Gibberellic Acid Treatment to Improve Rice Ratoon Stand and Yield.

Rice ratoon crop yield increases commonly occur in response to a Gibberellic Acid (GA) treatment of 10 grams active ingredient per hectare applied to the main crop between several days past peak flowering up to the soft dough stage. The yield increase results from enhanced early growth of the ratoon tillers; main crop yield is not affected. Main crop and ratoon crop milling quality are not affected. The GA application, however, slightly delays main crop development, thus influencing harvest planning. Ratoon yield was increased in 14 of 17 studies conducted on a range of cultivars and hybrids, and in several producer trials. The overall average increase from the 17 studies was 264 kg/ha. The very early maturing hybrids, such as RiceTec XL723, appear to be especially responsive to the GA treatment with an average ratoon yield increase of 697 kg/ha. The GA application at the soft dough stage can be tank mixed with insecticide applications applied during grain filling; this saves on application costs and provides an economical way of increasing yields. Although there is no negative effect from later GA applications up to main crop harvest, the benefit gained from enhancing early growth of the ratoon tillers would often be diminished. Gibberellic acid applied during active stem elongation can enhance stem elongation, thus increasing plant height and the potential for lodging, so early applications of the GA to tall cultivars should be avoided. Application during peak flowering can sometimes decrease main crop yield, according to research at Louisiana State University, therefore the GA should be applied after peak flowering. The GA treatment’s likelihood of benefit decreases when there is disease or nutritional stress on the ratoon crop. This treatment is applied to the rice main crop to benefit ratoon crop yield. Texas Rice Research Foundation.