Shoot Water Content Research Articles

Cold Hardiness in ‘Alphonse Lavallee’ (Vitis vinifera L. cv) Grape Dormant Buds and Phloem Tissue: Seasonal Insights and Some Treatment Impacts

Grapes are highly susceptible to cold damage during critical developmental stages, impacting viticulture. Understanding the intricate dynamics of cold hardiness in grape dormant buds and phloem tissue is crucial for developing effective mitigation strategies. In this study, we investigated the LT50 values, representing the temperature at which 50% of buds are damaged, under different treatments and sampling times. In our research, we evaluated the effects of four treatments—potassium oxide (K2O), calcium chloride (CaCl2), seaweed (SW), and a control—on the cold hardiness of grapevine buds and phloem tissue. Primary bud LT50 values varied across seasons, with January at −22.46 °C, February at −22.35 °C, and March at −20.45 °C. K2O treatment showed a trend toward improvement, although the difference from the control (−21.99 °C) was not statistically significant. Regarding LT50 values, CaCl2 and SW applications did not significantly differ from the control. Tertiary buds, however, exhibited a substantial enhancement in cold hardiness with K2O application, displaying significantly lower LT50 values compared to the control (−23.55 °C). Phloem tissue LT50 values did not significantly differ among treatments, showing less variability. Bud water content significantly increased with K2O application in all sampling periods (January: 35.41% vs. 35.61%; February: 34.03% vs. 39.16%; March: 42.40% vs. 37.82%), while shoot water content remained stable. In conclusion, K2O emerges as a key influencer, particularly in enhancing the cold hardiness of tertiary buds. These insights contribute to the knowledge base for targeted frost mitigation strategies in viticulture.

Fertigation frequency is a useful tool for nitrate management in intensive open-field agriculture

The main source of nitrogen for most cultivated plants is nitrate. Agriculture has overused this nutrient, resulting in serious environmental problems in various parts of the world. The common practice in open intensive horticultural fields with clay-loam soils with a high water retention capacity (e.g., high percentage of clay) is to irrigate two to four times per week. Technically and logistically, this is much easier than one or more irrigation events per day. However, the loss of nutrients and water below the root zone may occur, with the consequent loss of efficiency. In this work, two cultivation cycles in an open-field endive crop were carried out under plastic soil mulching. We compared three fertigation strategies based on different frequencies of fertigation events; low fertigation frequency (LF, two to three fertigation events per week that simulates common farmer practice), medium fertigation frequency (MF, one fertigation event per day), and high fertigation frequency (HF, three fertigation events per day). The three fertigation strategies applied equal water and fertilizers doses per week. The high fertigation frequency increased volumetric water content in the upper soil profile, while the low fertigation frequency in the lower soil profile. The results demonstrated that HF fertigation increases shoot fresh weight (harvest yield) by increasing shoot water content, but did not improve shoot nutrient uptake or nitrogen nutritional status. The important finding, from the environment point of view, is that high and medium fertigation frequencies decreased nitrate concentration in the root influence zone, where it may be prone to leaching due to heavy rain events.

Changes in water content and carbohydrate metabolism in the annual shoots of contrasting plum varieties in the autumn period

A study of the water content in autumn revealed a significant 1.7-2.9-fold increase in the ratio of bound and free water in plum genotypes in November compared with September. At the same time, a significant increase in the content of sugars amount (by 9.9 % and 10.8 %) was noted in the bark of annual shoots n the plants of Prunus salicina and Prunus × rossica Erem. The outcome obtained suggest that the varieties of Prunus × rossica Erem. – Vetraz, Gek, Zlato Skifov, Kubanskaya Kometa and Prunus salicina – Nezhenka, Orlovskaya Mechta, Skoroplodnaya, Suvenir Vostoka and ELS 18476 have greater frost resistance in winter, because their adaptive processes were more intense in autumn.

Preference of Silicon Accumulation on the Shade Foliage of Tree Crown and its Implication in Juniperus chinensis L.

