Maize or corn [Zea Mays (L.)] has been bred along two dis-

tinct lines. The most well known in the US are the hybrids bred

for high yield and high-energy-inputs (ie., high fertility,

irrigation, weed control, disease and insect control) that we

will designate as temperate corn. Wright, et al.(1987) have

shown the effect of planting date on temperate corn when it is

grown in a singlecrop system from early Feb to early May. We've

chosen Asgrow brand hybrid 5509 from this group. Year, planting

dates, grain yields and problems are shown in Table 3.


Table 4. Temperate corn (A5509) in relation to sowing date, har-
vest date, water use (ppt/irr), grain yield and some problems
when grown in a high-energy-input system and low-energy-input
system.


Year Sowing Harvest Applied Water ppt/ Grain Problems
 Date Date N Mgt. irr yield'
 (Ib/A) (in.) (bu/A)

High-energy-input

1985 28 Mar 5 Aug 260 irr. 22/5 196
1986 24 Mar 4 Aug 260 irr. 11/10 244
1987 16 Mar 10 Aug 260 irr. 22/6 175
1988 24 Mar 5 Aug 260 irr. 15/12 182

Low-energy-input

1987 16 Mar 10 Aug 260 dryland 22/0 48
1988 15 June 27 Oct 120 dryland 23/0 29 earworm and
 rice weevil


 Tropical corn has an interesting history. Plant breeding

knowledge was exported during the 50's and 60's (Abington, 1975)

to third world countries, hybrid seed company's picked up the

idea in the 70's and 80's and developed tropical hybrids for

third world countries that have caught the interest of farmers