Growing Points Density of Arachis Pintoi Cv. Belmonte Subjected to Intensities of Grazing.

Plant population or growing points density in communities of grazed plants is the result of a series of responses and strategies to ensure survival and propagation directly related to their plasticity and resistance to grazing. The objective of this experiment was to evaluate and describe how forage peanut responds to grazing intensities through variations in growing points population density (GPPD). It was carried out in Piracicaba, SP, Brazil, from January 2013 to March 2014. Treatments corresponded to four intensities of grazing characterized by the sward heights of 5, 10, 15 and 20 cm. These were allocated to experimental units (200 m² paddocks) according to a randomized complete block design, with four replications. The GPPD was determined by counting the total number of growing points (main stolons and associated branches) using two 0.25 m² (1.00 x 0.25 m) metallic frames per sampling paddock. The evaluations were conducted every 28 days. The GPPD varied with sward height and season of the year (P<0.05). Largest values were recorded during periods of high availability of climatic growth factors (spring and summer II). Larger values were consistently recorded on swards managed at 5 cm, except in summer I, when there was no difference between sward heights and swards were still adapting to treatments. At the end of the first year, during the second summer, GPPD was larger on swards managed at 5 cm and values decreased as sward height increased. Simultaneously, swards managed higher recorded largest lengths of internodes. These facts are indicative of plasticity and adaptations of forage peanut to the grazing regimes imposed, and suggest a compensation mechanism between size and number of growing points in order to maintain plant competitiveness and stability in the area.