Application Of Glycinebetaine Research Articles

Genetic engineering of the biosynthesis of glycinebetaine leads to alleviate salt-induced potassium efflux and enhances salt tolerance in tomato plants

Tomato (Solanum lycopersicum cv. ‘Moneymaker’) was transformed with the choline oxidase gene codA from Arthrobacter globiformis, which was modified to allow for targeting to both chloroplasts and the cytosol. Glycine betaine (GB) was accumulated in transformed plants, while no detectable GB was found in wild-type (WT) plants. Compared to WT plants, transgenic lines showed significantly higher photosynthetic rates (Pn) and antioxidant enzyme activities and lower reactive oxygen species (ROS) accumulation in the leaves when exposed to salt stress. Furthermore, compared with WT plants, K+ efflux decreased and Na+ efflux increased in roots of transgenic plants under salt stress; resulted in lower Na+/K+ ratios in transgenic lines. The exogenous application of GB also significantly reduced NaCl-induced K+ efflux and increased Na+ efflux in WT plants. A qRT-PCR assay indicated that GB enhanced NaCl-induced expression of genes encoding the K+ transporter, Na+/H+ antiporter, and H+-ATPase. These results suggest that the enhanced salt tolerance conferred by codA in transgenic tomato plants might be due to the regulation of ion channel and transporters by GB, which would allow high potassium levels and low sodium levels to be maintained in transgenic plants under salt stress condition.

Differential Effects of Glycine Betaine and Spermidine on Osmotic Adjustment and Antioxidant Defense Contributing to Improved Drought Tolerance in Creeping Bentgrass

Glycine betaine (GB) and spermidine (Spd) are known to play roles in plant adaptation to stresses that induce dehydration, including drought stress. The objectives of this study were to examine whether improved drought tolerance by exogenous application of GB or Spd is associated with the increases in the endogenous accumulation of those solutes under drought stress in cool-season turfgrass species, and to determine the relative effects of those solutes on osmotic adjustment (OA) and antioxidant metabolism for improving drought tolerance. Creeping bentgrass (Agrostis stolonifera cv. Penncross) plants were treated with 200 mm GB or 0.1 mm Spd for 3 weeks by weekly foliar application before the exposure to drought stress; those plants were subsequently subjected to drought stress by withholding irrigation. The endogenous content of GB and Spd increased significantly through the exogenous application of either compound, to a greater magnitude for GB. The comparison of GB- or Spd-treated plants to untreated plants exposed to drought stress for growth [turf quality (TQ)] and physiological responses (water relations, membrane stability, and antioxidant metabolism) demonstrated that both compounds led to significant improvement in drought tolerance in creeping bentgrass. The improved drought tolerance by exogenous GB could be due to its contribution to OA by significant accumulation of endogenous GB, and activation of antioxidant enzymes with the greatest effects on ascorbate peroxidase (APX). Exogenous Spd did not cause increases in leaf OA despite of the increased endogenous accumulation, but significantly enhanced antioxidant enzyme activities, with the most pronounced effects on catalase (CAT). This study demonstrated that GB and Spd had different effects on OA and activated different antioxidant defense pathways, protecting plants from drought damages in creeping bentgrass.

Attenuation of Negative Effects of Saline Stress in two Lettuce Cultivars by Salicylic Acid and Glycine Betaine

Reducing destructive effects of lettuce plants irrigated with saline water was investigated in two field experiments conducted at Ismailia Governorate in 2012–2013 and 2013–2014. Two lettuce (Lactuca sativa L.) cultivars, Great Lakes and Balady, irrigated with saline water (3.22 dS/m) were treated using two levels of salicylic acid (SA) and glycine betaine (GB) as a foliar application (200, 400 ppm and 15, 30 Mm, respectively). Generally, application of SA and GB enhanced growth parameters, i. e. plant height; root length; number of leaves per plant; plant fresh and dry weight; leaf relative water content (LRWC); membrane permeability (MP); lipid peroxidation (MDA); chlorophyll a, b and carotenoid content in leaf; proline; total soluble sugars (TSS); superoxide dismutase (SOD) and peroxidase (POD) activity; and Na, K, Ca content. GB treatments significantly increased most recorded growth parameters, especially at 30 mM, while this treatment decreased values of MP, (MDA) and Na content in two lettuce cultivars.

