Relative Water Content

A pot culture experiment was carried out to study the effect of short term water stress on free proline accumulation, relative water content (RWC) and potassium (K+)[r]

Water stress also reduces leaf production and promotes senescence and abscission [5], resulting in decreased total leaf area per plant. Reduction in leaf area reduces crop growth and thus biomass production. Seed production which is positively correlated with leaf area [6] may also be reduced by leaf area reductions induced by drought stress. Most cowpea is produced in arid and semi –arid zones of sub-Saharan Africa where drought is a major production constraint due to low and erratic rainfall [1]. For cowpea to be used as a forage or dual-purpose crop in the semi-arid areas, the effect of drought stress on leaf area, and the relationship between leaf area and seed yield, must be understood to maximize crop production. Changes in plant water status due to drought stress also need to be investigated since the growth of a leaf is intimately linked with its relative water content. Therefore, the aim of this study is to evaluate the effect of water stress on the leaf relative water content of some cowpea genotypes at different growth stages.

After the release of water stress the grafts performed better as indicated by the higher biological yield (Table 3). This difference between grafted and non-grafted plants [r]

2, and 4 mM) applied 20 days following the germination of seeds, on vegetative growth, morphological characteristics, integrity of cell-membrane, and the levels of photosynthetic pigments and enzymatic antioxidants in carrot cvs. Supertaj and Bharat, grown under 100% and 50% field capacity of soil moisture. The treated and untreated (control) carrot plants were harvested and analyzed 2 weeks following the GABA application. The results revealed that foliar application of GABA improved the vegetative growth and significantly increased the levels of free amino acids, plastid pigments, enzymatic antioxidants, and the relative water content in the root crop grown under 50% field capacity of soil moisture, compared to control. Additionally, the GABA application decreased the electrolyte leakage of ions and melondialdehyde (MDA) content in carrot leaves. The carrots harvested from GABA-treated or untreated (control) plants were not significantly different for their protein contents. In conclusion, the incorporation of GABA in the production management of carrots may help plants to mitigate the adverse effects of water deficit stress.

''tn the present investigation, all the genotypes showed differential response to soil water stress. Genotypes K 8627, C 306 and K 65, identified as drought tolerant, had higher flag leaf area, RWC and leaf water potential (lower negative value), with minimum reduction in yield parameters and yielded best under 30% ASW, as compared to other genotypes UP2003, K 8708, Hp2329, HUW 234 and HUW 206. Under 30% ASW conditions, lowest reduction in leaf water potential at anthesis stage, was more important than at milk stage. This may possibly be due to increase in relative water content of leaves at

Water potential, osmotic potential and relative water content (RWC) of leaves decreased significantly under water stress conditions (Table II).. Under water· stress, values [r]

Abstract: This study examines physiological and biochemical changes in three Moroccan varieties of young olive trees (Olea europaea L.) grown under three different water regimes (control, moderate stress and severe stress). Leaf relative water content (RWC), water potential (Ψw), transpiration rate (E), stomatal conductance (gs), maximum quantum effi- ciency of PSII (Fv/Fm), the contents of total chlorophyll (TCC), proline (ProC) and soluble sugars (SSC) were measured at the flowering stage during three growing seasons (2015, 2016 and 2017). ANOVA analyses showed that the effect of the water regime was predominant in all of the examined parameters, except for Fv/Fm, which was under the effect of both water regime and growing season. Impacts of variety and interactions were of lesser magnitude. Water deficit reduced E, Ψw and gs by 25%, while its effect on RWC and Fv/Fm was a decrease of about 7%; however, increases in SSC and ProC were more than 10%. Among the growing seasons, 2015 flowering displayed the lowest values for RWC, Ψw, E, gs, TCC and Fv/Fm, and the highest for ProC and SSC. Among plant varieties, no significant differences were observed. The three principal component (PC) axes accounted for 91% of total variance. PC1 was better explained by the water regime, while the growing season fitted PC3 variability. Correlation studies highlighted significant associations between most parameters. Positive relationships were found between RWC, Ψw, E, gs, Fv/Fm and TCC, while all of these parameters were negatively linked to ProC and SSC.

