The Yenuka explains that wheat is the secret of the correction of Malchut in Binah, a process that makes Malchut worthy of receiving all the upper Lights.
We ‘work’ under the system of the Tree of Knowledge Good and Bad. If we have merits, we connect to the ‘Good’ and if we’re not then we connect to the ‘Bad’ aspects.
When we connect/elevate the H ה of Malchut with the H ה of Binah we establish the central column and the outcome of our actions is good. The Light that runs down protects the חט and we reveal the positive aspect of the חט. The two letters have the numerical value of 17 that is the same for טוב, ‘good’. If we don’t follow the positive path we draw the aspect of sin from the חט and connect to the ‘bad’ of the Tree..
The five grains of wheat, barley, oats, spelt and rye are governed by YHVH. All others plants have appointed governors/angels. Because of YHVH’s connection, the other-side doesn’t have a hold on these grains. The only part that they can have is the chaff that covers the grain. It’s removed before the grains are grinded into flour to make bread for our blessings.
“לֹא-כֵן הָרְשָׁעִים: כִּי אִם-כַּמֹּץ, אֲשֶׁר-תִּדְּפֶנּוּ רוּחַ”
“The wicked are not so, But they are like chaff which the wind drives away.”
The negative side is always with us through the process of growth. When we want to benefit from the ‘fruit’, we should remove/’drive away’ the negativity from it and bless the fruit before enjoying it.