make white, whiten

Concise Bible Dictionary:

Wheat Growing in Israel
This cereal was extensively grown in Palestine; the harvest was in May and June. In the parable it is used by the Lord as representing the children of the kingdom, the fruit of the good seed that He was sowing on the earth, in contrast to the tares, or darnel, which Satan secretly sowed among the good seed.
The Lord Himself, being the second Man “out of heaven,” is compared to the grain of wheat that must have remained alone unless it had died, but which in dying would bring forth much fruit. This clearly shows that there was no union of Christ and natural man by His incarnation alone, and that through the death of Christ the fruit produced by His resurrection is of the same order as Christ Himself (Matt. 13:25-30; John 12:24; 1 Cor. 15:48-49).
There are three or four varieties of Triticum grown in Palestine.

Strong’s Dictionary of Greek Words:

Greek:
λευκαίνω
Transliteration:
leukaino
Phonic:
lyoo-kah’-ee-no
Meaning:
from 3022; to whiten
KJV Usage:
make white, whiten