Yield and Quality of a Sorghum ✕ Sudangrass Hybrid as Affected by Mixtures of a Grain Sorghum
1975
Horner, J. R. | Croy, L. I. | Denman, C. E.
Many state seed laws have very close tolerences with regard to genetic purity of sorghum [Sorghum bicolor (L.) Moench] ✕ sudangrass [Sorghum sudanense (Piper) Stapf] hybrids. Genetic purity of sorghum ✕ sudangrass hybrid seed is difficult to maintain because of contamination by outcrossing with foreign pollen or selfing of supposedly cytoplasmic male sterile plants which have some fertility. The effect of reduced genetic purity on yield and quality, as evidenced by in vitro dry matter digestibility and protein content, was estimated by mixing various percentages of seed of a sorghum ✕ sudangrass hybrid and a grain sorghum. Treatments consisted of a hybrid (A Redlan ✕ Greenleaf); the grain sorghum (B Redlan); and 90:10, 80:20, 70:30, 60:40, and 50:50 mixtures of a hybrid and grain sorghum. The study was conducted 3 years in a randomized, complete block design. Dry matter forage yields were not significantly affected by the various mixtures of a grain sorghum and hybrid. The grain sorghum yielded significantly lower than all other treatments. Dry matter digestibility of all treatments was above 59%, indicating high quality forage, and was not significantly different among treatments within years. There was no difference in protein content between the hybrid and all mixtures within years. Protein content of the grain sorghum was higher than the other treatments and approached significance. The grain sorghum made slower regrowth and was more immature than all other treatments at each harvest date. The results of this experiment indicate that a small reduction of genetic purity in hybrids would not decrease total forage yields or lower quality of forage, as evidenced by in vitro dry matter digestibility or protein percentages.
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