Increased Leaf Water Content Research Articles

تأثير الرش بمضادات النتح على النمو، الانتاجية وصفات الجودة للقطن المصري تحت ظروف الاجهاد المائي للأراضي الطينية

Two field experiments were conducted at Sakha, Agricultural Research Station, Egypt in two growing seasons during 2021 and 2022 seasons, to study the effect of three irrigation intervals (every 15, 30 and 45 days) and four foliar application with some anti-transpirants (without , linseed Oil (7%), Pure Gylatine (1.5 %) Magnesium Carbonate for dusting (250 g / plot), Potassium Silicate (3cm3 K2SiO3 / liter) on the growth, productivity, quality of Egyptian cotton plants (Super Giza 94 cultivar) and some water relations .The experiment was designed by using split plot design with three replicates. The results showed that, irrigation cotton plants every 30 days significantly increased leaf water content%, chlorophyll (a) in the second season, chlorophyll (b), number of open bolls / plant, earliness % in the second season, seed cotton yield, boll weight, seed index all in the two growing seasons compared with other two irrigation intervals. On the other hand, irrigation every 15 days was more effective on plant height, number of fruiting branches per plant in both seasons, fineness in the first season, fiber length in the second season and fiber strength in the two seasons. Foliar application of anti- transpirants significantly increased in the most studied characters, leaf water content%, chlorophyll a and b , plant height, number of fruiting branches, number of open bolls, earliness %, seed cotton yield, boll weight , seed index , fiber fineness , fiber strength and fiber length except fiber uniformity which was not affected in the two seasons as compared with the control in the two seasons. The highest values were obtained from potassium silicate compared with other anti- traspirants. Concerning the interaction effect between irrigation interval and anti-transpirants , the data indicated that the application of Potassium Silicate and irrigation cotton plants every 30 days produced the highest significant increase in leaf water content %, chlorophyll a , chlorophyll b , number of fruiting branches ,seed cotton yield and earliness % in the first and second season.

Intermittence in irrigation management and nitrogen optimize yield and water use efficiency in baby lettuce

Aim of the study: To evaluate the influence of irrigation management strategies and nitrogen (N) on baby lettuce growth, yield, and water use efficiency in a protected environment. Area of study: Botucatu, SP, Brazil. Material and methods: The experiments were conducted in two consecutive cycles, and the treatments corresponded to the combination of irrigation management strategies with N doses. Irrigation strategies comprised 3 possibilities: continuous irrigation (Cont); intermittent irrigation with three irrigation pulses at one-hour intervals (Int1); and intermittent irrigation with irrigation depth split and applied at 7:00, 11:00, and 15:00 h (Int2). Two N doses were evaluated, 100 and 130 kg/ha of N, applied in daily fertigation according to the irrigation management strategies. Main results: Intermittent irrigation strategies (Int1 and Int2) promoted the highest vegetative growth, increased leaf water content, and increased total yield (49.55 and 55.30; 46.83 and 49.50 t/ha) and marketable yield (46.77 and 52.44; 45.11 and 47.17 t/ha) in the first and second cycles, respectively, in addition to optimizing water use efficiency. The N dose of 130 kg/ha increased the total yield (51.61 t/ha), marketable yield (48.98 t/ha), and water use efficiencies of total yield (53.60 kg/m³) and marketable yield (50.88 kg/m³) only in the first crop cycle. Research highlights: The use of intermittence in irrigation management proved to be more efficient in obtaining high yields and maximized the efficiency of use of water as a factor of production.

Effects of experimental watering but not warming on herbivory vary across a gradient of precipitation.

Climate change can affect biotic interactions, and the impacts of climate on biotic interactions may vary across climate gradients. Climate affects biotic interactions through multiple drivers, although few studies have investigated multiple climate drivers in experiments. We examined the effects of experimental watering, warming, and predator access on leaf water content and herbivory rates of woolly bear caterpillars (Arctia virginalis) on a native perennial plant, pacific silverweed (Argentina anserina ssp. pacifica), at two sites across a gradient of precipitation in coastal California. Based on theory, we predicted that watering should increase herbivory at the drier end of the gradient, predation should decrease herbivory, and watering and warming should have positive interacting effects on herbivory. Consistent with our predictions, we found that watering only increased herbivory under drier conditions. However, watering increased leaf water content at both wetter and drier sites. Warming increased herbivory irrespective of local climate and did not interact with watering. Predation did not affect herbivory rates. Given predictions that the study locales will become warmer and drier with climate change, our results suggest that the effects of future warming and drying on herbivory may counteract each other in drier regions of the range of Argentina anserina. Our findings suggest a useful role for range‐limit theory and the stress‐gradient hypothesis in predicting climate change effects on herbivory across stress gradients. Specifically, if climate change decreases stress, herbivory may increase, and vice versa for increasing stress. In addition, our work supports previous suggestions that multiple climate drivers are likely to have dampening effects on biotic interactions due to effects in different directions, though this is context‐dependent.

