Resumen

ALONSO, A.; TRELLES, L.E.; JOUVE, V.V.  y  FERRI, C.M.. Fertilización nitrogenada en Panicum coloratum L. var coloratum: dinámica foliar, macollaje, partición de la biomasa y concentración de nitrógeno. RIA. Rev. investig. agropecu. [online]. 2021, vol.47, n.2, pp.189-197.  Epub 01-Sep-2021. ISSN 1669-2314.

The combination of high productive potential and nutrient assimilation capacity in Panicum coloratum L. var. coloratum would determine conditions to obtain a favorable response to the application of N. The study objectives were to quantify, at the plant level, 1) size and leaf blade accumulation, 2) tiller dynamics, 3) organic matter partition between aerial and subterranean fractions, and 4) N concentration, accumulation and use efficiency, under the application of different N doses. Four nitrogen doses equivalent to 0, 40, 80 and 120 kg N ha-1 (N0, N40, N80 and N120, respectively) were assayed, with eight replicates distributed in a random block design. The plants were grown in tubular PVC pots (11 × 50 cm) from mid-March. For the beginning of treatments, a cut of plants was made leaving a 5 cm remnant aerial fraction, and then the leaf blade length was recorded every 7 days and the number of emerged and dead tillers every 14 days. The application of N increased (p<0.05) the leaf blade final length, the leaf appearance rate, the accumulation of leaf blade, aerial biomass and length of the pseudo-stem/stem, but the number of tillers per plant and the underground biomass resulted similar (p>0.05) between treatments. The N concentration was greater (p<0.05) in N120 in relation to the average value for the rest of treatments (2.14 vs 1.90%; respectively). The agronomic N use efficiency was similar (p>0.05) between treatments, but the physiological N use efficiency increased (p<0.05) by 1.49 times in N120 compared to N40 treatment. Fertilization with N affected the morphogenetic expression at the tiller level and, consequently, plant structure, giving way to a greater dry matter accumulation in comparison to plants without fertilization. It also increased the N concentration in the dry matter which would improve the nutritional quality of aerial biomass. However that effect could be suppressed by the increase in the proportion pseudo stem/stem.

Palabras clave : warm-season grass; morphogenesis; leaf size; phylocron; N use efficiency.

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