Chemically enhanced lipid production from microalgae under low sub-optimal temperature

Low sub-optimal temperatures are one of the major environmental factors that significantly affects growth and lipid production of microalgae. However, until now little research has been done to estimate and reduce the effects of low sub-optimal temperatures (typically 15°C–20°C) on productivity of algal lipids, which serve as feedstock for biodiesel. We addressed this issue by growing the microalga Chlorella sorokiniana under a low sub-optimal temperature (18°C) (the optimal temperature was 26°C, which was used as a control). Algal growth was inhibited at 18°C compared to 26°C, resulting in overall decreased lipid productivity; however, decreased temperature increased the total lipid content of the algal cell. Importantly, decreased lipid productivity under the low sub-optimal temperature was improved by an application of exogenous glycine betaine at 500mg/L compared to the control treatment of 26°C. Quantitative PCR analysis showed that exogenous glycine betaine enhanced expression of genes encoding Rubisco, one of the key enzymes involved in carbon fixation through photosynthesis. The expression of other key genes involved in the Calvin cycle was up-regulated by treatment with glycine betaine at both 18°C and 26°C. In addition, glycine betaine treatment had little influence on algal fatty acid profiling, hence it did not affect the cetane number that is a key parameter of biodiesel quality. Taken together, our evidence supports a chemically enhanced lipid production of microalgae under low sub-optimal temperatures whose lipid output was comparable to those at optimal temperatures. The novel application of glycine betaine could strengthen the algal biodiesel industry by extending the geographical range for cultivation into areas with cooler climates.

Cadmium stress in cotton seedlings: Physiological, photosynthesis and oxidative damages alleviated by glycinebetaine

Cadmium (Cd) level is continuously increasing in agricultural soils mainly through anthropogenic activities. Cadmium is one of the most phytotoxic metals in soils. The present study investigates the possible role of exogenously applied glycinebetaine (GB) in alleviating Cd toxicity in cotton (Gossypium hirsutum L.) plants in a hydroponic system. Three concentrations of Cd (0, 1.0, and 5.0 μM) were tested with and without foliar application of GB (1.0 mM). Cadmium toxicity caused a significant decrease in plant height, root length, number of leaves per plant, fresh and dry weights of leaf, stem and root and intensively increased Cd concentration in different plant parts. Cadmium toxicity also decreased photosynthetic pigments and gas exchange characteristics in leaves. Superoxide dismutase (SOD), guaiacol peroxidase (POD), catalases (CAT) and ascorbate (APX) activities increased under lower Cd stress (1.0 μM) while decreased under higher Cd stress (5.0 μM). Cadmium toxicity increased the concentration of reactive oxygen species (ROS) as indicated by the increased production of malondialdehyde (MDA), hydgrogen peroxide (H2O2) and electrolyte leakage in both leaves and roots. Application of GB decreased Cd concentration in different plant parts, alleviated Cd-induced inhibition in plant growth and biomass and led to a significant increase in photosynthetic pigments, protein contents and antioxidant enzymes. Glycinebetaine application alleviated the oxidative damage as evidenced by the decreased production of electrolyte leakage, H2O2 and MDA contents. These results revealed that GB might alleviate Cd toxicity in cotton plants through lowering Cd concentrations and regulating Cd induced oxidative stress in different plant parts possibly by increasing the performance of the antioxidant enzymatic system.

Effects of high salinity and the exogenous application of an osmolyte on growth, photosynthesis, and mineral composition in two ornamental shrubs

