Victor Marzari

População de plantas, dose de nitrogênio e aplicação de fungicida na produção de arroz irrigado: I-características agronômicas

A field experiment was aimed at evaluating the effects of plant densities, nitrogen rates and chemical disease control on agronomic characteristics that affect grain yield of irrigated rice. The study was conducted during 2003/2004, in the Departamento de Fitotecnia of Universidade Federal de Santa Maria. The experiment was arranged in randomized blocks with sub-plots and four replicates, in Santa Maria-RS, Brazil and the treatments were: three plant densities (150, 260 and 380plants m-2), five nitrogen rates (0, 40, 80, 120 and 160kg ha-1) with and without chemical foliar disease control. The nitrogen was dressing was twice split at initial tillering and panicle differentiation. Grain yield increased in a quadratic fashion in response to nitrogen rates to up to 97kg ha-1. The use of fungicides to control foliar diseases resulted in higher grain yelds regardless of plant population or nitrogen fertilizer rates. Irrigated rice can compensate yield components between 150 and 380plants m-2. The most efficient rate of nitrogen was 97kg ha-1. Chemical foliar diseases control increases irrigated rice productivity even at low disease incidence.

Manejo da adubação do arroz irrigado em sistema pré-germinado na produtividade e perda de nutrientes através da água de drenagem inicial

The experiment was conducted aiming to evaluate the effects of fertilization management in the pregerminated system, on grain yield and nutrient loss through early drain discharge. The treatments were: T1- Control (without fertilization); T2- fertilization 20 days before sowing without incorporation; T3- fertilization 20 days before sowing with fertilizer incorporation; T4- fertilization 05 days before sowing without incorporation; T5- fertilization 05 days before sowing with fertilizer incorporation; T6- fertilizer application 10 days after sowing; T7- fertilizer application 25 days after sowing. Grain yield was not affected by the different fertilization management procedures. The fertilizer applied 05 days before sowing promoted the highest nutrients loss, especially potassium. However, recorded loss values were within the range allowed by current legislation.

População de plantas, dose de nitrogênio e aplicação de fungicida na produção de arroz irrigado: II. Qualidade de grãos e sementes

This study was aimed at evaluating the effect of plant densities, nitrogen rates and foliar diseases control on the physical, physiological and sanitary qualities of rice seeds. The experiment was conducted during 2003/2004 growing seasons in Santa Maria-RS, Brazil. The treatments were: three plant densities (150, 260 and 380 plants m-2), five nitrogen rates (0, 40, 80, 120 and 160kg ha-1), and control or no control of foliage diseases. The nitrogen fertilizer was top-dressed, and split in two times. There was no triple interaction among the parameters evaluated. Increasing nitrogen rates resulted in higher seed protein content. The chemical control of diseases contributed for better physiological and sanitary qualities such as better germination and vigor and lower incidence of pathogens associated with seeds.