Physiological changes of pepper accessions in response to salinity and water stress

Abstract

New sources of water stress and salinity tolerances are needed for crops grown in marginal lands. Pepper is considered one of the most important crops in the world. Many varieties belong to the genus Capsicum spp., and display wide variability in tolerance/ sensitivity terms in response to drought and salinity stress. The objective was to screen seven salt/drought-tolerant pepper accessions to breed new cultivars that could overcome abiotic stresses, or be used as new crops in land with water and salinity stress. Fast and effective physiological traits were measured to achieve the objective. The present study showed wide variability of the seven pepper accessions in response to both stresses. Photosynthesis, stomatal conductance and transpiration reduced mainly under salinity due to stomatal and non-stomatal (Na + accumulation) constraints and, to a lesser extent, in the accessions grown under water stress. A positive relationship between CO 2 fixation and fresh weight generation was observed for both stresses. Decreases in Ψ s and Ψ w and increased proline were observed only when accessions were grown under salinity. However, these factors were not enough to alleviate salt effects and an inverse relation was noted between plant salt tolerance and proline accumulation. Under water stress, A31 was the least affected and A34 showed the best tolerance to salinity in terms of photosynthesis and biomass.Additional keywords: osmotic potential; photosynthesis; proline; salinity ions; water potential. Abbreviations used: A N (maximum net CO 2 fixation rate); A N /C i (instantaneous carboxylation efficiency); C i (substomatal CO 2 concentration); DW (dry weight); E (transpiration); ETc (evapotranspiration); FW (fresh weight); g s (stomatal conductance to water vapour); Ψ s (osmotic potential); Ψ w (water potential).

Pepper Photosynthesis, Stomatal Conductance, Transpiration, and Water Use Efficiency Differ with Variety, Indigenous Habitat, and Species of Origin

“…Yun and Ahn (2009) reported that increasing temperature and atmospheric CO 2 concentrations increased the pepper P n , but not the pepper g S . The strong correlation between pepper g S and P n reported here (0.95) (Table 2) supports the assertion that g S limitations may reduce pepper P n (Serrano et al, 2017). However, the observations of Yun and Ahn (2009) suggested that g S limitations on P n may occur less if CO 2 concentrations are increased, as is common for greenhouse-produced bell peppers (Dorais, 2003;Erwin and Gesick, 2017).…”

“…Abiotic factors such as low temperatures, high temperatures, salt stress, drought (Serrano et al, 2017), and waterlogging can limit pepper yield (Ou and Zou, 2012;Zhai et al, 2016). For instance, optimal temperatures for pepper photosynthesis range from 25 to 35°C, and temperatures outside this range can limit the yield; for example, C. chinense flower abortion increased 2-fold and fruit set decreased 3-fold when greenhouse temperatures were increased from 30 to 40°C (Garruna-Hernandez et al, 2014).…”

Pepper Crop under Climate Change: Grafting as an Environmental Friendly Strategy

“…Currently, wild species of pepper from gene banks have been screened and phenotypically characterized as being tolerant to salinity and water stress under control conditions, and then used as rootstocks in the field, where abiotic stress problems occur, and productivity of grafted plants has been evaluated [132,143,144].…”

Growth, Yield, and Water Productivity Responses of Pepper to Sub-Irrigated Planter Systems in a Greenhouse

“…Considering that the pepper salinity tolerance level is 1 dS m −1 for irrigation water salinity [19][20][21], two qualities of water were obtained by the addition of NaCl to water irrigation (Table 1) to rise the Electrical Conductivity (EC) of 1.2 and 2.2 dS m −1 . Also, a nutrient solution (Table 1) was applied fortnightly at a rate of 70 mL per plant in both irrigation systems, to allow for a more efficient use of both water and fertilizers [22,23].…”

“…Other researchers [17] have reported that the soil salinity level was linearly related to the reduction of the total yield of pepper grown in the substrate, even under moderate salinity levels. Salinity not only affects crop yield, but also other physiological processes, such as root cellular turgor, net CO 2 assimilation rates, photosynthesis, stomatal conductance, and transpiration, among others [18][19][20]. Pepper was thus selected as an appropriate experimental crop because of its economic importance and its sensitivity to salinity.…”