Evaluation of Seeding Rate on Ratoon Yield in Drill-Seeded Delayed Flood Rice Cultivation

Rice ratooning is a widely adopted practice in southwest Louisiana because it allows production of an additional crop from the existing rice stand with relatively low input requirements. Although ratoon-crop yield is generally lower than main crop yield, the additional harvest can improve overall system productivity and profitability due to reduced establishment and production costs. This study evaluated the effect of seeding rates on ratoon yield using data collected from 2016 to 2021 across nine seeding rates ranging from 13.0 to 104.3 kg ha−1, 18 rice varieties, and 37 trials. Linear mixed-effects models were used with seeding rate and plant density as fixed effects and year and variety as random effects. Ratoon yield increased significantly with seeding rate (R = 0.285, p < 0.001), with an estimated gain of 7.48 kg ha−1 for each 1 kg ha−1 increase in seeding rate. The estimated optimum seeding rate was 72 kg ha−1; however, ratoon yield responses remained relatively broad near the optimum. Therefore, a practical seeding rate range of 50–80 kg ha−1 is recommended to maximize ratoon yield while accounting for environmental and varietal variability. Main crop yield was not correlated with ratoon yield (R = −0.044). Variance component analysis showed that year and variety contributed substantially to overall yield variability. These results indicate that ratoon yield is significantly influenced by seeding rates, with moderate to high seeding rates supporting greater ratoon productivity, while environmental and genetic factors also play important roles.