Morpho-physiological variations in response to NaCl stress during vegetative and reproductive development of rice

Abstract

The complex nature of plant resistance to adverse environmental conditions, such as salinity and drought requires a better understanding of the stress-induced changes that may be involved in tolerance mechanisms. Here we investigate stress-related morpho-physiological effects during vegetative and reproductive growth in two Japonica rice cultivars (Bomba and Bahia) exposed to a range of NaCl concentrations from the seedling stage. The stress-related detrimental effects were observed either earlier or to a higher extent in cv. Bomba than in Bahia. Damages to the photosynthetic apparatus were related to loss of chlorophyll (Chl) and to a decrease of the maximum potential efficiency of PSII (F v /F m ), affecting negatively net CO 2 assimilation rate (P N ). Stress-related leaf anatomical alterations were analysed during the vegetative and reproductive stages. The size of bulliform cells as well as dimensions related to the vascular system increased under mild stress but decreased in the longer term or under higher stress level. The pattern of the anatomical alterations observed at the reproductive stage under 20 mM NaCl was reflected in poor panicle development and yield loss, with effects more pronounced in cv. Bomba than in Bahia. In summary, our results show that some physiological and, particularly, leaf anatomical responses induced by NaCl stress are distinctive indicators of sensitivity to salt stress in rice cultivars.

Diffusional conductance to CO2 is the key limitation to photosynthesis in salt‐stressed leaves of rice (Oryza sativa)

“…In general, g m is related to leaf anatomical and biochemical traits under a given measurement condition (Evans et al 2009, Tomas et al 2013, Xiong et al 2017. Previous studies have shown that long-term salinity significantly influences the leaf anatomical traits (Delfine et al 1998, Wankhade et al 2013; however, short-term salt-stress as in this study, causing leaf anatomical variation has rarely been estimated. Generally, the cell wall thickness (T cw ) and the chloroplast surface area facing the intercellular airspace per unit leaf area (S c ) are the two most important parameters related to g m (Evans et al 2009, Tomas et al 2013, Xiong et al 2017.…”

“…The reduction of ETR in salt‐stressed leaves that is often associated with decreases in the actual quantum yield of PSII (Φ PSII ) and maximal efficiency of PSII photochemistry ( F v / F m ) was observed in some species (Moradi and Ismail , Koyro et al ) but not in others (James et al , Koyro et al ). Similarly, the responses of ETR, Φ PSII and F v / F m to salinity were genotype dependent in rice (Moradi and Ismail , Wankhade et al ). The reduction in Φ PSII in some species/genotypes may be due to the salt‐induced regulation of energy transduction from the antennae to the reaction centers to prevent photosystem energy surpluses.…”

“…Rice ( Oryza sativa L.) is one of the most important cereal crops; however, it has been reported to be very sensitive to salt stress, and it has been listed as the most salt‐sensitive cereal crop (Negrão et al , Munns et al ). Salinity reduces rice yield, partially by restraining biomass accumulation, which is associated with a decreasing rate of photosynthesis (Moradi and Ismail , Wankhade et al ). A considerable effort has been made, in recent decades, to understand the negative effect of salinity on photosynthesis, but it has yet to be fully understood.…”

Response of Rice under Salinity Stress: A Review Update

“…Hence, chlorophyll content, changes in chlorophyll fluorescence (Fv/Fm) and membrane permeability are efficient and potential indicators for understanding the inhibitory effect of salt on the photosynthetic efficiency [20,57]. Salinity has been reported to decrease leaf area tremendously and also showed profound changes in leaf anatomy in rice grown in-vitro [58] or in greenhouse [59] as verified by [60]. The ultra-structural observations briefed by [56] also ensured the inhibitory effect of salt on leaf thus hampering the photosynthetic efficiency: swelling of thylakoids followed by disruption of chloroplastids.…”

Satellite Thermography for Soil Salinity Assessment of Cropped Areas in Uzbekistan

“…Our study was carried out in a semi-arid cropped area where losses due to soil salinity are particularly high. The stress response in crops due to soil salinity is evident in decreased chlorophyll fluorescence (Jimenez et al, 1997;Percival, 2005;Biber, 2006;Li et al, 2010;Wankhade et al, 2013) and stomatal conductance (James et al, 2002;Biber, 2006;Munns & Tester, 2008;Rahnama et al, 2010;Hussain et al, 2012;Álvarez & Sánchez-Blanco, 2014). As a result of stomatal closure, significant changes in canopy temperature can be observed.…”