Efecto del arreglo espacial sobre la producción de biomasa de Crotalaria juncea L. en función del tiempo térmico bajo siembra tardía

Abstract

Crotalaria juncea L. is a legume widely used for its high biomass production. Under late sowing conditions, limited thermal time availability may restrict crop growth, making crop spatial arrangement an important management factor for optimizing resource capture. This study evaluated the effects of sowing density and row spacing on biomass production as a function of accumulated thermal time. The experiment was conducted in Tucumán, Argentina, using a randomized complete block design with a 2 × 2 factorial arrangement, including two sowing densities (8 and 13 kg ha⁻¹) and two row spacings (0.23 and 0.52 m). Aboveground biomass, intercepted photosynthetically active radiation (IPAR), plant density, and leaf-to-stem ratio were assessed at different crop stages defined by thermal time accumulation. Aboveground biomass increased significantly with thermal time (p < 0.0001), with no effect of sowing density. In contrast, row spacing interacted significantly with thermal time, with narrower rows producing greater biomass during later growth stages. IPAR dynamics were influenced by spatial arrangement, although all treatments reached high interception levels at advanced stages. These findings suggest that, under limited thermal time conditions, early radiation capture is the main driver of biomass production, highlighting row spacing as a key management strategy for late sowing conditions