Relative Water Content Values Research Articles

Monitoring plant responses in field-grown peanuts exposed to exogenously applied chitosan under full and limited irrigation levels

In recent decades, numerous studies have examined the effects of climate change on the responses of plants. These studies have primarily examined the effects of solitary stress on plants, neglecting the simultaneous effects of mixed stress, which are anticipated to transpire frequently as a result of the extreme climatic fluctuations. Therefore, this study investigated the impact of applied chitosan on boosting the resistance responses of peanuts to alkali and mixed drought-alkali stresses. Peanuts were grown in mid-alkaline soil and irrigated with full irrigation water requirements (100%IR), represented alkali condition (100% IR × alkali soil) and stress conditions (70% IR × alkali soil—represented mixed drought-alkali conditions). Additionally, the plants were either untreated or treated with foliar chitosan. The study evaluated various plant physio-chemical characteristics, including element contents (leaves and roots), seed yield, and irrigation water use efficiency (IWUE). Plants that experienced solitary alkali stress were found to be more vulnerable. However, chitosan applications were effective for reducing (soil pH and sodium absorption), alongside promoting examined physio-chemical measurements, yield traits, and IWUE. Importantly, when chitosan was applied under alkali conditions, the accumulations of (phosphorus, calcium, iron, manganese, zinc, and copper) in leaves and roots were maximized. Under mixed drought-alkali stresses, the results revealed a reduction in yield, reaching about 5.1 and 5.8% lower than under (100% IR × alkali), in the first and second seasons, respectively. Interestingly, treated plants under mixed drought-alkali stresses with chitosan recorded highest values of relative water content, proline, yield, IWUE, and nutrient uptake of (nitrogen, potassium, and magnesium) as well as the lowest sodium content in leaves and roots. Enhances the accumulation of (N, K, and Mg) instead of (phosphorus, calcium, iron, manganese, zinc, and copper) was the primary plant response to chitosan applications, which averted severe damage caused by mixed drought-alkali conditions, over time. These findings provide a framework of the nutrient homeostasis changes induced by chitosan under mixed stresses. Based on the findings, it is recommended under mixed drought-alkali conditions to treat plants with chitosan. This approach offers a promising perspective for achieving optimal yield with reduced water usage.

Mitigation of water stress by compost and arginine application and its impacts on barley production

BackgroundWater-scarce locations necessitate the deployment of creative and sustainable techniques for managing water for agricultural production. Field experiment was conducted at the Experimental Research Farm of National Research Centre, Nubaria region, Egypt to alleviate the harmful effect of water stress on the yield of Mediterranean barley varieties (Giza 125, Tombari, Ksar Megrine and Tamellat) by compost (0.0, 2.0, 4.0, 6.0-ton fed−1) and arginine application (0.00 and 1000 ppm) under deficit irrigation. The amounts of irrigation water applied were “900 and 450” m3 fed−1 to sufficient irrigation and deficit irrigation, respectively.ResultsThe greatest and most significant values of the chlorophyll values and relative water content values obtained at the treatment supplied with 6.0-ton compost fed−1 and sprayed with Arginine. There was a significant dramatic decrease in proline content with increasing compost application rates and treated barley plants by Arginine for all the studied barley varieties under both studied irrigation treatments. Increasing compost application rate is associated with significant increase in number of spike m−2 without or with arginine. Barley Tombari variety received 6.0-ton compost fed−1 gained changes to give a greatest significant value of grain (ton fed−1) under sufficient irrigation and Tamellat under deficit irrigation situation. The significant maximum values of the grain yield (1.96- and 2.09-ton fed−1) were attained at Tombari and Tamellat varieties which received 6.0-ton fed−1 compost with or without arginine under sufficient irrigation. The increases in compost rate increment changes to incremented grain yield values with arginine application more than untreated one. The greatest and significant grain yield was found at the treatment received 6.0-ton compost fed−1 with arginine foliar application.ConclusionCompost application has an important role in maintaining greatest water use efficiency for plant and arginine application reported to contribute in reduction in destructive effects of a biotic stress thus their importance in increasing the barley production under water stress.

