Track 2-11: Plant Nutrition and Nutrient Cycling

Description

Tiller appearance, death and survival rates determine the persistency of each grass species and their herbage accumulation. The balance between these factors may vary with frequency and intensity of grazing and nitrogen (N) fertilization. Separated analysis of data on tiller appearance and survival or death may not indicate if tiller population is stable in a given time, that is, if tiller appearance in relation to tiller survival is large enough to maintain tiller population stable. In order to avoid that, an integrated analysis of tiller appearance and death was used, the tiller population stability index (SI), as defined by Bahmani et al. (2003). Aruana Guineagrass (Panicum maximum Jacques cv. Aruana) is widely used as pasture for sheep, which are extremely susceptible to infestation by larvae of gastrointestinal parasites in tropical pasture-based systems. One way to mitigate this problem, reducing the need for the use of anthelmintics, is by managing pastures with post-grazing height low enough to favor the incidence of sunlight at the base of tussocks, killing and controlling larval development, without jeopardizing canopy regrowth and persistence. Sward targets for grazing Aruana Guineagrass correspond to a pre-grazing height of 30 cm, equivalent to 95% canopy light interception during regrowth, and a post-grazing height of 15 cm (Zanini et al. 2012). The objective of this experiment was to evaluate tiller population stability of Aruana Guineagrass subjected to cutting severities and N fertilization using the stability index.

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Tiller Population Stability of Aruana Guineagrass Subjected to Cutting Severities and Fertilized with Nitrogen

Tiller appearance, death and survival rates determine the persistency of each grass species and their herbage accumulation. The balance between these factors may vary with frequency and intensity of grazing and nitrogen (N) fertilization. Separated analysis of data on tiller appearance and survival or death may not indicate if tiller population is stable in a given time, that is, if tiller appearance in relation to tiller survival is large enough to maintain tiller population stable. In order to avoid that, an integrated analysis of tiller appearance and death was used, the tiller population stability index (SI), as defined by Bahmani et al. (2003). Aruana Guineagrass (Panicum maximum Jacques cv. Aruana) is widely used as pasture for sheep, which are extremely susceptible to infestation by larvae of gastrointestinal parasites in tropical pasture-based systems. One way to mitigate this problem, reducing the need for the use of anthelmintics, is by managing pastures with post-grazing height low enough to favor the incidence of sunlight at the base of tussocks, killing and controlling larval development, without jeopardizing canopy regrowth and persistence. Sward targets for grazing Aruana Guineagrass correspond to a pre-grazing height of 30 cm, equivalent to 95% canopy light interception during regrowth, and a post-grazing height of 15 cm (Zanini et al. 2012). The objective of this experiment was to evaluate tiller population stability of Aruana Guineagrass subjected to cutting severities and N fertilization using the stability index.