Qualidade fisiológica de semente de arroz irrigado colhidas em diferentes épocas

Abstract

The success of rice grain production depends, among other inputs, on the use of good quality seeds, since plants originating from seeds of high vigor have superior performance. The seeds of cultivar IRGA 424 RI were harvested from an experiment located at the Technological Center of Chasqueiro, Arroio Grande, RS. The analyzes were conducted at the Didactic Laboratory of Seed Analysis, Flávio Rocha, of the Phytotechnics Department of the Faculty of Agronomy “Eliseu Maciel” (FAEM), Federal University of Pelotas (UFPel), from March 2019 to January 2020. The sowing of the cultivar IRGA 424 IR was carried out on October 22 and its emergence occurred on November 2, 2018 in an area of 45.9m² (15m x 3.06 m). Fertilization was equivalent to doses of 170 Kg / ha of N - 96 kg / ha of P2O5 - 132 Kg / ha of K2O. The harvest was divided into 4 times with 3 samples, with different humidity at the time of harvest, the first was on March 20 (U% 28.18), second on April 1 (U% 18.77), third on 04 April (U% 19.78) and the fourth on April 8, 2019 (U% 16.78). The evaluation of the physiological quality of the seeds was based on the determination of the water content, germination test, cold test and accelerated aging test. The average germination percentage (G) varied from 78%, at 149 days after emergence (DAE), to 89%, at 161 DAE, showing three distinct groups of averages (Tukey 5%), in which the highest were observed in the harvests 2 and 3, at 161 and 164 DAE. No significant difference was observed between harvests for the cold and accelerated aging tests. From the experimental data, a regression analysis was performed, whose equations formed the basis for estimating the ideal period for harvesting the cultivar IRGA 424 RI. For the experimental conditions, the moisture point of the seeds in the harvest was calculated, related to the maximum germinative percentage (89.73%), estimated at 21.78%. A seed moisture interval between 19.92% U and 23.63% U was considered acceptable, in order to limit the germination percentage loss of up to 1% in relation to the maximum obtained. The ideal harvest period for IRGA 424 IR seeds was from 152 to 158 days after emergence.