MORPHOPHYSIOLOGICAL CHANGES IN SEEDLINGS OF Eugenia uniflora L. AFTER CHEMICAL HARDENING

Using quality seedlings increases the chances of survival and development after planting. Hardening aims to modify the morphology of seedlings to acclimatize them to stressful field conditions. The objective of this study was to quantify the effects of chemical hardening with methyl jasmonate on the morphophysiology of Eugenia uniflora L. seedlings subjected to 12 days of water deficit. Seedlings were hardened with doses of 0, 50, 100, and 150 μmol L-1 of methyl jasmonate (MeJA). Afterward, they were transplanted into pots with soil and subjected to water deficit for 12 days. During that period, we assessed shoot height (H), stem diameter (SD), leaf area (LA), leaf dry mass (LDM), stem dry mass (SDM), root dry mass (RDM), total dry mass (TDM), relative water content (RWC), robustness index (RI), Dickson quality index (DQI), shoot/root ratio (S/R), stomatal conductance (Sc) and evapotranspiration (ET). The experiment was conducted in a randomized block design with five blocks. Variables RI, DQI, LA, RWC, and TDM values presented a quadratic trend, with promising results from the 50 and 100 µmol L-1 doses. Sc and ET values were influenced by water deficit. Under conditions of water restriction, application of MeJA in adequate doses promoted morphophysiological changes and induced defense strategies in E. uniflora seedlings. Doses of methyl jasmonate between 50 and 100 µmol L-1 resulted in seedlings with greater tolerance to water deficit for 12 days.

Rationalization of the Water Requirement of the Cabbage Crop by Using Zeolite and Silica Gel and Their Effect on some Water Parameters of the Leaves of the Cabbage Crop

A field experiment was conducted at the research station of the Department of Soil Sciences and Water Resources, which is 66 km east of the city of Baghdad during the fall agricultural season for the year 2021. It is located at latitude 10.679" 33° 41′ north, longitude 36.569" 35′ 43° east and at an altitude of 43 m above. Sea level The study aimed at the effect of zeolite and silica gel in rationing the water requirement of the cabbage and some of the physical soil characteristics and the growth and yield of the cabbage plant. The experiment was designed according to the distribution of split-split boards in a completely randomized block system (R C B D) with three replications. The experiment included three factors, the first Which occupied the main panels is zeolite ((Z) with three levels (without adding zeolite Z0, adding 25 g to each plant Z1, adding 50 g to each plant Z2), and the second factor is silica gel (S) and with three levels (without adding silica S0, adding 10 g to each plant S1, adding 20 gm plant S2), and the third factor is the water requirement of the plant in two levels (adding the full amount of 100% of the water requirement for the plant W1, adding 50% of the water requirement for the cabbage plant W2). The dimensions of the experimental unit are 1.5 × 4 m, with an area of (6 m2) for one experimental unit. The most important results obtained can be summarized as follows: The highest value of relative water content % and the ability to bind water % and the ability to absorb water in treatment W1Z2S2 reached 87.96%, 10.733%, 6.123%, respectively. The lowest value of relative saturation deficit in treatment W1Z2S2 was 12.03%.. The interaction treatment between water requirement, zeolite and silica gel recorded a significant effect when treating W2Z2S2 in the ability to absorb water, as it recorded the highest value of 79.29% compared to the treatment W1Z0S0, which had the lowest value of 23.39%.

Seasonal Hydration Status of Common Bryophyte Species in Azorean Native Vegetation.

