Leaf Membrane Stability Index Research Articles

Co-application of silicon and biochar affected anatomical and biochemical properties of corn leaf (Zea mays L.) under soil nickel toxicity

Soil pollution with heavy metals is a threat to crop production. Practically, application of silicon (Si) with biochar can be a cost-effective approach to immobilize metals in contaminated soils. Investigation of the anatomical and biochemical changes of corn leaf is important for describing the mechanisms of Si and biochar soil application in alleviating the negative effects of nickel (Ni) toxicity. A factorial pot experiment was conducted to investigate the effect of Si (0, 250 and 500 mg Si kg-1 soil) in combination with rice husk biochar (RHB) or sheep manure biochar (SMB) prepared at two pyrolysis temperatures (300 and 500 °C) on anatomical and biochemical properties of corn leaves in a Ni-polluted soil. The length, width, area and weight of third-leaf, and metaxylem and protoxylem of midrib improved by application of Si250 with RHB more than SMB. At Si250, RHB300 and RHB500 improved the stomatal area by 31.7 and 27.7% compared to control (without biochar), respectively. The leaf membrane stability index was increased by increasing Si application level and reached 69% in RHB300. In contrast to total chlorophyll, the highest carotenoid content, catalase and peroxidase was obtained by control (without Si and biochar) followed by SMB. At Si250, the highest relative water content (RWC) was observed in RHB300 by 34.8% increase. Also, RHB300 had the highest total dry matter, with increases of 82.2, 120.0 and 83.1% at Si0, Si250 and Si500, respectively. By increasing the Si level and biochar application, the shoot Ni decreased between 42.1 to 133.3%. Combined application of Si250 with RHB300 resulted in the highest dry matter through improving the leaf dimensions, metaxylem and protoxylem areas of midrib, membrane stability index, total chlorophyll, and RWC, while Ni uptake was reduced.

Evaluation of bread wheat (Triticum aestivum L.) genotypes for drought tolerance using morpho-physiological traits under drought-stressed and well-watered conditions.

Increasing frequency of drought spells occasioned by changing climatic conditions, coupled with rise in demand for bread wheat, calls for the development of high yielding drought resilient genotypes to enhance bread wheat production in areas with moisture deficit. This study was designed to identify and select drought-tolerant bread wheat genotypes using morpho-physiological traits. One hundred and ninety-six bread wheat genotypes were evaluated in greenhouse and field experiments, under well-watered (80% of field capacity) and drought-stressed (35% of field capacity) conditions, for two years. Data were collected on five morphological traits (flag leaf size, flag leaf angle, flag leaf rolling, leaf waxiness and resistance to diseases) and 14 physiological traits. Relative water content (RWC), Excised leaf water retention (ELWR), Relative water loss (RWL), Leaf membrane stability index (LMSI), as well as Canopy temperature depression (CTD) at heading (CTDH), anthesis (CTDA), milking (CTDM), dough stage (CTDD) and ripening (CTDR) were estimated. Similarly, leaf chlorophyll content (SPAD reading) was recorded at heading (SPADH), anthesis (SPADA), milking (SPADM), dough stage (SPADD), and ripening (SPADR). Significant (p<0.01) genotypic differences were found for the traits under both well-watered and drought-stressed conditions. Associations of RWL with SPADH, SPADA, SPADM, SPADD and SPADR were significant (p<0.01) and negative under both watering regimes. The first three principal components accounted for 92.0% and 88.4% of the total variation under well-watered and drought-stressed conditions, respectively and comprised all the traits. The traits CTDD, CTDM, CTDR, SPADH, SPADA, SPADM, SPADD and SPADR with genotypes Alidoro, ET-13A2, Kingbird, Tsehay, ETBW 8816, ETBW 9027, ETBW9402, ETBW 8394 and ETBW 8725 were associated under both conditions. Genotypes with narrow flag leaves, erect flag leaf angles, fully rolled flag leaves, heavily waxed leaves, and resistant to disease manifested tolerance to drought stress. The identified traits and genotypes could be exploited in future breeding programmes for the development of bread wheat genotypes with tolerance to drought.

Efficiency of silicate solubilizing Bacillus tequilensis SKSSB09 in enhancing drought mitigation in Zea mays L.

