A History of Agriculture in India v1.c14.s2: Cultivation of Plants
A History of Agriculture in India v1.c14.s2
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Cultivation of Plants
v1.c14.s2.1
It is the cereals—wheat, barley, rice, millets and maize—which have contributed most to the building up of the Neolithic culture. They yield nutritious food and the grains can be easily stored for a number of years. All the cereals have arisen from wild grasses, and wild ancestors of a number of them are known. One of the major differences between the cultivated forms and the wild ancestors is that in the latter the seed is shed as soon as it is ripe, whereas in the former the seeds remain enclosed in their husks and can only be separated by threshing. The cultivated forms possibly arose from a lethal mutation as a result of which non-shattering varieties developed, and they could be successfully harvested, threshed and winnowed. A fascinating history of cultivated plants has been built up by the discovery of carbonized seeds and impressions on potsherds from archaeological sites. The study of pollen has provided us with evidence of farming, inferred from the occurrence of cereal pollen or the pollen of weeds associated with cultivation. Sculptures and paintings showing agricultural operations also provide evidence of past agriculture. Other evidences are storage pits, pots, sickles, hoe-blades and saddle-querns.
v1.c14.s2.2
Wheat. Vavilov recognized 14 species of *Triticum*, which fall into three groups with 7, 14 and 21 chromosomes respectively. Among these, the most ancient are the 7-chromosome wheats comprising *T. aegilopoides*, the wild einkorn, and *T. monococcum*, the einkorn. Carbonized seeds of both these species have been found at Jarmo. Both have fragile stems, loose spikelets, and a single seed in each spikelet. Both easily hybridize. The wild einkorn is found in Armenia and Georgia in the Soviet Union, and in western Iran. There are no records of this wheat in India, Africa or China. Einkorn is still cultivated in the hilly regions of Europe and the Middle East. Its importance lies in the fact that it is the ancestor of all other cultivated wheats, excepting emmer (Fig. 52).
v1.c14.s2.3
There are seven species of 14-chromosome wheats. They originated through hybridization and chromosome doubling of the 7-chromosome einkorn with a 7-chromosome wild grass which is still unidentified. The only wild species with 14 chromosomes is the wild emmer, *T. dicoccoides*, which is found in Armenia, northern Palestine, Syria, Turkey, and western Iran. The wheat found at Jarmo is of an irregular type with coarse and loose ears comparable with those of *T. dicoccoides*. From its original home, emmer diffused into Egypt, Ethiopia and Europe. It is still grown on a considerable scale in Ethiopia. Emmer was the wheat of Egypt until it was replaced by bread wheat after Alexander the Great conquered Egypt in the fourth century B.C. Outside Ethiopia, emmer lingers on as a relict crop in Yugoslavia and southern India.
v1.c14.s2.4
The third domesticated wheat was also a tetraploid. It was so trivial that there is no common name for it; scientifically, it is named *Triticum* timopheevi. It originated in Transcaucasian Georgia and has spread only as a collector's item for genetic studies.
v1.c14.s2.5
The 14-chromosome wheats have tough stems and seeds which thresh free from their glumes and consist of 4 species: *T. durum* (macaroni), *T. persicum* (Persian), *T. turgidum* (rivet) and *T. polonicum* (Polish).
v1.c14.s2.6
The wheat we grow today is none of these three early domesticates. All three are known as glume wheats because the spike, or the seed-bearing head, breaks up when it is threshed, leaving each seed enclosed in a hard, shell-like glume, or husk. The seeds must then be processed further, usually by pounding in a mortar, to free them of the husks. Some time after emmer was domesticated a mutation occurred that caused the base of the glume to collapse at maturity, freeing the seed. At the same time, the spike became tough, so that it did not fall apart as the ancestral spikes had done. The mutated, free-threshing emmer is the ancestor of our macaroni wheats.
v1.c14.s2.7
'The major wheat species of the world, and the one that contributes most to the annual harvest of 360 million tonnes, is still another kind, known generally as bread wheat. It is a hexaploid; that is, it has 21 pairs of chromosomes. It arose long after the initial domestication of the three primitive glume wheats. Its extra set of chromosomes was contributed by a wild goat-grass called *Triticum tauschii*, and the distribution of the wild progenitor suggests that the hybridization may have taken place somewhere near the southern end of the Caspian Sea. *T. tauschii* is the only species of goat-grass with a continental distribution, and it may have contributed to the adaptation that makes it possible for bread wheat to be grown on the dry steppes of the world. As a wild grass *T. tauschii* is essentially worthless, but as a contributor of genetic characteristics it literally made a billion-dollar crop out of a million-dollar one'.²
v1.c14.s2.8
² Harlan, J.R. The Plants and Animals that Nourish Man, *Scientific American*, Sept. 1976
v1.c14.s2.9
The 21-chromosome wheats comprise five species and are widely cultivated. Of these, *T. aestivum* (common), *T. sphaerococcum* (shot) and *T. compactum* (club) are true bread wheats which comprise 90 per cent of the wheat grown today. Grains of *T. sphaerococcum*, the common wheat of northern and central India, found from Mohenjo-daro are dated about 2300 B.C. This wheat seems to have been grown widely in the Indus Valley.
v1.c14.s2.10
Barley. There are two species of cultivated barely, the two-rowed (*Hordeum distichum*), and the six-rowed (*H. hexastichum*). The wild ancestor of the two-rowed barley is found in Palestine, Arabia, Asia Minor, Transcaucasia, Iran and Afghanistan, and the six-rowed barley in eastern Tibet. The earliest find of barley is from Jarmo.