PurposeThe passive accumulation of silicon (Si) generally depends on the regulation of plant transpiration rates after its uptake. It is challenging to comprehend how plants use Si to adapt to shady habitats where they have low transpiration rates and photothermal energy. Therefore, we speculated that Si accumulation is not entirely dependent on the transpiration rate.MethodsTo test this speculation, the concentrations of Si and total minerals and water status at various positions of shady shoots (stems and their foliage) and stems within the crown of Juniperus chinensis L. were examined to determine whether shady shoots or stems had a preferred allocation to resist shade.ResultsThe concentrations of total minerals and Si in the shoots were consistently higher in shady areas than in areas within the same crown, regardless of the position within the crown or shoot age. However, shoot Si accumulation displayed a greater dependence on available light or photothermal supply, which is linked to crown orientation. Additionally, stem Si accumulation displayed a weak dependence on available light. Compared with the bound water content, the water potential and free water content of shady shoots were higher than those of sunny shoots. In light of the fact that water prefers to move readily towards regions with low water potential, these results demonstrate that the movement of minerals and water is not fully coupled in the same crowns.ConclusionTherefore, the accumulation of Si and minerals in shady foliage is partially independent of water flow, which helps to offset the low-carbon supply due to the photothermal decrease in the shady crown area.

Drought stress induced by polyethylene glycol (PEG) in local maize at the early seedling stage

Drought stress adversely impacts growth, crop production, reproductive organ development, and yield characteristics in maize. As a drought-sensitive crop, maize (Zea mays L.) shows considerable varietal differences. A study was conducted at the Tissue Culture Laboratory, Department of Biology, Faculty of Mathematics and Natural Sciences, University of North Sumatra, Medan, Indonesia in order to identify drought-tolerant maize varieties. During germination and early seedling growth, 16 local accessions were evaluated for drought tolerance. Based on local climate and soil conditions, these specific accessions were chosen. The varieties were tested against five levels of drought stress imposed by Polyethylene glycol 6000 (PEG-6000) at 10, 20, 30, 40, and 50%. An experiment with three replications was conducted using a completely randomized design. In the study, local maize accessions (BI3, SB5, DS2, and MN3) and the hybrid variety (H) showed the capability of tolerating drought stress. Generally, germination time, germination percent and vigor index, root and shoot length, shoot ratio, and fresh and dry weight were decreased by increasing PEG concentrations (up to 50%). According to ANOVA results, shoot water content was not significantly affected by the PEG, nor was the interaction between the PEG and the accessions. The root water content, however, was significantly affected by PEG, and the interaction between PEG and accessions. Although interactions between accessions with low PEG concentrations improved germination characteristics, the root histology of the accessions varied. According to drought tolerance indexes, five maize accessions are drought-tolerant, including H (0.683), SB5 (0.617), DS2 (0.565), MN3 (0.512), and BI3 (0.504). The drought-tolerant varieties are recommended in regions with low rainfall or low water sources since they are less water-intensive and produce higher yields.

Growth of Lettuce in Hydroponics Fed with Aerobic- and Anaerobic–Aerobic-Treated Domestic Wastewater

Reusing water and nutrients from municipal wastewater can conserve resources and reduce wastewater treatment costs. In this study, the suitability of different qualities of treated wastewater for plant production in a hydroponic flow-through system was investigated. Lettuce (Lactuca sativa L.) was grown in hydroponic lines fed with treated wastewater, i.e., conventional effluent from aerobic wastewater treatment by the activated sludge process (CE), ozonised CE (CEO), anaerobically pre-treated and nitrified wastewater (AN) and biological activated carbon filtered AN (ANC) in comparison with a modified Hoagland nutrient solution. In CEO, AN and ANC, the lettuce reached a similar weight and elemental composition as that in HS. The low N and P concentrations in CE and CEO were quickly depleted, resulting in limited plant development at the ends of these lines. The lower water content in the CE shoots was probably related to hypoxia that occurred at higher temperatures. In the CEO line, this condition did not arise due to the constant decay of O3. At lower temperatures, the CEO shoot dry weight was 90% higher than that in CE. This was possibly an effect of residual ozone and/or oxygen supersaturation. AN produced the highest yield, while carbon filtration lowered the content of cations in ANC, inducing deficiency of Fe > Mn > Cu > Zn > K. Coupling wastewater treatment with hydroponics allows for efficient nutrient recovery, and thus could reduce the energy and reactor volume needed for N and P elimination.

Improving the monitoring of root zone soil salinity under vegetation cover conditions by combining canopy spectral information and crop growth parameters.

