Figure 1.

World yields for wheat, rice, and maize vs. time, 1988 to 2007. Source: FAOSTAT. 2009. (Available at [verified 23 Dec. 2009]).


Figure 2.

Farm yield vs. time (lower line) and potential wheat yield (upper line) vs. year of release in the United Kingdom; yields at 15% moisture. Potential yields were obtained under fungicide protection and are averaged over the period 2004 to 2008. Sources: FAOSTAT. 2009.(Available at [verified 23 Dec. 2009]); HGCA Recommended Lists 2004–08.


Figure 3.

Yield of wheat vs. time in the Yaqui Valley, Mexico, and potential yield (upper line) of bread and durum wheat varieties versus year of release; yields at 12% moisture. Potential yields were determined in experiments over the period 1990 to 2005 with fungicide protection and standardized against a common check, ‘Siete Cerros 66’, with an average protected potential yield of 7.0 t ha−1 Regressions refer to the last 30 yr data only. Source: K.D. Sayre, personal communication, 2009.


Figure 4.

Japan's rice yield vs. time and potential yield for varieties Nipponbare and Takanari; yields for rough rice at 14% moisture. Sources: FAOSTAT. 2009. (Available at [verified 23 Dec. 2009]); for potential yield see text.


Figure 5.

Farm rice yield vs. time of harvest in Central Luzon in the wet and dry seasons, and potential yield at IRRI; yields for rough rice at 14% moisture. Source: see text.


Figure 6.

Maize grain yield vs. year of harvest for (a) the United States and (b) the state of Iowa; yields at 15.5% moisture. Linear rates of yield increase are shown separately for 1961 to 2008 period. Split line regression resulted in a significantly improved fit for the Iowa yield data. Source: (verified 1 Jan. 2010).


Figure 7.

Nitrogen applied to maize in Iowa (upper curve) and the ratio of grain yield to N applied (lower curve), 1964 to 2005. Linear rates of increase for each variable are shown for 1990 to 2005 periods. Source: (verified 23 Dec. 2009).


Figure 8.

Iowa maize farm yield vs. time and potential yield (at optimum density) vs. time of hybrid release; yields at 15.5% moisture. Sources: (verified 1 Jan. 2010); Hammer et al. (2009)