Physiological and biochemical responses of Theobroma cacao L. genotypes to flooding

Abstract

Flooding is common in lowlands and areas with high rainfall or excessive irrigation. A major effect of flooding is the deprivation of O 2 in the root zone, which affects several biochemical and morphophysiological plant processes. The objective of this study was to elucidate biochemical and physiological characteristics associated with tolerance to O 2 deficiency in two clonal cacao genotypes. The experiment was conducted in a greenhouse with two contrasting clones differing in flood tolerance: TSA-792 (tolerant) and TSH-774 (susceptible). Leaf gas exchange, chlorophyll (Chl) fluorescence, chemical composition and oxidative stress were assessed during 40 d for control and flooded plants. Flooding induced a decrease in net photosynthesis, stomatal conductance and transpiration of both genotypes. In flood conditions, the flood-susceptible clone showed changes in chlorophyll fluorescence, reductions in chlorophyll content and increased activity of peroxidase and polyphenol oxidase. Flooding also caused changes in macro-and micronutrients, total soluble sugars and starch concentrations in different plant organs of both genotypes. Response curves for the relationship between photosynthetically active radiation (PAR) and net photosynthetic rate (P N ) for flooded plants were similar for both genotypes. In flood conditions, the flood-susceptible clone exhibited (1) nonstomatal limitations to photosynthesis since decreased in maximum potential quantum yield of PSII (F v /F m ) values indicated possible damage to the PSII light-harvesting complex; (2) oxidative stress; (3) increased leaf chlorosis; and (4) a reduction in root carbohydrate levels. These stresses resulted in death of several plants after 30 d of flooding.

Does Criollo cocoa have the same ecophysiological characteristics than Forastero?

“…A/C i curves. The A/C i curves showed no differences in A and CE between both types of Baligar et al 2008;Daymond et al 2011;Bertolde et al 2012;de Almeida et al 2014;Ávila-Lovera et al 2016). The saturating PFD in both types of cocoa is relatively low, around 400 µmol m -2 s -1 , similar to previously reported data (300-600 µmol m -2 s -1 , Joly and Hahn 1989;Balasimha et al 1991;Almeida et al 2014).…”

Assessment of tolerances in Mitragyna parvifolia (Roxb.) Korth. and Syzygium cumini Keels. seedlings to waterlogging

“…This trend is also commonly observed in other species such as Melaleuca alternifolia (Jing et al 2009). Greater WUE is commonly observed in plants under flooding conditions (Bertolde 2012). In our study, we did not identify any increase in WUE in both species, which supports the results of Mielke et al (2003) in their study on Genipa americana, the results of Arbona et al (2009) in citrus, and those of Islam (2004) in tamarack; however, our results were not supported by the findings of Islam (2004) in a study on black spruce.…”

Leaf gas exchange and biomass partitioning in Jatropha curcas L. young plants subjected to flooding and drought stresses

“…Moreover, low rates A/Ci, observed in flooded plants, suggest the occurrence of biochemical limitation (Silva et al, 2011). Flooding led to reduction of leaf gas exchange variables in contrasting clones of Theobroma cacao for flooding tolerance, but non-stomatal limitation were observed only in the susceptible one (Bertolde et al, 2012). In the present work, non-stomatal limitation to photosynthesis in flooded plants seems to be related more to biochemical constraints (as demonstrated by decreased A/Ci) than to photochemical constraints (as no stress effect on foliar pigment content has been detected).…”