Of the many factors that play a role in productive plant growth and survival, water is the most important because its availability can be so variable.
(the many factors; play; a role in productive plant growth and survival) (water; is; the most important; because its availability can be so variable) (its availability; can be; so variable)
the many factors water its availability
play is can be
a role in productive plant growth and survival
the most important because its availability can be so variable
so variable