Hydroponic Conditions Research Articles

Effects of Excessive Application of P and Zn Fertilizer on Growth and Yield of Maize under Hydroponic Conditions

Background: Phosphate is an essential nutrient but can be toxic to plants when phosphate accumulates in plants at high levels. The objective of the study was to find effects of excessive application of P and Zn fertilizer on growth and yield of maize under hydroponic conditions. Methods: Research of Experiment studied from August to December 2019 at the greenhouse of the Agriculture and Aquaculture School at Tra Vinh University. The study aimed to determine the effect of high phosphate application on growth, biomass, symptoms of poisoning, phosphate and zinc absorption in maize and vegetables grown in hydroponic solution. Result: Experimental results showed the symptoms of phosphate poisoning on maize when grown in Hoagland nutrient solution (2.0 mM P) with an additional phosphorus content of 0.1 mM P, 1.0 mM P, 3.0 mM P in the treatment with or without the addition of Zn. However, the poisoning symptoms have been yet clearly expressed when Zn was not added. Therefore, plants may exhibit phosphorus toxicity, reducing Zn absorption when the phosphorus concentration in solution was increased by more than 1%P2O5. It is necessary to continue investigating plants’ responses to phosphate fertilizers.

Primary, seminal and lateral roots of maize show type-specific growth and hydraulic responses to water deficit.

The water uptake capacity of a root system is determined by its architecture and hydraulic properties, which together shape the root hydraulic architecture. Here, we investigated root responses to water deficit (WD) in seedlings of a maize (Zea mays) hybrid line (B73H) grown in hydroponic conditions, taking into account the primary root (PR), the seminal roots (SR), and their respective lateral roots. WD was induced by various polyethylene glycol concentrations and resulted in dose-dependent inhibitions of axial and lateral root growth, lateral root formation, and hydraulic conductivity (Lpr), with slightly distinct sensitivities to WD between PR and SR. Inhibition of Lpr by WD showed a half-time of 5 to 6 min and was fully (SR) or partially (PR) reversible within 40 min. In the two root types, WD resulted in reduced aquaporin expression and activity, as monitored by mRNA abundance of 13 plasma membrane intrinsic protein (ZmPIP) isoforms and inhibition of Lpr by sodium azide, respectively. An enhanced suberization/lignification of the epi- and exodermis was observed under WD in axial roots and in lateral roots of the PR but not in those of SR. Inverse modeling revealed a steep increase in axial conductance in root tips of PR and SR grown under WD that may be due to the decreased growth rate of axial roots in these conditions. Overall, our work reveals that these root types show quantitative differences in their anatomical, architectural, and hydraulic responses to WD, in terms of sensitivity, amplitude and reversibility. This distinct functionalization may contribute to integrative acclimation responses of whole root systems to soil WD.

Testing of indeterminate heterotic tomato hybrids of Ural breeding in conditions of low-volume hydroponics

The purpose of the work is to create new domestic tomato hybrids for protected soil with high adaptability and an increased content of biologically active compounds for functional nutrition. 9 new tomato hybrids were evaluated in the control nursery of the preliminary test on the basis of Teplichnoye JSC in conditions of low-volume hydroponics without additional illumination. The hybrids G-1214-23, G-922-23, G-122-23, F1 Nastavnik had the highest productivity, providing yields above 50 kg/m2 in extended turnover. An extended biochemical analysis of the fruits of nine of the most promising tomato hybrids with more than 36 indicators was carried out. For further testing, registration and entry into the State Register of Breeding Achievements, a sample with a high content of biologically active compounds and high productivity G-922-23 and highly productive samples G-1214-23 and G-122-23 are recommended as a tomato hybrid for functional nutrition.

Study of Growth, Yield, and Yield Quality Indicators of Tomato Hybrids in Hydroponic Systems under Greenhouse Conditions

The main goal of the research was to study greenhouse tomato hybrids under hydroponic greenhouse conditions and to enhance the agro-economic properties of tomato hybrids, offering farmers the hybrid that ensures high efficiency of tomato cultivation under hydroponic greenhouse conditions. During the vegetation period, phenological observations, biometric measurements, and crop counting were performed. Producing and selling vegetables in the local market is the primary activity of greenhouses and tomatoes occupy a significant place in vegetable production. In recent years, various varieties and hybrids have been imported into Armenia, most without testing. Tomato cultivation in greenhouses occupies a leading place in Armenia. The greenhouse tomato hybrids Merlis, Plumola, and Endeavor were researched.

