Submitted to: Agronomy Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/1/2005
Publication Date: 3/1/2005
Citation: Bruns, H.A. Abbas, H.K. 2005. Responses of short-season corn hybrids to a humid sub-tropical environment. Agronomy Journal. 97(2):446-451. Interpretive Summary: Four corn hybrids adapted for production in the northern U.S. and Canada (short-season) and two hybrids commonly grown in the mid south were evaluated in 2002 and 2003 for their growth in the Mississippi Delta under furrow irrigation and nitrogen fertility treatments of 100 lbs/A pre-plant, 200 lbs/A pre-plant, and 100 lbs/A pre-plant plus 100 lbs/A at the sixth leaf growth stage. The objectives of the study were to determine if the short-season hybrids could yield as well or better than the adapted hybrids by avoiding high temperatures and drought during reproductive growth and if they might have less, or at least no more, aflatoxin and fumonisin contamination than the adapted hybrids. Also, the nitrogen fertility rates were varied to determine what would happen to yields and grain quality if the second fertilizer application were missed and if applying the full season's nitrogen requirement pre-plant is feasible. Two of the short-season hybrids yielded as well as the adapted hybrids but one of them yielded below the area's average yield indicating that not all short-season hybrids can adapt to the environment of the mid south. Aflatoxin levels of three of the short-season hybrids were higher than the other hybrids in the experiment. The current recommendation of splitting the nitrogen fertility application did not have an advantage in yield or grain quality over applying all of the required nitrogen pre-plant. Yields did suffer when only 100 lbs/A of nitrogen was applied pre-plant. Short-season corn hybrids can likely be profitable for the Mississippi Delta but a performance evaluation of such hybrids will be needed to determine which ones are suitable.
Technical Abstract: Corn (Zea mays L.) hybrids commonly grown in the lower Mississippi River valley often encounter heat and drought stress during reproductive growth which impairs yield and increases pre-harvest mycotoxin contamination. Four short-season corn hybrids (Hoegemeyer1 2593, Dekalb1 DK C42-22Bt, Pioneer1 3897, and Garst1-AgriPro 9185Bt) developed for production in areas greater than or equal to 40 degrees N latitude and two hybrids adapted to the mid south USA (Pioneer1 3394 and Syngenta1 N79-L3Bt) were grown at Stoneville, MS (lat. 33 degrees 26 minutes N 90 degrees 55 minutes W) in 2002 and 2003 using N fertility treatments of 112 kg N ha-1 pre-plant, 224 kg N ha-1 pre-plant, or 112 kg N ha-1 pre-plant + 112kg N ha-1 side-dress at growth stage V6. The growing degree units at 10 C base temperature (GDU 10's) required for growth stages R1 and R6 of the four short-season hybrids were greater than claimed by their supplier when grown in their adapted environments. Yields of DK C42-22Bt and 2593 compared well with the two adapted cultivars. Kernel weights and grain bulk density differed among the hybrids but none were below levels subject to dockage on the market. Aflatoxin and fumonisin levels were higher in 2002 than 2003. Three of the short-season hybrids did have higher aflatoxin levels in 2002. Plots receiving 224 kg N ha-1 pre-plant yielded more grain than the plots receiving other N fertility treatments. Greater kernel weights were noted for the higher N fertility levels. Nitrogen fertility had no effect on mycotoxins. Short-season hybrids need to be individually evaluated for production potential in the lower Mississippi River valley before being recommended for sale.