Soil salinization is one of the main causes of land degradation in arid and semi-arid areas. Timely and accurate monitoring of soil salinity in different areas is a prerequisite for amelioration. Hyperspectral technology has been widely used in soil salinity monitoring due to its high efficiency and rapidity. However, vegetation cover is an inevitable interference in the direct acquisition of soil spectra during crop growth period, which greatly limits the monitoring of soil salinity by remote sensing. Due to high soil salinity could lead to difficulty in plants' water absorption, and inhibit plant dry matter accumulation, a method for monitoring root zone soil salinity by combining vegetation canopy spectral information and crop aboveground growth parameters was proposed in this study. The canopy spectral information was acquired by a spectroradiometer, and then variable importance in projection (VIP), competitive adaptive reweighted sampling (CARS), and random frog algorithm (RFA) were used to extract the salinity spectral features in cotton canopy spectrum. The extracted features were then used to estimate root zone soil salinity in cotton field by combining with cotton plant height, aboveground biomass, and shoot water content. The results showed that there was a negative correlation between plant height/aboveground biomass/shoot water content and soil salinity in 0-20, 0-40, and 0-60 cm soil layers at different growth stages of cotton. Spectral feature selection by the three methods all improved the prediction accuracy of soil salinity, especially CARS. The prediction accuracy based on the combination of spectral features and cotton growth parameters was significantly higher than that based on only spectral features, with R2 increasing by 10.01%, 18.35%, and 29.90% for the 0-20, 0-40, and 0-60 cm soil layer, respectively. The model constructed based on the first derivative spectral preprocessing, spectral feature selection by CARS, cotton plant height, and shoot water content had the highest accuracy for each soil layer, with R2 of 0.715,0.769, and 0.742 for the 0-20, 0-40, 0-60 cm soil layer, respectively. Therefore, the method by combining cotton canopy hyperspectral data and plant growth parameters could significantly improve the prediction accuracy of root zone soil salinity under vegetation cover conditions. This is of great significance for the amelioration of saline soil in salinized farmlands arid areas.

Physiological and Canopy Temperature Responses to Drought of Four Penstemon Species

Available water for urban landscape irrigation is likely to become more limited because of inadequate precipitation and the ever-increasing water demand of a growing population. Recent droughts in the western United States have also increased the demand for low-water-use landscapes in urban areas. Penstemon species (beardtongues) are ornamental perennials commonly grown in low-water-use landscapes, but their drought tolerance has not been widely investigated. The objectives of this study were to determine the effects of water availability on the morphology, physiology, and canopy temperature of Penstemon barbatus (Cav.) Roth ‘Novapenblu’ (Rock Candy Blue® penstemon), P. digitalis Nutt. ex Sims ‘TNPENDB’ (Dakota™ Burgundy beardtongue), P. ×mexicali Mitch. ‘P007S’ (Pikes Peak Purple® penstemon), and P. strictus Benth. (Rocky Mountain penstemon). Twenty-four plants of each penstemon species were randomly assigned to blocks in an automated irrigation system, and the substrate volumetric water content was maintained at 0.15 or 0.35 m3⋅m−3 for 50 days. The decreased substrate volumetric water content resulted in a decreased aesthetic appearance of the four penstemon species because of the increased numbers of visibly wilted leaves and chlorosis. Plant growth index [(height + (width 1 + width 2)/2)/2], shoot number, shoot dry weight, leaf size, and total leaf area also decreased as the substrate volumetric water content decreased, but the root-to-shoot ratio and leaf thickness increased. Photosynthesis decreased, stomatal resistance increased, and warmer canopy temperatures were observed when plants were dehydrated. Additionally, as substrate volumetric water content decreased, the leaf reflectance of P. barbatus and P. strictus increased. Penstemon digitalis, which had the highest canopy–air temperature difference, was sensitive to drought stress, exhibiting a large proportion of visibly wilted leaves. Penstemon ×mexicali, which had the lowest root-to-shoot ratio, had the lowest shoot water content of the species studied and more than 65% of leaves visibly wilted when experiencing drought stress. Penstemon barbatus and P. strictus, native to arid regions, exhibited lower canopy–air temperature differences and better aesthetic quality than the other two species. Under the conditions of this study, Penstemon barbatus and P. strictus exhibited better drought tolerance than P. digitalis and P. ×mexicali.

