Combined effect of salinity and hypoxia in seedlings of two varieties of Panicum coloratum: Morphology, root system architecture, oxidative damage and antioxidant response

Abstract

The effect of the combination of salinity and waterlogging may be additive, or alternatively, more or less detrimental than effects of them separately. Our objective was to evaluate the effects of waterlogging, salinity and the combination of both on seedlings of Panicum coloratum, a subtropical forage grass. Seedlings of cultivars Kapivera INTA (KA) and Klein (KL) were exposed to treatments in a controlled hydroponic experiment and several morphological and physiological variables evaluated.The effect of hypoxia was almost null when the plants were already in salinity. KA showed lower reduction than KL in shoot biomass. Both varieties showed synergistic effect of stresses, indicating that biomass production was less affected under the combined treatment than predicted from them separately. Root length, tips, forks and volume were reduced by saline exposure, while no differences in root architecture was noticeable between cultivars. Plants of KA increased leaf temperature in salinity. Nonenzymatic oxidative response and the activity of antioxidant enzymes increased in saline conditions and were lower in KA than in KL. Oxidative damage was equivalent between cultivars and among stress conditions. Proline content was comparable to control in hypoxia but increased significantly in saline conditions, with a higher response in KL than in KA. Increases in Na + (over 900%) and decreases in K + (50%) tissue concentration in salinity occurred only in KA. In general, P. coloratum proved more tolerant to hypoxia than to salinity or their combination, KA being more tolerant than KL. Findings provide basis to deepen research into tolerance mechanisms.

Enterobacter and Pseudomonas: two dominant players in the rhizosphere phosphate-solubilizing bacterial communities of forage grasses adapted to alkaline-sodic soils of the flooding pampa

“…This suggests a greater need for P. coloratum to recruit and associate with IAAproducing microorganisms, as compared to S. indicus. Several reports related the adaptation of P. coloratum to stress conditions with the ability to develop a deep root system that allows to e ciently explore the soil pro le (Lifschitz et al, 2022). Thus, based on the high number of IAA-producing hereby found in the rhizosphere of P. coloratum, it can be speculated that IAA-producing PSB facilitate nutrient uptake and contribute to the ability of this plant species to thrive under growth-restrictive low nutrientavailability conditions.…”

Construction and application of a new index for root architecture quantification in arid and semi-arid regions

“…Most of the root mass is distributed in the downwind direction when plants grow on flat ground, whereas more of the root mass is distributed in the upwind direction when root systems grow on sloping ground. Therefore, future studies using the RFI should comprehensively consider the relationships among soil structure, species attributes, and the external environment, and should weight the parameters in the model to evaluate the stability and sustainability of plant communities on a larger scale (Lifschitz et al, 2022). The RFI constructed from the perspective of mutual matching of underground root systems is helpful for evaluating vegetation restoration effects, and it may support evaluations of regional ecosystem services (Zhu et al, 2019).…”