Application of proline to root medium is more effective for amelioration of photosynthetic damages as compared to foliar spraying or seed soaking in maize seedlings under short-term drought

Abstract

Exogenous proline (PRO) at low concentrations can enhance drought stress tolerance in different application modes such as application to rooting medium, foliar spray, and seed soaking. However, there is no information about which application mode is more effective for increasing the drought tolerance. Comparative effects of 1, 10, and 20 mM PRO applications through three application modes to hydroponically grown seedlings were examined under short-term drought stress in maize seedlings. Effects on leaf water potential, membrane damage, chlorophyll content, proline level, and gas exchange parameters such as net photosynthetic rate (Pn), transpiration rate (E), stomatal conductance (gs), and substomatal CO 2 concentration (Ci) were compared. Results indicated that PRO pretreatments raised the water potential, chlorophyll content, Pn, E, gs, and Ci but lowered the malondialdehyde content in the three application modes as compared to the untreated plants. Of the three different modes of PRO pretreatment, rooting medium treatment at 1 mM concentration was also more effective in alleviating stress-induced damages in maize seedlings. Moreover, effectively applied PRO increased the maximum quantum efficiency of PS II, quantum yield of PS II photochemistry, photochemical quenching, and electron transport rate but decreased nonphotochemical quenching of chlorophyll fluorescence under short-term drought stress. In conclusion, exogenous PRO was markedly more effective in the root-treated mode than in foliar spray or seed soaking mode, suggesting that PRO had a different ameliorating effect in different application modes. Proline application in an effective mode can induce photochemical efficiency under short-term drought in maize.

Seed priming with proline improved photosystem II efficiency and growth of wheat (Triticum aestivum L.)

“…It may probably result from photoinhibition [ 32 ] occurring either due to decrease in its rate constant of photochemistry (leading to rise in Fo) or by increase in rate constant of non-radiative dissipation of excitation energy (leading to decrease in both Fo and Fm) [ 33 ]. These results and arguments are similar to those of [ 34 ] who also reported that application of higher proline dose caused a decline in Fv/Fm in maize plants.…”

Investigation of Drought Stress Tolerance Levels in Landrace (Artvin-Şavşat) and Commercial Tomato Cultivars

“…Bitkiler, stres koşulları altında ozmolit birikimi ile tolerans kazanır. Prolin su eksikliği sırasında ozmotik düzenleyici olarak bitkilerde rol oynayan uyumlu çözünenlerden biridir ve ayrıca diğer çevresel stres faktörlerine karşı savunma sistemlerinde yer alır [17]. Her iki domates çeşidinin prolin seviyesi tüm PEG uygulamalarıyla birlikte kontrol grubuna kıyasla arttığı belirlenmiştir.…”

“…Birçok bitkide, biyotik ve abiyotik strese yanıt olarak serbest prolin birikir. Prolin kuraklık stresinin neden olduğu su eksikliğine karşı bitki stres toleransını artırmada etkili bir bileşiktir [16,17].…”

Foliar applied proline and acetic acid improves growth and yield of wheat under salinity stress by improving photosynthetic pigments, physiological traits, antioxidant activities and nutrient uptake

“…Proline is a signaling molecule and it regulates plant growth by triggering the signaling processes (Yildiz and Terzi, 2013). Moreover, Pro, also improves synthesis of photosynthetic pigments, normal photochemical functioning, activities of antioxidants and regulates Na + compartmentalization which protects the plants from adverse effects of SS thus resulting in a substantial improvement in growth and development (Alam et al, 2016;Demiralay et al, 2017;Rady et al, 2019).…”