Effects of Salt Stress on Some Physiological and Photosynthetic Parameters at Three Different Temperatures in Six Soya Bean (Glycine max L. Merr.) Cultivars

Abstract

IntroductionDuring their growth and development, plants are exposed to abiotic (high and low temperature, salinity, drought, radiation, etc.) and biotic (pathogen, fungus, etc.) stress factors, which decrease their yield and the quality of their products. To date, 20 %, 26 % and 15 % of suitable agricultural areas worldwide are affected by mineral, drought and temperature stresses respectively (Blum 1985, Ashraf 1994a, Flowers and Yeo 1995. In addition, there is a decay of 2 million ha of world agricultural lands to salinity each year (Kalaji and Pietkiewica 1993, Szabolcs 1994). Moreover, over 6 % of the world's total land area is affected by salinity and sodicity (Munns 2005). Plants are affected in several ways by increasing salt concentrations. It causes osmotic stress, specific ion toxicity and nutrient deficiencies, thereby affecting a range of physiological processes involved in cell metabolism (Munns 2002a).Salinity stress is often accompanied by temperature stress. Changes in ambient temperature occur more rapidly than changes in other stress factors and temperature extremes aggravate the adverse effects of other stresses, including salinity, on crop production and quality (Ashraf and Foolad 2007). It has been reported that environmental stresses lead to many social and economic problems in developing countries (Ashraf 1994a, Saiko andZonn 2000).Salt stress affects all the major processes such as photosynthesis, protein synthesis, and energy and lipid metabolism (Parida and Das 2005). Temperature and salt stresses directly or indirectly affect the photosynthetic functions by changing the structural organization and physicochemical properties of thylakoid membranes (Alia-Mohanty and Saradhi 1992, Karim et al. 1999, Lichtenthaler et al. 2005. The osmotic balance is essential for plants (Ashraf 2004). Plants have to maintain a high K + and a low Na + AbstractThe effect of NaCl ()0.1, )0.4 and )0.7 MPa) on some physiological parameters in six 23-day-old soya bean cultivars (Glycine max L. Merr. namely A 3935, CX-415, Mitchell, Nazlıcan, SA 88 and Türksoy) at 25, 30 and 35°C was investigated. Salt stress treatments caused a decline in the K + /Na + ratio, plant height, fresh and dry biomass of the shoot and an increase in the relative leakage ratio and the contents of proline and Na + at all temperatures. Effects of salt stress and temperature on Chl content, Chl a/b ratio (antenna size) and qN (heat dissipation in the antenna) varied greatly between cultivars and treatments; however, in all cases approximately the same qP value was observed. It indicates that the plants were able to maintain the balance between excitation pressure and electron transport activity. Pigment content and the quantum efficiency of photosystem II exhibited significant differences that depended on the cultivar, the salt concentration and temperature. The cultivars were relatively insensitive to salt stress at 30°C however they were very sensitive both at 25 and 35°C. Of the cultivars tested CX-415 and SA 88 were the best performers ...

Impact of salt stress on photosystem II efficiency and antioxidant enzyme activities of safflower (Carthamus tinctorius L.) cultivars

“…As with chlorophyll content, carotenoid amounts reduced in relation to salt treatments ( Figure 3B). Previous studies have shown that carotenoid content of leaves decreased due to salt stress (Çiçek and Çakırlar, 2008;Cha-um and Kirdmanee, 2009;Cambrollé et al, 2011). The reason for the decrease in pigment contents could be the increasing levels of ROS and the loss of membrane integrity.…”

“…In many studies it was reported that salinity affected plant nutrients (Na , growth, membrane integrity, osmotic adjustment, photosynthetic activity, and antioxidant activity (M'rah et al, 2006;Çiçek and Çakırlar, 2008;Ejaz et al, 2012;Shahzad et al, 2012).…”

“…In the second phase, which is known as the ionic effect, increasing Na + and Cllevels compete with nutrients such as K + , Ca +2 , and NO 3 and inhibit nutrient uptake or induce imbalances (Hu and Schmidhalter, 2005). In many studies it was reported that salinity affected plant nutrients (Na + , K + , Ca +2 , Mg + , and Cl -), growth, membrane integrity, osmotic adjustment, photosynthetic activity, and antioxidant activity (M'rah et al, 2006;Çiçek and Çakırlar, 2008;Ejaz et al, 2012;Shahzad et al, 2012).…”

Arbuscular mycorrhiza influences carbon‐use efficiency and grain yield of wheat grown under pre‐ and post‐anthesis salinity stress

“…Salinity, drought and heat stress events are major abiotic stress types that affect crop growth and development, and consequently biomass production, yield and quality (Çiçek & Çakirlar 2008; Zhu et al 2016). Salinity affects 20% of the global irrigated area (62 million ha) worldwide and reduces the productivity of food crops (Qadir et al 2014).…”

Interaction between salt and heat stress: when two wrongs make a right

“…Species‐ or variety‐specific factors, or the intensity and duration of the stress treatments can lead to different results. Çiçek & Çakırlar () found that the effects of salt stress and temperature on soybean photosynthetic parameters varied greatly between cultivars and stress intensity. In Jatropha curcas , the combination of salt (NaCl 100 m m ) with a heat stress treatment of 43 °C (which is stronger than the 35 °C used in Rivero et al .…”