Determinação da umidade de sementes pelos métodos da estufa a 105 e 130 oC

Abstract

Seeds are essential for agriculture and species conservation, and controlling their water content is crucial for maintaining their quality. This study compared the efficiency of the moisture determination method at 130 °C for different periods with the standard method at 105 °C for 24 hours. Additionally, the energy consumption of both procedures and the time required for the stabilization of water loss in seeds subjected to 105 °C were analyzed, considering different intervals relative to the standard. The experiment was conducted at the Forest Seed Laboratory of UFLA, using seeds from different species. The water content was determined with four replicates per treatment, following a completely randomized design. Statistical analysis included ANOVA and mean comparison using Dunnett’s test (α = 5%). Energy consumption was measured based on the incubator’s power and its effective operating time. Two independent experiments were conducted. In the first, seed moisture content was determined using two methods described in the Rules for Seed Analysis: the standard method (105 °C for 24 hours) and the 130 °C method, with drying times of 1, 2, 3, and 4 hours. In the second experiment, the drying time at 105 ± 3 °C/24h was extended to 6, 14, 30, 36, and 48 hours to identify the moment when the sample’s constant weight was reached. In both cases, the drying time count began after the incubator reached thermal stabilization. The results indicated that seed response varied depending on the species and method used. In the first experiment, the moisture content of banana-de-macaco and ipê-da-serra seeds did not statistically differ between the 130 °C method (1 to 4 hours) and the standard method at 105 °C for 24 hours. However, ipê-mirim and leucena seeds showed equal averages only in the first hour of drying at 130 °C compared to the standard method. For angico-amarelo and ingá-vera seeds, the averages were equal after 2 hours at 130 °C. Regarding energy consumption, the 130 °C treatments required less electricity than the standard method, with a reduction of up to 95.42% in the 1-hour treatment. Reducing drying time at higher temperatures increased energy efficiency and lowered operational costs. In the second experiment, evaluating different drying times at 105 °C, seeds such as tingui and aguaí showed statistically equal averages to the standard time after 6 hours. Other species required up to 48 hours for stabilization, demonstrating that the ideal time varies depending on the seed type. The results show that the 130 °C method can be a viable alternative for various species, reducing time and energy consumption without compromising analysis accuracy. Adjustments in drying time at 105 °C can also reduce the analysis time for some seeds, making laboratory processes more efficient.