Bryophytes play a crucial role in the ecosystem's water compartment due to their unique ability to retain water. However, their role within temperate native ecosystems is mostly unknown. To address this knowledge gap, a study was conducted on Terceira Island (Azores), focusing on 14 bryophyte species found at different altitudes (40 m, 683 m, and 1012 m); five samples were collected monthly, per species and location, and their fresh, saturated, and dry weights were examined in the laboratory; four species were collected from more than one site. Generalized linear models (GLM) were used to assert the influence of climate factors (temperature, precipitation, and relative humidity) and environmental variables on two water indicators: field water content (FWC) and relative water content (RWC). None of the examined factors, per se, were able to explain all cases. Species appear to respond to climate according to a limiting factor effect: at lower elevations, precipitation was determinant, while at medium elevations, FWC was influenced by a combination of precipitation and relative humidity. At higher elevations, temperature was retained for seven of the nine studied species. The RWC values indicated that the 14 bryophyte species remained hydrated throughout the year but rarely reached their maximum water-holding capacity, even at the highest altitude. Understanding the mechanisms by which native bryophytes acquire, store, and release water is crucial for comprehending the resilience of native vegetation in the face of climate change. This knowledge can also enable the development of strategies to mitigate the effects of climate change and protect vital water resources.

Six tree species physiological responses to air pollution in Pulogadung Industrial Estate, East Jakarta, Indonesia and Universitas Indonesia Campus, Depok, Indonesia

<span>Air pollution is a global issue that has a harmful impact on living things and the environment. It is commonly recognized that bioremediation, including the use of tree plants, helps reduce air pollution. Tree plants can respond physically to air pollution. The value of the air pollution tolerance index (APTI) can be used to determine the physiological response. Based on APTI values, this study seeks to determine the tolerance levels and physiological response differences of six tree plant species (<em>Mangifera indica, Pterocarpus indicus</em>, <em>Cerbera odollam</em>, <em>Pometia pinnata</em>, <em>Syzygium myrtifolium</em>, and <em>Swietenia macrophylla</em>) in Pulogadung Industrial Estate, East Jakarta and Universitas Indonesia (UI) Campus, Depok. Environmental factors and APTI values with relative water content parameters, leaf extract pH, ascorbic acid content, and total chlorophyll content were measured in six kinds of tree plants at both research sites. The maximum APTI score in the Pulogadung Industrial Estate was 9.79 0.13, indicating that <em>Mangifera indica</em> plants are air pollution tolerant. Meanwhile, <em>Pterocarpus indicus </em>is classified as sensitive to air pollution, with the lowest APTI score of 6.59 0.18 at the UI Campus, Depok. The APTI test results revealed that tolerant species had high relative water content (RWC) values and ascorbic acid concentration, whereas sensitive species had low RWC values and poor total chlorophyll content.</span>

Impact of conservation tillage practices on the growth and yield of blackgram (Vigna mungo) in rice (Oryza sativa)-blackgram cropping system

A field experiment was conducted during post rainy seasons of 2015–16, 2016–17 and 2017–18 (December-March) at research farm of Tamil Nadu Rice Research Institute, Aduthurai, Tamil Nadu to study the impact of tillage practices adopted in the rice (Oryza sativa L.) crop on the succeeding blackgram (Vigna mungo L.) grown as relay cropping. The treatment comprised of 2 tillage practices (puddled and non-puddled), 3 seed priming methods (Bio-seed priming with Rhizobium, hydropriming and no seed priming) and 2 foliar spray (2% DAP and 2% urea). The results indicated though blackgram grown as succeeding crop in the puddled tillage registered higher values of Relative water content (RWC) (83.06 and 83.72%), Specific leaf weight content (SLW) (6.83 and 6.28 g/cm2), Soil Plant AnalysisDevelopment chlorophyll meter values (40.88 and 39.75) at 30 and 45 DAS respectively, it was comparable with non-puddled tillage method. However, the blackgram sown as succeeding crop in non-puddled transplanted rice registered a greater number of nodules (23.67 and 17.44) and nodules dry weight (0.17 and 0.11 g) at 30 and 45 DAS respectively as compared to puddled transplanting. Similarly, the root length (6.93 and 8.62 cm) and root dry weight (0.151 and 0.174 g at 30 and 45 DAS respectively) were also higher with non-puddled tillage. The yield obtained under non-puddled tillage system was 11.8% higher than puddled method of tillage system. Bio-seed priming with rhizobium had higher values of growth and yield parameters, which eventually resulted in 25.0% yield increase over no seed priming. As far as foliar spray concerned, DAP 2% spray and Urea 2% spray did not differ significantly for none of the parameters except for yield.

