We learned on yesterday’s daf that there is a difference of opinion as to whether the obligation to separate terumot and ma’asrot from kitniyot (pulses) is of Biblical or Rabbinic origin. Our Gemara discusses the cases of orez (rice), dohan (millet) and peragin (identified by the ge’onim as the poppy). According to Rabba, kitniyot are unique in that it is the time that they take root that determines whether they are to be tithed with last year’s crop (if they take root prior to Rosh HaShana) or with next year’s crop (if they first take root after Rosh HaShana). This is different from olives and grain, whose readiness is determined by completion of one-third of their growth, from other fruits, which are determined by the time that they bud, and from vegetables, whose harvest establishes the year that they belong to. Rabba explains that kitniyot are different because they are made perakhim.
Some rishonim (Rabbeinu Hananel, the Arukh, the Ra’avad and others) understand this expression to mean that they do not all ripen at the same time and therefore are not all harvested at the same time, even if they were planted and took root at the same time.
Rashi, Tosafot and others suggest that this means that they are shelled (i.e. removed from their husks and prepared for sale) over a relatively long period of time. The Ran and the Ramban combine these explanations and say that the concern is that since the kitniyot do not ripen all together they are harvested slowly over a long period of time and are collected and stored prior to their sale. Therefore it is likely that we will find older and more recent harvests stored together and it would be difficult to clearly distinguish what belongs to this year’s crop and what belongs to last year’s crop unless a more standard date (taking root) was chosen.
It should be noted that in modern times, great efforts have been made to arrange that kitniyot (mainly produce like rice and millet) ripen together in order to allow for mechanical harvesting. The Talmud is discussing the situation at that time, when it was necessary to return to complete the harvest in a single field over and over again over a fairly lengthy period of time.