during grainfill increased in the East by up to 13% but decreased in Western areas by up to 15%. We show significant inter-varietal differences in yield responses to growing degree days, heavy rainfall and the occurrence of late frost. This highlights the importance of evaluating variety-climate interactions in variety trial analyses, and in climate-optimised selection of crops and varieties by growers. This work provides guidance for future research on how climate change is affecting the UK agroclimate and resulting impacts on winter cereal production.

Morphological, physiological and anatomical traits in durum wheat (Triticum durum Desf.) as affected by semi-arid conditions

Durum wheat (Triticum durum Desf.) is one of Algeria's primary cereal crops. Although the areas reserved for this species are estimated at approximately 40%, the production remains low to meet national grain requirements. This shortfall is primarily due to the impact of biotic and abiotic stresses, particularly drought, which significantly limit wheat yields. For that, this study assessed the behavior of five genotypes of durum wheat (Waha, Acsad1361, Vitron, Oued Zenati and Langlois) under water stress conditions. The experiment was carried out in Tiaret (Western Algeria). The studied parameters are morpho-physiological and anatomical of the flag leaf. The obtained results showed that the water deficit greatly affected the dimensions of the plant and triggered a decrease in the water content. Structural modifications due to cellular resizing of the structural constituents of the last leaf, reflected by variations in the rate of the outer epidermal wall thickness and reductions of leaf mesophiles. These modifications remain effective in maintaining the hydration of the aerial part by limiting water loss and increasing the hydraulic resistance of the leaves. According to this study, it seems that an inter-varietal difference has been highlighted. However, a genetic cross is recommended to combine the maximum number of resistant genes into a single variety. This strategy is considered as an effective solution for mitigating the effects of abiotic stresses, especially in semi-arid regions.

Root-zone regulation and longitudinal translocation cause intervarietal differences for phthalates accumulation in vegetables

Selecting and cultivating low-accumulating crop varieties (LACVs) is the most effective strategy for the safe utilization of di-(2-ethylhexyl) phthalate (DEHP)-contaminated soils, promoting cleaner agricultural production. However, the adsorption-absorption-translocation mechanisms of DEHP along the root-shoot axis remains a formidable challenge to be solved, especially for the research and application of LACV, which are rarely reported. Here, systematic analyses of the root surface ad/desorption, root apexes longitudinal allocation, uptake and translocation pathway of DEHP in LACV were investigated compared with those in a high-accumulating crop variety (HACV) in terms of the root-shoot axis. Results indicated that DEHP adsorption was enhanced in HACV by root properties, elemental composition and functional groups, but the desorption of DEHP was greater in LACV than HACV. The migration of DEHP across the root surface was controlled by the longitudinal partitioning process mediated by root tips, where more DEHP accumulated in the root cap and meristem of LACV due to greater cell proliferation. Furthermore, the longitudinal translocation of DEHP in LACV was reduced, as evidenced by an increased proportion of DEHP in the root apoplast. The symplastic uptake and xylem translocation of DEHP were suppressed more effectively in LACV than HACV, because DEHP translocation in LACV required more energy, binding sites and transpiration. These results revealed the multifaceted regulation of DEHP accumulation in different choysum (Brassica parachinensis L.) varieties and quantified the pivotal regulatory processes integral to LACV formation.

Evaluation of growth, physiological response, and drought resistance of different flue-cured tobacco varieties under drought stress.