Ectopic expression of Medicago truncatula homeodomain finger protein, MtPHD6, enhances drought tolerance in Arabidopsis

BackgroundThe plant homeodomain (PHD) finger is a Cys4HisCys3-type zinc finger which promotes protein-protein interactions and binds to the cis-acting elements in the promoter regions of target genes. In Medicago truncatula, five PHD homologues with full-length sequence were identified. However, the detailed function of PHD genes was not fully addressed.ResultsIn this study, we characterized the function of MtPHD6 during plant responses to drought stress. MtPHD6 was highly induced by drought stress. Ectopic expression of MtPHD6 in Arabidopsis enhanced tolerance to osmotic and drought stresses. MtPHD6 transgenic plants exhibited decreased water loss rate, MDA and ROS contents, and increased leaf water content and antioxidant enzyme activities under drought condition. Global transcriptomic analysis revealed that MtPHD6 reprogramed transcriptional networks in transgenic plants. Expression levels of ABA receptor PYR/PYLs, ZINC FINGER, AP2/EREBP and WRKY transcription factors were mainly up-regulated after transformation of MtPHD6. Interaction network analysis showed that ZINC FINGER, AP2/EREBP and WRKY interacted with each other and downstream stress induced proteins.ConclusionsWe proposed that ZINC FINGER, AP2/EREBP and WRKY transcription factors were activated through ABA dependent and independent pathways to increase drought tolerance of MtPHD6 transgenic plants.

Response strategies of Acer davidii to varying light regimes under different water conditions

Phenotypic plasticity is crucial for adaptation of plants to complex environmental gradients. It is not clear as to how phenotypic plasticity in response to a certain environmental factor is affected by another ecological factor. Water and light are important factors affecting the phenotype of plants. The interactive effects between drought and shade on plants differ markedly among studies. To address these questions, we subjected Acer davidii Franch. seedlings to five water regimes, combined with two light intensities. Drought decreased all growth and biomass parameters, and all leaf and root traits measured, and increased the root to shoot ratio and root biomass ratio. Shade decreased the shoot height, the diameter at ground height, the root surface area, and all biomass parameters, and increased leaf water content, leaf area ratio, specific leaf area, and total chlorophyll concentration. Significant interactive effects were found on all biomass parameters, half of the growth parameters, and most of the leaf and root traits; shade generally alleviated the negative effects on A. davidii seedlings to some extent. The simplified relative distance phenotypic plasticity indices (RDPIs) of A. davidii responding to light increased with the increase in soil water content whereas no significant trend was observed between the RDPIs and the light regime. The RDPIs of all growth parameters, average leaf area, and all biomass allocation parameters in response to water were greater than those of light. Phenotypic plasticity of one environmental factor might be affected by another across complex environmental conditions.

Bacillus subtilis ameliorates water stress tolerance in maize and common bean

ABSTRACT Water stress is one important abiotic stress with negative impacts on plant productivity. In order to ameliorate abiotic stress, plant growth-promoting rhizobacteria (PGPR), such as Bacillus subtilis, can be used due to their positive effects on plant physiology. The present study aimed to evaluate the effects of B. subtilis on the performance of maize and common bean under water deficit conditions. The study was performed in a plant growth chamber and the growth, gas exchange parameters and antioxidant activity were evaluated. B. subtilis promoted the growth of common bean and maize, and also increased the water use efficiency. The inoculation with B. subtilis increased leaf water content and the regulation of stomata, without damaging photosynthetic rates. Overall, B. subtilis decreased antioxidant activities in both plants. The results suggest that B. subtilis could be used as inoculants for common bean and maize to protect against water stress.

Alteration of Transcripts of Stress-Protective Genes and Transcriptional Factors by γ-Aminobutyric Acid (GABA) Associated with Improved Heat and Drought Tolerance in Creeping Bentgrass (Agrostis stolonifera).

