1st Aliyah

This section introduces us to the mitzvah of bikurim, the requirement to bring one's first fruits to the Holy Temple. This mitzvah applies to fruits and produce grown in the land of Israel, and only those for which the land of Israel is praised: wheat, barley, dates, figs, grapes, pomegranates and olives. When in the Temple, the owner of the fruits recites a brief thanksgiving prayer to G‑d and presents the produce to the priests.

2nd Aliyah

During Temple times, Jewish farmers were required to separate from their produce several different tithes. These were distributed to the priests, the Levites, the poor, and one tithe which was eaten by its owners in Jerusalem. The different tithes were not all given each year, rather there was a three-year cycle. In this aliyah, the Torah gives the procedure to be followed on the day before Passover during those years which followed the conclusion of a cycle. The farmer was to declare that he has performed all his tithing duties and then beseeches G‑d to bless His people and the Land.

Source: Chabad.org