Maturidade de sementes de arroz irrigado (Oryza sativa L.) e variação da qualidade fisiológica das sementes na panícula

Abstract

The knowledge of the seed maturation process and all the main factors involved on it, are of great deal for the seed producers, becoming a helping hand on the quality control, mainly when it comes to planning and deciding the right harvesting moment, while aiming at quality and yield. Having the objective of determining the physiological maturity moment of irrigated rice seeds, it were collected samples every four days, based on the number of days after antesis ( d. a. a. ), reaching then fifteen harvests of the cultivar BRS Atalanta, and 13 of the BRS Pelota. The seeds were evaluated by moisture content; dry matter; and viability, trough vigor and germination tests, as germination first counting, accelerated aging, and emergence velocity rate. The statistic delineation was complete randomized blocks, and the data was submitted to the variance analyses and polimonial regression, regarding the harvest moments for both cultivars, and then showing the results by the quadratic model. The seeds of the Cultivar BRS Atalanta presented maximum dry matter at 38 d. a. a., when the moisture content was 21,5%. The germination tests, germination first counting and the emergence velocity rate, also had their maximum values at 38 d. a. a.. However, the accelerated aging test did not correlated to the other tests, reaching maximum values only at 42 d. a. a.. To the BRS Pelota, the maximum dry matter was observed only at 40 d. a. a., when the moisture content was around 22%. The germination percentage, accelerated aging and emergence velocity rate, reached maximum values all together. The germination first counting reached it´s maximum at 36 d. a. a.. The best harvest moment for the rice seeds occurs between 36 and 42 d.a.a., when the seeds present superior rates of physiological quality.