Radiation Use Efficiency of Arrowleaf, Crimson, Rose, and Subterranean Clovers

Abstract

Parameters describing the growth of cool‐season annual clovers are necessary for potential growth simulations, but have not yet been determined. Accordingly, the objective of this study was to quantify and compare the key parameter for biomass production, radiation use efficiency (RUE), for arrowleaf (Trifolium vesiculosum Savi.), crimson (T. incarnatum L.), rose (T. hirtum All.), and subterranean (T. subterraneum L.) clovers. Data on the fraction of light intercepted and biomass were collected biweekly over 2 yr at Overton, TX, and were used to calculate the RUE. Radiation use efficiency was calculated for biomass as a function of cumulative intercepted photosynthetically active radiation (IPAR) for aboveground biomass and for total biomass including roots. Similarly, RUE was calculated for regrowth following one or two cuttings. Over the 2 yr of this study, the mean RUEs for aboveground biomass original growth were 2.92, 2.52, 1.94, and 1.86 g MJ−1 for rose, arrowleaf, crimson, and subterranean, respectively. The mean RUEs for the total biomass including roots, during this time were 3.01, 2.59, 2.00, and 1.98 g MJ−1, respectively. Relative to the original growth aboveground RUE values, the RUE of aboveground regrowth following one cutting averaged 92% across the four species. Likewise, the mean RUE of aboveground regrowth of the four species following two cuttings was 119%. These values of RUE will aid modelers in simulating these important N2 fixing species.