Gametes from two plant species combine and produce a haploid zygote, and that zygote develops into a haploid, hybrid plant. why is the hybrid plant sterile

When two gametes combine and produce a diploid zygote, it means that the chromosomes that were passed down by its parent organisms were possible to be matched and undergo a division through meiosis allowing the production of new gametes chromosome-like the parent gametes.

When two gametes, from different species, combine and produce a haploid zygote, it means that the chromosomes that were passed down by its parent organisms are not possible to be matched, although they may allow the zygote to be feasible and grow into an adult plant (in this case). Meanwhile, the fact that the chromosomes could not be matched, meiosis is not possible, meaning that gametes cannot be produced and, therefore, the hybrid plant is sterile.