the physiological reaction of common osier var. Jorr was examined. The content of as- similation pigments, the rate the CO 2 assimilation, transpiration, the indices of relative water content and the deficit of water saturation and the content of lead in the nutrient solution. The studied physiological parameters in common osier var. Jorr were differ- entiated by the rate of lead ions in the nutrient solution. The Jorr variety of common osier was characterised by good values of the determined physiological parameters under stressful conditions at a large accumulation of lead. This suggests that it shows quite a high tolerance to the stress caused by contamination of the subsoil with lead. Keywords: lead, photosynthetic pigments, CO 2 assimilation, transpiration, common osier.

The effects of water stress imposed at flowering stage on the leaf relative water content (RWC), electrolytic conductivity and levels of polyamines and abscisic acid (ABA) in three cultivars of french bean differing in drought tolerance were studied. Amongst the cultivars, tolerant cv. Contender showed lesser decline in RWC and maintained stable electrolyte leakage than the susceptible cv. Arka Suvidha. The effect of stress on polyamines content depended upon cultivars and stress severity. Putrescine content increased under 3 and 6 days stress condition but declined under 9 days. Increase in putrescine was more prominent in susceptible cv. Arka Suvidha under 3 days stress and in the tolerant cv. Contender under 6 days stress. In the 9 days stressed plants, the decline in this polyamine was marked in the tolerant cultivar. The spermidine content showed a declining trend in all the cultivars following increased duration of stress, with tolerant cv. Contender showing lesser changes. In contrast, the spermine content increased progressively with stress in all the cultivars, and the tolerant cv. Contender maintained high levels in the stressed plants. The abscisic acid (ABA) content that increased gradually with increasing durations of stress showed a pattern similar to spermine. Putrescine and spermidine contents in stressed plants did not show any relationship with electrolyte leakage/RWC while spermine content was positively related to ABA content. The possible role of spermine in water stress tolerance has been discussed.

The sensitivity level of plants to air pollutants is evaluated by air pollution tolerance index (APTI). Parameters of leaf like pH, relative water content, chlorophyll, ascorbic acid were analyzed for the computation of air pollution tolerance index (APTI). In the present research, leaf sample of different plant species like Ficus religiosa (Peepal), Nerium indicum (Kaner), Azadirachta indica (Neem), Mangifera indica (Aam), Cassia fistula (Amal tas), Eucalyptus (Nilgiri), Ficus religiosa (Peepal) and Calotropis procera (Aak) were taken from Pratapnagar Circle of Udaipur city, which is connected from national highways and has a heavy load of vehicles. The results obtained showed highest APTI values of Eucalyptus (Nilgiri), followed by Mangifera indica (Aam), Azadirachta indica (Neem), Ficus religiosa (Peepal) and Nerium indicum (Kaner). Highlights

Water potential, osmotic potential and relative water content of leaves decreased significantly under water deficit. Potassium treatment improved the relative water content of leaves irrespective of soil moisture conditions. Potassium improved the water status of the plant through osmotic adjustment. Water stress adversely affected the yield and its attributes. Potassium leads to a considerable increase in yield and its attributes. Therefore, potassium in mungbean played a vital role in increasing water stress resistance and stabilizing yield. Increased concentration of potassium brought a consecutive improvement in water relations and yields both under stress and normal conditions. Therefore, it is concluded that potassium helps in maintaining the water status of the plants under water stress which in turn maintains various physiological processes and thereby increase the growth and yield.