ABSTRACTA greenhouse experiment was carried out to determine the growth, photosynthetic activity, and mineral composition in two ornamental shrubs [Viburnum lucidum L. (arrow-wood) and Callistemon citrinus (Curtis) Stapf. (red bottlebrush)] that had been treated or not treated with 2.5 mM glycine betaine (GB) or 5.0 mM proline (Pro). Plants were supplied with a non-salinised or salinised nutrient solution containing 200 mM NaCl. Salinity caused reductions in plant growth parameters, shoot biomass production, and net CO2 assimilation in both species. Neither Pro nor GB were able to mitigate the adverse effects of salinity in bottlebrush, whereas GB reduced the deleterious effects of salt stress on arrow-wood, indicating a differential species-specific response to these osmolytes. The application of GB to salt-stressed arrow-wood increased apical and lateral shoot lengths, the number of leaves per plant, and shoot dry biomass by 222%, 113%, 238%, and 49%, respectively, compared to untreated or Pro-treated plants. The improved performance of salt-stressed arrow-wood plants whose roots were treated with 2.5 mM GB was attributed to partial suppression of Na uptake, higher chlorophyll concentrations, and the better nutritional status (higher K) of shoots.

Enhancing antioxidant–yield relationship of pea plant under drought at different growth stages by exogenously applied glycine betaine and proline

Pod filling stage considers as a receiver (sink), which reflects plant performance during previous growth stages. In order to study, the influence of drought imposed at different growth stages, and the impact of foliar applied glycine betaine (GB) and proline on the status of osmolytes and antioxidant defense system of pea plant during pod filling stage, a field experiment was conducted in 2012/2013 and 2013/2014 on clay loam soil. Four different irrigation regimes were applied to provide drought at different growth stages: (1) vegetative stage, (2) flowering stage, as short-term drought stress, (3) throughout the stages of vegetative+flowering growth (long-term drought stress), and (4) control (without stress). Foliar applications of GB and proline at 4mM for each, in addition to distilled water as control, were conducted. Generally, drought applications reduced the growth and yield of pea plant. Long-term drought was more effective to reduce growth and yield than drought at flowering stage. GB increased the yield and its soluble protein concentration more than proline. Proline recorded the maximum increase in non-enzymatic antioxidant defense system under drought. Application of GB or proline enhanced the activity of SOD, APX and catalase in leaves under drought, while in seeds they increased SOD activity under long-term drought stress. APX activity in seeds under drought decreased by GB application. The maximum positive effect was for GB under unstressed condition and drought at vegetative stage, by maximizing APX activity, in addition to enhancing the production and translocation of assimilates from source to sink.

Glycinebetaine mediates chromium tolerance in mung bean through lowering of Cr uptake and improved antioxidant system

A pot experiment was conducted to evaluate the role of glycinebetaine (GB) in chromium (Cr) tolerance in mung bean (Vigna radiata L.) grown in Cr-stressed soil. Three concentrations of Cr (0, 250 and 500 µM) were tested with three (0, 50 and 100 mM) concentrations of foliar-applied GB. Cr alone led to a significant decrease in plant growth, biomass, and concentrations of chlorophyll a, b and carotenoids. Cr concentration and electrolyte leakage significantly increased in plants with increasing Cr levels in the soil. Lower Cr stress enhanced the activities of superoxide dismutase (SOD), peroxidases (POD) and catalase (CAT), while higher Cr concentrations decreased the activities of these enzymes. Foliar application of GB successfully alleviated toxic effects of Cr on mung bean and increased plant growth, biomass and chlorophyll contents under Cr stress. GB application reduced Cr accumulation and electrolyte leakage in plants and enhanced the activities of antioxidant enzymes in both shoots and roots as compared with Cr treatments alone. These findings suggest that foliar-applied GB alleviated Cr-induced oxidative stress in mung bean by reducing Cr uptake. The protective effect of GB against Cr stress varies with the concentrations of GB and Cr stress applied. Thus, further studies are still needed to specify the concentrations of GB required for detoxification of specific Cr concentrations under various climatic conditions.

Exogenous glycinebetaine alleviates the detrimental effect of Cd stress on perennial ryegrass.

