The success of maize + soybean intercrop depends on the plant arrangement. An experiment was carried out to evaluate different row arrangements on intercrop forage yield, silage quality and maize grain yield in relation to maize as a sole crop. The experiment was set up with a randomized complete block design with eight row arrangements between maize and Soybean. Maize biomass yield among crop arrangements were similar, although, lower than the maize sole crop. On the other hand, these treatments showed higher soybean biomass yield, which in turn increased silage crude protein and crude protein yield per unit area. Maize thousand grain weight, grain yield per plant and per area was affected by the intercrop arrangements. The use of two corn rows + two soybean rows (2M+2S-30 cm) and four corn rows + four soybean rows (4M+4S-30 cm) showed higher crude protein yield per area associated with similar maize grain yield in relation to the sole maize crop. In conclusion, alternating four maize rows with four soybean rows was the optimum row ratio in maize + soybean intercrop, though this needs to be further confirmed by more trials.

Sypnosis The application of ground limestone in every instance resulted in significant increases in the yields of corn and wheat. The yields of corn and wheat following soybeans were much lower than those following the other legumes. Lespedeza compared very favorably with the clovers. The yields in all cases tended to increase throughout the duration of the experiment. Except for a decrease on the plots on which soybeans were grown for hay, soil nitrogen was maintained at, or near, the original level.

O cultivo com milho safrinha no sul do Brasil tem aumentado nos últimos anos. Neste contexto, o objetivo do estudo é avaliar o rendimento de grãos de híbridos de milho, cultivados em diferentes densidades e com distintos níveis de nitrogênio. O estudo foi conduzido no município de Dois Vizinhos – PR e utilizou-se delineamento de blocos ao acaso, em esquema fatorial (2x4x4), no qual o fator A, refere-se a híbridos de milho (2B587 e AG9030), o fator B: densidades de semeadura (45.000, 55.000, 65.000, 75.000 plantas ha-1), e o fator C: níveis de nitrogênio (0, 50, 100, 150 kg ha-1). O híbrido 2B587 apresentou maiores valores de população final, número de espigas por área, número de grãos por fileira e produtividade, porém menor quantidade de fileiras por espiga e massa de mil grãos em relação ao híbrido AG9030. Observou-se resposta linear dos níveis de nitrogênio sobre a produtividade (9158 + 3,265x) porém sem viabilidade econômica devido às boas condições de fertilidade do solo. O aumento da densidade de semeadura reduziu a prolificidade do milho. Os dois híbridos avaliados apresentam melhor resposta de produtividade nas densidades de 55.000 e 65.000 plantas por hectare.Palavras-chave: Zea mays, componentes de rendimento, produtividade. DENSITIES OF PLANTS AND NITROGEN LEVELS IN MAIZE HYBRID PERFORMANCE IN THE SECOND SUMMER CROP ABSTRACT: Maize grown as a second summer crop areas in southern Brazil has increased in recent years. In this context, the objective of the study was to evaluate the grain yield of maize hybrids grown at different plant densities and levels of nitrogen. The study was carried out at Dois Vizinhos (PR) in a randomized complete block design with a factorial scheme (2x4x4), being factor A referent to maize hybrids (2B587 and AG9030), factor B (45,000, 55,000, 65,000, 75,000 plants ha-1), and factor C: nitrogen levels (0, 50, 100, 150 kg ha-1). The hybrid 2B587 showed higher values of final plant population, number of spikes per area, number of grains per row and final yield, but smaller number of rows per spike and thousand grain weights in relation to the Hybrid AG9030. There was a linear response of nitrogen levels over maize yield (9,158 + 3.265x) was observed but without economic viability due to good soil fertility conditions. The increase of the sowing density reduced corn prolificacy. Both evaluated hybrids showed a better yield response at plant densities from 55,000 to 65,000 plants per hectare.Keywords: Zea mays, yield components, productivity.

The objectives of our study were to estimate the components of variance for burley tobacco (Nicotiana tabacure L.) grown at six locations for 3 years and to determine their implications on testing procedures.Eleven commercial hurley tobacco cultivars were grown at 6 locations in 4 states for 3 years. For each experiment we recorded the number of days to flowering; number of leaves and plant height after topping; length and width of fifth leaf from the top; internode length; yield of cured leaf; percent total nitrogen; percent α‐amino nitrogen; water‐soluble acids; pH; and percent ash, K2O, nicotine, and secondary amine alkaloids. Estimates of variance components and correlations among years and among locations were computed for each variable.Estimates of variance components for cultivars were highly significant for all traits. Cultivar ✕ location and cultivar ✕ year interactions were relatively small for all traits. Second‐order interactions were large relative to first‐order interactions for most variables, but in most instances were much smaller than the component for cultivars.The cultivars source of variation for yield was subdivided to elucidate the variance among F1 hybrids and pure lines and their interactions with environments. The location ✕ hybrid mean square was statistically significant, but the one for location ✕ pure lines was not. These results suggest that some hybrids may not have as much internal buffering capacity as pure lines in burley tobacco.Our results show that years and locations may be considered random environments and may be used interchangeably. Adding more years costs more in time and money than does adding locations; therefore, using several locations for 2 years seems best for testing burley tobacco.

O cultivo de soja em safrinha no Paraná foi restringido e o milho tende a ser cultivado em maior escala no Estado. O objetivo do estudo foi avaliar os componentes de rendimento do milho safrinha, manejado com diferentes níveis de adubação nitrogenada (0, 50, 100 e 150 kg ha-1) e com densidades de semeadura elevadas (65.000 e 75.000 sementes ha-1). O experimento foi conduzido em Dois Vizinhos (PR), durante a safrinha 2015, em sistema de plantio direto e foram avaliados os componentes de rendimento da cultura. Foram observados maiores valores de número de espigas por planta, número de grãos por fileira, número de grãos por espiga, produtividade por planta e por espiga na menor densidade. O número de grãos por espiga aumentou de forma linear com o acréscimo dos níveis de nitrogênio, porém as demais variáveis não foram influenciadas pelos níveis do nutriente. A massa de mil grãos e a produtividade do milho safrinha não sofreram influência dos fatores avaliados, porém com produtividade média de 10.113 kg ha-1, o cultivo de milho safrinha em Dois Vizinhos (PR) apresentou-se como satisfatório, mesmo sem aplicação de nitrogênio, sendo uma alternativa para os produtores.