Why is there a Nun at the end of "Chitin"?
Radak: We find like this, e.g. "l'Ketz ha'Yamin" (Daniel 12:13) and "Kol ha'Ratzin" (Melachim II, 11:13) are like Yamim and Ratzim.
What is the significance of these species?
Rashi: It is a sign of the hunger that will be during the siege, and they will eat bread of a mixture [of grains] and it is repulsive. Radak - people make bread from beans and lentils only at times of hunger.
Malbim: Wheat and barley signify preparing food for the siege.
Why should he put then in one Kli?
Radak: He should mix them. All this was in a prophetic vision.
Why does it mention 390 days?
Radak #1: This teaches that this is when he is on his left side.
Radak #2: He did not say on which side he lies, to include the days on both sides. It mentions the days on the left, and the same applies to the days on the right.
Malbim: Melech Bavel besieged Yerushalayim on the 10th of the 10th month (Teves) in Tzidkiyah's ninth year. He conquered it in the fourth month (Av) of Tzidkiyah's 11th year. The siege was for 18 months. It is clear in Yirmeyah (37:5) that in the middle, Melech Bavel left Yerushalayim due to Pharaoh's army. It seems that he returned in Tzidkiyah's 10th year. We can say that there were 430 days from when he returned until Tamuz 10 1 (four weeks before the Churban). They were able to prepare food for only 390 days; after that there was hunger in it the city. People died of hunger, plague and the sword, until the city was breached.
Why does he say Tamuz 10? It says (Yirmeyah 39:2, 6) that on Tamuz 9, the city was breached and there was no bread for the commoners! (PF)