Drought is an abiotic stress which causes huge economic losses in agriculture. Silicon is considered the best element which plays a key role in inducing drought mitigation properties. Silicate solubilizing bacterial strains were evaluated for their survivability in the low water activity potential. Bacillus tequilensis SKSSB09 showed high survivability at 40% polyethylene glycol 6000 concentration i.e. -1.76 MPa. ACC deaminase activity of the silicate solubilizing bacterial strains was assessed, among which B. tequilensis SKSSB09 showed ACC deaminase production in Dworkin and Foster minimal media. In–planta studies showed the survivability of maize plants till 23 days without water. Silicon deposition in the maize leaves showed 0.0384±0.0021μg/g. The leaf membrane stability index of the inoculated plants showed 72.2 ±3.8% which also correlates with the epicuticular wax content (2.4±0.56 mg/g). Proline content plays a key role in enhancing drought tolerance in plants. The inoculated plants showed high proline content (39.8±3.7 μg/g) which plays a key role in maintaining the cell sap and increasing the photosynthetic rate. Scanning electron microscopic studies revealed the deposition of silicon in the leaves and the formation of sunken stomata which reduces the transpiration rate. Based on the above results, Bacillus tequilensis SKSSB09 can be used as a plant growth-promoting rhizobacterial inoculant during drought conditions.

Cattle manure compost and biochar supplementation improve growth of Onobrychis viciifolia in coal-mined spoils under water stress conditions

Surface mining is a critical anthropogenic activity that significantly alters the ecosystem, while the use of appropriate revegetation techniques can be considered an important and feasible strategy in the way to improve the ecosystem services of degraded land. In the present study, we carried out a pot experiment to investigate the effects of three different variables on morpho-physiological and biochemical parameters of Onobrychis viciifolia to assess the capability of this species to be used for restoration purposes. Specifically, the variables studied were: (a) water (W) regime, working at five values as regards field capacity (FC) (i.e., 80% FC = highest, 72% FC = high, 60% FC = moderate, 48% FC = low, and 40% FC = very-low dose); and (b) rates of cattle manure compost (CMC) and wood biochar (BC) (weight/weight ratio), working at five rates (i.e., 4.0% = highest, 3.2% = high, 2.0% = moderate, 0.8% = low, and 0% = either no-CMC or no-BC dose). In addition, soil physical-chemical properties and enzyme activities were also investigated at the end of the experimental period. It was found that morphological growth attributes such as plant height, maximum root length, and dry biomass significantly increased with W, CMC and BC applications. Compared to control, moderate-to-high W, CMC and BC doses (W80CMC2BC2) increased net photosynthesis rate (by 42%), stomatal conductance (by 50%), transpiration rate (by 29%), water use efficiency (by 10%), chlorophyll contents (by 73%), carotenoid content (by 81%), leaf relative water content (by 33%) and leaf membrane stability index (by 30%). Under low-W content, the application of CMC and BC enhanced osmotic adjustments by increasing the content of soluble sugar and the activities of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase, decreasing the oxidative stress, as verified by low levels of hydrogen peroxide, superoxide anion, malondialdehyde and proline contents in leaf tissues. Moreover, application of W, CMC and BC significantly improved soil water holding capacity, available nitrogen, phosphorus and potassium, urease and catalase activities, which facilitate plant growth. These results would aid in designing an appropriate strategy for achieving a successful revegetation of O. viciifolia, providing optimum doses of W (64% field capacity), CMC (2.4%) and BC (1.7%), with the final aim of reaching ecological restoration in arid degraded lands.

Application of Silica Gel on Growth and Yield of Camelina sativa L.

The present study was designed to evaluate the effect of different concentrations of Silica gel on the growth and yield of Camelina sativa. A pot experiment was laid out in Completely Randomized Design (CRD) with three replications at Nanotechnology Laboratory, Department of Agronomy, PMAS Arid Agriculture University Rawalpindi. The experiment consisted of 4 levels (0.15 mg/g, 0.30 mg/g, 0.45 mg/g and 0.60 mg/g) of each mentioned nutrient along with control. The data were recorded and analyzed according to recommended procedure for following parameters viz., germination %, root and shoot length (cm), root and shoot biomass (g), relative water content of leaf and leaf membrane stability index. It was observed that 0.60 mg/g silica gel application increased the seed germination (80%), root length (6.67) cm, shoot length (35.33) cm, root biomass (1.7) g, shoot biomass (5.57) g, relative water content of leaf (0.69) and leaf membrane stability index (0.07). The study concluded that significant effect of silica gel application is crucial and important to improve vegetative attributes of false flax.

