Tiller dynamics of grazed swards.

Abstract

Topics discussed in this review, mainly of the major forage grasses include tiller morphology, canopy leaf area optimization for continuously and rotationally grazed swards, and tiller population demography including its manipulation and the effects of mixed species swards. It is considered that the primary driving principle for tiller dynamics is the optimization of leaf canopy area in relation to defoliation intensity and available resources, such as light and water. The concept of a multiphase size-density compensation relationship along an environmental boundary may rationalize otherwise conflicting observations on tiller density and on tiller appearance and death rate and are relevant to issues such as carrying capacity or sustainability. There remain substantive complex differences in tillering behaviour, often unique to a particular species, which are best explained from a tiller demography basis. A well-directed understanding of tiller demography may result in significant improvements in productivity in some situations.

Nitrogênio e as características anatômicas, bromatológicas e agronômicas de cultivares de Brachiaria brizantha

“…Pastos mantidos sob regime intenso de desfolhação apresentam perfilhos com folhas mais curtas e maior densidade populacional de perfilhos pequenos (Matthew et al, 2000). Fato coerente ao observado nesta pesquisa, pois o corte das forrageiras foi realizado à aproximadamente cinco centímetros da superfície do solo.…”

Sward structure of marandu palisadegrass subjected to continuous stocking and nitrogen-induced rhythms of growth

“…Grant et al (1983) stated that seasonal variation in solar radiation and sward herbage mass are the main determinants of tiller population density, indicating that tiller population is frequently being adjusted. The persistency and productivity of grass swards are directly dependent of the combined effect of tiller appearance and death (Matthew et al, 2000). These patterns vary with grass species and defoliation management imposed.…”

“…For tropical grass species the general pattern of responses is the same, only changing the relative importance of specific characteristics, particularly stem elongation (Da Silva, 2004). Plants have three possibilities to invest and form LAI: tiller population density, number of leaves per tiller and leaf size (area) (Matthew et al, 2000). Fricke et al (1997) and Matthew et al (2000) suggest that nitrogen supply increases the flux of cells from leaf growing zones, increasing LER and length of fully expanded leaves which, in association with the faster growth rhythm of individual tillers and patterns of tiller appearance and death, results in a larger population with high proportion of young tillers.…”

“…Such response was consequence of the low stocking rates used to maintain swards on target ( Table 1). Considering that tiller appearance rate is significantly reduced and morphogenetic processes limited by the low availability of environmental growth factors (Matthew et al, 2000), particularly light and rainfall, tiller death is increased, especially in early spring, causing reduction of sward LAI during that time of the year. During the period of low rainfall and light availability, swards subjected to the faster rhythms of growth were capable of maintaining upper strata with larger proportion of leaves in relation to those subjected to slower rhythms of growth ( Figure 4B).…”

Tiller density and tillering on Brachiaria brizantha cv. Marandu pastures inoculated with Azospirillum brasilense

“…According to Matthew et al, (2000), many grass species appear to have programmed seasonal patterns of tiller birth and death, which may be referred to as perennation strategies. Knowledge regarding the perennation strategy for particular cultivars or species can enable the identification of management and fertilization strategies that will improve their productivity, through the enhancement of the natural cycle of tiller replacement.…”