Demand-Driven Technologies for Sustainable Maize ... - IITA

16Figure 15. Total maize grain production (million t) in WCA countries,1980–2003 (FAO data, 2004).Figure 16. Grain yield per unit land area in WCA from 1980 to 2003(FAO data, 2004).For the subregion as a whole, total maize grain production increasedfrom about 2.5 million t in 1980 to a peak of about 11 million t in 1994–1995 and remained at about 10–11 million t thereafter (Fig. 15). Linearregression of the production data on years showed an estimated increaseof 0.36 million t/year (r 2 =77.1%). A quadratic regression model, however,produced a better fi t to the grain production data, with R 2 value of 95%.According to the FAO data summarized in Fig. 16, the productivityof maize varieties in the fi elds of WCA farmers was below 1 t/ha from1980 until about 1999 when it rose to 1.2 t/ha and has remainedthereabouts since then.A quadratic regression model produced a good fi t to the data, withR 2 value of about 80% (Fig. 16). The quadratic b-value was positivethus indicating that the grain yield improvement in the later part of theperiod under study was larger than that for the earlier years.