RESUMOA utilização de reguladores vegetais em arroz pode proporcionar redução na altura de plantas e diminuir o acamamento. Objetivou-se verificar a influência da aplicação do regulador vegetal thidiazuron na cultura do arroz de terras altas, em região de Cerrado brasileiro. Utilizaram-se as cultivares BRS Esmeralda e IAC 202, bem como delineamento experimental de blocos casualizados, em esquema fatorial 4 x 3 para cada cultivar, constituído de doses de thidiazuron (0 g ha-1; 0,3 g ha-1; 0,6 g ha-1; e 0,9 g ha-1) e três épocas de aplicação (perfilhamento, diferenciação floral e emborrachamento), com quatro repetições. O número de espiguetas por panícula e fertilidade das espiguetas da cultivar BRS Esmeralda foram maiores utilizando-se a dose de 0,9 g ha-1 de thidiazuron, com aplicação na fase de perfilhamento. A massa de 100 grãos da BRS Esmeralda se ajustou a uma equação quadrática, enquanto, para a IAC 202, houve ajuste a uma equação linear, com melhor época de aplicação durante o perfilhamento. Para massa hectolítrica da BRS Esmeralda, os resultados também se ajustaram a uma equação quadrática, enquanto, para a IAC 202, houve diferença significativa apenas entre as épocas, sendo o emborrachamento a melhor época de aplicação. As produtividades de grãos da BRS Esmeralda e IAC 202 apresentaram ajuste linear positivo, com ganhos de 23,5 % e 6,5 %, respectivamente, em relação à testemunha. O thidiazuron influencia positivamente na produtividade da cultura do arroz de terras altas.

Global rice (Oryza sativa L.) cultivation is expected to increase, especially in upland no‐tillage systems (NTS). The difficulty in producing and maintaining straw in NTS in the Brazilian Cerrado and comparative regions worldwide can be overcome by using cover crops in irrigated areas. The potential of straw accumulation, soil cover maintenance, and nutrient cycling is considered while choosing cover crop species, because these characteristics may interfere with subsequent crop cultivation. This study was conducted to determine whether cover crops could benefit the development, productivity, and industrial quality of upland rice grains irrigated by sprinklers and cultivated in succession. The experiment was conducted in the Cerrado, with a summer rainy season and a dry winter. The treatments consisted of six cover crops (millet [Pennisetum glaucum], sunn hemp [Crotalaria juncea], pigeonpea [Cajanus cajan], millet + sunn hemp, millet + pigeonpea, and fallow) sowed in winter or spring. Compared to fallow, the cover crops cultivated in winter or spring led to increased straw production, accumulation of approximately 150% more nitrogen in straw, and possibly improved rice nutritional value because of the higher N content. Rice plants cultivated after sunn hemp developed a greater dry mass than rice cultivated after the fallow treatment. Grain yield was not influenced by the cover crops. However, sunn hemp cultivation increased the milling yield, head rice yield, and the milled rice productivity (MRP), compared to cultivation following the fallow treatment. Cultivation of sunn hemp before the upland rice crop improved MRP compared to that following the fallow treatment.

The study was carried out in Selvíria-MS, in the 2011/12 and 2012/13 agricultural years, aiming to evaluate the efficiency of Azospirillum brasilense in nitrogen fixation in upland rice, as a function of doses and application methods of the inoculant containing this diazotrophic bacterium. The experimental design was randomized blocks, arranged in a 4 x 4 factorial scheme, with 4 doses of inoculant (control without inoculation, 100, 200 and 300 mL of the commercial product ha-1) and 4 application methods (seed inoculation, application in the sowing furrow, soil spraying after sowing, and foliar spraying at the beginning of plant tillering), with 4 replicates. During the experiment, the agronomic characteristics, production components and yield of the rice crop were evaluated. It was concluded that the inoculant containing Azospirillum brasilense promotes increase (19%) in the yield of upland rice under sprinkler irrigation when used at the dose of 200 mL ha-1, regardless of the application methods.

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