Resumen

RENGEL, Marcos; GIL, Fernando  y  MONTANO, José. Growth and dynamics of nutrient accumulation in sugarcane. I. Macronutrients. Bioagro [online]. 2011, vol.23, n.1, pp.43-50. ISSN 1316-3361.

With the purpose of assessing the growth and macronutrient accumulation patterns of the sugar cane plant and promote a rational fertilization management of the crop, an evaluation was carried out in a plot cropped with the RB 85-5035 variety, in Chivacoa, Yaracuy State, Venezuela. The trial consisted on taking ten monthly samplings of the aerial portion of the plant, along the whole crop cycle. Each sample consisted of three stumps, taken at random in a surface of 0.6 m2 per stump, and dry biomass content and macronutrient concentrations were determined on both leaves and stalks. In the months 11 and 12, additional samples were taken to determine the final dry biomass. At the end of cycle the crop accumulated 43.7 t·ha^-1 dry biomass, with 75.1 % corresponding to the stalks and the remaining to the leaves. The accumulation of N, P, K, Ca, Mg, and S at 300 days after cutting (dac) was 201,4; 43,2; 149,0; 112,7; 71,1 y 71,6 kg·ha^-1, respectively. Nitrogen accumulated mainly in leaves during a good part of the cycle but at the end the nutrient was mainly translocated to the stems; it were found two critical periods of absorption, the first of which covered the stages of tillering and vegetative growth phase, and the second one was located at the stage of maturation of the reproductive phase. The nutrients P, K, Mg and S were proportionally distributed in leaves and stems for most of the crop cycle, but differed dramatically from 251 dac, when the accumulation was directed mainly towards the stem. Calcium was stored mainly in the leaves but at the end of the cycle the trend was reversed and the nutrient in the stems moderately exceeded that in the leaves. It was found that for the first four months of the plant growth the crop had produced just 16,5 % of its total biomass, but it had accumulated between 20 and 40 % of the macronutrients, which suggests the needs of their supply since the initial steps of the crop cycle.

Palabras clave : Dry biomass; mineral nutrition; Saccharum spp hybrid.