Influence of Exogenous Glycine Betaine on Gas Exchange and Biomass Production in Sunflower (Helianthus annuus L.) under Water Limited Conditions

Abstract

This study investigated whether the exogenous application of glycine betaine (GB) could alleviate the adverse effects of water deficit on sunflower. Two sunflower lines, Gulshan‐98 and Suncross, were subjected to water deficit at the vegetative or the reproductive stages of plant growth. Three levels (0, 50 and 100 mmol l−1) of GB were applied as a pre‐sowing seed treatment or as a foliar spray at the time of initiation of water deficit at the vegetative or reproductive stages. Foliar application of GB at the time of initiation of water deficit treatments showed a marginal increase in shoot biomass in drought‐stressed plants. Exogenously supplied GB as a foliar spray also showed a positive role in reducing the effects of water deficit on net CO2 assimilation rate, transpiration rate and sub‐stomatal CO2 concentration in both sunflower lines. Pre‐sowing seed treatment with GB had no effects on the above‐mentioned physiological and growth attributes in both normally irrigated and drought‐stressed plants. Taken together, foliar application of GB increased net CO2 assimilation rate which in turn showed a slight increase in growth of water‐stressed plants but this increase was not related to stomatal regulation.

Modulation of endogenous levels of some key organic metabolites by exogenous application of glycine betaine in drought stressed plants of sunflower (Helianthus annuus L.)

“…It is well established that its exogenous application might have some advantages as it improves drought tolerance in plants (Agboma et al 1997;Gorham et al 2000;Iqbal et al 2008;Mahmood et al 2009). It has been also reported earlier that rate and timing of GB application significantly affects drought tolerance ability of sunflower (Iqbal et al 2008(Iqbal et al , 2009). This shot-gun approach of exogenous application of GB has been used to increase the drought tolerance in some other crop species (Agboma et al 1997;Makela et al 1998;Gorham et al 2000).…”

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

“…Exogenous application of GB enhanced plant growth and biomass under drought stress in wheat and lentil(Raza et al 2014;Molla et al 2014) and under salinity stress in rice and soybean(Rezaei et al 2012;Hasanuzzaman et al 2014). GB-mediated increase in plant growth under Cr stress might be due to enhanced nutrients uptake by plants and increase in gas exchange attributes of plants as was previously reported in wheat plants under drought stress(Iqbal et al 2009; Shahbaz and Zia 2011).Furthermore, under abiotic stress, GB may protect CO2-fixing enzymes such as Rubisco and Rubisco activase and thus plant growth may increase (Chen and Murtaza 2011) Wang et al (2010). reported that GB application under drought and heat stress positively affected the Downloaded by [RMIT University] at 05:thylakoid lamellae and increased gas exchange characteristics of wheat plants.…”

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

“…Increase in biomass with GB might be due to enhanced uptake of nutrients, such as nitrogen, phosphorus, and potassium, by plants under stressful conditions (Shahbaz et al 2011). Moreover, the increase in growth and biomass might be due to positive effects of GB on net CO 2 assimilation rate, transpiration rate, and substomatal CO 2 concentration of wheat plants as reported in sunflower lines with foliar applied GB under water limited conditions (Iqbal et al 2009). Under abiotic stress, GB may activate the expression of genes for ROSscavenging enzymes, and as result, photosynthetic machinery is protected which positively affected plant growth and biomass of wheat plants .…”