Influência das cultivares e níveis de adubação na qualidade física de grãos de arroz após beneficiamento

Abstract

Rice is one of the most cultivated cereals in the world and the increase of crop productivity is associated with the development of new cultivars adapted to different climates and levels of soil fertilization, and may undergo alterations in grain quality after processing. The objective of this work was to evaluate the physical quality of grains of rice benefited (polished and integral) as a function of cultivars IR 424 IR and IR 431 CL and different levels of fertilization (control, low, medium, high and very high ). The experiment was carried out at the Post-Harvest Laboratory (LAPOS) of the Federal University of Santa Maria (UFSM), Cachoeira do Sul Campus (CS) and the Riograndense Rice Institute (IRGA), located in Cachoeira do Sul, RS, 2017/18. The experiment was conducted in a completely randomized design, with three replicates, for each treatment, considering the sources of variation of cultivars (CL), levels of fertilization (NA) and types of processing, performed in a factorial scheme (2x5x2): two cultivars (CL) of rice grains (IR 424 RI and IR 431 CL), five levels of fertilization (NPK): NPK control, low with 60 N 30 P 40 K, medium with 90 N 40 P 55 K, high with 120 N 50 P 70 K, very high with 150 N 60 P 85 K) and two types of processing (BF): (polished and integral). After the harvest, the grains were subjected to the debarking and polishing process. Quality analysis was performed according to the physical classification of rice. The cultivar IR 424 RI obtained a higher percentage of defects, yellow, burned and cast grains, and in the cultivar IR 431 CL it was observed the highest percentage of broken, chopped and stained grains. The average yield of whole grains of polished rice of cultivar IR 431 CL was 44.54% and cultivar IR 424 RI was 56.80%. Meanwhile, the average yield of whole rice of cultivar IR 431 CL was 65.02% and cultivar IR 424 RI was 73.08%. In the conditions under which this experiment was carried out, the cultivar IR 424 RI had a higher percentage of defects in yellow, burned and grained grains and in the cultivar IR 431 CL the highest percentage of broken, chopped and stained grains, which influenced the physical typification the quality of the rice benefited. The management of the production system, with levels of "High" fertilization for the cultivar IR 424 RI, reached the best technical-economical results regarding the yield of whole grains, and levels of "Very High" fertilization, independent of the cultivar, for the processing of polished grains.