Effects of different concentrations of polyethylene glycol 400 (PEG 400) on viability, relative water content, total chlorophyll content, total soluble protein and antioxidant enzymes activities of protocorm-like bodies (PLBs) of Aranda Broga Blue Bell orchid hybrid were determined. Different concentrations of in vitro drought-inducing chemical, PEG 400 at 0, 5, 10, and 15% (v/v) were used in this study. From the results obtained, lower concentration of PEG 400 at 5% produce minimum impact on the relative water content and morphological changes of treated PLBs. Percentage of viable PLBs at 5% PEG 400 treatment showed no significant difference with the control PLBs. However, significant reduction in total chlorophyll content and total soluble protein content of PLBs verified that supplementation of PEG 400 into Vacin and Went medium caused severe interruptions on various biochemical processes. Excessive production of free radical molecules increased the total activity of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). Specific localization, affinity and role of these enzymes resulted in different patterns of their overall activity. These findings suggested that the PLBs of Aranda Broga Blue Bell were drought tolerant orchid explants at low intensity of in vitro drought stress condition.

4.2. Correlation of Leaf Micromorphological Traits with Leaf Relative Water Content Variation in leaf micromorphological traits is derived from genotypic and environmental factors. Micromor- phological observations highlighted phenotypic variation among three Populus alba L. genotypes (6K3, 2AS11 and 14P11), of which the salinity-tolerant genotype 14P11 showed significantly smaller epidermal cells and higher stomatal density [15]. The present study indicated that the derived line Z58 could rapidly decrease stomatal area by closure of the stomatal aperture early in water- deficit stress (24 h water-deficit stress) without a signifi- cant reduction in stomatal size, which could effectively decrease water loss. However, Y478 may reduce stoma- tal size by pore

Santa Barbara, USA). The relative water content (RWC) was measured on the latest fully expanded leaf according to Li et al. (2015). For measure- ments of sodium (Na) concentration, 100 mg leaf sample was incubated in 5 mL concentrated sul- phuric acid completely digested with 30% H 2 O 2 as catalyst. The digestive solution was transferred to 50 mL volumetric flask to the constant volume and diluted before the test with a TAS 986 atomic absorption spectrophotometer (Beijing Purkinje General Instrument, Beijing, China). Concentration of ABA was measured with ELISA following the protocol of Li et al. (2015). H 2 O 2 concentration in leaf was measured by monitoring the absorbance of titanium peroxide complex at 410 nm following the methods of Li et al. (2013). The superoxide dismutase (SOD) activity was assayed by monitor- ing the inhibition of photochemical reduction of nitroblue tetrazolium, the activity of ascorbate per- oxidase (APX) was measured following ascorbate oxidation by monitoring the decrease at 290 nm, and the catalase (CAT) activity was measured as described by Li et al. (2014a).

Ten varieties of ground nut were screened for relative drought tolerance based on the magnitude of free proline accumulation in the leaves, relative water content and 1[r]

The aim of this work was evaluate the water potential, relative water content, and the osmoregulators in young plants of acapu submitted to water déficit. The experiment was conducted in a greenhouse at Federal Rural University of Amazônia, Belém, Brazil, in a period of 9 months. The experimental in factorial 2x4 (two water conditions: control and drought and four times of evaluation) with 5 repetitions, totaling 40 experimental units. The imposition of water deficit was obtained by suspension of irrigation in 30 days time, with first time (zero days of drought), time 2 (10 days), time 3 (20 days) and the time 4 (30 days). In these plants, was verified a , in the end of the experiment. The drought induced as in sucrose, proline and glycine betaine concentrations on leaves and also in the roots. The lack of water caused a reduction of starch in both organs studied. The accumulation of these osmorregulators in response to drought provided a decrease in water potential in these plants, reducing the effects of stress on the relative water content in the leaf.

Increased relative water content, indicating retention of water in cells that leads to enhanced water stress tolerance and reduced proline level was observed when Si was applied to wheat grown under salinity (Tuna et al .,2008). In present study, OSA increased resistance of plant to water stress and improved water status. Similar studies were reported in sorghum (Hattori et al., 2005), maize (Kaya et al., 2006) and wheat with soil silica application (Pei et al., 2010). The foliar application of 32 ppm of OSA under water stress was highly subjective in holding maximum relative water content (RWC), maintenance of cooler canopy and increased chlorophyll content along with root profile in wheat crop to sustain under water stress conditions (Ratnakumar et al., 2015). A recent study also showed that silicon induced alleviation was independent of leaf water status (Hattori et al., 2008). TU and OSA significantly increased SPAD chlorophyll in all cultivars that were tested, similarly in maize, foliar spray of TU increased both canopy photosynthesis and photosynthetically active leaf surface during grain filling (Sahu et al., 1993) and OSA largely improved the total DM, chlorophyll content, RWC and proline accumulation (Meena et al., 2013). These results suggested that the surrogate traits RWC and SPAD chlorophyll content have contribution in grain yield under water stress which was greatly enhanced by TU and OSA.

