Impact of sowing dates on the yield efficiency of upland rice cultivars

The choice of cultivars adapted to different regions and the determination of the best sowing dates are indispensable tools for crop development. This allows the installation of the crop in times favorable to its development, as well as cultivars that manage to reach their maximum yield potential. The objective of this study was to determine the best sowing dates and the cultivars that can adapt to the low-altitude Cerrado region and have the best development and yield efficiency. The experiment was conducted on a typical clayey dystrophic Red Latosol soil. The experimental design was in randomized blocks in a factorial scheme, comprised by four sowing dates during the spring/summer season (October, November, December, and February) and in each sowing date there were eight upland rice cultivars (BRS Esmeralda, ANa 6005, ANa 5015, IPR 117, IAC 203, IAC 500, ANa 7211 and BRSGO Serra Dourada) with four replicates. Sowing in October and November benefited the aerial dry mass and the spikelets fertility however, sowing in November provided higher plant height, which caused lodging in plants. Sowing in December caused the incidence of scald, mainly affecting the cultivar ANa 7211. For all cultivars, sowing in October favored the yield efficiency of upland rice in the low-altitude Cerrado, followed by sowing in November. The cultivars which demonstrated higher yield efficiency in the conditions of the region were BRS Esmeralda and ANa 5015.

Reguladores de crescimento e seus efeitos sobre a qualidade fisiológica de sementes e crescimento de plântulas de crotalária / Growth regulators and its effect on the physiological quality of seeds and growth seedlings of sunn hemp

Informações referentes à utilização de reguladores de crescimento em crotalária ainda são escassas, notadamente sobre a qualidade fisiológica de sementes e o crescimento de plântulas. Nesse aspecto, o conhecimento do produto e da dose de aplicação se destaca como fatores relevantes na produção de sementes de boa qualidade. Este trabalho objetivou avaliar o efeito da aplicação foliar de reguladores de crescimento (cloreto de mepiquat, etil-trinexapac e paclobutrazol) em diferentes doses (0; 75; 150; 225 e 300 g ha-1), sobre a qualidade fisiológica de sementes e o crescimento de plântulas de Crotalaria juncea cultivada em sistema plantio direto. Os tratamentos foram dispostos em delineamento experimental de blocos ao acaso em esquema fatorial 3 x 5 (reguladores x doses de aplicação), com quatro repetições. Os resultados foram submetidos à análise de variância, com os reguladores de crescimento comparados pelo teste de Tukey e as doses por regressão polinomial. Não se recomenda a aplicação de cloreto de mepiquat na cultura da crotalária por reduzir o potencial de germinação das sementes e a biomassa fresca de plântula. O etil-trinexapac deve ser aplicado na dose de 300 g ha-1, com base na redução do grau de umidade e na condutividade elétrica das sementes, maior comprimento total de plântula e biomassa fresca de plântula. O paclobutrazol deve ser aplicado na dose de 75 g ha-1 , considerando o potencial e velocidade de germinação das sementes.

Information regarding the use of growth regulators in sunn hemp is still scarce, especially on the physiologic quality of seeds and growth seedlings. In this aspect, product knowledge and application rate stands out as relevant factors in production of quality seeds. This work aimed to evaluated the effect of the foliar application of growth regulators (mepiquat chloride, etil-trinexapac and paclobutrazol) in different rates (0; 75; 150; 225 and 300 g ha-1), on the physiological quality of seeds and growth seedlings of Crotalaria juncea cultivated in no-tillage system. The treatments were disposed in randomized complete block design in factorial scheme 3 x 5 (regulators x rates of application), with four replications. The results were submitted to the variance analysis, with the growth regulators compared by Tukey test and the rates for polynomial regression. Not if recommended the application of mepiquat chloride in sunn hemp culture by reducing the potential of seeds germination and dry biomass of seedlings. The etil-trinexapac must be applied in rate of 300 g ha-1, based on the reduction of moisture content and the electrical conductivity of seeds, the greater total length of seedlings and dry biomass of seedlings. The paclobutrazol must be applied in rate of 75 g ha-1, considering the potential and speed of seeds germination.