Plant-Water Relations of Kidney Bean Plants Treated with NaCl and Foliarly Applied Glycinebetaine

Abstract

Salinity is at present one of the most serious environmental problems in¯uencing crop growth. It has been extensively demonstrated that salinity aects several physiological processes in the plant, including the plant±water relations of most salt-sensitive crops species. In this study, the eects of salinity on the plant±water relations of kidney bean (Phaseolus vulgaris L.) and the possibility that foliarly applied glycinebetaine improves these water relations are examined. Kidney bean plants were grown in a greenhouse and treated with 0, 30, 50 and 100 mM M NaCl, combined with 0, 10 and 30 mM M glycinebetaine in foliar applications. Increased salinity levels decreased stomatal conductance, photosynthetic rate, transpiration and leaf relative water content in the 30, 50 and 100 mM M treatments relative to the control treatment. Glycinebetaine applications of 10 mM M increased stomatal conductance at 50 mM M NaCl, ameliorating signi®cantly the eect of salinity on water relations through increases in the leaf relative water content. At 100 mM M NaCl, 30 mM M glycinebetaine applications in particular contributed to osmotic stress, and had an adverse eect on plants. Our experiment suggests that glycinebetaine can be used as an alternative treatment to reduce the eects of salt stress on the water relations of salt-sensitive plants, but only to limited salinity levels. Furthermore, the improvement in the water status of kidney beans was dose dependent, suggesting that the concentration of glycinebetaine essential for the survival of salt-sensitive plants is species speci®c and must be determined individually for each plant species.

Does exogenous glycinebetaine affect antioxidative system of rice seedlings under NaCl treatment?

“…Since the betaine level in the plant tissue serves as an index of the internal water status of plants (Hanson and , 1978), an increased level of leaf RWC in both Pokkali and IR-28 under salt treatment suggests that GB may play an osmoprotective role in preventing cell injury from stress-induced dehydration as suggested by Yancey et al (1982) and Chen et al (2000). These results are also in conformation with the results of Lopez et al (2002), who found that 10 mM GB sprayed through the leaves of kidney bean plants precluded the decrease in leaf RWC, thereby increasing the tolerance of these plants to salinity. Peroxidation of lipid membranes of higher plants reflects free radical-induced oxidative damage at the cellular level under salt stress conditions (Halliwell, 1987;Hernández et al, 2001;Sudhakar et al, 2001).…”

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

“…The positive effects of foliar supplied GB on the rate of net CO 2 assimilation as observed in the present study were not related to stomatal conductance as it was not affected by exogenous GB. While working with GB non‐accumulator crop, kidney bean, Lopez et al (2002) reported a positive relationship between stomatal conductance and rate of photosynthesis under salt stress. Similarly, Makela et al (1999) also reported a positive relationship in both of the above‐mentioned characteristics in tomato and turnip rape under the combined effect of exogenous GB and water stress.…”

Genetic Relationship among Wild Medicinal Genotypes of <i>Ziziphora canescens</i> Benth. and <i>Ziziphora tenuior</i> L. and Detection of Genetic Variations Resulted From Tissue Culture, Salinity and pH Media

“…Salinity is one of the most environmental stresses that affect on growth and productivity of agricultural crops (Al-Karaki, 2000;Lopez et al, 2002). Also pH of medium is one of important environmental chemical and physical factors during the evolution of plant tissue in the conditions of in vitro culture .…”