X-radiation of Lotus corniculatus L. seeds improves germination and initial seedling growth

Purpose Lotus corniculatus L. (bird’s foot trefoil, BFT) is a valuable perennial legume forage species due to its high nutritive value, persistence under grazing, and condensed tannin content that improves ruminant production and prevents bloating. However, it is less preferred by farmers compared with other perennial forage legumes such as alfalfa because of slow germination, slow establishment and low seedling vigor. This study was conducted to determine whether X-ray seed priming could improve these deficiencies. Materials and methods Seeds of L. corniculatus cv. ‘AC Langille’ were irradiated at 0, 100, and 300 Gy. Non-irradiated and irradiated seeds were sown on Murashige and Skoog/Gamborg medium under in vitro conditions and cultured for 21 days. Germination percentage, mean germination time (MGT), germination rate index, length of shoot and root, fresh and dry weight of shoot and root, dry matter ratios of shoot and root, water content of shoot and root, and seedling vigor index were measured. Results The results of this study demonstrated that X-ray seed priming significantly increased the germination percentage of L. corniculatus, increased the germination rate and thereby shortened the MGT, and improved seedling growth. However, X-ray pretreatment also decreased seedling shoot and root biomass. Conclusions In this study, it is reported for the first time that X-ray seed pretreatment has the potential to address important seedling establishment issues in L. corniculatus.

Effect of Seawater Irrigation on Arthrocnemum macrostachyum Growing in Extensive Green Roof Systems under Semi-Arid Mediterranean Climatic Conditions

The effects of climate change in coastal semi-arid and arid Mediterranean areas are intense. Green roofs planted with native plant species that are able to withstand saline conditions can contribute to supporting climate-change adaptation and species preservation in wetlands, enhancing the character of local landscapes and reducing disaster risk. Considering the limited availability of water resources, there is increasing interest in the use of seawater for irrigation, particularly near coastal areas. The growth of a native Mediterranean halophyte, Arthrocnemum macrostachyum, on a simulated extensive green roof system with six different irrigation treatments with or without seawater for 97 days is presented. The irrigation treatments included tap water every 4 or 8 days, seawater every 4 or 8 days, and seawater alternated with tap water every 4 or 8 days. The plants’ growth indices, heights, ground-cover surface areas, and relative shoot water content, as well as the electrical conductivity of the green roof’s substrate leachates (ECL), were measured at regular intervals. Overall, the plants irrigated with tap water every 4 days and the plants irrigated with seawater alternated with tap water every 4 days showed the greatest growth amongst the different irrigation treatments, while the plants irrigated with seawater or seawater alternated with tap water every 8 days showed the least growth. Furthermore, the plants irrigated with tap water every 8 days or seawater every 4 days showed intermediate growth. To conserve water, irrigation with seawater alternated with tap water every 4 days is proposed. To further conserve water, irrigation every 4 days with seawater only is also proposed.

Low water supply differentially affects the growth, yield and mineral profile of kabuli and desi chickpeas (Cicer arietinum)

AbstractThe climatic events predicted to increase in intensity and frequency in the near future, including drought, may influence the quality and productivity of several important crops for human nutrition, such as legumes. Herein, two chickpea genotypes (Cicer arietinum) were analysed for their resilience to low water supply: a commercial white chickpea (kabuli) and a traditional black chickpea (desi) with marginal production in occidental countries. Plants were grown under four levels of water supplies (90%, 75%, 50% and 25% of field capacity) and biometric variables (root, shoot, pods and seeds), proxies of plant fitness (water content and oxidative stress) and the seed nutritional profile (protein and mineral concentrations) were analysed at plant maturity. The results show that the water content in shoots and roots decreased with the decrease in water supplies, with kabuli plants generally having higher water content in shoots and desi in roots. The shoot length was significantly higher in kabuli compared to desi, while the root length increased up to 11% in both species with the decrease in water supplies. The root‐to‐shoot ratio was higher in kabuli and increased with the decrease in the water supply, being negatively correlated with the number of pods and seeds per plant. Lipid peroxidation also increased with the decrease in the water supply, having slight positive correlations with plant growth parameters while being negatively correlated with plant productivity. No significant effects of plant genotype and water supply were observed on seed K, Ca and protein, but desi was able to sustain higher P, Mg, Zn, Fe, Mn and B concentrations than kabuli, including at lower water supplies. The results suggest that water stress negatively impacts plant growth and productivity and that the two chickpea genotypes have distinct biomass and water allocation strategies to cope with low water supply. These findings may be useful in strategies for improving the productivity and nutritional profile of chickpea crops under water‐limited conditions.

