Split and simplify the following sentence while retaining its full meaning: Whereas experience has shown that present production techniques and the species , varieties and hybrids of lilium bulbs now marketed make it necessary to modify the botanical descriptions and minimum sizes specified in respect of those products ; whereas the relevant standards should therefore be adjusted accordingly.
 Simplified version:
Experience has shown that current cultivation practices and the species , varieties and hybrids of lily bulbs on the market make it necessary to adapt the botanical names and the minimum sizes of these products . It is therefore advisable to adapt these standards .