In recent years, more severe droughts have occurred frequently in many parts of the world, drought stress is the primary abiotic stress factor restricting the growth and quality of flue-cured tobacco. Therefore, screening dryland cultivation-compatible flue-cured tobacco varieties will help reduce the negative impact of drought. Tobacco varieties were selected: Qinyan 96 (Q96), Zhongyan 101 (Z101), Yunyan 87 (Y87), and Yunyan 116 (Y116). A pot experiment was conducted with four water supply gradients: sufficient, mild stress, moderate stress, and severe stress. The aim was to analyze inter-varietal differences in agronomic traits, photosynthetic traits, reactive oxygen species (ROS) metabolism, and antioxidant enzyme system under drought stress. Additionally, the drought resistance of four flue-cured tobacco varieties was evaluated using principal component analysis and membership function analysis. The results showed that drought intensification inhibited seedling growth and development across all varieties, with Q96 showing the least decrease and Y116 the greatest. With the increasing degree of drought stress, photosynthetic rates (Pn), transpiration rate (Tr), and stomatal conduction (Gs) have shown gradually decreasing trends, while substomatal cavity CO2 concentration (Ci) showed a growing trend. Severe drought corresponded with lower chlorophyll content and decreased the maximal photochemical efficiency (Fv/Fm), photosystem II (PSII), and photochemical quenching coefficient (qP) in all varieties, while steady-state non-photochemical quenching (NPQ) increased. Increased drought stress led to significantly higher reactive oxygen species (ROS) and malondialdehyde (MDA) content accumulation in tobacco seedlings. The antioxidant enzyme activities in, Q96, Z101, and Y87 increased under mild drought stress, whereas Y116 showed decreased activity. The drought resistance ranking among the four varieties is as follows: Q96 > Z101 > Y87 > Y116. Therefore, Q96 is a promising drought-tolerant breeding material that can be used as a reference for dryland cultivation of flue-cured tobacco.

Comprehensive analysis of nanoplastic effects on growth phenotype, nanoplastic accumulation, oxidative stress response, gene expression, and metabolite accumulation in multiple strawberry cultivars

Nanoplastics (NPs) have emerged as a novel environmental threat due to their potential impacts on both animals and plants. Currently, research on the ecotoxicity of NPs has mainly focused on marine aquatic organisms and freshwater algae, with very limited investigations conducted on horticultural plants. This study examined the effects of varying concentrations (0, 1, 10, 50 mg·L−1) of polystyrene NPs (PS-NPs) on strawberry growth. The findings revealed that low concentrations of PS-NPs stimulated strawberry growth, whereas high concentrations impeded it. Notably, diverse strawberry cultivars displayed considerable differences in their sensitivity to PS-NP exposure. Laser scanning confocal microscopy confirmed the absorption of PS-NPs by strawberry roots, with variations in PS-NP accumulation observed across different cultivars. Comparative transcriptomics analysis suggested that the differential expression of genes responsible for calcium ion transport played a significant role in the observed intervarietal differences in PS-NP accumulation among strawberry cultivars. Furthermore, distinct variations in endogenous oxidative responses were observed in different strawberry cultivars under PS-NP treatment. Further analysis indicated that the down-regulation of peroxidase (POD) gene expression and terpenoid compounds accumulation were responsible for heightened endogenous oxidative stress observed in certain strawberry cultivars under PS-NP treatment. Transcriptomic and metabolomic analyses were performed on six strawberry cultivars to investigate their response to PS-NPs in terms of endogenous gene expression and metabolite accumulation. The results identified one commonly up-regulated gene (wall-associated receptor kinase-like) and sixteen commonly down-regulated genes associated with lipid metabolism and carbohydrate metabolism. In addition, a significant reduction in fatty acid metabolite accumulation was observed in the six strawberry cultivars under PS-NP treatment. These findings have significant implications for understanding the effects of NPs on strawberry growth, metabolism, and antioxidant responses, as well as identifying marker genes for monitoring and evaluating the impact of NP pollution on strawberry.

Modals and Quasi-Modals in English World-Wide

This study explores the distribution of modals and quasi-modals in the twenty English dialects represented in the Global Web-based English Corpus (GloWbE). Intervarietal trends are observed across and within the Englishes of the “Inner circle” and “Outer circle.” Ratios calculated for onomasiological pairings of modal expressions suggest that Inner circle varieties tend to be associated more closely than Outer circle varieties—and “epicentral” varieties more so than non-epicentral ones—with trends of frequency change that have been identified in previous diachronic studies of the reference varieties, British and American English. A further type of change is revealed by semantic analysis: Inner circle varieties tend to embrace epistemic modality more readily than Outer circle varieties. Possible explanations considered for intervarietal differences include areal proximity, epicentrality, evolutionary status, and colloquiality.