Biofortificação foliar com nanopartículas de cobre e seu efeito na qualidade fitoquímica e atividade enzimática em alface

ABSTRACT The objective of this study was to evaluate the foliar application of copper oxide nanoparticles (NPs-CuO) on the phytochemical quality, yield, catalase and peroxidase activity of the hydroponic lettuce crop. Five concentrations (5, 10, 15, 20 and 25 mg/L) of NPs-CuO and a control (0 mg/L) were compared. The experiment was established in a completely randomized design with five repetitions. Data were analyzed with analysis of variance and mean comparisons using Tukey's test (0.05). The results indicate that, under the hydroponic conditions, the lettuce plants showed a greater number of leaves, leaf width and the peroxidase enzyme activity was recorded with the concentration of 15 mg/L NPs-CuO. The concentration of 10 mg/L of NPs-CuO yielded higher contents of total phenols, total flavonoids and antioxidant capacity, being 46.63, 34.21 and 28.23% higher compared to the control treatment, respectively. Regarding the concentration of Cu in the lettuce leaf, the 20 mg/L treatment showed the highest concentration with a value of 9.93±2.40 µg/L DW. The use of copper nanoparticles could be an effective alternative to mitigate copper deficiency in the diet of the human population.

Effects of Planting Dates, Chilling Periods and Foliar Spray with N/P Ratio on Growth Characteristics of Strawberry (Fragaria x ananassa.) cv. Robygem under Hydroponic Conditions

Effects of Planting Dates, Chilling Periods and Foliar Spray with N/P Ratio on Growth Characteristics of Strawberry (Fragaria x ananassa.) cv. Robygem under Hydroponic Conditions

Exogenous silicon induces aluminum tolerance in white clover (Trifolium repens) by reducing aluminum uptake and enhancing organic acid secretion.

Excessive aluminum (Al) in acidic soils is a primary factor that hinders plant growth. The objective of the present study was to investigate the effect and physiological mechanism of exogenous silicon (Si) in alleviating aluminum toxicity. Under hydroponic conditions, 4 mM Al significantly impeded the growth of white clover; however, pretreatments with 1 mM Si mitigated this inhibition, as evidenced by notable changes in growth indicators and physiological parameters. Exogenous silicon notably increased both shoot and root length of white clover and significantly decreased electrolyte leakage (EL) and malondialdehyde (MDA) content compared to aluminum treatments. This positive effect was particularly evident in the roots. Further analysis involving hematoxylin staining, scanning electron microscopy (SEM), and examination of organic acids (OAs) demonstrated that silicon relieved the accumulation of bioactive aluminum and ameliorated damage to root tissues in aluminum-stressed plants. Additionally, energy-dispersive X-ray (EDX) analysis revealed that additional silicon was primarily distributed in the root epidermal and cortical layers, effectively reducing the transport of aluminum and maintaining the balance of exchangeable cations absorption. These findings suggest that gradual silicon deposition in root tissues effectively prevents the absorption of biologically active aluminum, thereby reducing the risk of mineral nutrient deficiencies induced by aluminum stress, promoting organic acids exudation, and compartmentalizing aluminum in the outer layer of root tissues. This mechanism helps white clover alleviate the damage caused by aluminum toxicity.

