Desempenho de cultivares de arroz com uso de reguladores de crescimento, em diferentes sistemas de cultivo

Abstract

Resumo -O objetivo deste trabalho foi avaliar o efeito de reguladores de crescimento sobre o estabelecimento inicial e o desempenho agronômico de cultivares de arroz irrigado, em diferentes sistemas de cultivo. O experimento foi conduzido em ambiente controlado e em campo, com as cultivares Irga 424 e Irga 425, e os produtos ácido giberélico, tiametoxam e Haf Plus. Em campo, os tratamentos foram testados nos sistemas de cultivo convencional e pré-germinado. Em ambiente controlado, as substâncias avaliadas promoveram a germinação de Irga 425, com incremento de 50% na germinação com o uso de tiametoxam, e de 39% com Haf Plus e ácido giberélico. Em campo, esse desempenho foi dependente do sistema de cultivo e da cultivar utilizada. O ácido giberélico causou estiolamento inicial, com reflexos na estatura da planta, na emissão de perfilhos e na deposição de biomassa vegetal. Tiametoxam e Haf Plus estimularam o perfilhamento das cultivares de arroz, nos dois sistemas de cultivo. Apesar de todos os produtos estimularem o número de panículas por metro quadrado, sua influência na produtividade de grãos não foi observada nos sistemas avaliados.Termos para indexação: Oryza sativa, ácido giberélico, estabelecimento inicial, sistema pré-germinado, tiametoxam. Performance of rice cultivars with the use of growth-regulators in different cropping systemsAbstract -The objective of this work was to evaluate the effect of growth-regulating substances on initial establishment and agronomic performance of irrigated rice cultivars, in different cropping systems. The experiment was carried out in controlled environment and in field conditions, using the cultivars Irga 424 and Irga 425, and the products gibberellic acid, thiamethoxam and Haf Plus. At field, treatments were tested with conventional and pre-germinated sowing systems. In the controlled environment, the evaluated substances promoted the germination of Irga 425, with an increase of 50% in germination with the use of thiamethoxam and of 39% with Haf Plus and gibberellic acid. In the field, this performance was dependent on the system and the cultivar used. Gibberellic acid caused initial blanching, which reflected in plant height, tiller emission, and deposition of vegetal biomass. Thiamethoxam and Haf Plus stimulated tillering of rice cultivars in both cultivation systems. Although all the products stimulated the number of panicles per square meter, there is no influence on grain yield in the evaluated systems.Index terms: Oryza sativa, gibberellic acid, early establishment, pre-germinated system, thiamethoxam. IntroduçãoAlém do estresse causado por baixas temperaturas, o estabelecimento das plântulas de arroz (Oryza sativa L.) pode ser afetado por diversos outros fatores. Características intrínsecas de cada genótipo de arroz podem condicionar plântulas mais ou menos vigorosas, o que está associado a balanços hormonais. Porém, a atuação do ambiente sobre a semente também é de grande importância.No sistema pré-germinado, é comum o acamamento das plantas, o que pode ser agrav...

Physiological Effects of Insecticides and Fungicide, Applied in the Treatment of Seeds, on the Germination and Vigor of Soybean Seeds

“…In the corn crop, according to Dan et al (2010), significant reductions in vigor that were caused by Carbofuran in corn seeds were observed after treatment and storage for a period of 30 days. Grohs et al (2012), evaluating the first count of normal seedlings at 7 days after sowing, verified that the applications of Cruiser 350 FS were efficient in stimulating the germination of different rice cultivars. According to these same authors, thiamethoxam as well as gibberellic acid, promoted a stimulus germination that was already expected, because these substances act in different stages of the germinative process, stimulating mainly the activity of key enzymes involved.…”

The effect of a fungicide treatment on the physiological potential of rice seeds after storage

“…Similarly, Avelar et al (2011) reported that soybean seeds stored for six months with no treatment exhibited higher performance in comparison to treated seeds. In experiment with rice seed treated with Thiamethoxam was observed stimulus the first count, cultivar IRGA 425 obtained higher percentage compared to the control (Grohs et al, 2012).…”

“…In maize seeds subjected to phytosanitary treatment and stored for six months exhibited lower normal seedlings number, indicating a possible phytotoxic effect of the treatment (Pereira et al, 2005). Grohs et al (2012) observed that of rice seeds germination treated with thiamethoxam was 50% higher than the witness. In another study, it was observed that rice seeds treated with thiamethoxam presented accelerated germination (Clavijo, 2008).…”

Physiological quality of Urochloa seeds treated with thiamethoxam

“…In cv. Irga 425 rice seeds, thiamethoxam treatment resulted in an increased germination of up to 60% (GROHS et al, 2012 (MAPA, 2008). Thus, thiamethoxam use increased germination to a level that meets the standards established by the current legislation, except for U. brizantha cv.…”