Dinâmica do perfilhamento, crescimento e senescência dos capins Marandu, Mulato II, Mavuno e Ipyporã sob diferimento

Abstract

The objective of this work was to know the dynamics of growth, senescence and accumulation of the morphological components of the aerial part of the plant, as well as the tillering pattern during deferral, of the cultivars Marandu, Mavuno, Ipyporã and Mulato II. The experimental area consisted of 16 plots of 12.25 m² each, which had four forage grasses as experimental treatments: Urochloa brizantha cv. Marandu and the hybrid Brachiaria Mulato II, Mavuno and Ipyporã. The experimental design was completely randomized, with four replications. The experiment was repeated for two years (2020, 2021). Appearance rate (LAR) and leaf elongation rate (LER), stem elongation rate, tiller population density, and canopy level growth rates, as well as canopy leaf senescence rate, were higher in the beginning than at the end of the deferral. Leaf life span showed an inverse response pattern. Among the cultivars, mavuno grass showed higher LAR and total canopy growth rate, compared to the others. LER and canopy leaf growth rate were higher in mavuno and marandu grasses than in mulatto II and ipyporã grasses. The stem elongation rate was higher in mavuno and ipyporã grasses, compared to mulatto II and marandu grasses. The tiller appearance rate (TAR) showed a similar pattern among grasses, being higher in the previous and initial period of deferment. Among the forages, the ipyporã grass showed the highest TAR in the pre-deferral period. In general, the tiller mortality rate was higher at the end of the deferral, in relation to the beginning and pre-deferral. The survival rate was higher in the period before and at the beginning of the deferral, intermediate in the middle and lower at the end of the deferment. The balance between tiller appearance and mortality rates (BAL) was positive in the previous and initial period of deferral and negative in the intermediate and final phase of deferral. The BAL of the ipyporã grass was superior in the pre-deferral, in relation to the other grasses. The stability index showed a response pattern similar to the BAL. The number of tillers was higher in the middle, intermediate in the beginning and end and lower in the pre-deferral period. In general, the growth rate of individual tillers and canopy during the deferral period decreases in the following sequence: mavuno grass > marandu grass > ipyporã grass > mulato grass II. Ipyporã grass has less regrowth vigor in spring. Population stability of tillers of Marandu, Mavuno, Ipyporã and Mulato II grasses is not compromised during the deferral period.