Regrowth patterns of elephant grass (Pennisetum purpureum Schum) subjected to strategies of intermittent stocking management

Abstract

The morphogenetic responses of individual tillers and the composition of tiller populations throughout regrowth in response to all 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) were studied in swards of elephant grass (Pennisetum purpureum Schum. cv. Napier) from November 2011 to April 2012. Swards were subjected to the same treatments from January 2011 until measurements began, to enable them to adapt to the defoliation regimes. Treatments were allocated to experimental units (850 m2 paddocks) according to a 2 × 2 factorial arrangement in a randomized complete block design, with four replications. The total number of tillers (basal + aerial) was similar for both LI pre‐grazing targets. However, there was a change in the preferential growth pathway used by plants characterized by modification in the proportion of tiller classes in plant population. Swards managed with the LIMax target had a smaller population density of basal tillers and used the recruitment of aerial tillers as the main growth pathway. Although effective for maintaining stable rates of leaf elongation and senescence, such a strategy resulted in greater tiller death. Additionally, stem elongation, a consequence of the competition for light under those circumstances, resulted in differences in sward herbage mass and morphological composition with potential implications for herbage feeding value.

Ecophysiology of C4 Forage Grasses—Understanding Plant Growth for Optimising Their Use and Management

“…Planaltina [123]), Xaraés palisade grass (Brachiaria brizantha cv. Xaraés [96]), and Napier elephant grass [94,95,124] under rotational grazing, similar values of total herbage accumulation have been reported for grazing severities equivalent to a removal of 40%-60% of the pre-grazing height when associated with grazing at LI95%. On the other hand, definition of post-grazing targets also influences the short term rate of herbage intake of grazing animals by interfering with their ability to graze [3].…”

“…This pattern of variation in the short-term rate of intake in relation to the decreasing sward height during grazing was formally described by Fonseca et al [127,132] and corroborated by Mezzalira et al [128], indicating the potential for manipulating pre-and post-grazing conditions as a means of optimising herbage production and intake in rotationally managed pastures. In general, more frequent defoliations (at 95% canopy light interception) than traditionally used, associated with moderate grazing severity (post-grazing heights around 50% of the pre-grazing height), result in greater leaf dry matter production [84,93,96,124], higher nutritive value [89,90] and intake rate of animals [127][128][129]132], augmenting animal performance and productivity [133], indicating that rational intensification of grassland use could be an effective way of ensuring sustainability of tropical pastoral systems of animal production. These results are in line with the findings of Knoke et al [134] and provide feasible options for recovering degraded areas, reducing pressure on forest lands and releasing additional area for cropping and food production.…”

Sward Structure and Herbage Accumulation of Massai Guineagrass Pastures Managed According to Pre-Grazing Heights, in the Northeast of Brazil

“…Pereira et al (2015) also describes that severe defoliation may reduce the size and quality of the residual leaf area and decrease the rate at which the swards recover. The authors describe other experimental results: Sousa et al (2013) studied the same response variables in Pennisetum purpureum Schum cv.…”

Grazing management and tussock distribution in elephant grass

“…In this way, tillering is an important component of tussock growth and expansion, determining the efficiency of soil surface occupation through variation in the frequencies of colonized and bare ground areas in the pasture. Grazing, through leaf area removal, alters the quantity and the quality of the light reaching the sward base (Deregibus et al ., ), interfering with the dynamics of tiller replacement (Pereira et al ., ) and affecting the balance between the processes of tiller appearance and death, which are represented by the tiller population stability index (Bahmani et al ., ) and have consequences for sward structure and herbage accumulation (Pereira et al ., ).…”