Glycinebetaine (GB) is an important organic osmolyte that accumulates in many plant species in response to abiotic stresses including heavy metals. The objective of this study was to investigate whether exogenous GB would ameliorate the adverse effect of cadmium (Cd) stress on perennial ryegrass (Lolium perenne). Fifty-three days old seedlings were exposed to hydroponic culture for 7 days with six treatments: T1 (control), T2 (0 mM Cd + 20 mM GB), T3 (0 mM Cd + 50 mM GB), T4 (0.5 mM Cd + 0 mM GB), T5 (0.5 mM Cd + 20 mM GB), T6 (0.5 mM Cd + 50 mM GB). Cd stress resulted in a remarkable decrease in turf quality, vertical shoot growth rate (VSGR), normalized relative transpiration (NRT) and Chlorophyll (Chl) content; with significant increases in electric conductivity (EL), malondialdehyde (MDA) content, superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) activity, oxalic and tartaric acid content. Exogenous application of GB decreased EL and MDA content in Cd stressed plants, and increased turf quality, VSGR, NRT, Chl content, SOD, CAT, POD activity, oxalic, tartaric acid content, and the gene expression level of SOD and POD when compared with Cd stressed without GB. Perennial ryegrass with 20 mM GB application suppressed the Cd accumulation in both shoots and roots. A lower translocation factor of Cd was found in GB treated plants than non-GB treated plants, and the lowest translocation factor was observed in the 20 mM GB application. These results suggested that GB could alleviate the detrimental effect of Cd on perennial ryegrass and the amelioration was mainly related to the elevation in SOD, CAT, and POD at enzyme and gene expression levels, which reduced Cd content in shoots and improved cell membrane stability by reducing oxidation of membrane lipids. These findings lead us to conclude that application of GB with 20 mM is the best strategy to ameliorate the detrimental impacts of Cd stress on perennial ryegrass.

Alleviation of salt-induced oxidative stress in rice seedlings by proline and/or glycinebetaine

The effects of proline and/or glycine betaine (GB) application on growth, photosynthetic pigments, H2O2 content, and activities of antioxidant enzymes in rice (Oryza sativa L. cv. KDML105) under salt stress were investigated. The H2O2 content and the activities of superoxide dismutase (SOD), glutathione reductase (GR), and ascorbate peroxidase (APX) but not catalase (CAT) increased under salinity. Under 160 mM NaCl, the CAT activity was maintained on the pre-stress level in the presence of proline, whereas in the presence of GB, the GR activity increased more than without GB application. A co-application of 30 mM proline and 1 mM GB did not reduce the increase in H2O2 caused by the NaCl stress more than applying each of the osmoprotectants and no synergistic effect on the antioxidant enzymes was observed. However, the application of both the osmoprotectants was the most effective in alleviating degradation of photosynthetic pigments.

Physiological and biochemical response to drought stress in the leaves of Aegiceras corniculatum and Kandelia obovata.

Drought stress is one of the major abiotic stresses that affects plant growth and metabolism adversely around the world. According to this research, the effect of drought stress on the activity of antioxidative enzymes, soluble sugar, protein and lipid peroxidation were studied in leaves of two mangrove plants, Kandelia obovata and Aegiceras corniculatum. The result showed that superoxide dismutase (SOD) and peroxidase (POD) varied significantly between the leaves and roots studied. The activities increased in different stress levels. The production rate of O 2 (-·) changed with the activity of SOD and POD. Lipid peroxidation was enhanced and Glycine betaine (GB) could decrease the level of malonaldehyde in order to reduce the damage of membrane system. The content of soluble sugar and protein also increased under drought stress and GB helped to eliminate the accumulation of them which somehow enhance the ability of defensing the plants under drought stress. These results indicated that antioxidative activity may play an important role in A. corniculatum and K. obovata and that cell membrane in leaves of K. obovata had greater stability than those of A. corniculatum. Exogenous application of GB had positive effects on A. corniculatum and K. obovata under drought stress which could be products exogenously applied to mangrove plants in order to alleviates the adverse effects.

Photosynthetic capacity of canola ( Brassica napus L.) plants as affected by glycinebetaine under the salt stress

