Macronutrient Uptake and Removal by Upland Rice Cultivars with Different Plant Architecture
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Modern high-yielding rice cultivars possibly take up and remove greater quantities of macronutrients than traditional and intermediate cultivars. This study was carried out with the aim of evaluating the extraction and removal of macronutrients by upland rice cultivars. These information are of utmost importance for the correct fertilizer management. The treatments consisted of three upland rice cultivars (Caiapo, a traditional type; BRS Primavera, an intermediate type; and Maravilha, a modern type). Macronutrient accumulation by rice cultivars up to the end of tillering (46 DAE) accounted for only 25 % of the total N and P, and between 35-45 % of the total K, Ca, Mg, and S; after that time, accumulation was intensified. In all of the cultivars, the period of greatest nutrient uptake occurred from 45 to 60 DAE for K, Ca, Mg, and S, and after 65 DAE for N. Phosphorus was taken up at greater rates at 70 DAE by the cultivar BRS Primavera and after 90 DAE by the cultivars Caiapo and Maravilha. The cultivars of the traditional (Caiapo) and intermediate (BRS Primavera) groups took up greater amounts of Ca (143 kg ha(-1)), Mg (46-53 kg ha(-1)), and S (45-52 kg ha(-1)), but amounts of N (147-156 kg ha(-1)) and P (18-19 kg ha(-1)) were similar to those of the cultivar of the modern group (Maravilha). Caiapo cultivar took up more K (245 kg ha(-1)) than other cultivars (204-207 kg ha(-1)). The cultivars Caiapo and Maravilha showed similar grain yield (4,157 and 4,094 kg ha(-1)); however, this was lower than the grain yield of cultivar BRS Primavera (6,010 kg ha(-1)). Cultivars with greater yield levels did not necessarily exhibit a greater uptake and removal of nutrients per area, even if they had greater capacity for conversion of the nutrients taken up into the biomass.