Effect of NaCl Salt Stress on Growth, Ions and Organic Solutes Contents in a Local Cultivar Kpinman of African Eggplant (Solanum macrocarpon L) in the Republic of Benin

Aims: This research has as objective to evaluate the effect of NaCl salt stress on African eggplant plant growth and to determine the implication of the accumulation of Na+, proline and soluble sugars and the reduction of K+ in the detrimental effect of NaCl in the growth of this plant species.
 Study Design: The experiment was laid out in a Completely Randomized Design (CRD) having five treatments and three replications.
 Place and Duration of Study: The experiment was carried out in screening house under natural conditions at the International Institute of Tropical Agriculture, Commune of Abomey-Calavi. Republic of Benin from June to august 2022.
 Methodology: Five NaCI concentrations (0, 30, 60, 90 and 120 mM) were used to irrigate four weeks old plants for two weeks. Plant growth, sodium (Na), potassium (K), proline, and soluble sugars contents of leaves and roots were determined at the end of the experiment.
 Results: Salt stress induced a significant reduction (P = .001) in shoot and root growth from 30 : 60 or 90 mM NaCI according to the growth parameter but had no impact on shoot water content. Leaf and roots Na+ contents significantly increased (P = .001) under salt stress whereas K+ content deoreased significantly (P = .05) only in root. Na change was observed for proline and soluble sugars contents in both leaf and root.
 Conclusion: Salt stress reduces the growth of plants of African eggplant due mainly to Na+ ion toxicity. The ionic selectivity ratio (K+/ Na+) rather than the K+ ion content plays an important role in the response of plants of African eggplant to salt stress. Proline and soluble sugars accumulation appeared not to intervene.

Influence of Salicylic and Succinic Acids on the Indicators of Growth and Photosynthesis and the Content of Chlorophyll in Wheat Plants Grown under Water Deficiency

In the conditions of climate warming, the frequency and intensity of droughts have increased, therefore, the development of methods that increase the resistance of crops to water scarcity is of great importance. The aim of the work is to study the effect of salicylic and succinic acids on growth indicators, photosynthetic activity indicators and on the content of pigments in the leaves of plants grown under conditions of irrigation and water scarcity. Wheat plants were grown under laboratory conditions. The seeds were pre-soaked in distilled water (control), in a solution of 0.05 mM salicylic acid or in a solution of 0.05 mM succinic acid. After the appearance of the first roots on the 3rd day, the germinated seeds were transferred to 200 ml vegetative vessels filled with soil and grown at 22-24C in natural light and daily watering. On day 5, the plants were divided into groups watering and water shortage. The water shortage group was stopped watering until the end of the experiment. On day 11, the indicators of the maximum and effective quantum yield of photosystem II, photochemical and non-photochemical quenching and electron flux density were determined using a FRAME-fluorimeter. On the 16th day of growing plants, the quantitative content of chlorophyll a and b and carotenoids was determined, the relative water content in shoots and roots was calculated. The relative water content in plants hardly changed when treated with acids under irrigation conditions, but in case of water deficiency, treatment with succinic acid reduced the water content in the root by 6%. In conditions of lack of moisture, acid treatment increased the effective quantum yield of photosystem II, the photochemical quenching coefficient of chlorophyll and the electron flux density by an average of 17-20%. Under irrigation conditions, treatment with salicylic and succinic acids caused a decrease in the content of chlorophyll a (by 11 and 32%, respectively), carotenoids (by 57 and 32%) and an increase in the content of chlorophyll b (by 49 and 23%). When treated with succinic acid, the total content of chlorophyll a + b decreased by 14%. In conditions of water deficiency, treatment with salicylic acid increased the relative content of chlorophylls and carotenoids by an average of 2.6 and 3.3 times, when treated with amber - by 3.5 and 2.0 times, respectively, compared with the control in terms of raw weight. The use of the studied acids can be recommended for potential use in agriculture.

Iron Status Affects the Zinc Accumulation in the Biomass Plant Szarvasi-1.

