Leaf economics and tissue turnover dynamics in four perennial C4 grasses

Abstract

Warm‐season perennial grasses are important components of pasture systems in the United States, yet their functional characteristics and relationships with productive attributes remain poorly understood. This study evaluated tissue flow dynamics and leaf economic traits in four C4 forage grasses: eastern gamagrass ( Tripsacum dactyloides (L.) L.), switchgrass ( Panicum virgatum L.), big bluestem ( Andropogon gerardii Vitman), and indiangrass ( Sorghastrum nutans (L.) Nash). The objective was to characterize their resource‐use strategies. Species differed significantly in leaf dry matter content, with switchgrass exhibiting greater values (36%) compared to other species (average 30%). Eastern gamagrass displayed the greatest leaf elongation (5.93 cm tiller ⁻¹ day ⁻¹ ) and senescence rates (1.09 cm tiller ⁻¹ day ⁻¹ ), while switchgrass showed the lowest senescence (0.37 cm tiller ⁻¹ day ⁻¹ ). Daily tissue production rate was greatest for eastern gamagrass (0.037 g tiller ⁻¹ day ⁻¹ ) and lowest for switchgrass (0.015 g tiller ⁻¹ day ⁻¹ ). Big bluestem exhibited the greatest stem elongation rate (0.93 cm tiller ⁻¹ day ⁻¹ ). These results reveal distinct positions along the leaf economics spectrum: eastern gamagrass represents a resource‐acquisitive strategy with rapid tissue turnover and individual tiller productivity, while switchgrass exemplifies a resource‐conservative strategy with slower tissue dynamics. These contrasting functional strategies provide a mechanistic explanation for field performance differences and can help guide species selection in forage‐based livestock systems.