Growth analysis of kikuyo grass Cenchrus clandestinus (Hochst. ex Chiov.) Morrone fertilized with different levels of nitrogen

Abstract

Contextualization: Forage production response is determined by factors inherent to the ecotype and external environmental and management conditions. The high variation of factors influencing forage growth implies the need to establish responses based on the biological development regarding the accumulated temperature. Knowledge gap: The growth response of Cenchrus Clandestinus expressed in heating degree days (HDDs) when fertilized with different doses of N is unknown to establish grazing times at peak biomass accumulation accurately. Purpose: To determine the growth dynamics of kikuyu grass with different levels of nitrogen fertilization. Methodology: A control treatment without application of any source of N (T0) was evaluated, a dosage of 100 kg. N ha.-1 (T1) and a dosage of 150 kg. N ha.-1 (T2). The fertilization plan was programmed for 42-day defoliation with a residual height of 10cm. Subsequently, the growth of kikuyu grass was evaluated with a seven-day frequency based on the analysis of dry matter, chlorophyll content, stomatal conductance, number of leaves, height, leaf area, and dry matter of leaves and stems. Growth rates were calculated from the dry matter of the forage: Absolute Growth Rate (AGR), Relative Growth Rate (RGR), Net Assimilation Rate (NAR), Specific Leaf Area (SLA), Leaf Area Ratio (LAR), and Leaf Area Index (LAI). Analysis of repeated measures was carried out to determine the effect per sampling point (HDDs) in a completely randomized arrangement. Results and conclusions: With the application of 150 kg. N ha.-1 and defoliation at 208.5 Grade Days Cumulative (GDC), plants showed higher growth rate, leaf tissue production, increased leaf expansion and greater height (p<0.05).