Dynamics of photosynthetic responses in 10 rubber tree (Hevea brasiliensis) clones in Colombian Amazon: Implications for breeding strategies

Abstract

The rubber tree [Hevea brasiliensis (Willd. Ex Adr. de Juss.) Muell.-Arg] is the main source of natural rubber in the world. However, in the Amazon region, its production is reduced by biotic and abiotic limitations, which have prompted breeding programs in order to identify desirable agronomic and physiological indicators. The objective of this study was to analyze the temporal dynamics of photosynthetic responses based on the parameters of leaf gas exchange and chlorophyll a fluorescence in 10 rubber tree clones during the immature phase (pre-tapping) in three large-scale clone trials, during daily cycles and under two climatic periods (dry and rainy) in the Caquetá region (Colombian Amazon). The variables A, LT, ΦPSII, ETR and qP were significantly higher in the dry period, where the highest values of PAR, AT and VPD were seen. In San Vicente del Caguán and Florencia, the highest averages were estimated for A, E and gs, as compared with Belén de los Andaquíes. In Florencia, the highest fluorescence parameters of chlorophyll a were recorded. At 9:00 h and 12:00 h, the highest means of A, E, ΦPSII and ETR were observed. The majority of the clones displayed the highest Fv/Fm mean (0.82–0.84) in the dry period. The clones FX 4098, FDR 4575, MDF 180, GU198 and FDR 5788 represent genotypes with the best photosynthetic performance (greater photosynthetic rates and better ability of the photosynthetic apparatus to capture, use and dissipate light energy). These desirable genotypes constitute a promising gene pool for expanding the genetic resource of rubber trees in the Colombian Amazon.

Exogenous melatonin ameliorates salinity-induced oxidative stress and improves photosynthetic capacity in sweet corn seedlings

“…It suggested that exogenous MT possesses the ability to alleviate the salinity stress-inhibited growth and development in maize seedlings to a certain extent. Plant photosynthesis is a complex physiological process, which is easily affected by environmental conditions (Sterling et al 2019. The primary limiting factor for photosynthesis upon exposure to salinity is the closure of stomata.…”

Photosynthesis-Related Responses of Colombian Elite Hevea brasiliensis Genotypes under Different Environmental Variations: Implications for New Germplasm Selection in the Amazon

“…Thus, various physiological traits related to the photosynthetic performance of H. brasiliensis, such as the photosynthetic rate, water use efficiency, girth growth, latex yield, and biomass production are influenced by the interaction of the genotype with environmental variations that allow the species to adapt or acclimate to limiting or stressful conditions [13,19,20,25,27,28].…”

“…Thus, one of the main approaches for early selection in juvenile plants for promising progeny uses physiological characteristics related to the efficiency of photosynthesis in various environments [11]. Traits such as gas exchange, pigment content (Chl a, Chl b, and carotenoids), chlorophyll a fluorescence, and water relations have shown high potential for the selection of desirable genotypes in various species [12][13][14][15]. The use of physiological traits, such as identification and selection criteria that improve the tolerance or sensitivity of the species to the stress factor, generates high heritability in the population of interest [10,16].…”

“…The use of physiological traits, such as identification and selection criteria that improve the tolerance or sensitivity of the species to the stress factor, generates high heritability in the population of interest [10,16]. It has been reported, in tree species such as Populus [17], Pinus [18], Eucaliptus [14] and even in Hevea [13], that physiological traits are key to rapid selection in the first selection cycles.…”

“…Various studies carried out in the Colombian Amazon have sought to identify new introduced genotypes with desirable characters that are adaptable to different conditions and environments in the growth phase [13,20] and in the early production phase [21]. One of the greatest opportunities for the genetic improvement of H. brasiliensis lies in the regional elite germplasm [22].…”