Vine leaf decomposition: Feeding preferences and effects of physico-chemical traits of litter on life-history traits of the woodlice Armadillidium vulgare Latreille, 1804

Litter decomposition is a key ecosystem process which is dependent on the litter characteristics and diversity, the decomposer community and activity, and the environmental conditions. We assessed vine leaf decomposition by Armadillidium vulgare (Latreille, 1804), a terrestrial isopod widely distributed and naturally present in vineyards. We compared the decomposition of three grape varieties (Chardonnay, Pinot Noir and Sauvignon) with regular laboratory food (Tilia tomentosa (Moench, 1785)) for seven consecutive weeks. Seven traits were measured on the four litters tested in order to define their importance concerning (i) litter mass loss by the action of microorganisms and isopods (ii) the trophic traits (consumption and assimilation) and (iii) life-history traits (survival and growth) of A. vulgare. Thus, the chemical and physical traits (C/N ratio, tannin and fiber content, thickness) known to influence litter palatability and digestibility for decomposers were determined by standardized methods. In addition, the copper frequently used in viticulture as a fungicide which is potentially responsible for toxic effects on decomposers was measured by ICP-OES after litter mineralization in nitric acid. Our results showed a higher percentage of decomposability by microorganisms in litter with low cellulose content and C/N ratio. Higher isopod consumption and assimilation was found in the litters which is the poorest in tannin, lignin and copper contents. Variation of consumption according to litter was on average 1.5 to 2.7 lower for grape varieties compared to T. tomentosa litter. Assimilation was significantly lower with Pinot Noir than the other litters. To conclude, after seven weeks of experimentation, this study showed that if the growth and survival of woodlice were not affected by inter-varietal differences in vine leaf quality, their role in the decomposition process may be strongly modulated and reduced, especially after consumption of grape variety litters rich in copper, lignin and tannin.

Floral scent of the Mediterranean fig tree: significant inter-varietal difference but strong conservation of the signal responsible for pollinator attraction

For thousands of years, humans have domesticated different plants by selecting for particular characters, often affecting less-known traits, including the volatile organic compounds (VOCs) emitted by these plants for defense or reproduction. The fig tree Ficus carica has a very wide range of varieties in the Mediterranean region and is selected for its traits affecting fruits, including pollination, but the effect of human-driven diversification on the VOCs emitted by the receptive figs to attract their pollinator (Blastophaga psenes) is not known. In the present study, VOCs from receptive figs of eight varieties in northern Morocco, were collected at different times within the manual pollination period and analyzed by gas chromatography-mass spectrometry. Genetic analyses using microsatellite loci were performed on the same varieties. Despite strong inter-varietal differences in the quantity and relative proportions of all VOCs, the relative proportions of the four pollinator-attractive VOCs showed limited variation among varieties. There was no significant correlation between genetic markers and chemical profiles of the different varieties. While diversification driven by humans has led to differences between varieties in VOC profiles, this paper suggests that throughout the process of domestication and varietal diversification, stabilizing selection has maintained a strong signal favoring pollinator attraction.

Comparative profiling of small-sized phenolics throughout maturation in grape seeds of six Vitis vinifera L. red varieties grown under normalized ambient and viticultural conditions

Phenolic composition of Vitis vinifera grape berry seeds is greatly influenced by genetic background, edaphoclimatic factors and cultural practices. Berry seed phenolics are major determinants of wine quality and core of emerging nutraceutical products. Profiling berry seed phenolics has usually controlled for particular variables, thus producing valuable data that may not be generalizable. Studies involving series of influencing variables are desirable. This study characterizes at five maturation stages the phenolic composition of seed extracts from six world-wide distributed grape varieties grown in a single valley under common edaphoclimatic and cultural conditions. Quantitative intervarietal differences in particular phenolics at corresponding maturation stages and differential progression of varietal phenolic profiles throughout maturation were observed. Throughout maturation, most of monomeric, dimeric and trimeric flavan-3-ols showed somewhat similar declines, in striking contrast to the invariability of the B2 procyanidin dimer. These findings highlight the relevance of a broad comparative perspective for defining berry seed phenolic profiles.

