All sorghums are indigenous to Africa, but the plant reached Asia so long ago that thousands of cultivars developed there. Indeed, the Far East devotes a huge area to this crop. It is especially surprising to find this tropical crop in chilly climes as far north as Manchuria. Throughout northern China, however, farmers rely on sorghum not only to keep themselves fed when wheat fails but also for many of their household needs (see box opposite). Even when wheat is available, the people often eat a cheap and rather coarse sorghum bread. Special steamed breads are made from sorghum in some areas. Sorghum also goes into noodles, porridges, and boiled (ricelike) dishes. A significant proportion is used to produce strong liquor. Sorghum is also eaten, although to a lesser extent, in Japan.
China contains a cornucopia of types that are unknown elsewhere. The Flora of Chinese Sorghum Varieties, for example, lists more than 1,000 local varieties: 980 for food, 50 for industrial use, and 14 for sugar. All of these should be rapidly gathered and tested elsewhere in the world. They undoubtedly offer many genetic benefits. Eventually, they and their genes may become critical to human survival in many areas outside China.
Reuniting the genes of these Far Eastern types with those of Africa after a 2,000-year separation could be an extremely powerful genetic intervention leading to a whole new line of "Chinaf" hybrids.
When CIMMYT first tried growing sorghum in the Valley of Mexico, the crop would not set seed. The problem was low temperatures at night. The researchers then got some high-elevation sorghums from Ethiopia, made crosses, and now have types adapted for that upland valley with its chilly nights. Cold tolerance is available in the germplasm but has not yet been fully exploited.
Sorghum thrives under searing conditions. Air temperatures of 45°C leave it unfazed. Even at that temperature, young plants have been known to grow 20 percent in height in a single day. But sorghum has its limits. When soil temperatures climb above 50°C, its seedlings struggle to survive. Such temperatures are not uncommon at the soil surface in semiarid areas, and the consequences for sorghum farmers are often dire, sometimes even disastrous.