Abstract:

In this study, the medium-early maturing varieties (‘HQY971’ and ‘QY1719’) and the medium-late maturing varieties (‘SY21’ and ‘SY28’) were used to analysis the effects of meteorological factors on the grain water content of rapeseed varieties at different maturity stages. The Logistic power model was used to fit the active accumulated temperature ( ≥ 0°C) and grain water content of four rapeseed varieties from pollination to harvest between 2019 and 2020. The results showed that: (1) the grain water content of the four rapeseed varieties showed a slow decline first and then a rapid decline at the pollination-harvest stage. The average grain water content of the medium-early maturing varieties at physiological maturity stage was higher than that of the medium-late maturing cultivars. The average grain water content at harvest stage decreased with the extension of growth period. Among them, the grain dehydration rate of the medium-early maturing variety 'HQY 971' was 9.66 percentage points·d⁻¹, which was significantly different from the other three rapeseed varieties. (2) The trend water content fitting curves of medium-early maturing varieties and mid-late maturing varieties showed an "S" shaped change trend. Moreover, the meteorological water content of medium-early maturing varieties was greatly affected by meteorological factors, while the meteorological water content of mid-late maturing varieties was less affected by meteorological factors. (3) The dehydration of rapeseed varieties at different maturity stages was mainly affected by meteorological factors such as average temperature, maximum temperature, minimum temperature and accumulated temperature. The average temperature (−1.125) had an indirect effect on the meteorological water content of the mid-early maturing varieties, while the maximum temperature (−0.347), minimum temperature (−0.472) and accumulated temperature (−0.936) had a direct effect. For the mid-late maturing varieties, the average temperature (−0.847) was indirect, while the maximum temperature (−0.288), minimum temperature (−0.250) and accumulated temperature (−0.877) were direct effects. (4) The path analysis showed that the R² of each factor to the determinants of meteorological water content was 0.8433 (mid-early maturing varieties) and 0.8130 (mid-late maturing varieties), respectively, which indicated that accumulated temperature had the greatest impact on the meteorological water content of rapeseed varieties at different maturity stages. The fitting results of all equations in the stepwise regression analysis reached the extremely significant level, indicating that the influence of meteorological factors on meteorological water content can be explained to a certain extent.

Key words: Rapeseed, Maturity, Grain dehydration, Meteorological factors