Evaluating Germplasm of Cultivated Oat Species from the VIR Collection under the Russian Northwest Conditions.

Oat is one of the most widespread and important cereal crops in the global agricultural production. Searching for new high-yielding and nutritious forms continues to be relevant, especially under the global trend of climate change, when most local oat cultivars may become economically inefficient. Spring oat accessions from VIR collection served as the material for this study; their origin is diverse, as they came from 11 countries. The basic nutritional value (the content of protein, oil, starch, and β-glucans) and characters important for breeding (plant height, panicle length, number of spikelets, number of grains per panicle, 1000 grain weight, and grain yield) were analyzed in 49 accessions of the cultivated covered oat species: Avena sativa L., A. strigosa Schreb., A. abyssinica Hochst., and A. byzantina Coch., grown under the conditions of the Russian Northwest (Leningrad Province) for two years. Variability parameters, interspecific and intervarietal differences, and the effect of weather conditions were assessed. Sources of useful agronomic traits were identified; they can be used to expand the range of the source material for the development of new high-yielding and highly nutritious oat cultivars adapted to local cultivation conditions. It is demonstrated that the VIR collection has a great potential for contemporary food and feed production and for the breeding of new oat cultivars for various purposes. Thus, the contribution of Nikolai Vavilov to the plant genetic resources investigation for the benefit of humanity is invaluable.

Impact of climate change on wheat grain composition and quality.

Wheat grain quality, an important determinant for human nutrition, is often overlooked when improving crop production for stressed environments. Climate change makes this task more difficult by imposing combined stresses. The scenarios relevant to climate change include elevated CO2 concentrations (eCO2 ) and extreme climatic events such as drought, heat waves, and salinity stresses. However, data on wheat quality in terms of climate change are limited, with no concerted efforts at the global level to provide an equitable and consistent climate risk assessment for wheat grain quality. Climate change induces changes in the quality and composition of wheat grain, a premier staple food crop globally. Climate-change events, such as eCO2 , heat, drought, salinity stress stresses, heat + drought, eCO2 + drought, and eCO2 + heat stresses, alter wheat grain quality in terms of grain weight, nutrient, anti-nutrient, fiber, and protein content and composition, starch granules, and free amino acid composition. Interestingly, in comparison with other stresses, heat stress and drought stress increase phytate content, which restricts the bioavailability of essential mineral elements. All climatic events, except for eCO2 + heat stress, increase grain gliadin content in different wheat varieties. However, grain quality components depend more on inter-varietal difference, stress type, and exposure time and intensity. The climatic events show differential regulation of protein and starch accumulation, and mineral metabolism in wheat grains. Rapid climate shifting impairs wheat productivity and causes grain quality to deteriorate by interrupting the allocation of essential nutrients and photoassimilates. © 2022 Society of Chemical Industry.

Investigation of genetic polymorphism of Russian rape and turnip rape varieties using SSR and SRAP markers.

Rapeseed (Brassica napus L.) and turnip rape (B. rapa L. subsp. campestris (L.)) are important agricultural plants widely used for food, fodder and technical purposes and as green manure. Over the past decades, a large number of perspective varieties that are being currently cultivated in every region of Russia have been developed. To increase the breeding eff iciency and facilitate the seed production, modern molecular-genetic techniques should be introduced as means to estimate species and varietal diversity. The objective of the presented research study was to investigate DNA polymorphism of the rapeseed and turnip rape varieties developed at Federal Williams Research Center of Forage Production and Agroecology and detect informative markers for varietal identif ication and genetic certif ication. To genotype 18 gDNA samples, 42 and 25 combinations of respective SSR and SRAP primers were used. The results obtained demonstrate that SRAP markers were more effective for polymorphism analysis: 36 % of the tested markers revealed genetic polymorphism compared with only 16.7 % of microsatellite loci. Molecular markers to detect differences at interspecif ic and intervarietal levels have also been found. For the investigated set, such microsatellite loci as Na12A02, Ni2C12, Ni02-D08a, Ra02-E01, Ni03H07а and SRAP-marker combinations as F13-R9, Me4- R7, F11-Em2, F10-R7, F9-Em2 and F9-R8 proved to be informative. Application of the two marker techniques made it possible to detect a higher level of DNA polymorphism in plants of different types (spring and winter varieties) if compared against the intervarietal differences within a species or a group. According to Nei’s genetic diversity index, in the cluster of winter rapeseed, VIK 2 and Gorizont varieties had the longest genetic distance, and in the spring cluster, these were Novosel and Veles. A high level of similarity was found between Vikros and Bizon winter rapeseed varieties. The results obtained have a high practical value for varietal specif ication of seed material and genetic certif ication of rapeseed and turnip rape varieties.

Continuity and change in the evolution of French yes-no questions

AbstractThis present study contributes to research on the structure of yes-no questions in French. Informed by previous historical linguistic research tracing developments from the Old French period onwards, we focus on qualitative analysis of grammatical commentary and variationist analysis of Acadian French spoken-language data. We compare the evolution of yes-no questions in Acadian, Metropolitan, and Quebec French, reconstructing the history of variants up to the present. While in most cases we encounter slow-moving change, we do find inter-varietal differences in degree of retention of individual variants, including outright loss; in development of stylistic differentiation; and in analogically based innovation. We also find inter-varietal differences in grammatical constraints governing usage and in the fine detail regarding sentential polarity, illuminated in terms of the semantico-pragmatic functions of negative yes-no questions. The overall results underline the importance of considering sociolinguistic histories, including histories of dialect contact, along with local linguistic markets.

Factors affecting total antioxidant activity and polyphenol content in beet root chips during production and storage

Relevance and methods. Chips are considered to be one of the most popular food products with high content of biologically active compounds. The aim of the present work was evaluation of quality and antioxidant self-life of beet chips from different cultivars. Effect of drying method (convection, freeze drying) and storage conditions (paper, vacuum plastic bags and aluminum foil) on beet root chips from 4 cvs self-life was investigated. Biochemical methods of analysis and tasting evaluation were used.Results. Beet intervarietal differences in self-life of chips fat soluble antioxidants were indicated. Paper bags were shown to produce the highest AOA and phenolics values of convection drying products contrary to freeze drying chips in vacuum plastic bags. Differences in AOA and phenolics self-life of products produced via convection and freeze drying are absent. Tasting evaluation (appearance, taste, texture, aroma) revealed the lowest score for Gaspadynya cv. The highest polyphenols loss in chips stored in aluminum foil was typical for Gaspadynya cv chips, while storage in paper bags – for chips from Dobrynya cv chips. In a whole, the results of the present investigation indicate the importance intervarietal differences in beet chips production, as genetic differences determine taste and storability of the product.

Instrumental assessment of the formation of the elemental composition of wines with various bentonite clays

The work is devoted to the study of the influence of clarification and stabilization of wines with bentonite clays (BT) on their elemental composition, which determines their varietal differences. Raw wine samples produced from grape varieties Cabernet Sauvignon, Merlot and Moldova in the Krasnodar Territory were clarified and stabilized with 32 BT samples of various degrees of dispersion and trademarks. The ICP-OES and ICP-MS methods were used to quantify 39 elements in 96 treated and 3 untreated wine samples, as well as BT samples. To establish possible mechanisms of metal exchange in the studied samples, a qualitative and quantitative phase analysis of the components was carried out, according to which BT were divided into four groups. The wine samples treated with BT of various groups had a different chemical composition, which differed from the initial ones in the concentration of almost all the determined elements. At the stabilization and clarification stages of wines with BT samples, a violation of the relationship between the elemental composition of wine, grapes and soil was observed. It was noted that when identifying marker elements determining the varietal affiliation of wine, it is necessary to take into account the contribution of BT to the formation of its elemental composition. Considering the contents of 16 isolated metals in the treated wine samples, the presence of cluster structures was established by the discriminant analysis and principal component analysis, indicating the preservation of intervarietal differences and intravarietal similarity after treatment with BT. BT did not change the varietal identity of wines, but influenced their elemental composition.