Eco-Physiological Behavior of Five Tunisian Olive Tree Cultivars under Drought Stress

Tunisia is known to be a country with poor water resources, and water scarcity is evident in certain regions. In the long term, this situation could worsen, given the increased risk of drought. The olive tree (Olea europaea L.) is one of the plants best adapted to this climate, and numerous studies have been carried out to assess the effects of water stress. The aim of this work was to study and compare the ecophysiological behavior of a main Tunisian olive cultivar (Chetoui) and four rare Tunisian olive cultivars (Chemchali, Besbessi, Sayali and Jarboui) under drought stress and to identify the main parameters while comparing the tolerance of the cultivars studied to this abiotic stress. One-year-old olive trees grown in pots in a greenhouse were subjected to four drought treatments (i.e., 15, 30, 45 and 60 days of drought stress) in comparison with control trees. The evaluation of the response of the olives to this induced stress was based on five parameters: relative water content (RWC), stomatal resistance (SR), photosystem PSII, maximal photochemical efficiency (FV/FM), performance index on absorption basis (PI), measured by the handy PEA, and chlorophyll index, measured by SPAD. The relative water content (RWC) of the five cultivars decreased with increasing drought stress. Jarboui showed lower RWC values than Chemchali, especially under severe drought stress. This result was confirmed by changes in fluorescence characteristics. FV/FM, PI and SPAD index decreased during the development of drought stress. These observations are discussed in relation to the strategies developed by the cultivars to grow under drought stress. The Principal Component Analysis allowed the parameter with the strongest loading factor, which is FV/FM, to be highlighted and the cultivars most tolerant to drought stress to be distinguished. These cultivars, Besbessi and Sayali in the north of Tunisia and Chemchali in the south, can present a possible alternative to replace the local or foreign cultivars most cultivated in the country, which are characterized by high water needs.

Changes in physio-biochemical parameters and expression of metallothioneins in Avena sativa L. in response to drought

Drought is one of the major threats to food security. Among several mechanisms involved in plant stress tolerance, one protein family—the plant metallothioneins (MTs)—shows great promise for enhancing drought resistance. Plant metallothioneins in oat (Avena sativa L.) have not yet been deeply analysed, and the literature lacks a comprehensive study of the whole family of plant MTs in response to drought. In this study, we showed that the number and nature of cis-elements linked with stress response in promoters of AsMTs1–3 differed depending on the MT type. Drought stress in oat plants caused an increase in the expression of AsMT2 and AsMT3 and a decrease in the expression of AsMT1 compared to well-watered plants. Moreover, the low values of relative water content, water use efficiency, net photosynthesis (PN), transpiration (E), stomatal conductance (gs), chlorophyll a, and carotenoid were accompanied by high levels of electrolyte leakage, internal CO2 concentration (Ci) and abscisic acid content, and high activity of antioxidants enzymes in plants under drought stress. The present study puts forward the idea that AsMTs are crucial for oat response to drought stress not only by regulating antioxidant activity but also by changing the plant water regime and photosynthesis. Our results support the hypothesis that structural differences among types of plant MTs reflect their diversified physiological roles.