Gamma-aminobutyric acid (GABA) may play a positive role in regulating plant tolerance to drought or heat stress. The objectives of this study were to investigate the physiological effects of GABA on tolerance of creeping bentgrass (Agrostis stolonifera) to heat and drought stress and to determine whether enhanced heat and drought tolerance due to GABA treatment was associated with the up-regulation of selected genes and transcriptional factors involved in stress protection. Creeping bentgrass (cultivar “Penncross”) plants were treated with 0.5 mM GABA or water (untreated control) as a foliar spray and were subsequently exposed to heat stress (35/30 °C, day/night), drought stress by withholding irrigation, or non-stress conditions in controlled-environment growth chambers. Exogenous application of GABA significantly improved plant tolerance to heat and drought stress, as reflected by increased leaf water content, cell membrane stability, and chlorophyll content. The analysis of gene transcript level revealed that exogenous GABA up-regulated the expression of ABF3, POD, APX, HSP90, DHN3, and MT1 during heat stress and the expression of CDPK26, MAPK1, ABF3, WRKY75, MYB13, HSP70, MT1, 14-3-3, and genes (SOD, CAT, POD, APX, MDHAR, DHAR, and GR) encoding antioxidant enzymes during drought stress. The up-regulation of the aforementioned stress-protective genes and transcriptional factors could contribute to improved heat and drought tolerance in creeping bentgrass.

Systematic analysis of the G-box Factor 14-3-3 gene family and functional characterization of GF14a in Brachypodium distachyon

The 14-3-3 proteins are highly conserved and ubiquitously found in eukaryotes. Plant 14-3-3 proteins are involved in many signaling pathways to regulate plant growth and development. Here we identified seven Brachypodium distachyon 14-3-3 genes and analyzed the evolution, gene structure and expression profiles of these genes. Several cis-elements involved in stress response and hormone pathway were found in the promoter region of 14-3-3 genes. Results of gene expression analysis showed that these genes were induced by abiotic stresses or hormone treatments. Transgenic Arabidopsis overexpressing BdGF14a exhibited increased leaf water content (LWC) and decreased electrolyte leakage (EL) and showed improved drought stress tolerance. BdGF14a transgene significantly up-regulated expression levels of DREB1A and DREB1B, but slightly elevated ABI1 expression. These results indicated that BdGF14a functioned as a positive regulator in plant response to drought stress mainly via ABA independent pathway.

Effects of Organic and Inorganic Nutrient Sources on the Growth, Total Chlorophyll and Yield of Three Bambara Groundnut Landraces in the Coastal Region of Cameroon

Growth and yield parameters of bambara groundnut [Vigna subterranea L. Verdc. landraces: White Seed Coat (WSC), Black Seed Coat (BSC) and Light Red Seed Coat (RSC)] were evaluated under organic and inorganic fertilization in order to determine the field performance, for the improvement of smallholder agriculture in Cameroon. Four fertilizer application rates (0, 3, 6 and 12 t ha-1) of Water Lettuce (WL) and Poultry Manure (PM) and four fertilization rates (0, 100, 150 and 200 kg ha-1) of N, P and K were used in a randomized complete block design experiment with four replications. Application of WL or PM at 12 t ha-1 significantly (p<0.001) increased leaf water content, plant dry weight and total chlorophyll content in RSC landrace. Application of PM at 12 t ha-1 increased significantly (p<0.001) the number of pods per plant, the number of seeds per pods, the 1000 grain weight, the grain yield and the pod yield in RSC landrace. Significant (p<0.001) increase in plant dry weight was observed in all landraces at 100 kg ha-1 N, P or K fertilization. The fertilization rates above 100 kg ha-1 N, P or K led to a decline in yield in all the bambara groundnut landraces compared to the optimum 100 kg ha-1 N, P or K fertilization. RSC landrace showed better growth and yield than WSC and BSC landraces revealing a greater response of this cultivar to fertilization.

Seed enhancement with cytokinins: changes in growth and grain yield in salt stressed wheat plants

Leaf yellowing is a major problem in Alstroemeria and absence of leaf senescence symptoms is an important quality attribute. Two Alstroemeria cultivars ‘Yellow King’ and ‘Marina’ were sourced from a commercial farm and harvested when sepals began to reflex. Stems were re-cut under water and kept in vase solutions of gibberellin A4+7 (0, 2.5, 5.0, 7.5, 10.0, 12.5 or 15.0 mg l−1 [Provide r ]). Treatments and cultivars were combined in a factorial fashion and arranged in a completely randomised design. Application of GA4+7 in the holding solution at 2.5–10.0 mg l−1 significantly delayed the onset of leaf senescence by around 7 days and significantly increased days to 50% petal fall by ca. 2 days. Additionally, these GA4+7 concentrations resulted in higher retention of leaf nitrogen, leaf chlorophyll and also increased leaf water content, while reducing leaf dry weight, all relative to untreated controls. Cultivar ‘Yellow King’ had significantly longer vase life and a better retention of leaf quality than ‘Marina’. Our results suggest that a concentration of 10 mg l−1 GA4+7 can be used to prolong vase life, delay leaf senescence and enhance post-harvest quality of Alstroemeria cut flowers during their transport to market.

