Non-linearity in rate-temperature relations of germination in oilseed rape

Open Access
Publisher Website
Google Scholar
Abstract
Predominantly linear relations between germination rate and temperature (over specific ranges) have hitherto been found among the main crop plants. Given linearity, accumulated temperature above a base (Tb) is a reliable predictor of germination time. In contrast, this paper shows marked non-linearities in the response of germination to temperature for four oilseed rape cultivars, two ‘double high’ (Martina and Askari) and ‘two double low’ (Rocket and Express). Linear regressions of 1/time to germination of given percentiles indicate Tb is about 3 °C for all cultivars. However, consistent deviations from linearity occur especially at low temperature, such that germination time at 5°C is up to twice as fast as predicted from a linear model. Moreover, two of the cultivars show an increasing proportion of seeds not germinating as temperature is lowered. These seeds were still viable as demonstrated by their ability to germinate when transferred to warmer temperature. The consequence of non-linearity was to increase the spread of time over which seeds germinated at low temperature. This paper defines the effects and indicates the margin of error likely to follow from applying linear rate/temperature models to whole populations. The findings have implications for the propensity of different oilseed rape cultivars to become volunteer weeds and feral populations.

This publication has 0 references indexed in Scilit: