Crescimento do capim-Tifton 85 submetido a doses e épocas de aplicação de nitrogênio após o corte

Abstract

Two experiments were carried out in a greenhouse to evaluate the effects of nitrogen rates and time of application after cutting in Tifton 85 (Cynodon spp) yield production, as well as, the effects of nitrogen in the SPAD values in leaf lamina of this bermudagrass. Plants were grown in a TYPIC QUARTZIPSAMMENT. The first experiment was set in a factorial design (rates x time of application) whereas the second one had nitrogen rates, established in a complete randomized block design, with four and six replications, respectively. The rates of nitrogen were 0, 80, 160 and 240 mg kg-1 of soil and the times of application were immediatly after cutting and then seven days after. In the first experiment there was an effect of nitrogen in increasing dry matter yield of plant tops. Maximum dry matter yield occurred at nitrogen rates of 217 and 205 mg kg-1 of soil, respectively for the first and second growth periods. Dry matter of roots was influenced by nitrogen and lower production was observed when the application of nitrogen was one week later than just after cutting. There was a variation in stem+sheath/lamina ratio with the nitrogen rates. The concentration of nitrogen in plant tops and roots increased with the rates of nitrogen applied and higher nitrogen concentration was found in tops with nitrogen supply seven days after cutting than with the application just after cutting. There was an increasing in the SPAD values according to the rates of nitrogen and a high coefficient of correlation between SPAD values and concentration in the leaf lamina was observed.