Morphological and Physiological Responses of Grafted Melon Subjected to Fusarium Wilt and Water Stress

This study aimed to determine the effects of different rootstocks on crop water stress index (CWSI), some morphological and physiological parameters of grafted melon under soil-borne pathogen (Fusarium oxysporum f.sp.melonis) and water stress conditions. The study was carried out in Çumra District of Konya Province in Türkiye for two years. The main plots consisted of three different irrigation levels and the sub plots consisted of subjects with melon plants with different rootstocks. The experiment was carried out in a split-plot design with three replications. In the study, four different rootstocks; 1-Ungrafted, 2-Ferro, 3-Maximus and TZ 148 were used. Edalı F1 variety (Cucumis melo var. Edalı F1) was used as a scion in the experiment. Irrigation was done in the four vegetation periods (early vegetative, late vegetative, flowering-fruit setting and ripening) of plant. Irrigation consisted of issues to increase soil depth from 0-90 cm to field capacity (I100), 50% (I50) of soil available water field capacity and rainfed (I0). As a result of the experiment, while leaf water potential (LWP) and leaf relative water content (RWC) increased with the increase of irrigation water in both years, the chlorophyll content was higher in I100, stomatal conductance was the highest in I50 of irrigation water, while the increase in irrigation water decreased stomatal conductance. In terms of physiological parameters measured in the plant, chlorophyll content and RWC values in the first year, Ferro, TZ-148 and Maximus rootstock, respectively, in the second year, Maximus rootstock reached the best value stem diameter in both years. CWSI was also affected by the applications.

Interspecific differences in desiccation tolerance of selected Antarctic lichens: Analysis of photosystem II effectivity and quenching mechanisms

Lichens can survive and cope with unsufficient water supply resulting in low intrathalline relative water content. Under such conditions, photosynthesis is negatively affected by different degree of dehydration. In our study, fully hydrated samples of Xanthoria elegans, Umbilicaria decussata and Usnea aurantiaco-atra were light-acclimated and during following desiccation from a fully hydrated to dry state, steady-state chlorophyll fluorescence (FS), effective quantum yield of photochemical processes in PSII (ФPSII), and nonphotochemical quenching (qN) were measured in response to decreasing relative water content (RWC). The three experimental lichen species showed a high desiccation tolerance. The desiccation-induced decrease in ФPSII was found in X. elegans, U. decussata and U. aurantiaco-atra, at the RWC values below 30%. This is well comparable to the evidence reached in other Arctic / Antarctic lichen species. Interspecific differences in desiccation tolerance of these selected Antarctic lichens, based on the analysis of photosystem II effectivity and quenching mechanisms, were described and discussed.

Agronomic Performance of Chickpea Affected by Drought Stress at Different Growth Stages

Susceptibility to drought stress has restrained chickpea productivity at a global level, and the development of drought-tolerant varieties is essential to maintain its productivity. Therefore, the present study was conducted to evaluate genetic divergence in selected genotypes of chickpea and their morpho-physiological responses under irrigated and stressed conditions to identify the traits that account for the better performance of these genotypes under stressed conditions, as well as genotypes with improved drought tolerance. The genotypes were evaluated for two years under irrigated and drought stressed conditions, and significant variation was found amongst the genotypes for different morpho-physiological and yield traits. The maximum reduction was observed for plant yield (33.23%) under stressed conditions. Principle component analysis (PCA)-based biplots and correlation studies established its strong positive correlation with relative water content (RWC), membrane stability index (MSI), chlorophyll index (CI), secondary branches (SB) and yield traits and negative correlations with drought susceptibility index (DSI), days to maturity (DM) and 100 seed weight (100 SW) under drought stress, suggesting their use in selecting drought-tolerant germplasm. Ten genotypes with high values of RWC, MSI, CI, SB, yield traits and lower DSI were identified as drought-tolerant and might serve as ideal donors in the forthcoming breeding of elite chickpea cultivars. The seed-filling stage began earlier in these genotypes, with significantly reduced days to maturity under stressed conditions. Our results indicate selection for earliness offers a promising strategy for the development of drought-tolerant chickpea cultivars.