Comparative study of physiological compound and variability studies in different Allium species

Onion (Allium cepa L.), a member of Alliaceae family, is one of the important export oriented vegetable crop cultivated across the world. In India, it is the most popular and consumed spices in the daily human diet. In world, India ranks first in area and second in onion production (Kumar et al., 2015). Most cultivated Alliums lack many important traits, including resistance to pests and environmental stresses. Both producers and consumers face severe problems during crop failure due to price fluctuations. Underutilized Allium genotypes are an essential source of various biochemical components, vitamins, micronutrients and, thus, these are valuable component to attain nutritional security. Underutilized Alliums spp. can be used as a supplement to onion and garlic during crop failures. Current efforts and employment of both classical and novel tools for genetic and physiological studies are expected to accelerate improvements in terms of distribution, yield, and quality of these important crops. The present investigation was framed and conducted with 40 Allium genotypes laid out in RBD in three replications at ICAR-Directorate of Onion and Garlic Research, Rajgurunagar, Pune, Maharashtra, during rabi season of 2017-18. Physiological traits namely, chlorophyll, leaf membrane stability index, Relative water content, TSS, Leaf area, Dry matter content and Moisture content were estimated from leaf sample. Allium tuberosum showed the highest total chlorophyll content (3.92g/ml), Allium angulosum showed the highest membrane stability index (34.61%) Allium angulosum showed the highest relative water content (84.04%) Allium macranthum showed the highest TSS (11.33%) Allium cepa showed the highest leaf area (19.53 cm²) Allium chinense showed the highest dry matter content (40.78%), Allium angulosum showed the highest moisture content (86.13%) physiological content in underutilized Alliums was significantly higher compared to cultivated Alliums which provide ample scope for selection of promising genotypes under study.

Phenotyping for drought resistance in bread wheat using physiological and biochemical traits

Drought is one of the most prominent limiting factors that negatively affect crop productivity by manipulating its physiological pathway. One hundred twenty diverse bread wheat genotypes were used in a pot experiment to explore the relationship among their fifteen physio-biochemical traits (PBT) by using multivariate analysis, heatmapping and stress tolerance index (STI) for grain yield as a marker trait to identify high yielding genotype with maximum stress tolerance capability. Increased proline and sugar accumulation were observed from control to moisture deficient environments by 159% and 122%, respectively. Moreover, leaf membrane stability index (LMSI), leaf relative water content (LRWC), relative dry weight (RDW), chlorophyll content, leaf surface area (LSA), Leaf succulence (LS), canopy temperature depression (CTD), relative excised leaf water loss (RELWL) and leaf osmotic potential (LOP) showed significantly decreasing trend in drought stress treatment as compared to well-watered plants by −21%, −21%, −34%, −22%, −38%, −37%, −46%, −18% and −35% respectively. Additionally, principal component analysis and genotype by trait biplot analysis showed that initial 7 principal components (PC1 to PC7) represented 77.27% and 79.02% of total cumulative variation under control and drought stress respectively. Genotypic-Phenotypic correlation revealed that most of the attributes were higher in case of genotypic correlation component (rg) as compared to the phenotypic correlation component (rp) indicating more genetic association between traits. The darker and lighter colour scale produced by heatmap exhibited contrasting nature of genotypes, as positive side with higher values represented drought resistance while values on the negative side with lower values showed susceptible performance of genotypes. Our results concluded that the studied PBT associated with STI for grain yield are the main factors which may contribute in improved productivity of wheat crop and if these traits show appropriate performance under stress condition the crop will show the more productive returns under changing climate.

Physiological alterations due to field salinity stress in melon (Cucumis melo L.)

This study was aimed to assess physiological responses of melon (Cucumis melo L.) cultivars to salinity stress under field conditions. Seventeen melon cultivars including 16 widely distributed native and one exotic (‘Galia’) were subjected to 2-year (2014–2015) field salinity stress. Leaf relative water content (RWC), membrane stability index (MSI), pigments [chlorophyll a, b, total chlorophyll (TChl), carotenoid (Car) and their ratios], malondialdehyde (MDA), H2O2 content, proline content (Pro), total soluble sugar content (TSC), salinity tolerance and susceptibility indices as well as yield were evaluated. The results of combined analysis of variance showed significant genotypic variation for all the traits and significant effect of salinity stress on all the traits with the exception of Chla/Chlb and TChl/Car ratios. Overall, field salinity stress caused an increase in leaf MDA, H2O2, Chla, Chlb, TChl, Car, Pro and TSC and caused a reduction in leaf MSI and RWC as well as yield. The results of correlation coefficients showed that accumulation of osmolytes (proline and TSC) led to an increase in RWC and a decrease in MDA contents. In addition, the results of multiple regression analysis showed that leaf MDA, TSC, MSI and Chla contents were the most important predictors of yield justifying 72% total variation of yield under saline conditions. These results may highlight a dynamic interplay among biomarkers for lipid peroxidation (MDA), sugar osmolytes (TSC) and photosynthetic pigment (Chla) to maintain cell viability and cell wall integrity under salinity stress conditions in melon.