Application of SCoT markers for accessing of genetic diversity of gramineous forage grass species

Using the SCoT marker system, 8 varieties of cereal grasses belonging to 5 species were analyzed: Festuca pratensis, Lolium perenne, Lolium multiflorum, Festuca rubra, Festulolium. Of the 10 tested SCoT markers, 7 informative markers were selected that reveal interspecies genetic polymorphism. According to the results of the analysis, DNA profiles characteristic of each studied species were obtained, and primers allowing to detect intervarietal differences for subsequent identification and molecular genetic passportization were selected.

Phenotypic variability of seedling organs of winter triticale varieties and its relationship with economically valuable features

The degree of seedling organ development is recommended for predicting seed yield properties and selecting valuable forms for selection. However, most work has been done on spring crops. The research was conducted during 2018 to 2020 at the Izhevsk State Agricultural Academy, Russia with an objective to determine the nature and the strength of the relationship between the degree of seedling organ development of different varieties of winter triticale with economically valuable features for further use in selection and seed production work. The character of seed germination of 10 winter triticale varieties, which were subsequently sown under laboratory conditions on two mineral nutrition backgrounds: sowing without fertilizer, N30 fertilizer in spring; before sowing fertilizer N32P32K32, N30fertilizer in spring, foliar Nfertilizer in the earing phase. During the growing season winter hardiness, productive tillering, and ear weight were evaluated. The correlation analysis between the given parameters and parameters of seedlings (coleoptile length, sprout, and length and number of germinal roots) was carried out. As a result of studies, significant inter-varietal differences in parameters of winter triticale seedlings were established, which allowed them to be considered as varietal features. Fractional application of fertilizers provided better development of plants, winter hardiness increased on average by 0.3 points (NSR05 = 0.1 points), productive tillering by 0.2 units (NSR05= 0.1 points), and ear weight by 0.15 g (NDS0.5=0.04 g). Tulus variety was the most responsive to fertilizer application. Sprout length and germinal root length can serve as an indirect indicator of winter hardiness since a direct average and strong correlation (r = 0.54…0.85) was established between these indicators in most varieties.

Pulsed magnetic field impact on adaptation and vegetation of strawberry microplants (<i>Fragaria×ananassa</i> Duch.)

Microplant adaptation to non-sterile conditions is critical in clonal micropropagation providing for plant establishment and the overall method efficiency. Various techniques are employed to facilitate microplant establishment, including physical exposures like pulsed magnetic field. The study aimed to investigate the effect of pulsed magnetic field on establishment during adaptation to non-sterile conditions and subsequent vegetation of adapted strawberry plants. Research focused on strawberry microplants of the Tsaritsa and Nashe Podmoskovye cultivars originated by the All-Russian Horticultural Institute for Breeding, Agrotechnology and Nursery. Magnetic pulse treatment (MPT) was carried out with an AMIS-8 magnetic stimulator developed at the Institute. A positive impact of some MPT modes on microplant establishment, leaf and stolon formation was registered during strawberry adaptation to non-sterile conditions. Relatively low frequencies of 0.8-21 Hz exerted best effect in strawberry for most criteria. MPT contributed to an 11.5 % improvement in microplant establishment in Nashe Podmoskovye and 23.1 % — in Tsaritsa cultivars vs. no treatment. In best MPT assays, the number of leaves increased by 9.2—15.4 % and of stolons — 6.2-6.5 times in adapted strawberry plants compared to control. No significant inter-varietal differences were observed in Nashe Podmoskovye and Tsaritsa for vegetation criteria during adaptation to non-sterile conditions.