Thinopyrum obtusiflorum (syn. Elymus elongatus subsp. ponticus) cv. Szarvasi-1 (Poaceae, Triticeae) is a biomass plant with significant tolerance to certain metals. To reveal its accumulation capacity, we investigated its Zn uptake and tolerance in a wide range: 0.2 to 1000 µM Zn concentration. The root and shoot weight, shoot length, shoot water content and stomatal conductance proved to be only sensitive to the highest applied Zn concentrations, whereas the concentration of malondialdehyde increased only at the application of 1 mM Zn in the leaves. Although physiological status proved to be hardy against Zn exposure, shoot Zn content significantly increased in parallel with the applied Zn treatment, reaching the highest Zn concentration at 1.9 mg g-1 dry weight. The concentration of K, Mg and P considerably decreased in the shoot at the highest Zn exposures, where that of K and P also correlated with a decrease in water content. Although the majority of microelements remained unaffected, Mn decreased in the root and Fe content had a negative correlation with Zn both in the shoot and root. In turn, the application of excessive EDTA maintained a proper Fe supply for the plants but lowered Zn accumulation both in roots and shoots. Thus, the Fe-Zn competition for Fe chelating phytosiderophores and/or for root uptake transporters fundamentally affects the Zn accumulation properties of Szarvasi-1. Indeed, the considerable Zn tolerance of Szarvasi-1 has a high potential in Zn accumulation.

Using multi-omics approach to investigate the effect of a moon soil simulant on Vigna radiata seedling root and shoot growth, stress responses, and photosynthesis

The Moon's first habitats with a support system and semi-permanent lunar settlement are projected for the 2030s. Growing plants for a food supply is one of the most important factors supporting human life on the Moon. A Moon soil simulant was used in this study as a simulation of the use of available resources on the Moon and a representation of one of the possible alternatives to Moon agriculture. A few studies present the effect of Moon soil simulant on plant growth; however, no study has shown the effect of Moon soil simulant on physiology, proteome, and metabolome simultaneously. Effect of a Moon soil simulant on Vigna radiata seedling growth, physiology, proteins, and metabolites, both in the shoot and root parts were observed. V. radiata seedlings were grown on a Moon soil simulant and Earth soil, as a control, under the same environmental conditions. Vigna radiata seedlings grown on the Moon soil simulant showed no significant difference in shoot height, shoot biomass, or shoot water content compared to the control. However, water stress metabolites, l-proline and kaempferol, were higher. Stress response proteins and metabolites related to jasmonic acid (JA) biosynthesis were also higher, which might be due to the increase of malondialdehyde (MDA) in shoots and reduced chlorophyll content. The shoot also had reduced PS II activity (Fv/Fm) and downregulation of proteins related to carbon and energy metabolism. Vigna radiata seedlings grown on the Moon soil simulant showed downregulated lipoxygenase (LOX) proteins that might affect the maintenance of MDA at a certain level in roots and the lower expression of glutathione, superoxide dismutase (SOD), and peroxidase. Jasmone and epi-jasmonic acid were lower compared to the control, which might affect the downregulation of proteins related to stress response in roots and proteins related to the biosynthesis of stress secondary metabolites. The higher expression of aquaporins may have contributed to maintaining the root water content compared to the control. In addition, the low N content in the Moon soil simulant might induce the upregulation of proteins related to root elongation as a foraging strategy, resulting in increased root length and root biomass compared to the control. Interestingly, formononetin, which has a role in arbuscular mycorrhiza fungi (AMF) colonization and nodule primordia organogenesis by symbiotic soil bacteria, was found to be higher in root seedlings grown on the Moon soil simulant. This study provides a deeper understanding of the effect of Moon soil simulant on a plant at early growth stages as basic knowledge to support future Moon agriculture.

Drought Stress Priming Improved the Drought Tolerance of Soybean.