Physiological and Genetic Variation of Hordeum vulgare L. and Triticum aestivum L. Lines Planted in Turkey

Hordeum vulgare L. (barley) and Triticum aestivum L. (wheat) are among the most valuable crops cultivated and planted in many regions including Turkey. These plants have wide range of adaptation ability and capacity; they represent high level of variation in terms of physiological, genetics and epigenetics parameters and characteristics. Physiological and genetic variations were investigated by relative water content (RWC) assays, measuring electroconductivity (EC) levels and amplification of microsatellite markers in 21 barley and 43 wheat lines. At least three drought sensitive and three drought resistant lines were detected in barley and wheat lines via RWC assays. RWC values were recorded between 0.05±0.013 and 0.55±0.003%. Similarly great variation was detected for EC values of both barley and also wheat lines. Minimum and maximum EC values were ranged from 4.00±0.06 μS cm-1 to 59.88±3.209 μS cm-1. Three microsatellite markers, Bmag0120, Bmag0306 and Bmag375, were targeted in barley genome. Similarly, Han18, Wmc506 and Wmc623 microsatellite markers were targeted in wheat genome. Among these markers only Bmag0120 and Han18 were amplified from each line’s genome by PCR and qPCR assays. In PCR and qPCR analysis homozygous and heterozygous lines were detected for Bmag0120 while each line was homozygous for Han18. Idiomorphic band size as 300 bp was detected in Han18 while it was ranged from 224 to 279 bp for Bmac0120 marker. Results showed that homozygous lines were drought resistant ones in barley lines whereas no correlation was found for wheat lines investigated in this study.

Screening for drought tolerance potential of nine cocoa (Theobroma cacao L.) genotypes from Ghana

This study was conducted with a view to screen nine genotypes of Cacao from The Cocoa Research Institute of Ghana (CRIG) to test their abilities to withstand drought stress conditions using parameters such as leaf relative water content (RWC), proline accumulation in leaves and trichomes. The experimental design consisted of three replicates of the genotypes used and these were laid out in Complete Randomized Block Design (CRBD) to determine the drought tolerance potentials of the nine genotypes of cocoa at the seedling stage. Two water treatments were used which involved withholding water from one day after full saturation with water prior to the first appearance of drought symptoms (FADS) and watering every two days to the completion of the experiment. Results in this research revealed that proline was found to gather in water-stressed seedlings, and the differences in the mean proline amounts in the genotypes was found to be significant. Genotype T63/971 x Sca9 had the most elevated concentration of free proline at FADS (4 μg/g DW) followed by genotype T60 x Pound10 (3.5 μg/g DW) whereas genotype PA150 × 9006 had the smallest amount of accumulated proline in leaves. Genotype PA150 × 6020 had the highest RWC and SMC of 65% and 1.5% respectively at FADS whilst genotype PA7 x 6035 had the lowest RWC of 43%. There was a direct relationship between the amounts of free proline of genotypes T63/971 x SCA9 and T60 x POUND10 and their respective RWC of the leaves. Genotypes T63/971 x SCA9 and PA150 × 9006 had the highest and lowest numbers of trichomes respectively. Inference from this study revealed that T63/971 x SCA9 and T60 x POUND10 genotypes appear to be the most drought-tolerant genotypes in view of their relatively high values of free proline content, leaf RWC, trichomes and lower values of soil water use (SMC).

Mitigation of High-Temperature Damage by Application of Kaolin and Pinolene on Young Olive Trees (Olea europaea L.): A Preliminary Experiment to Assess Biometric, Eco-Physiological and Nutraceutical Parameters

