In sorghum, a single recessive gene Wx conditions waxy endosperm type. While parental inbred lines and hybrids with waxy endosperm have been developed, there has been little to no adoption of these hybrids by producers, primarily because waxy hybrids consistently yield 5-10% less than non-waxy hybrids and end-use buyers will not pay for the utilization benefits. While current waxy germplasm does not yield competitively at this time, there is a question as to whether the yield reduction is due to a negative relationship between waxy per se or due to the lack of effort to develop high yielding waxy germplasm. The purpose of this study is to determine the relationship between the waxy endosperm phenotype and grain yield in sorghum. From each of two F2 breeding populations segregating for waxy endosperm, 50 inbred lines were derived, selected only for homozygosity of endosperm type. No selection for yield was practiced during the development of these lines. Approximately 25 waxy and 25 non-waxy lines were selected for further evaluation from each population. These lines and a set of testcross hybrids were evaluated in four environments. When combined across environments and populations, waxy inbred lines and hybrids yielded 17% less than non-waxy inbred lines and hybrids. However, analysis of the individual inbred lines and hybrids indicated that several waxy inbred lines were competitive in yield with the best non-waxy genotypes. The results indicate that it should be possible to develop waxy hybrids that are competitive in yield, but that this will require additional breeding efforts to identify the correct inbred lines and hybrids.

In sorghum, a single recessive gene Wx conditions waxy endosperm type. While parental inbred lines and hybrids with waxy endosperm have been developed, there has been little to no adoption of these hybrids by producers, primarily because waxy hybrids consistently yield 5-10% less than non-waxy hybrids and end-use buyers will not pay for the utilization benefits. While current waxy germplasm does not yield competitively at this time, there is a question as to whether the yield reduction is due to a negative relationship between waxy per se or due to the lack of effort to develop high yielding waxy germplasm. The purpose of this study is to determine the relationship between the waxy endosperm phenotype and grain yield in sorghum. From each of two F2 breeding populations segregating for waxy endosperm, 50 inbred lines were derived, selected only for homozygosity of endosperm type. No selection for yield was practiced during the development of these lines. Approximately 25 waxy and 25 non-waxy lines were selected for further evaluation from each population. These lines and a set of testcross hybrids were evaluated in four environments. When combined across environments and populations, waxy inbred lines and hybrids yielded 17% less than non-waxy inbred lines and hybrids. However, analysis of the individual inbred lines and hybrids indicated that several waxy inbred lines were competitive in yield with the best non-waxy genotypes. The results indicate that it should be possible to develop waxy hybrids that are competitive in yield, but that this will require additional breeding efforts to identify the correct inbred lines and hybrids.

Sorghum (Sorghum bicolor (L). Moench) is used for human consumption in parts of Africa and Asia and as an animal feed mainly in the U.S. Though sorghum grain contains higher amounts of protein than other cereal grains such as wheat and corn, it is not as readily available for enzyme degradation in humans and animals. Protein body matrices called kafirins surround the starch granules in sorghum. Because the protein is less digestible, the starch is also less digestible for biofuel production. However variation for this trait exists and the line P850029 has a higher protein digestibility compared to other normal grain sorghum lines. This increase in digestibility of protein is due to the rearrangement of the kafirins in the prolamin protein bodies where, the γ-kafirins are rearranged in the seed endosperm and the amount of γ-kafirin in the grain is also reduced. The assay to phenotype the HD trait is time consuming and unpredictable. So identifying a quantitative trait loci (QTL) controlling the protein digestibility trait in sorghum would be beneficial in breeding. A recombinant inbred lines (RILs) population derived from P850029 x ‘Sureno’, were developed and used to map QTL regulating the protein digestibility trait. A single QTL was identified on chromosome 1 between Xtxp43 and Xtxp329. Validation of the identified QTL was done on heterogenous inbred families (HIFs). The results validate the same QTL identified on the RIL population on chromosome 1. Later the high digestibility trait (HD) was integrated with the Waxy trait in sorghum. The Waxy (WX) sorghums have starch completely in the form of amylopectin. The effect of endosperm type on ethanol yield and fermentation efficiencies was studied among HD, WX and HD-WX lines. The HD-WX lines fermented in a shorter time i.e. completed fermentation in 48 h and their fermentation efficiencies were also higher around 90%. The DDGS of the HD-WX lines also had lower residual starch content and 50% higher amino acid lysine content when compared to wildtype sorghum. Moreover, the relation between endosperm traits and grain yield in sorghum has not been fully explored. In this study, we compared the yield and yield components of four unique endosperm phenotypes, HD, WX, HD-WX and wildtype lines. A total of 100 F2:4 derived recombinant inbred lines population from a cross between Tx2907/P850029 were selected with 25 lines from each HD, WX, HD-WX and wild-type line were included in the study. These lines were grown in three replications in College Station and Halfway, Texas in a randomized complete block design. The results show that there are no significant differences in the grain yield.