WHILE rice transplantation is a traditional practice in Asia, maize transplantation, a fairly recent technique, is now gaining ground in many countries. The technique helps farmers harvest a third crop in areas where none would have been possible because of a short summer.

North Korea has already doubled its maize crop area from 3,50,000 be to 7,00,000 he with the new transplantation technique. Improved maize varieties are sown in a nursery in early April and transplanted a month later in the open field. With the help of high-yielding varieties (HYVs), production has increased from 5.6 tonnes/ha in 1979-81 to 6.5 tonnes/ he in 1990.

A transplanted maize crop can be harvested in just 50 to 80 days, depending on local temperature and the variety of grain used. No rice or wheat variety can be produced in such a short time. Maize also needs far less water than rice for an equivalent yield.

Now Vietnam is applying the same technique for the first time in tropical conditions. The area of transplanted maize in the Red River delta has increased five-fold from 50,000 ha/year in 1983-86 to almost 2,50,000 he in 1990, Over the same period, the use of HYVs has improved yields from 1,S00 kg/ha to 2,000 kg/ha. By introducing more productive hybrids and increasing fertiliser applications both in the nursery and in the field, still higher yields can be achieved.

Food and Agriculture Organisation (FAO) scientists believe that countries ranging from Bangladesh and Indonesia in Asia to Haiti in Latin America can benefit from maize transplantation. In Bangladesh, soil moisture is high in January and February.

An early maize variety transplanted immediately after the rice harvest could produce a harvest in 70 to 80 days. In densely populated Java, maize is already a traditional crop. But transplanted maize could be squeezed in as a third crop.