FEATURES OF THE GROWTH AND DEVELOPMENT OF LETTUCE PLANTS SOWED UNDER HYDROPONIC GROWING

Research is devoted to the study of the assortment of lettuce seeded under hydroponics conditions. The survival rate of lettuce plants depended on the type and variety, and also differed to a certain extent by the terms of sowing. Plants of the Aficion variety of leaf lettuce (control) had the highest percentage of engraftment - 98.1%, which is 0.6 and 3.7% more compared to other variants of the experiment. Plants of the Raphael variety had a higher survival rate in romaine lettuce – 97.9%, which is 1.4% more than the control variant. Among the varieties of romaine lettuce, plants of the Maximus variety (control) had a higher height – 16.1 cm, which is 3.8 cm more than the Raphael variety. Comparing leaf lettuce plants, the highest height was noted in the Aficion variety (control) – 13.3 cm, which is 0.9 and 1.8 cm more than the other tested variants. In romaine lettuce, a larger diameter of the rosette was noted in the Maximus variety – 25.2 cm, which is 9.1 cm more than the Raphael variety. Among the leaf-type lettuce varieties, the largest diameter of the rosette of leaves was characterized by plants of the Aficion variety (Batavia type) – 28.3 cm, which is 4.0 and 7.9 cm more than the other studied variants of the experiment. In romaine lettuce, plants of the Maximus variety were characterized by a greater mass of the above-ground part – 210 g, which is 80.0 g more than the Raphael variety. Among the varieties of leaf lettuce, the Kirinia variety had the largest mass – 200 g, which is 60.0 more than the control variant. Mr. Maximus variety romaine lettuce had the highest yield – 9.3 kg/m2, and in terms of rows – 37.0 kg/m2, which is 14.1 kg/m2 more than the Raphael variety. Among the leafy types of lettuce, plants of the Kirinia variety were characterized by a higher yield – 8.8 kg/m2, in terms of rows – 35.2 kg/m2, where the increase compared to the control was 10.6 kg/m2. The yield of different types of lettuce ranged from 158.4 t/ha to 369.6 t/ha, taking into account the rows of racks. The highest yield, taking into account the tiering of racks, was obtained by growing Maximus (romaine type) – 369.6 t/ha and Kirinia (oak type) – 352.0 t/ha with an increase of 42.9 t/ha compared to the control variant.

Plant vs. Metal: Manganese Uptake in Raphanus sativus Under Hydroponic Conditions

Plant vs. Metal: Manganese Uptake in Raphanus sativus Under Hydroponic Conditions

Improvement of technology in the cultivation of strawberries hybrid Soraya F1 during a vegetative trial

The Strawberry (Fragaria x ananassa Duch.) is a favorite dessert crop, which is in great demand and ranks first among fruit and berry crops. The principle of growing strawberries directly from seeds gives the advantages of obtaining clean, reliable plant material and improving phytosanitary conditions. The aim of the research was to introduce innovations in the technology of growing high-quality planting material of garden strawberries (Fragaria x ananassa Duch.) of the Superelite class based on healthy hybrid seeds of the first generation of strawberry hybrid Soraya F1 under artificial lighting conditions in hydroponic culture. As a result, innovations in the artificial lighting regime, hydroponic culture conditions, substrate composition, irrigation regime and composition of the nutrient solution for root nutrition of plants were introduced, the flow of phytohormones, phytosanitary condition and quality of strawberry crop were analyzed.

The effectiveness of flow-through substrateless hydroponics in the adaptation of strawberry microplants

A new approach to the adaptation of test-tube strawberry microplants under flow-through hydroponics conditions was tested. The study was carried out on strawberry cultivars “Asia”, “Florence”, “Kimberly”. Murashige-Skoog medium was used for in vitro cultivation. During propagation, 1.0 mg•L-1 6-BAP was added to the medium, during elongation - 0.05 mg•L-1 6-BAP, and during rooting - 1.0 mg•L-1 IBA. Plants were grown in vitro in a light room at a temperature of 23±1°C, a 16-hour photoperiod and a light intensity of 5-6 klx. Flow hydroponics was used to adapt microplants. Plastic containers with dimensions of 0.6 x 0.4 x 0.04 m (volume 9 l), specially prepared for working in a hydroponic system, were taken. They were covered on top with non-woven polymer material, perforated with planting holes with a diameter of 3-4 mm according to a 4 x 4 cm pattern (150 pcs/box), into which plants were planted. This reduced labor costs for adaptation and ensured the efficiency of the operation to 86- 100% within 1 month.

Hydroponic cultivation enhances the morpho-physiological traits and quality flower production in three cultivars (marigold scarlet red, marigold orange, and marigold yellow) of French marigold (Tagetes patula L.)

