Maize, called as "ChOLam" (சோளம்) in Tamil is thought to have been indigenous to Mesoamerica. The Mayans were known to have cultivated it since before the start of the Common Era. It was only after the European connection with Americas in the 15th and 16th centuries, cultivation of maize started in Europe. As a result, maize was thought to have been brought from Europe to India, after colonial connection with India. This idea got a beating when sculptures of deities holing maize in their hands have been noticed in India. Predominantly belonging to the Hoysala period in Karnataka, these figures were dated at 12th to 13th century CE when maize was not even known in Europe. This gave rise to a notion that Mesoamericans and Indians had connections earlier which was responsible for having brought maize from the Mayan lands in Mexico. Pity that they never like to give credit to Indians and that maize went from India to Mexico!
A broad based articulation on this issue had been written by Dr S.Kalyanaraman which has been reproduced below. He has shown that maize-type depictions and sculptures are there in West Asian Meluhha hieroglyphs and even in the Vatican. I am giving here my insights in this topic.
First of all let me take up the maize- holding sculptures of the Indian temples. Till today, no temple image is made without following the guidelines of iconography of the olden texts of Shilpa sastra. If a temple image is seen with maize in hand, it must be understood that it was done within some rule of iconography. It cannot be done by someone's whims and fancies when a fruit was imported from a foreign land. Another point is that the foreign vegetables such as carrot, beetroot etc are still not used by orthodox Hindus (there are many in South India) mainly because they are not indigenous and have no sanction from our Dharma texts. Therefore it can be said without any hesitation that a vegetable product like maize, if not available as an indigenous product could not have found its way in the temple sculptures.
The second issue is why maize found its way in temple sculptures of a specific period in a specific locality. For this, one must know that no major deity of Vedic pantheon had been described to hold maize. However in the case of other or lesser deities, the general rule is to represent suitable items that depict the characteristics of the said deity. One can read such a verse in the vaastu text of "Mayamatham",chapter 36, verse 288 under the caption "Saamaanya vidhi". So whatever figures we find in temples with maize in hand, we must know that they are deities with combined characteristics that are related to some idea denoted by maize.
Thirdly, there does exist in Iconography a concept called "Sriphala", a fruit held by Lakshmi. In chapter 36, verse 250 of Mayamatham, it is said that Lakshmi is depicted as holding Sriphala in her left hand. Sriphala means wood apple or Vilva floweror any fruit that exudes splendour or cocoa-nut or indigo plant. For example, the following figure found at Somnathpur near Myosre, is that of a female deity with maize in the left hand. This is a depiction of Sriphala, a splendorous fruit that shows Aishvarya (prosperity) and growth.
The following figure from the same temple at Somathpur has a twin image of female deities holding the maize in opposite hands to complete the notion of a pair.
The following image is from Belur and the next one is from Halebid in Karnataka. The maize is in the left hand of the female deities.