AbstractEleven sorghum forage entries, including five single crosses, five threeway hybrids and DeKalb hybrid SX-17 were evaluated for yield of green forage (GF), yield of dry forage (DF), crude protein (CP) content, CP yield, height, leaf area, number of tillers, leaf-stem ratio and hydrocyanic acid potential (HCN-p) at lsabela, Puerto Rico. Four cuttings were made. The second harvest, 112 days after planting, had the highest DF yield, and the lowest CP content. When data for all harvests were combined, the single cross of ATX624 x Common sudangrass, three-way hybrid (ATX624 x BRhodesian) x Common sudangrass and single cross hybrid ARhodesian x Common sudangrass produced the highest DF yields. These were significantly higher than those of OeKalb hybrid SX-17. The highest DF yield was that from single cross hybrid ATX624 x Common sudangrass (17,303 kg/ha in 217 days), which exceeded by 11% and 13% the 2nd and 3rd highest producers. Based on orthogonal comparisons, single crosses were on the average superior to three-way hybrids in yield and most of the other characteristics studied. Three-way hybrids had a lower average HCN content (250 p/m) than single crosses (285 p/m). These values are slightly higher than the 200 p/m level at which HCN toxicity may begin to affect animals. Results indicate that any of the three top hybrids of this study would be an excellent choice for farmers desiring high forage production under irrigation in Puerto Rico.
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