As we explained yesterday (see here) there are only five grains which could become Chametz: wheat, barley, rye, oats, spelt.
Rice, obviously, is not Chametz. Is not one of the five grains and there are examples in the Gemara of Chakhamim that ate normally rice during Pesach. Still, the Ashkenazi and the Moroccan custom is to refrain from rice during Pesach. Why? The practical reason for the abstention of rice has to do with the fact that it was very common to find grains of wheat in the bags of rice, since the fields where rice was grown, in some areas, were nearby or within the same fields where wheat was grown. Even today, there are many places in the world (India, Pakistan, Iran) where they rotate wheat and rice crops yearly (See here).
Therefore, it would not be unthinkable to find a grain of wheat mixed with the rice. To avoid the possibility of accidental presence of a grain of wheat in rice (rice and wheat, especially in the form or whole grains, share the same color) , the Persian and Syrian custom is to check the rice very carefully, three times before using it for Pesach.
One has to refrain from buying enriched rice, which sometimes could be enriched with wheat starch.
Brown rice could also be used, provided is not enriched and there are no other additives.
The following brands of rice are recommended by Rabbi Eliyahu Ben Haim as being 100% pure, not enriched, and with no additives or preservatives. LALQUILA - SHAHZADEH - PARI - ROYAL - ZEBRA - DEER BRAND - INDIA GATE - TILDA
The Ahskenazi custom is to refrain also from consuming any seeds (qitniot) during Pesach. For a good explanation of the Ashkenazi custom of qitniot, click here.
Rabbi Sandler (30) , his two sons Aryeh (3) and Gabriel (6) and Miriam Monsonego (8). All killed in a Jewish School in Tolouse, France.
(HaShem Iqom damam)