The geomagnetic field effect hypothesis and the variability among replications in germination and growth tests in Triticum. – During previous eperiments on germination and growth ofTriticum, we have often found many cases of heteroscedasticity and of statistically significant differences among contemporary replications (i.e. germinators). In such experiments all the caryopses were oriented in the same way inside the germinators, whilst the germinators were randomly set inside the thermostats: therefore the seeds of different germinators might result differently oriented. Some researchers report that seeds differently oriented according to the lines of force of the geomagnetic field, may respond with different germination, growth rates and growth directions of shoots and roots (magnetotropism). The present investigation was designed to ascertain if these effects might be responsible of the variability among the contemporary replications. The different caryopses orientation within laboratory geomagnetic field, does not give evidence of any effect on germination, growth rate and direction. The caryopses show no germination sensibility neither related to different age, light and temperature conditions, neither to different cultivars, neither to varying orientation from the geomagnetic North every 15° and to varying time of ≪ preorientation ≫ in dry conditions. Differences between the variability of randomly and North oriented subsamples are not observed. No statistically significant differences are observed among shoots and roots lenghts of seedlings from differently oriented caryopses neither in different environmental conditions, nor as function of the orientation (24 angles of 15°), nor after different preorientations, nor after repeating the test on 608 subsamples (12.000 seedlings). Therefore the variability among contemporary replications is not imputable to the geomagnetic field. The variability and the distributions structure analysis suggest that both the heteroscedasticity and the significant differences among the replications may be due to an interaction among the caryopses inside the germinators through the substrate. This is probably related to the cultivar characteristics. We emphasize that an accurate evaluation of the variability is particularly necessary in germination and growth tests.