proportional to the availability of water in the soil [48]. Water stress results in significant decline in relative water content [1] and causes loss of turgor which causes impaired mitosis, cell elongation and expansion resulted in reduced growth and yield of crop plants[49]. Water stress reduced the leaf growth and leaf area in many species of populus [50] and soybean [51]. The silicon deposited as colloidal gel in the conducting tissues i.e. xylem vessels and cell wall of leaves restricts the transpired water bypass flow and hence offers an obstacle to transpiration through cuticle [52]. Thus improves the water status of plants and keeping the leaves erect and increases light penetration hence improving photosynthetic efficiency of plants under water deficit situation. Pei et al. [53] reported that silicon sustains water potential of leaves in wheat plants under water stress at the similar level as that of the well watered plants. Therefore, it is obvious that a positive correlation exists between silicon uptake and water potential of plants under drought condition. The beneficial impact of silicon on water

In this study, a pot experiment was carried out in greenhouse to investigate the potentials of Xerocomus badius and Serendipita indica to penetrate and colonize roots of ryegrass (Lolium multiflorum Lam.) and to induce beneficial effects on seed germination and seedling growth. The results showed that X. badius and S. indica successfully colo- nized in the root system of L. multiflorum seedlings and the root colonization rate was 72.65% and 88.42%, respec- tively. By microscopy, the hyphae, chlamydospores and spores produced by S. indica were observed in roots cortex of L. multiflorum seedlings. In comparison with the non-inoculated seedlings, seedlings inoculated with X. badius and S. indica showed significant increase in growth parameters with plant height, basal diameter, biomass accumulation, relative growth rate, leaf relative water content and chlorophyll content. Also, we found that seedlings inoculated with S. indica exhibited a greater growth-promotion as compared with X. badius-inoculated seedlings. No significant influence of the two fungus application has been observed with respect to seed germination. It suggested that well establishments of mutualistic symbiosis between L. multiflorum and X. badius or S. indica were not so essential to seed germination but contributed highly to the survival and growth of the seedlings.

measurements necessary to characterize the environ- mental conditions and finishing with the interpretation of results. Water stress experiments should distinguish between plants presenting dehydration avoidance or tol- erance strategies [11]. The use of environmental cham- bers offers a controlled environment in terms of light and relative humidity but not regarding substrate water con- tent and distribution, which are key elements to account for water availability. In this sense, a homogeneous sub- strate in terms of composition and water release proper- ties is an important requirement. Soil moisture/relative water content must be monitored throughout the experi- ment to pair these data with plant physiological/ana- lytical measurements [12]. Another critical point is the irrigation strategy to reach a given low soil moisture goal in a reproducible way, which is commonly performed by measuring the soil water content and replenishing the water loss to the given predetermined low content. In terms of physiological responses, this strategy can cause short daily cycles of hydration/dehydration with unreal and unpredictable consequences [13, 14]. Plant morpho- logical characterization (size, leaf area, number of leaves, growth rate…) is also necessary in a dynamic (hence non-destructive) way, as soil water uptake rate is pri- mary influenced by plant size/leaf area. When compar- ing mutants or ecotypes with different sizes, it must be considered that smaller plants uptake and transpire water from the substrate at a slower rate. Moreover, water stress is not a single condition but a process with multiple stages ranging from a well-watered plant to a plant that has completely lost turgor (and eventually will die) due to a water uptake insufficient to match transpirational water loss. To identify plant stress responses, we need to char- acterize this dynamic process influenced by the severity of the stress condition (water content, temperature and VPD) and time of exposure to the condition.