The use of light-transparent acetate sheet to measure canopy height of marandu palisadegrass: the influence of development stage and sward height

Abstract

The use of light-transparent acetate sheet (LAS) may generate variations in the height measured in the sward. However, we compared the use or non-use of LAS to measure the average sward height of marandu palisadegrass (Urochloa brizantha syn. Brachiaria brizantha cv. Marandu) pastures. In the first experiment, the methods were applied in pastures with different average heights (15, 25, 35, and 45 cm), managed under continuous stocking with sheep, and with predominance of vegetative tillers. The shorter pastures (15 and 25 cm) had similar heights with or without the use of the LAS. However, in the taller pastures (35 and 45 cm), the use of LAS resulted in lower height values, compared with its absence. In the second experiment, we compared both methods for measuring the height of deferred marandu palisadegrass and fertilized with two nitrogen levels (50 and 200 kg ha^-1) and with high presence of reproductive tillers. A completely randomized design with four replicates was adopted. With 200 kg ha^-1 of N, the canopy height was greater than when it was fertilized with 50 kg ha^-1 of N. With the use of LAS, the height of deferred and reproductive canopy was greater than without it. In a taller marandu palisadegrass pasture with predominance of vegetative tillers, the use of LAS results in smaller height, contrary to what occurs in deferred swards with reproductive tillers.