Respostas morfogênicas e estruturais de Panicum maximum cv. Mombaça sob diferentes níveis de adubação nitrogenada e alturas de corte

Abstract

The morphogenetic and structural characteristics of Panicum maximum cv. Mombaça were evaluated in response to different levels of nitrogen supply and cutting regimes. The study was conducted in a glasshouse with natural conditions of light and temperature. Treatments corresponded to four levels of nitrogen supply (0, 50, 100 and 200 mg/dm3) and three cutting heights (5, 10 and 20 cm). The morphogenetic evaluations included leaf appearance and elongation rate, phyllochron and leaf lifespan. The structural measurements were: number of leaves, number of tillers and leaf lamina length of fully expanded leaves. The morphogenetic responses were affected by nitrogen supply during regrowth, highlighting the importance of that nutrient for manipulating sward structure. All variables responded positively to nitrogen supply, except phyllochron. Cutting height had a significant effect on leaf lifespan, leaf lamina length of fully expanded leaves and number of green leaves per tiller. Leaf appearance and elongation rate per tiller were increased in 133 and 104%, respectively, by nitrogen supply. The relationship between both group of variables was determinant for the characterization of the main vegetative changes on plants. The responses observed on morphogenetic characteristics comprise an efficient attribute to manipulate canopy structure, allowing improved allocation of productive resources to growth and developmental processes.