Qualidade fisiológica de sementes de arroz em diferentes períodos de armazenamento após tratamento com dietholate

Abstract

The seed is one of the main agricultural inputs and should take to the field all the desirable characteristics for the crop establishment. In conjunction with seed quality, crop management directly interferes with productivity and in this context the control of the weeds is indispensable. These weeds compete for the resources of the environment, reducing the ability of the culture to develop with quality. The chemical control of weeds is the most used method in irrigated rice. Among the used techniques, the seed treatment dietholate, is recommended to reduce the phytotoxic effect of the herbicide belonging to the chemical group of the Isoxazolidinonas, clomazone. The treatment is done in advance, and the seeds are stored for later sowing. The effects of this practice are still poorly understood. The objective of this research was to evaluate the influence of seed treatment with dietholate, submitted to different storage periods, on the initial quality of rice seeds. The experimental design used was completely randomized with four replicates. Seeds of the cultivar GURI INTA CL treated with 6.25 mL kg-¹ of seed were used and submitted to seven storage periods (0, 7, 14, 21, 28, 35 and 42 days). The evaluations were carried out through germination tests, cold test without soil, shoot length and root length. The results were submitted to analysis of variance and comparison of means by use of the Tukey test at 5% of probability. The treatment of rice seeds with dietholate interfered negatively in the germination percentage of the seeds when sown immediately after the treatment or when the storage period was less than 14 days, presenting a significant difference in relation to the control (without treatment). In the same way, the seeds submitted to the cold test and sown immediately after receiving the treatment had the lowest germination index. On the other hand, the storage of seeds treated for periods greater than 7 and 14 days were beneficial for root growth and initial growth of aerial part of the rice comparing to untreated seeds and also in relation to seeds treated and stored for periods smaller than 7 or 14 days respectively. Therefore, seed treatment with dietholate followed by storage for periods longer than 14 days favored vigor of the seedlings, while storage for more than 21 days did not interfere with seed germination.