In soil-less agriculture, hydroponic is considered a potential farming system for the production of uniform quality plant material in significantly less time. Therefore, for the first time, the current investigation corroborates the effect of different cultivation conditions (open-field, poly-house, and hydroponic) on morpho-physiological traits, phenolic content, and essential oil components analysis in three French marigold cultivars (marigold scarlet red, marigold orange, and marigold yellow) of Tagetes patula L. The results revealed that the maximum plant height, number of secondary branches, number of flowers, photosynthesis, stomatal conductance, and transpiration rate were observed under the hydroponic system as compared to other conditions. However, the maximum content of gallic acid (0.82 mg/g dry weight), syringic acid (3.98 mg/g dry weight), epicatechin (0.48 mg/g dry weight), p-coumaric acid (7.28 mg/g dry weight), protocatechuic acid (0.59 mg/g dry weight), ferulic acid (2.58 mg/g dry weight), and luteolin (8.24 mg/g dry weight) were quantified under open-field conditions. However, under hydroponic conditions, the higher content of vanillic acid (0.43 mg/g dry weight), caffeic acid (0.49 mg/g dry weight), and quercetin (0.92 mg/g dry weight) were observed. In addition, a total of nineteen volatile components were identified in the essential oil of different French marigold cultivars (marigold scarlet red, marigold orange, and marigold yellow) T. patula L. cultivated under different conditions. The major reported volatile components in essential oil were (-)-caryophyllene oxide, trans-β-caryophyllene, trans-geraniol, 3-methyl-benzyl alcohol, and 2,2′:5′,2″-terthiophene. It has also been observed that the volatile component percentage range in all cultivars was observed in open-field (70.85 % to 90.54 %), poly-house (59.03 % to 77.93 %), and hydroponic (68.78 % to 89.41 %). In conclusion, the research highlighted that maximum morpho-physiological performance with a higher number of flower production per plant was observed under hydroponic cultivation conditions. However, phenolic content and volatile components were maximally observed under open-field conditions. Though, significant results have been reported under hydroponic conditions in all studied parameters, so it could be a potential strategy for quality flower production in T. patula.

Enhanced Stomatal Conductance Supports Photosynthesis in Wheat to Improved NH4+ Tolerance.

The impact of ammonium (NH4+) stress on plant growth varies across species and cultivars, necessitating an in-depth exploration of the underlying response mechanisms. This study delves into elucidating the photosynthetic responses and differences in tolerance to NH4+ stress by investigating the effects on two wheat (Triticum aestivum L.) cultivars, Xumai25 (NH4+-less sensitive) and Yangmai20 (NH4+-sensitive). The cultivars were grown under hydroponic conditions with either sole ammonium nitrogen (NH4+, AN) or nitrate nitrogen (NO3-, NN) as the nitrogen source. NH4+ stress exerted a profound inhibitory effect on seedling growth and photosynthesis in wheat. However, these effects were less pronounced in Xumai25 than in Yangmai20. Dynamic photosynthetic analysis revealed that the suppression in photosynthesis was primarily attributed to stomatal limitation associated with a decrease in leaf water status and osmotic potential. Compared to Yangmai20, Xumai25 exhibited a significantly higher leaf K+ concentration and TaAKT1 upregulation, leading to a stronger stomatal opening and, consequently, a better photosynthetic performance under NH4+ stress. In conclusion, our study suggested stomatal limitation as the primary factor restricting photosynthesis under NH4+ stress. Furthermore, we demonstrated that improved regulation of osmotic substances contributed to higher stomatal conductance and enhanced photosynthetic performance in Xumai25.

