Abstract
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.
Highlights
Rice is a staple food for a large part of the world’s population, including Brazil
The dry matter (DM) accumulation in the stem + sheath and in the leaf blades was approximately 1,550 and 1,355 kg ha-1 from emergence up to 46 days after emergence (DAE), and did not differ between the cultivars (Figures 1a and 1b). This shows that the DM production of the cultivars Caiapó, BRS Primavera, and Maravilha in the first 46 days of development is slow and represented only 11 % of the total DM produced by the plant (Figures 1a, 1b, and 1d)
After 46 DAE, the DM accumulations in the stem + sheath and in the leaf blades of all the cultivars increased to almost the end of the cycle, at which time the amounts of DM accumulated in these plant organs decreased by a maximum of 16 % (Figures 1a and 1b)
Summary
Rice is a staple food for a large part of the world’s population, including Brazil. Brazil is currently the ninth largest producer of rice worldwide, with more than 70 % of the Brazilian production of this cereal crop coming from the flood irrigation growing system. Due to the environmental risks associated with this growing system and because of the increase in rice consumption worldwide in recent years, the search for dryland or upland production systems has been encouraged, especially within the Brazilian Cerrado (tropical savanna) region, where this cereal crop is grown in no-tillage (NT) areas (Guimarães et al, 2006; Cazetta et al, 2008). In this system, in addition to the high yields that have been obtained by rice growers, integrating this cereal crop in rotation programs and/or crop successions has favored the performance of grain species grown in succession, such as soybean (Guimarães and Stone, 2004). Studies indicate that the uptake and adequate use of nutrients by rice plants depend on the physiological processes inherent to the cultivars used (Fageria et al, 1995a), which, depending on the type of plant, may exhibit expressive differences in biomass production and grain yield (Guimarães et al, 2008; Alvarez et al, 2012)
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