Salinity causes reduction in growth and severe losses of crop productivity by affecting various biochemical and physiological processes including photosynthesis. Plants sense and adapt to salt stress by modulating different physiological processes including accumulation of osmoprotectants. Glycinebetaine (GB) is an important osmoprotectant and found to have ameliorative effects on the growth of plants by altering ion homeostasis, photosynthetic and antioxidant capacity. In this study, it was attempted to reveal how GB improves photosynthetic activity and salt tolerance of two canola cultivars which differ in degree of salt tolerance. Two cultivars (Dunkled and Cyclone) of canola ( Brassica napus L.) were grown under non-saline or saline (150 mM NaCl) conditions. Glycinebetaine (100 mM) was foliarly applied to both non-stressed and salt stressed plants of both canola cultivars at the vegetative growth stage. Salt stress reduced growth of both canola cultivars, however, cv. Dunkled was superior to cv. Cyclone. Foliar application of GB improved leaf relative water contents (RWC), osmotic potential and proline accumulation in salt stressed plants. The chlorophyll fluorescence transient (CFT) remained unchanged at O and J phase while at I and P phase it was affected by salt stress in both cultivars that was ameliorated by GB application. The positive values of K band after 1000 µs under salt stress revealed the reduced efficiency of oxygen evolving complex (OEC). The GB application enhanced electron transport chain and decreased heat dissipation under salt stress. This effect was more in cultivar Cyclone as compared to Dunkled. Furthermore, a considerable proteomic variation was noted in canola cultivars after application of GB under both saline and non-saline condition. The results suggested that exogenous foliar application of GB ameliorated the adverse effects of salt stress on both cultivars of canola by osmotic adjustment, growth improvement, increased light absorption by reaction centers, efficient energy trapping and enhanced electron transport chain in both cultivars of canola.

Roles of glycine betaine in mitigating deleterious effect of salt stress on lettuce (Lactuca sativa L.)

This study was conducted to evaluate the roles of glycine betaine (GB) in mitigating deleterious effect of salt stress on lettuce. Lettuce plants were subjected to two salinity (0 and 100 mmol l−1 NaCl) and four GB levels (0, 5, 10, 25 mmol l−1). Salinity resulted in a remarkable decrease in growth parameters, relative leaf water content and stomatal conductance. Plants subjected to salt stress exhibited an increase in membrane permeability (MP), lipid peroxidation (MDA), leaf chlorophyll reading value, H2O2 and sugar content. Exogenous foliar applications of GB reduced MP, MDA and H2O2 content in salt-stressed lettuce plants. Salt stress increased Na and generally decreased other nutrient elements. GB reduced Na accumulation, but significantly increased other element contents under salinity conditions. The study showed that gibberellic acid (GA) and salicylic acid (SA) content in salt-stressed plants were lower than those of nonstressed plants. However, salinity conditions generally increased the abscisic acid content. GB treatments elevated the concentrations of GA, SA and indole acetic acid (IAA) at especially 10 and 25 mmol l−1 GB under salt stress conditions. It could be concluded that exogenous GB applications could ameliorate the harmful effects of salt stress in lettuce.

Preharvest foliar applications of glycine-betaine protects banana fruits from chilling injury during the postharvest stage

Banana plantations are affected by environmental factors such as chilling injury, which reduces the quality of fruits and causes losses of up to 50% in the yield of banana and it will be more important in terms of global climate change. Chilling injury of the fruits can also occur during transport and storage at low temperatures, particularly in tropical fruits. In banana, losses of up to 20% can occur during postharvest handling. Given this situation, it is necessary to explore alternatives that might reduce chilling injury, such as the use of compatible solutes including glycine-betaine (GB). In the present work, experiments were performed to analyze the possible role of preharvest foliar applications of GB, to prevent the subsequent development of chilling injury of banana fruits during the postharvest storage at low temperatures. After 3 days of the preharvest application of 100 mM GB over banana leaves (250 ml/plant), the fruits were harvested and first stored at 10°C for 6 h and then transferred to 23°C ± 1°C until they reached commercial ripening. A second group of plants were not treated with GB during the preharvest stage, but their fruits were exposed to 10°C for 6 h before transferring them to 23°C ± 1°C until they reached commercial ripening. A control group was untreated with GB during the preharvest stage, and fruits were not exposed to low temperatures but they were kept at 23°C until they reached commercial ripening. The results showed that the preharvest foliar application of GB (100 mM) to banana plants reduced the biochemical and physiological alterations caused by chilling injury on harvested fruits.

Influence of exogenous application of glycinebetaine on antioxidative system and growth of salt-stressed soybean seedlings (Glycine max L.).