The capability of a plant to protect itself from stress-related damages is termed "adaptability" and the phenomenon of showing better performance in subsequent stress is termed "stress memory". While drought is one of the most serious disasters to result from climate change, the current understanding of drought stress priming in soybean is still inadequate for effective crop improvement. To fill this gap, in this study, the drought memory response was evaluated in cultivated soybean (Glycine max). To determine if a priming stress prior to a drought stress would be beneficial to the survival of soybean, plants were divided into three treatment groups: the unprimed group receiving one cycle of stress (1S), the primed group receiving two cycles of stress (2S), and the unstressed control group not subjected to any stress (US). When compared with the unprimed plants, priming led to a reduction of drought stress index (DSI) by 3, resulting in more than 14% increase in surviving leaves, more than 13% increase in leaf water content, slight increase in shoot water content and a slower rate of loss of water from the detached leaves. Primed plants had less than 60% the transpiration rate and stomatal conductance compared to the unprimed plants, accompanied by a slight drop in photosynthesis rate, and about a 30% increase in water usage efficiency (WUE). Priming also increased the root-to-shoot ratio, potentially improving water uptake. Selected genes encoding late embryogenesis abundant (LEA) proteins and MYB, NAC and PP2C domain-containing transcription factors were shown to be highly induced in primed plants compared to the unprimed group. In conclusion, priming significantly improved the drought stress response in soybean during recurrent drought, partially through the maintenance of water status and stronger expression of stress related genes. In sum, we have identified key physiological parameters for soybean which may be used as indicators for future genetic study to identify the genetic element controlling the drought stress priming.

CO2 enrichment changed N metabolism of tomatoes under salinity stress

• Elevated CO 2 reduced the negative effect of salinity stress in tomato. • Photosynthesis and transpiration improved in 50/50 v/v NO 3 : NH 4 but growth parameter was improved in 100/0 NO 3 : NH 4 in salinity stress in tomato. • The rate of reduction of vegetative traits due to salinity stress was significantly reduced by increasing the nitrate in the ratio of NO 3 : NH 4 in salinity stress in tomato. • Carbon dioxide enrichment was significant on protein and nitrate concentration. Salinity is a worldwide concern. The effects of CO 2 enrichment and N sources under salinity on the vegetative, photosynthetic, and biochemical parameters of tomato was explored. The tomato plants are cultivated in two climate-controlled greenhouses with two CO 2 levels: 300 (C1) and 700 (C2) ppm. Five NO 3 :NH 4 ratios (25/75(N1), 50/50(N2), 75/25(N3), and 100/0 (N4)) were used to fertilize plants in two salinity conditions (0 (S1) and 50 mM (S2)). When NH4 was raised, vegetative, yield and biochemical characteristics were seen to decline. By increasing nitrate, yield, and desirable tomato characteristics such as fresh weight of shoot, root, and fruit, dry weight of shoot and fruit, and the number of fruits per plant, photosynthesis, and water content of shoot were enhanced. Increased CO 2 mitigated the detrimental effects of salt stress. By increasing the nitrate in the ratio of NO 3 :NH 4 , notably in the S2N4 treatment, the rate of decrease of vegetative characteristics caused by salinity stress was greatly slowed. Under the detrimental influence of salinity stress, photosynthesis and transpiration improved in NO 3 :NH 4 , 50/50 (S2N2 treatment). In general, when the amount of ammonium was greater than nitrate (NO 3 :NH 4 ratio of 25/75) in both saline and non-saline conditions, the examined attributes did not demonstrate a favorable influence on all features.

A heat shock transcription factor gene (HaHSFA1) from a desert shrub, Haloxylon ammodendron, elevates salt tolerance in Arabidopsis thaliana

Haloxylon ammodendron is a typical desert xerophyte with worthy genetic resources, therefore, it is necessary to explore the resistance genes of H. ammodendron , and to improve the stress tolerance of other plant species through genetic engineering. In this study, a heat shock transcription factor gene, HaHSFA1 , was firstly cloned from H. ammodendron and overexpressed in Arabidopsis thaliana . The sensitivity of transgenic plants to exogenous ABA, osmotic stress and salt stress were analyzed; the effects of overexpression of HaHSFA1 in Arabidopsis on salt tolerance were deeply investigated. The results indicated that overexpression of HaHSFA1 increased chlorophyll content in Arabidopsis, and the growth of plants was promoted. The leaf soluble sugar and proline contents in OE lines were significantly increased compared with those in WT. OE lines maintained lower osmotic potential and higher shoot water content. Overexpression of HaHSFA1 in Arabidopsis also enhanced antioxidant activity, which may be important for protecting plasma membrane integrity in cells. Overexpression of HaHSFA1 in Arabidopsis improved root activity and increased selective absorption and transport capacity for K + over Na + , which was of great significance to reduce the toxic effect of Na + . This study indicated that overexpression of HaHSFA1 from H. ammodendron significantly elevates the salt tolerance of Arabidopsis, and HaHSFA1 has potential application values in improving abiotic stress tolerance in crops by genetic engineering. • HaHSFA1 was firstly cloned from a desert shrub, Haloxylon ammodendron . • Overexpression of HaHSFA1 enhanced osmotic adjustment and ROS scavenging ability in Arabidopsis. • Overexpression of HaHSFA1 maintained higher selectivity of absorption and transport for K + over Na + in Arabidopsis.