Coordinated impact of ion exclusion, antioxidants and photosynthetic potential on salt tolerance of ridge gourd [Luffa acutangula (L.) Roxb.

The contribution of one major or a combination of several physiological processes in salt tolerance was assessed in three local varieties (Blacklong, Advanta-1103, and Dilpasand) of ridge gourd [Luffa acutangula (L.) Roxb.] at varying salt levels (0, 75, and 150 mM NaCl). Based on growth attributes, var. Dilpasand as salt-tolerant and var. Blacklong as moderately salt-tolerant, while var. Advanta-1103 as salt-sensitive. Inter-varietal differences for photosynthetic pigments and relative water content (RWC) was not observed. The salt-sensitive variety Advanta 1103 had greater Na+ accumulation (73.72%) in the leaves than those in the moderately tolerant and tolerant varieties. Total soluble proteins were relatively lower (58.25%) in the salt-sensitive variety but maximal increase (69.34%) in total free amino acids was observed. However, accumulation of proline was maximal in the salt-tolerant variety (Dilpasand). Salt-tolerant variety exhibited minimal oxidative stress (relative low levels of H2O2) and membrane damage (low content of MDA and electrolytic leakage) and higher activities of antioxidant enzymes (catalase and peroxidase). Although all ridge gourd varieties down-regulated the electron transport through PSII by increasing the safe dissipation of heat Y(NPQ) to lower the ROS generation, this was maximal in the salt-tolerant variety Dilpasand. Relatively greater reduction in Y(ND) and enhancement in Y(NA) indicated PSI-photoinhibition in salt-sensitive variety. The greater salt tolerance in var. Dilpasand was due to the coordinated impact of ion exclusion, higher accumulation of proline, better capacity to manage electron transport from PSII to PSI with higher Y(NPQ) and antioxidant capacity.

The indicator of cell membrane permeability of wheat seedlings in assessing stress resistance of wheat varieties

The paper presents the results of studies on the use of the permeability index of cell membranes, determined by the relative change in the specific electrical conductivity (EC) of water extracts of tissues of spring wheat seedlings, varieties Novosibirskaya 18, Novosibirskaya 44, Sibirskaya 21 and Omskaya 18, under the combined action of stressors. In model laboratory vegetation experiments, the hourly dynamics of the EC of water extracts of seedling leaves (exposure of leaves to water for 0.5-4.5 h) was investigated under the simultaneous action of chloride salinity (1.3%) and the causative agent of common rot of cerealsBipolaris sorokinianaShoem. (5000 conidia per grain). It was established that EC increased by 1.5 times and the rate of electrolyte leakage increased twofold in the less resistant variety Novosibirskaya 44 compared to the more resistant Omskaya 18. The daily dynamics of the EC of 10-16-day-old seedlings was studied under the sequential action of seed hyperthermia (43 °C), chloride salinity (1.3%), andBipolaris sorokinianaShoem. (5000 conidia per grain). The protective effect of hyperthermia was established in the more resistant variety Sibirskaya 21 (a decrease in EC up to 1.3 times) in comparison with the variant without heating the seeds. In the less resistant variety Novosibirskaya 18, heating the seeds destabilized the state of the cell membranes (increase in EC and electrolyte leakage rate by 1.5 and 1.2 times respectively). The conditions that ensure the identification of the maximum differences in the studied wheat varieties were experimentally determined: the age of seedlings 10 days, the time interval of exposure of the samples to water 1.5-4.5 h. Intervarietal differences in the relative change in the EC values in the variant without heating the seeds were 1.9 times and in the variant with heating the seeds - 3.7 times, with the significance of difference at the levelsp≤ 0.05 andp≤ 0.01. Intervarietal differences in the relative change in the EC, established for the time interval exposition of electrolytes leakage of 1.5-4.5 h, were 1.50-1.67 times with the significance of difference at the level ofp≤ 0.05. The proposed approach will make it possible to develop a methodology for assessing new genotypes for resistance to the combined action of biotic and abiotic stressors.