Glycinebetaine is one of the most competitive compounds which play an important role in salt stress in plants. In this study, the enhanced salt tolerance in soybean (Glycine max L.) by exogenous application of glycinebetaine was evaluated. To improve salt tolerance at the seedling stage, GB was applied in four different concentrations (0, 5, 25 and 50mM) as a pre-sowing seed treatment. Salinity stress in the form of a final concentration of 150mM sodium chloride (NaCl) over a 15day period drastically affected the plants as indicated by increased proline, MDA and Na(+) content of soybean plants. In contrast, supplementation with 50mMGB improved growth of soybean plants under NaCl as evidenced by a decrease in proline, MDA and Na(+) content of soybean plants. Further analysis showed that treatments with GB, resulted in increasing of CAT and SOD activity of soybean seedlings in salt stress. We propose that the role of GB in increasing tolerance to salinity stress in soybean may result from either its antioxidant capacity by direct scavenging of H2O2 or its role in activating CAT activity which is mandatory in scavenging H2O2.

Alleviation of chromium toxicity by glycinebetaine is related to elevated antioxidant enzymes and suppressed chromium uptake and oxidative stress in wheat (Triticum aestivum L.).

Little information is available on the role of glycinebetaine (GB) in chromium (Cr) tolerance while Cr toxicity is widespread problem in crops grown on Cr-contaminated soils. In this study, we investigated the influence of GB on Cr tolerance in wheat (Triticum aestivum L.) grown in sand and soil mediums. Three concentrations of chromium (0, 0.25, and 0.5 mM) were tested with and without foliar application of GB (0.1 M). Chromium alone led to a significant growth inhibition and content of chlorophyll a, b, proteins and enhanced the activity of antioxidant enzymes. Glycinebetaine foliar application successfully alleviated the toxic effects of Cr on wheat plants and enhanced growth characteristics, biomass, proteins, and chlorophyll contents. Glycinebetaine also reduced Cr accumulation in wheat plants especially in grains and enhanced the activity of antioxidant enzymes in both shoots and roots. This study provides evidence that GB application contributes to decreased Cr concentrations in wheat plants and its importance in the detoxification of heavy metals.

EXOGENOUS APPLICATION OF GLYCINEBETAINE IMPROVES ANTIOXIDANT SYSTEM IN GREEN BEAN (PHASEOLUS VULGARIS) SEEDLINGS UNDER SALINITY STRESS

Salt stresses collectively are responsible for many crop losses worldwide especially salt -sensitive plants. The present study investigates the roles of exogenous application of glycinebetaine (GB, 5mM) in improving salt stress tolerance in salt sensitive green bean seedlings. Salt stresses (45mM NaCl for one week) significantly reduced leaf relative water (RWC) and chlorophyll (chl) content and increased percentage of electrolyte leakage, endogenous Proline and lipid peroxidation. Activities of peroxidase(PX), ascorbate peroxidae (APX), superoxide dismutase (SOD), and catalase (CAT), were significantly increased in shoots and roots of green bean seedlings subjected to salt stress. Exogenous application of GB improves salt tolerance of green been seedlings as shown by increased RWC and chlorophyll contents in leaves and reduced percentage of electrolyte leakage, lipid peroxidation and proline content. Under salinity stress condition, GB application decreased the activities of PX, CAT, APX and SOD in seedling shoots, whereas, it increased the activities of CAT and AP in roots. The result suggests that exogenous application of GB increased green bean seedlings' tolerance to salt-induced oxidative damage by upregulating their antioxidant defense system where this compatible solute protect plant cell against salinity stress.

