Tillering dynamics of Mulato grass subjected to strategies of rotational grazing management

Abstract

SUMMARYPlants’ ability to rebuild their tiller population is affected by weather changes and management strategies. The hypothesis of the present study was that frequency and severity of defoliation alter Mulato grass (Brachiaria ruziziensis × Brachiaria brizantha cv. Marandu) sward development, and the proportion of aerial and basal tillers, interfering with sward stability. The objective was to evaluate aerial, basal and total tiller population density and changes in tillering dynamics. Treatments corresponded to strategies of rotational grazing characterized by combinations between two pre-grazing (95% and maximum canopy light interception during regrowth; LI95% and LIMax) and two post-grazing conditions (15 and 20 cm stubble height). The experimental period comprised four seasons of the year: summer 2008 (February–March 2008); autumn–early spring (April to mid-November 2008); late spring (mid-November–December 2008); and summer 2009 (January–March 2009). Density of aerial tillers decreased from summer 2008 to late spring. Tiller death decreased from summer 2008 to autumn–early spring. Aerial and total tiller death increased from late spring to summer 2009, mainly for the LI95% treatment. No differences were observed in the tiller population stability index of aerial tillers for LI treatments or post-grazing heights. The balance between tiller appearance and death for basal tillers remained relatively stable from summer 2008 to late spring. For aerial tillers the balance decreased to negative values from summer 2008 to autumn–early spring for both LI treatments. For total tiller population, the balance decreased to negative values from summer 2008 to autumn–early spring. Results indicated a strong seasonal effect on Mulato grass tillering and growth. Tillering dynamics were affected primarily by grazing frequency, which changed the relative importance of basal and aerial tillers. The results suggested that basal tillering was the predominant perennation pathway.

Grazing height management does not change the persistence pathway of Andropogon lateralis in a natural pasture

“…Therefore, it is possible that the autumnal renewal of tillers is associated with a tillering strategy that Matthew et al (2000) referred to as a "reproductive mechanism", according to which the highest renewal of tillers in pastures is associated to the death of reproductive tillers and to the appearance of new tillers from the bud bank of the plants. The highest-tiller appearance rates observed in the lower-management heights corroborate the results obtained by Giacomini et al (2009) and Silva et al (2017), who showed that pastures of 'Marandu' and 'Mulato' palisadegrass, managed with 95% of light interception, showed the highest-tiller appearance rates, in comparison to those managed with about 100% light interception. The higher-grazing intensity at the 12 cm height pastures certainly allowed a higher-light intensity to reach the base of the plants, a condition that allows of the differentiation of the buds and the appearance of new tillers (Matthew et al, 2000).…”

“…agropec. bras., Brasília, v.54, e00405, 2019 DOI: 10.1590/S1678-3921.pab2019.v54.00405 in cultivated C 4 plants, such as those belonging to the Brachiaria genus, a similar pattern of response was observed, with a high-population recomposition occurring during the late spring (Silva et al, 2017). However, the appearance of tillers in the early autumn, which is relatively uncommon in warm season perennial species (Silva et al, 2015), is associated with low rates of tiller appearance in summer.…”

“…The increase of TBR in early autumn shows a unique strategy used by this plant to recompose its population. Perennial grasses of warm season usually have high-tillering rates in the summer (Giacomini et al, 2009;Caminha et al, 2010;Sbrissia et al, 2010;Silva et al, 2017). However, in A. lateralis, the appearance of tillers in the summer period (in both 2016 and 2017) was not significant, and it was greater only to tillering during the winter period (Table 1).…”

Population dynamics and structural characteristics of 'Survenola' digit grass subjected to intermittent defoliation strategies

“…The stability of the population of aerial tillers showed a greater variation in relation to the basal ones. This occurred certainly because aerial tillers have a short life, since they are located in the grazable stratum, which facilitates their removal during defoliation (Santos et al, 2014), as well as they are highly dependent on basal tillers for nutrition, water supply, and support (Silva et al, 2017). Within the evaluated period, no strategy contributed to the degradation of the forage plant (Sousa et al, 2019).…”

“…It is also possible that the basal tillers of the treatments with 20 cm height after defoliation, due to less forage removal, had reached an advanced stage of development, which may have favored the activation of axillary buds and, consequently, favored the aerial tillering that can be an important competition strategy for forage plants. Despite being generally short-lived and highly dependent on basal tillers for nutrition, water supply, and support (Silva et al, 2017), aerial tillers have a high share of leaves and have softer stems, allowing of a better nutritional value, in addition to being located in the grazable stratum, which facilitates their apprehension by animals for forage (Santos et al, 2014). In fact, aerial tillers of 'Survenola' digit Figure 3.…”