Photosynthesis and Survival of Young Carpotroche brasiliensis Endl. (Achariaceae) Plants Subjected to Flooding

Abstract

Carpotroche brasiliensis is a native tree of the Brazilian Atlantic Forest with potential economic value for cultivation in agroforestry systems. We conducted an experiment to determine the photosynthetic and survival responses of young C. brasiliensis plants to electrochemical changes in flooded soils as an indication of their flood tolerance and potential for cultivation in flood-prone areas. Soil flooding decreases the reduction–oxidation potential (redox) potential (Eh), pH, and electrical conductivity (Ec) of the soil, with subsequent recovery of the pH and Ec. Decreases in Eh negatively affect net photosynthesis (A). In flooded soil, decreased A was associated with decreased stomatal conductance (gs) and after 21 days was also associated with decreases in the instantaneous carboxylation efficiency (A/Ci) and potential quantum yield of photosystem II (Fv/Fm). Although flooded C. brasiliensis seedlings developed morphological structures known to increase flood tolerance, this was not enough to prevent severe signs of flooding stress. After 21 days of flooding, flooded plants were unflooded, and 17 days after plants were removed from flood, 90 percent of the unflooded plants died. Our results demonstrate that young plants of C. brasiliensis are suitable for planting in agroforestry systems only in areas with well-drained soils.

Predicting flooding tolerance of native tree species to restore flooded forests

“…This finding is consistent with observations in other restored flooded forests in Brazil (Zamith & Scarano, 2010) and in other regions of the world (Conner et al ., 1997), and can be explained by the inhibition of cellular respiration and water and nutrient absorption due to oxygen limitation to roots (Oliveira & Joly, 2010). Oxygen limitation is due to changes in the electrochemical properties of the soil that may occur after soil is flooded, such as in the oxidation (redox) potential, pH, and the electrical conductivity (Queiroz‐Alves et al ., 2019). This may produce a decrease in stomatal conductance and thus in photosynthesis rates (Herrera et al ., 2010; da Silva Branco et al ., 2017).…”

“…This may produce a decrease in stomatal conductance and thus in photosynthesis rates (Herrera et al ., 2010; da Silva Branco et al ., 2017). For instance, the electrical conductivity may show a sharp decrease with flooding, suggesting a progressive loss of oxygen in the soil, which induces the initial stress because of oxygen deficiency (hypoxia) or even absence (anoxia) (Queiroz‐Alves et al ., 2019). Under hypoxia, changes in the hormone balance may cause stomatal closure and a decrease in absorption of water by roots, bringing about a decrease in intercellular CO 2 concentration and photosynthetic rates (Herrera, 2013).…”

“…The water‐saturated soil that makes flooded forests so special for water‐related ecosystem services may also hamper seedling establishment and growth (Simmons et al ., 2011; Pezeshki & DeLaune, 2012; Baattrup‐Pedersen et al ., 2013). The long residence time of water in the soil may result in hypoxic conditions at different levels for seedlings (low oxygen) or even anoxia (absence of oxygen, like when seedlings are totally submersed in Amazon Igapó forests), which impact some important physiological functions (Queiroz‐Alves et al ., 2019). Under soil flooding, root permeability is usually low (Rodríguez‐González et al ., 2010) and thus their aerobic respiration is affected (Yamauchi et al ., 2017).…”

“…Stomata close (Herrera et al ., 2008), photosynthesis (Glenz et al ., 2006; Silva et al ., 2010; Dalmolin et al ., 2013; Li et al ., 2015) and nutrient absorption decline (Oliveira & Joly, 2010; Liu et al ., 2015), and thus the production of new leaves and leaf expansion stops (Parolin & Wittmann, 2010). All these processes may affect plant survival and growth, and constrain seedling establishment and recruitment in such stressful conditions (Rodríguez‐González et al ., 2010; Queiroz‐Alves et al ., 2019).…”

Root deformation affects mineral nutrition but not leaf gas exchange and growth of Genipa americana seedlings during the recovery phase after soil flooding

“…Such changes allow these species to survive for long periods when their roots are submerged (Mielke et al, 2003). Despite the ability of some tree seedlings to survive soil flooding, physiological and growth responses after soil drainage are very variable among species (Ortuño et al, 2007;Mielke and Schaffer, 2010;Queiroz-Alves et al, 2019).…”