Shuja ur Rehman Qureshi If you applied MANOVA, low significance of G xE values can be caused by different trends in reaction of G in variable E. Repeat the data analysis using ANOVA for one factor (E) for each G.
It is advisable to reanalyse the data. Nonetheless, the differences can sometimes be insignificant provided, there is no siginificant variation in soil and environmental parameters, and even cultural practices are also similar. You may verify this by having a look into major agro-meteorological parameters for the duration of the experiment. In that case normal and late-sowing condition will not offer much data to you to reach an inference.