Tuesday, November 14, 2006 - 10:45 AM

Gibberellin applied to the rice main crop increases ratoon-crop yield.

Elliott Rounds1, Abdul-Razack Mohammed1, and Lee Tarpley2. (1) Texas A&M University, 2474 TAMU, 2474 TAMU, College Station, TX 77843-2474, United States of America, (2) Mississippi State University, Texas A&M Agricl. Res. & Ext. Ctr., 1509 Aggie Dr., Beaumont, TX 77713

The U.S. Gulf Coast has a relatively long growing season favorable for ratoon rice (Oryza sativa L.) production.  Ratoon rice is the regrowth crop after the main crop harvest.  The application of gibberellin (GA) to the main crop late in development could increase ratoon-crop yield by promoting ratoon tiller vigor and ratoon crop earliness.  This was a 3-year study conducted in 2003, 2004 and 2005 at the Texas A&M Agricultural Research and Extension Center locations at Beaumont and Eagle Lake, TX.  Various cultivars were tested in field research plots.  Gibberellin was applied at 10 g a.i. ha-1 when the main-crop developmental stage was between 3-d post-flowering and soft-dough.  The data was analyzed using a paired t-test of the median on each research block to evaluate GA-treated experimental plots compared to the untreated control plots.  There is not a significant response of main-crop yield to gibberellin applications.  The ratoon-crop yield is significantly increased by 286 kg ha-1 over the untreated control with GA application.  Whereas the GA treatment worked well on both conventional and hybrid rice, the very-early maturing, vigorous hybrids responded better in ratoon-crop yields.  For these hybrids, the typical increases in ratoon yield were 400 to 700 kg ha-1.