|Evett, Steven - Steve|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/1997
Publication Date: N/A
Interpretive Summary: Corn Hybrids which have a shorter season can be harvested sooner than longer season hybrids, and then it is possible to double crop with wheat, particularly under center pivot irrigation. Also, short-season corn may reduce irrigation requirements thereby permitting greater water conservation. This study measured yield, water use, and water use efficiency (yield per unit of water used) of two corn hybrids that had short and long season maturities. The short-season corn (SS) was shorter in height by 0.55 m, produced 390 g m**-2 less dry matter, and produced 298 g m**-2 less grain. SS corn did use 129 mm less water, but produced almost identical water use efficiency of full-season (FS) corn based on both dry matter and grain yields. For the hybrids used, the SS corn was harvested 11 days sooner. SS corn did not appreciably reduce peak daily water use rates. This study demonstrated that SS corn can reduce seasonal irrigation nrequirements, but that SS corn would not reduce irrigation capacity (flow rate per unit area) needed for corn to avoid yield reductions caused by low rainfall.
Technical Abstract: Short-season corn (Zea mays L.) hybrids can reduce the irrigation requirement and provide earlier harvest which permits double cropping to winter wheat in the Southern High Plains. Water use of a short-season (SS) hybrid (Pioneer 3737) and a full-season (FS) hybrid (Pioneer 3245) were compared under full irrigation in 1994 at Bushland, TX, on a Pullman clay loam (Torrertic Paleustoll). Both hybrids were planted the same day in tw 4 ha fields each containing a weighing lysimeter, used to measure water use, and were irrigated similarly using a lateral-move sprinkler system until the shorter season hybrid reached mid grain fill (dent stage). Seasonal evapotranspiration (ET) was reduced from 802 mm to 673 mm by the SS hybrid with the primary reduction occurring after anthesis of the SS hybrid. However, peak daily ET rates were largely unaffected by hybrid type. Grain yields declined by 298 g m**-2 for the SS hybrid, but grain water use efficiency (grain yield/ET) (WUE) was practically identical at 1.68 kg m**-3 for the SS hybrid and 1.65 kg m**-3 for the FS hybrid. Dry matter (DM) WUE was identical for the two hybrids at 3.02 kg m**-3. The SS hybrid reached physiological maturity 12 days earlier than the FS hybrid and was harvested 11 days sooner. Leaf area index was markedly different for the two hybrids with the full-season hybrid exceeding 5.5 while the shorter-maturity hybrid barely exceeded 4.0. DM was reduced by over 390 g m**-2 for the shorter-maturity hybrid, but this hybrid had a slightly higher harvest index. These results show shorter-season corn hybrids reduce seasonal water use and irrigation requirement and shorten the season permitting earlier harvests, but do not appreciably affect WUE or peak-daily ET rates when fully irrigated.