Various products are used to mitigate the negative effects of abiotic stress in olive trees. The aim of the research was to examine an anti-transpirant product (Vapor Gard®, V) and a kaolin- based product (Manisol, K) effect on the growth of two-year-old olive tree seedlings under high temperature. The study was conducted in a greenhouse on trees of a native cultivar of Campania (cv. Salella) grown in pot during the growing season from May to September 2020. The experimental design included two products: di-1-p-menthene (product V) and kaolin (product K), applied five times at 20 day intervals compared with a control. The following biometric, physiological, and nutraceutical parameters were evaluated: stomatal conductance, chlorophyll a fluorescence, Soil Plant Analysis Development (SPAD) index, relative water content (RWC), shoots growth, total leaf area per plant, trunk cross-sectional area, dry matter partitioning, total polyphenols, and antioxidant activity. The results obtained showed that the application of di-1-p-menthene (V) was able to induce a significant improvement of shoots growth (+37.22%) and trunk cross-sectional area (+46.60%) and a reduction of the stomatal conductance and an increase of leaf RWC values. Application with kaolin had positive effects on the total polyphenol content, with an increase over the control of 240.33% and higher antioxidant activity values. Further studies are necessary to determine the effect of these products on the biometric, physiological and nutraceutical parameters of mature olive trees cultivated in open field conditions.

Seed discontinuous hydration does not benefit germination, but improves drought tolerance of Triplaris gardneriana seedlings

The discontinuous seed hydration enables the acquisition of tolerance to environmental stresses, causing a stress imprint. It may modify metabolic patterns and lead to improved stress responses. This study aims to evaluate the effects of discontinuous hydration on germination and on seedling growth of Triplaris gardneriana Wedd. under intermittent drought. The seeds have gone through cycles (0, 1, 2 and 3) of hydration and dehydration (HD). The seedlings produced were subjected to water deficit (daily watering and intervals of seven and fourteen days between watering). Seed germinability parameters and, relative growth rate (RGR) of seedling, leaf area, dry matter yield and leaf relative water content (RWC) were evaluated. The HD cycles did not benefit germination, but two HD cycles induced a better biomass accumulation and increased leaf area in seedlings under moderate water deficit, while three HD cycles promoted an increase in RGR and influenced the RWC values. Severe stress affects seedling growth, but subjection to HD cycles minimizes the deleterious effects of drought, suggesting discontinuous hydration acts leading stress imprint in plants.

Evaluation of Drought Tolerance of Some Wheat (Triticum aestivum L.) Genotypes through Phenology, Growth, and Physiological Indices

Increasing human population and changing climate, which have given rise to frequent drought spells, pose a serious threat to global food security, while identification of high yielding drought tolerant genotypes remains a proficient approach to cope with these challenges. To offer a methodology for the evaluation of the drought-tolerant wheat genotypes based on the pheno-physiological traits, a field experiment was executed, entailing four wheat genotypes viz. BARI Gom 26, BAW 1158, BAW 1167, and BAW 1169 and two water conditions viz. control treatment (three times irrigation at 20, 50, and 70 DAS, i.e., 100% field capacity) and stressed treatment (no irrigation during the entire growing season). The results revealed that drought stress drastically reduced the days to booting, heading, anthesis and physiological maturity, relative water content (RWC), chlorophyll content, canopy temperature depression (CTD), and photo-assimilates-spike dry matter (SDM), grains spike−1 and grain yield of all wheat genotypes. In addition, the genotypes BAW 1167 and BARI Gom 26 remained more prone to adverse effects of drought as compared to BAW 1169 and BAW 1158. Furthermore, DS induced biosynthesis of compatible solutes such as proline, especially in BAW 1169, which enabled plants to defend against oxidative stress. It was inferred that BAW 1169 remained superior by exhibiting the best adaptation as indicated by the maximum relative values of RWC, total chlorophyll, CTD, proline content, SDM, grains spike−1, and grain yield of wheat. Thus, based on our findings, BAW 1169 may be recommended for general adoption and utilization in future wheat breeding programs aimed at developing potent drought-tolerant wheat genotypes to ensure food security on a sustainable basis.