Plant Responses to Water Deficit and Shade Stresses in Pigweed and Their Influence on Feeding and Oviposition by the Beet Armyworm (Lepidoptera: Noctuidae)

Water deficit and shade stress in weed-infested crops could alter plant growth and biochemistry and feeding and oviposition by the beet armyworm, Spodoptera exigua Hubner. Palmer amaranth pigweed, Amaranthus palmeri S. Wats., was grown under 25% of full watering (water deficit), 30% of full light (shade), or combined stress. All treatments decreased plant height and weight. Shade and combined stresses decreased leaf counts and increased leaf water content. Water deficit stress increased leaf water potential, soluble protein and carbohydrate contents, peroxidase activities, and accumulations of 10 individual free amino acids (FAAs), summed essential FAAs, and total FAAs. Combined stress increased water potential, soluble carbohydrates, 12 individual FAAs, summed essential FAAs, and total FAAs. Shade stress decreased water potential, soluble carbohydrates, seven individual FAAs, and essential FAAs. Beet armyworm larvae consumed similar leaf areas on water deficit–stressed and nonstressed plants and larger areas on plants grown under shade or combined stress. Larval survival was reduced, and time to pupation was higher on shade-stressed leaves. Adult females deposited more eggs on shade and combined stress plants and fewer eggs on water deficit-stressed plants compared with controls. Beet armyworm feeding and oviposition responded to variation in water content. Stress-induced changes in nutrients were not tied to insect preference but could have negatively influenced survival under shade stress. The results have implications for the plant stress hypothesis and for the use of pigweeds for beet armyworm detection.

Response of Creeping Bentgrass to Nitrogen and Ethephon

Ethephon is an effective growth retardant for suppressing Poa annua (L.) seedheads in creeping bentgrass putting greens; however, ethylene induction may cause bentgrass leaf chlorosis, reduced rooting, and quality decline. Two greenhouse experiments investigated the effects of nitrogen (N) fertility and ethephon applications on `L-93' creeping bentgrass over 9 weeks. Ethephon was applied at 0, 3.8, and 7.6 kg·ha–1 a.i. per 3 weeks and N was applied at 4 and 8 kg·ha–1·week–1. Ethephon applications linearly reduced bentgrass quality on every weekly observation. Increased N rate to 8 kg·ha–1·week–1 improved turf quality about 10% to 20% and 10% to 30% from ethephon applied at 3.8 and 7.6 kg·ha–1 per 3 weeks, respectively. Increased N rate to 8 kg·ha–1·week–1 enhanced shoot growth 30% but reduced root mass and length 12% and 11%, respectively. After 9 weeks, ethephon reduced root length by about 30% and root mass about 35% at both rates. From nine weekly samples, ethephon reduced dry clipping yield 10% and 16% at 3.8 and 7.6 kg·ha–1 per 3 weeks, respectively. From 2 to 9 weeks after initial treatments, ethephon linearly increased leaf water content. Increasing N fertility effectively reduced bentgrass leaf chlorosis from ethephon; however, repeat applications of ethephon and increased N may restrict bentgrass root growth. Chemical names used: [(2-chloroethyl)phosphonic acid] (ethephon).

Space and time dependence of temperature and freezing in evergreen leaves.

Infrared video thermography was used to study space and time dependence of freezing in intact, attached leaves of snow gum (Eucalyptus pauciflora Sieb. ex Spreng.) seedlings. Freezing initiated in the midvein and spread through the apoplast at 10 mm s-1. Freezing of apoplastic water was detected by a local, rapid increase in temperature, and was followed by a slower increase in leaf temperature to the equilibrium freezing temperature as symplastic water moved from cells to extracellular sites of ice formation. The duration of freezing varied with position, leaf thickness and water content. Most of the cellular water in the leaf tip and margins froze quickly, while freezing was slower near the petiole and midvein. Regions that had frozen more rapidly then began to cool more rapidly, producing steep gradients in leaf temperatures and hence also freeze-induced dehydration. Thus, spatial variation in physical properties of leaves could affect the distribution of minimum leaf temperatures, and hence, the distribution and extent of damage due to freeze-induced dehydration. These results are consistent with patterns of freezing damage in autumn when the duration of freezing may be insufficient for the whole leaf to freeze before sunrise, and may explain the general observation of increased leaf water content and thickness with altitude.