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Contribution of basal and aerial tillers to sward growth in intermittently stocked elephant grass

Pereira, Lilian Elgalise Techio, Paiva, Adenilson José, Geremia, Eliana Vera, Da Silva, Sila Carneiro
Grassland science 2018 v.64 no.2 pp. 108-117
Cenchrus purpureus, canopy, defoliation, dry matter accumulation, forage grasses, grazing, grazing management, leaves, pastures, plant response, regrowth, stem elongation, sward, tillering, tillers
Elephant grass (Pennisetum purpureum Schumach. cv. Napier) is characterized by high dry matter production and a high contribution of aerial tillers to the tiller population. However, grazing management strategies that favor an increase in aerial tillers, such as long regrowth periods, particularly when associated with severe grazing, can result in a decrease in sward growth, as they are subject to a high level of intraclonal competition. We evaluated the contribution of basal and aerial tillers to sward growth in Napier elephant grass to comprehend how strategies of intermittent stocking management interfere with the relative contribution of each tiller class. Treatments corresponded to combinations of two post‐grazing heights (35 and 45 cm) and two pre‐grazing conditions (95% and maximum canopy light interception during regrowth—LI₉₅% and LIMₐₓ, respectively) and were allocated to experimental units (850 m² paddocks) according to a 2 × 2 factorial arrangement in a randomized complete block design with four replicates from January 2011 to April 2012. Basal tillers were the main contributors to sward growth in elephant grass. In this way, although the production of aerial tillers is an important adaptive response of this forage grass species, grazing management strategies that maximize aerial tillering do not result in greater leaf growth or minimize stem growth rates. The frequency of defoliation was the main modulator of plant responses related to light competition, and the higher leaf growth associated with lower stem growth rates were obtained with the LI₉₅% pre‐grazing target. Severe grazing (35 cm) associated with LI₉₅% is the grazing management strategy recommended to maximize leaf and sward growth rates in Napier elephant grass subjected to rotational stocking.