An Attempt to Mitigation of Irrigation Water Deficit Stress in Pea (Pisum sativum, L) Plants by Phosphorus Fertilizer

This investigation was carried in order to elucidate the response of pea (cv. Master pea) to various levels of Phosphorus fertilizer, i.e 45, 60, 75 and 90 kg as P2O5 /fed. under three levels of irrigation water deficit (100% of common irrigation as control, moderate stress 75 % of common irrigation and severe stress 50 % of the common irrigation). Therefore, two field experiments were conducted in the Experimental Station, Faculty of Agriculture, Mansoura University during 2015 and 2016 in winter seasons. The results indicated that vegetative growth characters (plant height, plant fresh weight, branches number, leaves fresh weight, leaves number and leaves area) per plant, leaves chemical composition (N, P, K and chlorophyll pigments), pods yield and its quality (pods weight per plant, pods number per plant, seeds fresh weight per plant, 100 seeds fresh weight, seeds dry weight yield and pods yield per fed., Vit. C and TSS) and plant water relations (leaf relative water content and leaf membrane stability index) were decreased by increasing of irrigation water deficit. On the contrast, leaves and seeds dry matter % were increased by increasing of irrigation water deficit. On the other hand, water use efficiency is not affected with irrigation water deficit. With respect to the effect of phosphorus fertilizer rates, the data show that, the mentioned attributes were increased up to 60 kg as P2O5 /fed then declined at and 75 kg as P2O5 /fed. On the other hand, 45 kg as P2O5 /fed gave the lowest values for most effective mentioned parameters. As for the interaction between irrigation water deficit and Phosphorus fertilizer rates showed that common irrigation and 60 kg as P2O5 /fed combination recorded the maximum values for more effective mentioned characters. In addition, results showed that common irrigation or moderate stress treatments with Phosphorus fertilizer rates had insignificant differences for most effective previous parameters.

Influence of packaging material along with wet refrigerated storage conditions on post-harvest life of cut chrysanthemum cv. Reagan White

An experiment was carried out to investigate the effect of different packaging films comprising of LDPE (100 and 200 gauge), polypropylene, polyethylene, micro-perforated polyethylene and cellophane bags on low temperature storage of cut chrysanthemum flowers cv. Reagan White. The results obtained showed that the LDPE was most effective film in enhancing the vase-life and quality under both refrigerated wet storage and normal ambient conditions. The LDPE 100 gauge packed flower stems resulted in enhanced vase-life compared to other treatments by maintaining flower and leaf membrane stability index coupled with lower physiological loss in weight. The percent decline in total soluble sugars and reducing sugar contents in leaf and ray floret tissues was less in LDPE packaged flowers as compared to other treatments and control. The wrapped flowers stems in refrigerated wet storage after 15 days at 4°C were held in vase at ambient conditions. The maximum vase-life (12.67 days) was found with LDPE 100 gauge packaged flower stems. The higher CO2 and lower O2 concentrations were recorded in LDPE packed flower stems, which were attributed to prevention of oxidative stress. There was marked favourable biochemical changes in the cut flower tissue, viz. total soluble sugars, reducing sugar, leaf chlorophyll content, MDA content, and superoxide dismutase activity in vase under ambient conditions.

