Root Cortical Aerenchyma in Sorghum Increases its Root Elongation and Volume, Favoring Nutrient Uptake and Gas Exchange Compared to Maize Under Water Limitation

Abstract

This work investigated how root anatomical traits, such as aerenchyma development, are related to root growth and volume and nutrient acquisition capacity in maize and sorghum plants under water limitation. Experiments were conducted in a greenhouse in a factorial 2 × 2 scheme (two plant species, maize and sorghum) and two water availabilities (well-irrigated and limited irrigation) with six replicates. Leaf gas exchange, growth, aerenchyma formation, root tissues in both maturation and piliferous regions, and macro and micronutrient uptake were analyzed. Water limitation reduced maize growth with no significant changes in sorghum. Sorghum showed higher photosynthesis and transpiration compared to maize, which exhibited higher water use efficiency; nonetheless, water limitation increased the leaf water content in sorghum but not in maize. Water limitation increased the root length, volume, and aerenchyma development in sorghum plants only. Increased root elongation and volume favored macro (N, Mg, and Ca) and micronutrient (Zn, Cu, Mo, and Fe) acquisition in sorghum compared to maize. Water limitation stimulated the acquisition of B, Mn, Zn, Cu, Mg, and N in both species, but Fe and Mo contents under water limitation increased only in sorghum. Sorghum’s root aerenchyma development and volume under water limitation seem related to a higher elongation capacity, favoring nutrient acquisition in this species compared with maize under water limitation.

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