Citrus sinensis manganese tolerance: Insight from manganese-stimulated secretion of root exudates and rhizosphere alkalization

We used manganese (Mn)-tolerant ‘Xuegan’ (Citrus sinensis) seedlings as materials and examined the characterization of Mn uptake and Mn-activated-release of root exudates under hydroponic conditions. We observed that root and shoot Mn bioaccumulation factor (BCF) reduced with the increase of Mn supply, and that Mn transfer factor (Tf) reduced greatly as Mn supply increased from 0 to 500 μM, beyond which Tf slightly increased with increasing Mn supply, suggesting that Mn supply reduced the ability to absorb and accumulate Mn in roots and shoots, as well as root-to-shoot Mn translocation. Without Mn, roots alkalized the solution pH from 5.0 to above 6.2, while Mn supply reduced root-induced alkalization. As Mn supply increased from 0 to 2000 μM, the secretion of root total phenolics (TPs) increased, while the solution pH decreased. Mn supply did not alter the secretion of root total free amino acids, total soluble sugars, malate, and citrate. Mn-activated-release of TPs was inhibited by low temperature and anion channel inhibitors, but not by protein biosynthesis inhibitor. Using widely targeted metabolome, we detected 48 upregulated [35 upregulated phenolic compounds + 13 other secondary metabolites (SMs)] and three downregulated SMs, and 39 upregulated and eight downregulated primary metabolites (PMs). These findings suggested that reduced ability to absorb and accumulate Mn in roots and shoots and less root-to-shoot Mn translocation in Mn-toxic seedlings, rhizosphere alkalization, and Mn-activated-release of root exudates (especially phenolic compounds) contributed to the high Mn tolerance of C. sinensis seedlings.

Bioaccumulation Capacity of Onion (Allium cepa L.) Tested with Heavy Metals in Biofortification.

On a worldwide scale, A. cepa is among the most commonly consumed vegetables. In Europe, the leading onion producers are Russia, the Netherlands, Spain, Poland and Germany. In this study, the bioaccumulation of heavy metals (Cr, Cu, Zn, Ni, Fe, Mn, Co, Sr, Cd and Pb) by Allium cepa L. plants was followed under hydroponic conditions. The heavy metals were applied at six concentrations (0, 25, 50, 100, 200 and 400 mg L-1) over three weeks. The quantitative analysis of selected heavy metals in plant tissues (bulbs, roots and assimilation leaves) was performed using atomic absorption spectrometry with flame atomization (F-AAS). The accumulation of metal ions was strongly dependent on their concentrations in the solution and the analyzed parts of plants. The highest accumulation of metal ions was confirmed for the roots and ranged from 8.48 to 5912.34 µg g-1 DW (dry weight). All parts of A. cepa were characterized by the high accumulation of Mn2+. The lowest accumulation was confirmed for Co2+ in the roots, Pb2+ in the assimilation leaves and Cu2+ in the bulbs of onion. Moreover, the study showed that the highest concentrations of heavy metals decreased the growth of bulbs and even caused them to die off. In contrast, lower concentrations of some elements stimulated plant development.

Applying Nitrogen Fertilizer at the Full Heading Stage Has the Potential to Decrease Brown Rice Cd Accumulation

Soil contamination by cadmium (Cd) has presented a major challenge in China. The objective of the field experiments in this study was to examine the influence of nitrogen fertilizer application at the full heading and milky stages on minimizing the absorption of Cd in rice. This was achieved by affecting the distribution of Cd in root plaques and subcellular compartments of the root and flag leaf. The hydroponic culture experiments aimed to examine the effect of nitrogen and Cd interaction or deficiency on Cd accumulation in rice during the late growth stage. The findings revealed that adequate nitrogen supply during the early growth stage, coupled with nitrogen application during the full heading and milky stages, led to a notable increase in Fe concentration in the root plaques during the milk and mature stages. Furthermore, it elevated the Cd proportion in the soluble fraction of the flag leaves at the milky stage. Conversely, nitrogen deficiency during the early growth stage resulted in a significant increase in Fe concentration in the root plaques, along with a decrease in Cd concentration. Additionally, the proportion of Cd in the flag leaf cell walls increased significantly, while the proportion in the soluble fraction decreased notably. Irrespective of nitrogen supply during the early growth stage, applying nitrogen at the full heading stage significantly reduced Cd transport from shoots to brown rice, leading to a considerable reduction in the Cd concentration in brown rice. Under hydroponic culture conditions, combined Cd exposure with nitrogen supply significantly increased the Cd concentration in brown rice. Nitrogen supply had no impact on the Cd concentration in brown rice in the absence of Cd. The study showed that applying nitrogen fertilizer at the full heading stage effectively decreased the brown rice Cd concentration. This was achieved by elevating the concentration of Fe in the root plaque, thereby influencing the adsorption of Cd by the roots. Additionally, nitrogen application at the full heading stage can influence the distribution of Cd in flag leaf cells during the filling stage. Ensuring ample nitrogen supply in the early stage of rice growth is crucial, and nitrogen application at the full heading stage can effectively reduce the Cd concentration in brown rice.

