Don't know, but line 20 of your shell script looks fishy to me. It doesn't invoke the Perl executable; merely references its location, so that part is either redundant or wrong.
And despite your assertion that the modis_greening.pl runs but fails to use the module, I have to wonder if you have CHMODed your Perl script appropriately. Crontab won't be running under your id and you haven't cited any evidence that "the script works," whatever that means when you're telling us it doesn't do what you intended.
Note that I haven't even looked closely at most of modis_greening.pl. As the advice on posting questions notes, post a minimal sample that reproduces the problem. 400 lines, even with generous whitespace is more than I'll bother to download, absent some far more intriguing problem description. The prior respondent may be onto sometime, but that suggests s/he did at least run your script against perl -c ....