Effect of pre-harvest treatments on equilibrium moisture contents and safe storage of canola

Abstract

For safe storage of canola seeds, the effect of different preharvest treatments on seed storability should be determined. Safe storage times of canola seeds (Bayer L233P) with the following five pre-harvest treatments were evaluated: swathed, Glyphosate application + straight cut, Heat and Glyphosate application + straight cut, Reglone application + straight cut, and natural ripening + straight cut. The preharvest treated seeds were stored at 20, 25, 30, or 35oC and 52, 63, 75, or 93% relative humidity (RH). The following parameters were measured to estimate the safe storage time: seed equilibrium moisture content (EMC), germination, fatty acid value (FAV), yellow seed count, and invisible mould. The measured EMCs were compared with the EMCs predicted by the equations recommended by the ASABE standard. Different pre-harvest treatments resulted in different desorption properties of canola. None of the ASABE equations was able to predict the measured EMCs correctly. Different pre-harvest treatments had different initial fungal infections. However, these differences did not affect the fungal infection, FAV, germination, and yellow seed counts, with some exceptions for swathed canola in the storage period. The yellow seed count decreased under safe storage conditions (lower than 75% RH and 25oC), but increased at 93% RH and 25oC except for the swathed canola. Therefore, canola seeds with different pre-harvest treatments had a similar storability at below 75% RH or below 30oC. However, the spoilage rates of canola with different pre-harvest treatments at storage conditions of high temperatures (≥30oC) and high RHs (≥75%) were different.