An appropriate ammonium: nitrate ratio promotes the growth of centipedegrass: insight from physiological and micromorphological analyses.

Reasonable nitrogen fertilizer application is an important strategy to maintain optimal growth of grasslands, thereby enabling them to better fulfil their ecological functions while reducing environmental pollution caused by high nitrogen fertilizer production and application. Optimizing the ammonium (NH4 +):nitrate (NO3 -) ratio is a common approach for growth promotion in crops and vegetables, but research on this topic in grass plants has not received sufficient attention. Centipedegrass, which is widely used in landscaping and ecological protection, was used as the experimental material. Different NH4 +:NO3 - ratios (0: 100, 25:75, 50:50, 75:25, 100:0) were used as the experimental treatments under hydroponic conditions. By monitoring the physiological and morphological changes under each treatment, the appropriate NH4 +:NO3 - ratio for growth and its underlying mechanism were determined. As the proportion of ammonium increased, the growth showed a "bell-shaped" response, with the maximum biomass and total carbon and nitrogen accumulation achieved with the NH4 +:NO3 - ratio of 50:50 treatment. Compared with the situation where nitrate was supplied alone, increasing the ammonium proportion increased the whole plant biomass by 93.2%, 139.7%, 59.0%, and 30.5%, the whole plant nitrogen accumulation by 44.9%, 94.6%, 32.8%, and 54.8%, and the whole plant carbon accumulation by 90.4%, 139.9%, 58.7%, and 26.6% in order. As a gateway for nitrogen input, the roots treated with an NH4 +:NO3 - ratio of 50:50 exhibited the highest ammonium and nitrate uptake rate, which may be related to the maximum total root length, root surface area, average root diameter, root volume, and largest root xylem vessel. As a gateway for carbon input, leaves treated with an NH4 +:NO3 - ratio of 50:50 exhibited the highest stomatal aperture, stomatal conductance, photosynthetic rate, transpiration rate, and photosynthetic products. The NH4 +:NO3 - ratio of 50:50 treatment had the largest stem xylem vessel area. This structure and force caused by transpiration may synergistically facilitate root-to-shoot nutrient translocation. Notably, the change in stomatal opening occurred in the early stage (4 hours) of the NH4 +:NO3 - ratio treatments, indicating that stomates are structures that are involved in the response to changes in the root NH4 +:NO3 - ratio. In summary, we recommend 50:50 as the appropriate NH4 +:NO3 - ratio for the growth of centipedegrass, which not only improves the nitrogen use efficiency but also enhances the carbon sequestration capacity.

Foliar zinc spraying improves assimilative capacity of sugar beet leaves by promoting magnesium and calcium uptake and enhancing photochemical performance

Sugar beet, a zinc-loving crop, is increasingly limited by zinc deficiency worldwide. Foliar zinc application is an effective and convenient way to supplement zinc fertilizer. However, the regulatory mechanism of foliar zinc spraying on sugar beet leaf photosynthetic characteristics remains unclear. Therefore, we investigated the effects of foliar ZnSO4·7H2O application (0, 0.1%, 0.2%, and 0.4%) on the photosynthetic performance of sugar beet leaves under controlled hydroponic conditions. The results indicated that a foliar spray of 0.2% Zn fertilizer was optimal for promoting sugar beet leaf growth. This concentration significantly reduced the leaf shape index of sugar beet, notably increasing leaf area, leaf mass ratio, and specific leaf weight. Foliar spraying of Zn (0.2%) substantially elevated the Zn content in sugar beet leaves, along with calcium (Ca) and magnesium (Mg) contents. Consequently, this led to an increase in the potential photochemical activity of PSII (Fv/Fo) (by 6.74%), net photosynthetic rate (Pn) (11.39%), apparent electron transport rate (ETR) (11.43%), actual photochemical efficiency of PSⅡ (Y (Ⅱ)) (11.46%), photochemical quenching coefficient (qP) (15.49%), and total chlorophyll content (25.17%). Ultimately, this increased sugar beet leaf dry matter weight (11.30%). In the cultivation and management of sugar beet, the application of 0.2% Zn fertilizer (2.88 mg plant−1) exhibited the potential to enhance Zn and Mg contents in sugar beet, improve photochemical properties, stimulate leaf growth, and boost light assimilation capacity. Our result suggested the foliar application of Zn might be a useful strategy for sugar beet crop management.

