Vegetative growth, compatible solute accumulation, ion partitioning and chlorophyll fluorescence of 'Malas-e-Saveh' and 'Shishe-Kab' pomegranates in response to salinity stress

Abstract

The present research was conducted to assess physiological responses of 'Malas-e-Saveh' (Malas) and 'Shishe-Kab' (Shishe) pomegranates to water of different salt content and electrical conductivity (1.05, 4.61, and 7.46 dS m −1). Both cultivars showed a reduced trunk length due to salinity. Relative water content and stomatal conductivity of both cultivars were significantly reduced under salt stress, but ion leakage increased. In both cultivars, total chlorophyll (Chl) and carbohydrates decreased with rise in salinity, while proline accumulation increased. With salinity increment, the Chl fluorescence parameters (maximum photochemical efficiency of PSII and effective quantum yield of PSII) declined significantly in both cultivars, with higher reduction observed in Shishe. Generally, more Na + accumulated in shoots and more Cl − was observed in leaves. Cl − accumulation increased by salinity in leaves of Malas, but it was reduced in Shishe. The K + /Na + ratio in leaves decreased in both cultivars by salinity increment. Malas was less affected by osmotic effects of NaCl, but it accumulated more Cl − in its leaves. Thus, Malas might be more affected by negative effects of salinity.

Research on the adaptive mechanism of photosynthetic apparatus under salt stress: New directions to increase crop yield in saline soils

“…For instance, carotenoids absorb residual energy in the cells and scavenge ROX as endogenous antioxidants, thereby preventing membrane lipid peroxidation (Szabó, Bergantino, & Giacometti, ). Recent trials revealed that carotenoid content varies with salinity in Kalidium foliatum and Punica granatum , and salinity reduces the Chl a , Chl b , carotenoid content and Chl a / b ratio of sweet‐forage and sorghum (Gong et al, ; Khayyat, Tehranifar, Davarynejad, & Sayyari‐Zahan, ; Sayyadamin, Jahansooz, Borzouei, & Ajili, ).…”

“…The F V / F M determines the maximum quantum efficiency of PSII, and provides a measure of the rate of linear electron transport (Rehman, ); the ratio in most plants fluctuates between 0.80 and 0.86 under normal conditions (Björkman & Demmig, ). The F V / F M and ΦPSII (operating efficiency) declined in P. granatum compared with control under salinity (Khayyat et al, ). Another study pointed out that the decrease in F V / F M and ΦPSII is probably due to damage to the photosynthetic mechanism and photoinhibition, although photoinhibition is supposed to protect the photosynthetic mechanism by non‐radiative dissipation of excess energy (Demmig‐Adams et al, ; Mehta et al, ).…”

Characterization of the ecophysiological responses of three pomegranate cultivars to salinity

“…This implies that in the variety 'Valenciana', the carbon metabolism could have been adjusted so that the carbohydrates intervened in the processes of osmotic adjustment as well as in the deactivation of free radicals of oxygen, while in the varieties 'Wonderful' and 'Mollar', it tends to be directed towards the osmotic adjustment of the plant, or the protection against oxidative stress, respectively. This response was completely different to the one found for the varieties of Iranian pomegranates 'Malas Torsh', 'Malas Shirin', 'Alak Torsh', 'Malas-e-Saveh', and 'Shishe-Kab', where a decrease in the concentration of TSS in the leaves was observed in trees watered with saline water (Naeini et al 2006, Khayyat et al 2014.…”

“…According to Sun et al (2018), pomegranate plants are very tolerant to saline water irrigation up to an EC of 15 dS m -1 . In the Iranian varieties 'Malas' and 'Shishe', it has been shown that when the salinity in the irrigation water increased from 1.05 to 4.61 and 7.46 dS m −1 , relative water content, stomatal conductance, total Chl, sugars, and Chl fluorescence parameters decreased (Khayyat et al 2014(Khayyat et al , 2016. Okhovatian-Ardakani et al (2010) observed different levels of salinity tolerance in a study with ten Iranian cultivars of pomegranate watered with 4, 7, and 10 dS m -1 ; however, the differential responses were not directly related to the accumulation of Cl − and/or Na + in the leaves.…”

Effects of NaCl stress on growth and ion homeostasis in pomegranate tissues

“…Under salt stress, the amount of Na + and Clin pomegranate tissues increased, but the amount of Ca 2+ , Mg 2+ and K + varied among different cultivars (Hasanpour et al, 2015;Mastrogiannidou et al, 2016;Naeini et al, 2005). The K + /Na + , Ca 2+ /Na + , and NO 3 -/Clratios are crucial for tolerance or adaptation to salt stress (Apse and Blumwald, 2007;Khayyat et al, 2014). Changes in these ratios may provide evidence of disruption to the ionic equilibrium induced by salinity (Apse and Blumwald, 2007).…”