Hilchos Shemittah v’Yoveil 4:11
If rice, millet, poppy, sesame or Egyptian beans were planted in order to produce seed, their status depends on when their growth is complete. If the growth is complete before Rosh Hashana, the seeds may be harvested during shemittah the same as sixth-year produce. If the growth is complete only after Rosh Hashana, then they are prohibited as aftergrowth even if they took root before Rosh Hashana.
Hilchos Shemittah v’Yoveil 4:12
The status of vegetables depends on when they were harvested. An esrog must be tithed like sixth-year produce even if it was the size of a bean before Rosh Hashana and it grew to the size of a loaf (of bread) during shemittah. On the other hand, if it was harvested during shemittah, it is considered shemittah produce. This is so even if it grew to the size of a loaf in the sixth year. Tithes are taken like sixth-year produce as a stringency.