BROCCOLI GROWTH, ANTIOXIDANT ACTIVITY AND HEALTH TISSUES RESPONSES TO ASCORBIC ACID UNDER DEFICIT IRRIGATION

Two field experiments were conducted during 2013/2014 and2014/2015 in a private Farm, Ibshway district, Fayoum, Egypt to study deficitirrigation (60, 80 and 100% ETc) and ascorbic acid foliar application (0, 200and 400 mg l-1) on growth, relative water content (RWC), membrane stabilityindex (MSI), electrolyte leakage (EL), leaf photosynthetic pigments (LPS),osmoprotectants (OS) and DPPH radical-scavenging activity of broccoliplants. The obtained results clarified that, irrigation amount at 80% or 100%ETc, significantly, resulted in higher mean values of stem length anddiameter, number of leaves plant-1, leaf MSI, RWC, carotenoids, DPPHradical-scavenging and total free amino acids content than irrigation amountat 60% ETc. On other side, irrigation amounts, irrespective the level used, didnot reflect any noticeable impact on number of branches plant-1 and headcontents of ascorbic acid. Increasing irrigation water from 60% up to 100%ETc decreased the contents of leaf EL, chlorophyll A, B, A + B, anthocyanin,free proline and TSS. Exogenous application of ascorbic acid atconcentrations of 200 and 400 mg l-1, significantly improved most studiedgrowth parameters, RWC, MSI, anthocyanin, DPPH, total free amino acidsand endogenous ascorbic acid however, leaf EL decreased gradually.Moreover, the impact of ascorbic acid, irrespective of the concentration used,on leaf photosynthetic pigment, free proline and total soluble sugars contentswas at par.

Improvement of wheat (Triticum aestivum) drought tolerance by seed priming with silicon

Silicon has the potential to improve drought tolerance in crops. Seeds primed with silicon were used in the present study to explore its potential benefit to withstand water stress. Seeds of two wheat varieties, NARC-2009 and Chakwal-50, were sown in pots after priming with distilled water and different concentrations (0.5%, 1.0% and 1.5%) of silicon sources (silicic acid, sodium silicate and silica gel) at PMAS, Arid Agriculture University, Rawalpindi. Maximum silicon uptake at three-leaf stage (0.028 µg g−1 dry weight (DW)), anthesis (0.072 µg g−1 DW) and maturity (0.103 µg g−1 DW) was recorded for silica gel. Silicon uptake increased significantly in response to increase in Si concentration from 0.5% to 1.5%. Leaf membrane stability index, epicuticular wax, relative water content and proline remained maximum – 78.90%, 2.6 mg g−1 DW, 83.88% and 54.90 µg g−1 – for silica gel treatments compared with others. Silica gel with 1.5% silicon concentration resulted in maximum spike length (14.3 cm), biological yield (7.63 g pot−1), hundred-grain weight (3.97 g pot−1) and grain yield (2.46 g pot−1). Based on the study outcomes, it is concluded that silica gel might be a good priming option with 1.5% silicon concentration to establish plant under drought stress.

Effect of gamma radiation on wheat plant growth due to impact on gas exchange characteristics and mineral nutrient uptake and utilization

The experiment was conducted to determine the effect of gamma radiation on plant growth and development, flag leaf gas exchange characteristics such as net photosynthetic rate (P N), stomatal conductance (g s), and transpiration rate (E) and activity of key carbon and nitrogen assimilating enzymes like Rubisco, starch synthase (SS) and nitrate reductase (NR) in field grown wheat. Grains of cultivar PBW-343 were exposed to a 60Co (Cobalt-60) gamma source at a dose range from 0 to 500 Gy (Gray). Gas exchange characteristics of flag leaf were measured using Infrared Gas Analyzer (IRGA), while mineral nutrients were analyzed spectrophotometrically. Our results show that an irradiation treatment, in general, caused an improvement in plant growth and yield characteristics such as shoot and root mass, root length and surface area, leaf area and chlorophyll SPAD index, tiller number and grain yield. However, irradiation exceeding 5 Gy reduced the magnitude of radiation advantage for most of the investigated physiological and biochemical traits. No germination was recorded at 500 Gy irradiation dose. A dose-dependant increase in shoot Fe in radiated plants up to 25 Gy reflected its higher plant root to shoot translocation which may yield micronutrient rich grains. At higher dose of 100 Gy, there was a drastic reduction in flag leaf membrane stability index (MSI), photosynthesis, Rubisco, NR, and nutrients like K, P, Mg, Fe, and Zn. Starch synthase enzyme activity was unaffected by gamma irradiation indicating that the negative effect of high dose (100 Gy) on the grain yield were caused by the adverse effect of radiation on the gas exchange attributes particularly photosynthesis, carbon, and nitrogen assimilation efficiency and the plant uptake of mineral nutrients. The study concludes that gamma radiation at a low dose (25 Gy or lower) stimulates, while a high dose (100 Gy and above) inhibits plant growth and development of wheat. The adverse effect at 100 Gy and beyond could be attributed to the poor carbon and nitrogen assimilation efficiency and the plant uptake of mineral nutrients, all of which are the ultimate determinant of plant health.