Accessibility and availability of individual leaves on a tiller in bahiagrass (Paspalum notatum Flügge) swards: Effects of nitrogen fertilizer and defoliation intensity

Abstract

Canopy structure of bahiagrass (Paspalum notatum Flügge) swards was analyzed in terms of accessibility and availability of individual leaves on a tiller. Tillers in swards under three nitrogen rates (0, 12 and 24 g m−2 year−1) × two cutting heights (3 and 10 cm above ground level) were measured in May (spring), July (summer) and October (autumn), for the heights of the basal and the highest point and the dry matter (DM) weights of individual leaves (laminae; L1, L2, L3 and so on; L1 = the uppermost or the youngest lamina) and a stem (inclusive of leaf sheaths). The tillers were relatively short in May and October and tall in July, having 10, six and seven leaves, respectively. The leaves were almost always green (no dry part) until L5 in May and until L4 in July and October. In each season, the relative accessibility (height rank of the maximum point) and availability (weight rank) of the leaves on the tiller was almost constant across the nitrogen rates and cutting heights, showing L1–L4 to be highly accessible and L3–L5 and L2 or L6 to be highly available (top four leaves). L3 was almost always the most accessible and available leaf across the seasons and the treatments, followed by L4 and L2. The results indicate the usefulness of the constant relative accessibility and availability of individual leaves on the tiller in the management and modeling of bahiagrass swards.

Spatiotemporal variation in aboveground biomass in a tropical grass pasture over a 22‐year period

“…The values of 0.16–0.94 (Figure 5) is close to the range of 0.20–1.16 obtained on the same land area basis (0.5 × 0.5 m) in other pastures (Do Carmo et al, 2020; Dobos et al, 2021; Shiyomi et al, 1983, 1984). The maximum would have been higher if the measurements had included occasions immediately after the rotational stocking periods in the paddock (Hirata, 2000a, 2000b, 2002; Hirata & Fukuyama, 1997; Ogura et al, 2002). was affected positively by cumulative stocking density and negatively by air temperature, precipitation and N fertilizer rate (Equation ).…”

“…They also did not incorporate management as a possible predictor because of the extensive system (e.g., free-range grazing of animals and no fertilizer application). With respect to spatial variation, previous studies that monitored within-pasture variation in aboveground biomass under livestock grazing covered relatively short periods of 5 months to 3 years (Dos Reis et al, 2020;Hirata, 1998Hirata, , 2000aHirata, , 2000bHirata, , 2002Hirata et al, 2011;Hirata & Fukuyama, 1997;Ogura et al, 2002;Ogura & Hirata, 2001)…”

“…They also did not incorporate management as a possible predictor because of the extensive system (e.g., free‐range grazing of animals and no fertilizer application). With respect to spatial variation, previous studies that monitored within‐pasture variation in aboveground biomass under livestock grazing covered relatively short periods of 5 months to 3 years (Dos Reis et al, 2020; Hirata, 1998, 2000a, 2000b, 2002; Hirata et al, 2011; Hirata & Fukuyama, 1997; Ogura et al, 2002; Ogura & Hirata, 2001). Long‐term changes in within‐pasture variability in aboveground biomass in response to climate and management, including temporal stability or instability of the spatial distribution pattern of biomass, remain unexplored.…”

“…They also did not incorporate management as a possible predictor because of the extensive system (e.g., free-range grazing of animals and no fertilizer application). With respect to spatial variation, previous studies that monitored within-pasture variation in aboveground biomass under livestock grazing covered relatively short periods of 5 months to 3 years (Dos Reis et al, 2020;Hirata, 1998Hirata, , 2000aHirata, , 2000bHirata, , 2002Hirata et al, 2011;Hirata & Fukuyama, 1997;Ogura et al, 2002;Ogura & Hirata, 2001) During the stocking season (May to October or November) in the study years, the paddock was stocked 6-9 (mean ± SD = 6.4 ± 0.8) times by a herd of 24-35 (28.1 ± 1.7) cows and 4-18 (7.6 ± 1.9) calves for 1-7 (4.3 ± 1.2) days at about half monthly to monthly intervals. Total duration of stocking and cumulative stocking density during the stocking season were 22-32 (27.3 ± 2.8) days and 625-970 (768 ± 87) cow-days per ha, respectively.…”

Bahiagrass (Paspalum notatum CV. Inia Sepé) responses to defoliation intensities

“…Paspalum notatum (Bahiagrass) is a native type C 4 summer perennial grass, and one of the most frequent species in the natural fields of Uruguay noted for its high stability and the longevity of the plant population in communities (Hirata, 2004). Taking into account the potential of P. notatum , and to value the genetic resources of Uruguay, a national collection of germplasm was done in 2006 to characterize, value and conserve genetic resources.…”