Wheat (Triticum aestivum L.) Reaction to New Bifunctional Carbamate Compounds

Extreme environmental conditions increase the risk of abiotic stresses in plants, which reduce productivity of land. The investigation and developmentof synthetic approach to new antistress compounds, increasing the resistance of plants to negative factors, are relevant to the present. The objective of this study was to synthesize and to test the effect of a series of new carbamate and oxamate plant growth regulators on early vegetation processes of wheat (Triticum aestivum L.). Three independent series of experiments were conducted using lipophilic compounds N-(2,4-Dimethylphenyl)-N’-i-propoxycarbonylaminoethylurea (1) and O-Isopropyl-N-[2-(4-methylphenylaminocarbonyloxy)etyl]oxamate (2) and water-soluble compounds O-i-Propyl-N-(2-hydroxyethylamino)carbamate (3) and O-i-Propyl-N-(2-hydroxyethyl)oxamate (4). Strong stimulating effect on shoots and roots growth in the wheat was found for all studied compounds in all experiments. The highest germination rate (89.6-96.3%) was registered for compound 4. The use of the studied substances 1, 3 and 4 in all cases leads to significant increase in the Seedling Vigor Index (SVI). The high energy index of compounds 3 and 4 can lead to increased photosynthesis and, as a result, to an increase in crop yield. Based on the data obtained on the values of relative water content (RWC) indicators and their components, it can be assumed that all plants after treatment with substances 1-4 are able to tolerate unfavorable weather phenomena. Experimental results show that the percentage of plant recovery after resuming watering was 84-100%. Thus, the data obtained indicate that the synthesized compounds exhibit antistress and growth regulatory activity.

Effect of Acacia saligna (Labill.) Wendl. extracts on seed germination and seedling performance of three native Mediterranean shrubs

ABSTRACT Invasive exotic species are an ongoing cause of native biodiversity degradation, and allelopathy may assist in the degradation process. We studied the allelopathic potential of leaf and root aqueous extracts of Acacia saligna (Labill.) Wendl. in the early settlement of three native Mediterranean shrubs (Astragalus armatus Willd., Retama raetam (Forssk.) Webb & Berthel., and Helianthemum kahiricum Del.). Aqueous extracts were applied at 0%, 5%, 10%, 15%, and 20%. For all three test species, increasing extract concentrations significantly increased the inhibition of seed germination and shoot and root elongation and gradually decreased seedling performance; the decreasing values of relative water content and F v /F m indicated that the plants had been exposed to stress. The leaf aqueous extracts of A. saligna were significantly more phytotoxic than the root aqueous extracts, even at the lowest concentration (5%). Fabaceae species had significantly less growth inhibition than Cistaceae species. The results from this study suggest that A. saligna has strong allelopathic potential, which emphasizes the importance of reducing its allelopathic effects and developing effective management strategies for mitigating invasion risk and protecting native species in Mediterranean arid environments.

Too dry to survive: Leaf hydraulic failure in two Salvia species can be predicted on the basis of water content

Global warming is exposing plants to increased risks of drought-driven mortality. Recent advances suggest that hydraulic failure is a key process leading to plant death, and the identification of simple and reliable proxies of species-specific risk of irreversible hydraulic damage is urgently required.We assessed the predictive power of leaf water content and shrinkage for monitoring leaf hydraulic failure in two Mediterranean native species, Salvia ceratophylloides (Sc) and S. officinalis (So).The study species showed significant differences in relative water content (RWC) thresholds inducing loss of rehydration capacity, as well as leaf hydraulic conductance (KL) impairment. Sc turned out to be more resistant to drought than So. However, Sc and So showed different leaf saturated water content values, so that different RWC values actually corresponded to similar absolute leaf water content. Our findings suggest that absolute leaf water content and leaf water potential, but not RWC, are reliable parameters for predicting the risk of leaf hydraulic impairment of two Salvia species, and their potential risk of irreversible damage under severe drought. Moreover, the lack of any KL decline until the turgor loss point in Sc, coupled to consistent leaf shrinkage, rejects the hypothesis to use leaf shrinkage as a proxy to predict KL vulnerability, at least in species with high leaf capacitance. Robust linear correlations between KL decline and electrolyte leakage measurements suggested a role of membrane damage in driving leaf hydraulic collapse.