Glycinebetaine Improved Photosynthesis in Canola under Salt Stress: Evaluation of Chlorophyll Fluorescence Parameters as Potential Indicators

AbstractSalinity is a widespread soil problem limiting productivity of oilseed crops worldwide. Reduction in growth generally associated with decline in photosynthesis. Accumulation of osmo‐protectants such as glycinebetaine (GB) permits the plant to cope with salt stress. This study was aimed to understand the mechanism by which exogenous GB application improves photosynthetic capacity and salt tolerance in two diverse lines of canola differing in salt tolerance using chlorophyll fluorescence technique. Glycinebetaine was applied as foliarly or through rooting medium to two canola lines Dunkeld and Cyclone that were grown under non‐saline or saline conditions. Root‐applied GB caused adverse effects whereas foliar application of GB was effective in improving growth of canola cultivars. However, the response of salt‐tolerant cultivar Dunkeld was stronger than that of salt sensitive Cyclone. Foliar application of GB improved accumulation of proline and plant water status. Application of GB enhanced the photosynthetic CO2 fixation, stomatal conductance (gs) and water‐use efficiency. The tolerant lines Dunkeld had more responsive to GB application. Chlorophyll fluorescence measurements (Fo, Fm, Fv, Fo/Fm, Fv/Fo and Fv/Fm ratios) revealed that salt stress reduced energy trapping efficiency by damaging oxygen evolving complex, over reduction of QA resulting in occurrence of chronic photoinhibition. However, exogenous GB protected the oxygen evolving centre of PSII and maintains activity of PSII. Although root‐applied GB adversely affected the growth of canola plants, it did not have any adverse effect on PSII photochemistry. Moreover, fluorescence parameters could provide a rapid means for determining salt tolerance in canola and could be a rapid and sensitive test to identify genotypes highly tolerant to salt stress.

Radiation, water, and nitrogen use efficiencies of Gossypium hirsutum L.

Resource use efficiency is a baseline for productive agriculture and proper management of different resources (water, nitrogen, light, and land), and it plays a pivotal role in the accomplishment of this goal. Three field experiments were carried out at the experimental farm area of the Central Cotton Research Institute, Multan, Pakistan, in 2009 and 2010 to investigate the effects of different resources on cotton crops. Treatments for the first experiment included 4 cultivars and 6 nitrogen levels. The second experiment comprised 3 variables, irrigation methods, cultivars, and plant spacing, whereas 2 variables, including different irrigation regimes and glycinebetaine application, were used in the third experiment. Different attributes, such as physiological efficiency, irrigation water use efficiency, and agronomic and economic nitrogen use efficiency, were studied during the course of experimentation. The statistical results revealed that cumulative intercepted photosynthetically active radiation, radiation use efficiencies, water use efficiencies for total biomass, seed cotton, lint, and cottonseed yield were enhanced with the addition of each incremental dose of nitrogen fertilizer and were also recorded as higher for the application of irrigation water through the drip method at the narrow plant spacing of 10 cm. Furthermore, exogenously applied glycinebetaine also significantly increased the attributes studied. Different agronomic and economic nitrogen use efficiencies for seed cotton, lint, and cottonseed yield were notably increased with the application of different nitrogen fertilizer levels and were greater at 160 kg N ha-1.

Influence of Exogenous Glycinebetaine on Hot Pepper under Water Stress

A study was conducted to evaluate the effect of exogenous application of glycinebetaine (GB) on physiological response in hot-pepper (Capsicum annuum L. vs. Arka Lohit and Pusa Jwala) under water stress. Glycinebetaine was applied to seeds as well as plants through foliar applications. Water stress affected considerably the morphophysiological parameters in both the cultivars. However, in glycinebetaine (GB) treated plants, plant height, leaf area (LA), flower and fruit number and total dry matter (TDM) were greater compared to the untreated stress plants (T4) under water stress. Glycinebetaine application enhanced the photosynthesis (PN) in water deficit experiencing plants, mostly due to a greater stomatal conductance (gs) and carboxylation efficiency of CO2 assimilation. In both the cultivars after 12 day of stress, the PN decreased from 10.1 to 1.0-1.3 μ mol m-2 s-1 in untreated stressed plants (T4), while in the treated stressed plants PNhad reduced to 2.0 - 3.0 μ mol m-2 s-1 (T1 - T3). The application of GB increased the WUE in both the cultivars. The better WUE in treated plants of hot-pepper under stress was attributed to the improved PN. The higher per plant yield in the GB applied plants under stress in both the cultivars associated with higher PNrate, gs and WUE in treated plants. Though there was an increase in PN rate, WUE and plant yield in the treated plants (T1 - T3), the better results were found in the plants (T2) where seeds were treated and foliar application was given at the time of imposing stress.