Advanced Mutant Line Developed from Fatemadhan Shows Salinity Tolerance at both Seedling and Reproductive Stages

The generation of high-yielding rice mutants and their assessment under salt stress offers a great possibility to isolate salt tolerant line(s) with desired trait of interest. Two separate experiments were conducted at the seedling and reproductive stages of rice to assess the level of salinity tolerance of few advanced high-yielding rice mutants. In the first experiment, rice seedlings were grown under hydroponic conditions and 14-day-old seedlings were subjected to salt stress (EC=10 dS/m; 7 days). Salt stress caused significant reduction in root and shoot length and biomass and leaf chlorophyll content; however, a little reduction was found in the mutant Line-1. In contrast, a sharp increase in shoot Na+/K+ ratio was found in all the genotypes except, Binadhan-10, FL-478 and the mutant Line-1, which exhibited little increased ratio. The second experiment involved exposure of plant to salt stress (EC=10 dS/m) for three weeks at the late booting stage in a sizable plastic tub filled with field soil. Salt stress resulted in a significant decrease in yield and yield attributing traits in all the genotypes except Binadhan-10. Grain yield per panicle was found significantly positive correlation with panicle length, the number of filled grains per panicle, and 100-seed weight under both control and salt stress conditions. Based on the studied traits and stress tolerance indices, Binadhan-10 and mutant Line-1 categorized as salt tolerant and rest of the genotypes were categorized as susceptible, which is also evident from the biplot of principal component analysis. Considering the results from both of the experiments, mutant Line-1 was found tolerant genotype at both seedling and reproductive stage. However, further studies are required to determine the genetic issues controlling the salinity tolerance in mutant Line-1 and the high-yield potential of mutant Line-65 under control condition in a way to develop salt tolerant and high-yielding rice varieties, respectively.

Rootstock effects on leaf function and isotope composition in apple occurred on both scion grafted and ungrafted rootstocks under hydroponic conditions.

Rootstocks are used in modern apple production to increase productivity, abiotic and biotic stress tolerance, and fruit quality. While dwarfing for apple rootstocks has been well characterized, the physiological mechanisms controlling dwarfing have not. Previous research has reported rootstock effects on scion water relations. Root architecture and variability in soil moisture across rooting depths can also contribute to these differences among rootstocks in the field. To exclude these effects on rootstock behavior, scions were grafted onto four different rootstocks with varying effects on scion vigor (B.9, M.9, G.41 and G.890). Non-grafted rootstocks were also grown to examine whether the effects of rootstock occurred independently from scion grafting. Plants were grown in a greenhouse under near steady-state hydroponic conditions. Carbon (δ13C), oxygen (δ18O) and nitrogen (δ15N) isotope composition were evaluated and relationships with carbon assimilation, water relations, and shoot growth were tested. Rootstocks affected scion shoot growth, aligning with known levels of vigor for these four rootstocks, and were consistent between the two scion cultivars. Furthermore, changes in water relations influenced by rootstock genotype significantly affected leaf, stem, and root δ13C, δ18O, and δ15N. Lower δ13C and δ18O were inconsistently associated with rootstock genotypes with higher vigor in leaves, stems, and roots. G.41 had lower δ15N in roots, stems, and leaves in both grafted and ungrafted trees. The effects of rootstock on aboveground water relations were also similar for leaves of ungrafted rootstocks. This study provides further evidence that dwarfing for apple rootstocks is linked with physiological limitations to water delivery to the developing scion.