Differential photosynthetic and survival responses to soil drought in two evergreen Nothofagus species

Abstract

-We asked if differences in distribution betweenNothofagus nitida and N. dombeyi were associated with differences in drought tolerance. Survival, gas exchange and chlorophyll fluorescence were measured on seedlings subjected to a gradual drought. At a predawn leaf water potential (Ψ m ) of −2.7 MPa, survival of N. nitida was 50%, compared to 100% in N. dombeyi. Under well-watered conditions, the two species displayed similar stomatal conductance (g w ) and transpiration (E), but net photosynthesis (A) and instantaneous water-use efficiency (WUE i ) were slightly higher in N. nitida. A, E and g w declined in N. nitida along the gradual drought but increased in N. dombeyi at a Ψ m between −1.5 and −2.5 MPa, and declined then drastically at a Ψ m below < −2.5 MPa. As N. dombeyi was able to maintain A at higher levels despite declining g w , this species displayed significantly increased WUE i at Ψ m below -2.5 MPa. Photochemical efficiency of PSII in the light (∆F/Fm ) and photochemical quenching (qP) were always lower in N. nitida and along with the photochemical efficiency in the dark (Fv/Fm) they declined in both species. Non-photochemical quenching (NPQ) increased slowly in N. dombeyi along with the gradual drought, whilst it decreased in N. nitida. These results show that differences in drought tolerance are in agreement with sorting of Nothofagus species along moisture gradients in south-central Chile.

Interactive responses of Quercus suber L. seedlings to light and mild water stress: effects on morphology and gas exchange traits

“…Stomatal conductance variation across light environments was smaller than differences in photosynthesis leading to similar water expenses but lower carbon gain in shaded seedlings. This is in agreement with the authors that describe that changes in water use efficiency are driven mainly by changes in photosynthesis rate (Boodrib and Hill, 1998;Piper et al, 2007). However, drought and midday conditions tended to decrease IWUE in the differences between light treatments, since no clear differences between light treatments in IWUE can be found at midday in the first measurement and in water stressed seedlings in the second measurement.…”

Effect of drought and ABA on growth, photosynthesis and antioxidant system of Cotinus coggygria seedlings under two different light conditions

“…This result possibly due to a decrease in stomatal conductance ) has been detected in several previous studies (Bacelar et al, 2007;Piper et al, 2007). Furthermore, ␦ 13 C induced by drought, exogenous ABA application and the D + ABA treatment under SL was lower than that under FL, which suggests that the water use efficiency of seedlings is more sensitive to drought, ABA application and the combination of drought and ABA under FL.…”

Study of the Interactive Effects of Calcium and Abscisic Acid on Drought Stressed Triticum aestivum Seedlings

“…In accordance with these findings, it was reported that drought stress led to a decrease in the Fv/Fm ratio in bean plant, STUDY OF THE INTERACTIVE EFFECTS OF CALCIUM ... suggesting chronic photo-inhibition due to photooxidation of photosynthetic apparatus (Sewelam et al, 2014) and damage to the PSII oxygenevolving complex possibly attributable to D1 protein damage under drought stress (Zlatve & Yordanov, 2004). Likewise, it was suggested that the photosynthetic efficiency has been declined in Nothofagus species under drought stress (Piper et al, 2007 andLuo et al, 2015). Similar effects on chlorophyll fluorescence parameters under drought stress have been observed in different species, among them Brassica napus (Kauser et al, 2006) and Aegilops species (Dulai et al, 2006).…”