Physiological and Canopy Traits of Two Perennial Arachis Species in Response to Clipping Height

Abstract

‘Belmonte’ pinto peanut (PP; Arachis pintoi Krapov. W. C. & Greg cv. Belmonte) and ‘Florigraze’ rhizoma peanut (RP; Arachis glabrata Benth cv. Florigraze) are two perennial peanut species used as forages in tropical and subtropical regions. They contrast in their physiology and productivity, but information is lacking on how this contrast impacts responses to stubble height. Our objective was to assess the impact of stubble height on the physiological and productive responses as expressed by the total herbage accumulation and leaflet accumulation rate, leaf photosynthesis rate and stomatal conductance of PP and RP. Herbage was harvested every 42 days at 4- and 8-cm stubble heights during both warm and cool seasons under irrigation, for a total of 1096 days in Piracicaba, Brazil. In the warm season, RP had a lesser leaflet photosynthesis rate than PP (A, 33 vs. 36 μmol CO₂ m⁻² leaf s⁻¹), as well as lesser stomatal conductance (gs, 0.64 vs. 0.88 mol H₂O m⁻² leaf s⁻¹). Belmonte pinto peanut had herbage accumulation rate (HAR) 52% greater than RP (53 vs. 35 kg ha⁻¹ d⁻¹). In the cool season, RP also exhibited lesser A (25 vs. 34 μmol CO₂ m⁻² leaf s⁻¹), and lesser gs (0.64 vs. 0.91 mol H₂O m⁻² leaf s⁻¹). The 4-cm stubble resulted in greater leaflet accumulation rate and herbage accumulation rate and under the 8 cm stubble there was greater CO₂ assimilation, potentially improving long-term regrowth. Leaflet physiological responses of RP limited HAR, especially during the cool season. Belmonte pinto peanut performed better than RP at our location regardless of stubble height and season. These responses support PP as a better option for pasture diversification in sustainable animal production systems in southeastern Brazil.