"This plays an important role in increasing company's productivity."
The last sentence in the second paragraph ^, doesn't make sense to me.
"Both the reading and the listening mention the relationship between rewards and productivity in business management."
This is your opening sentence, known alternately to some as the most important one in a non academic essay (thesis is paramount there and it can be long winded sometimes, but I digress).
If you augment it slightly, you can improve the essay drastically. Here's how I'd write it:
The text and auditory portion both argue about a relationship between reward and productivity in business management, but they differ on the effect of the relationship, the first supporting an increase in the independent variable (IV) reward, as causing an increase in the dependent variable (DV), productivity, while the second attempts to deconstruct the very nature of the DV productivity, poking holes in its ability to be defined comprehensively through conventional quantitative measures by citing qualitative properties such as employees' perceptions -- as they relate to bona fide productivity captured in innovations created benevolently, for example -- being entirely absent from consideration.
Heh, I think I started arguing there for a minute myself. Mind you, you can clarify the original obscure sentence, more simply.
Both portions, text and lecture, mention the relationship between reward and productivity, but differ on how they are related.
Practice makes perfect.
Mustafa