Oxidative stress impedes recovery of canola (Brassica napus) plants from waterlogging by inhibiting aquaporin-mediated root water transport

We exposed hydroponically grown canola plants for three days to root hypoxia (waterlogging) followed by re-aeration. Hypoxia decreased root hydraulic conductivity ( L pr ) and the apoplastic contribution to water transport, which impacted gas exchange and plant water relations. However, the most severe reduction of L pr was one day following re-aeration and it was accompanied by an increase in the contribution of apoplast to water flow. After one day of re-aeration, a sharp increase in ROS in roots was measured together with a decrease in transcript abundance of most BnPIP2 aquaporins in roots and leaves. A water permeability assay of these BnPIP2 s heterologously expressed in yeast confirmed that they are fast water transporters. All yeast strains displayed decreased water permeability with increased concentrations of applied H 2 O 2 and exogenous application of H 2 O 2 to plant roots resulted in a decrease of L pr . The yeast H 2 O 2 survival assay demonstrated that BnPIP1;2 and BnPIP1;3 facilitate H 2 O 2 transport and, therefore, the increase in gene expression of these aquaporins during re-aeration likely contributed to plant waterlogging recovery. A gradual recovery of L pr following re-aeration was accompanied by up-regulation of BnPIP s in roots and leaves and the activation of antioxidant enzymes in roots. Net photosynthesis, transpiration rates, and shoot water contents remained depressed one day after re-aeration but recovered over time. Collectively, the results demonstrate that oxidative burst had a decisive impact on modulating the hydraulic recovery of plants upon re-aeration. Since plant injury from root hypoxia involved both the hypoxic event and the ROS burst that occurred soon after root aeration, the ability of plants to recover from waterlogging was partly determined by their ability to handle oxidative stress. • Both root hypoxia and oxidative burst during re-aeration of canola plants had a severe impact on root hydraulic properties and gas exchange. • Increases in gene expression of BnPIPs in hypoxic and reaerated roots likely helped facilitate oxygen and hydrogen peroxide transport. • Sincehypoxia injury involves the hypoxic event and oxidative burst following aeration, waterlogging recovery requires resistance to both stresses.

SEED PRIMING OF WHEAT THROUGH SALICYLIC ACID TO INDUCE SALT TOLERANCE

Wheat is an important cereal crop consumed throughout the world. Present study was planned to conduct in greenhouse of IMBB, University of the Lahore for determination of effects of salt stress on growth of wheat seedlings. Seed from selected wheat genotypes (SHAFAQ-2006, ANAJ-2017and Galaxy-2013) were used to grow in 54 pots, which were filled with 2kg pure washed sand. The sand was mixed with 500mg/kg of salt NaCl in each of the pot except of the control pots for wheat sowing. The seed of wheat variety were sown in triplicate pots with all irrigation requirements in equal manners. The use of salicylic acid (SA) for seed priming was more effective for number of roots per plant. The highest root length was recorded for treatment of SA priming + NaCl which indicated that the application of SA induced higher number of roots and long roots under salt stress conditions. The higher root water contents and shoot water contents were recorded under the application of water priming of seeds. The positive contribution of root water contents to root length indicated that the higher root water contents caused increase in shoot length due to higher water, mineral and nutrient absorption and retention which caused increase in photosynthetic rate and vice versa. It was found from results that the genotype GALAXY-2013 performed better under different treatments and SA priming application for root length, shoot length and number of roots per plant. The results suggested that the genotype GALAXY-2013 may be used to develop different wheat genotypes which may show higher grain yield under the applications of SA as seed priming compound while growing wheat in slat stress environment.