Browsing by Subject "Sorghum -- Breeding"
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Item Environmental Factors Affecting Seed Development of Grain Sorghum.(Texas Tech University, 1974-05) Gerik, Thomas JosephNot AvailableItem Evaluation of backcross progenies and recombinant inbred line populations of sorghum (Sorghum bicolor (L.) Moench)(Texas Tech University, 2002-12) Coulibaly, Sidi BekayeIn the past, breeding sorghum for resistance to greenbugs and drought has used traditional breeding methodology. Marker-assisted selection has been used to accelerate the recovery of the recurrent parent genome in backcross breeding and to transfer desirable traits such as post-flowering drought resistance trait known as stay-green into greenbug resistant and elite lines of sorghum. The objectives of the study were to: 1. Evaluate under post-flowering drought stress the performance of the backcross generations from the Introgresslon of stay-green Into greenbug resistant and elite lines of sorghum. 2. Evaluate under stress and non-stress environments the recombinant inbred lines derived from a cross between B35 and Tx7000. 3. Identify quantitative traits loci affecting grain yield in stress and nonstress environments. In the introgresslon of stay-green Into greenbug resistant lines study, 217 backcross lines ranging from BC2 to BC4 generations and derived from 9 populations were evaluated under post-flowering drought stress along with 15 parental lines used as checks at the Texas A&M University Agricultural Research and Extension Center, Lubbock, during the summer of 2001. Four backcross progenies rating between 2.5 and 2.9 could be classified as post-flowering drought stress resistant. The progeny P8-01PR1057-4 (4568 kg ha"^) had significantly 77% and 50% higher grain yield than B35 and Tx7000, respectively. Overall, the populations generally produced more grain yield than the parental lines. In general, progenies or parental lines with multiple QTLs were resistant to moderately resistant to both greenbug biotypes E and I. In the introgression of stay-green into elite lines study, 150 BC2 to BC4 progenies from 5 populations and 15 parental lines used as checks were evaluated under post-flowering drought stress conditions at Texas A&M University Agricultural Research and Extension Center, Lubbock, during the 2001 summer. Results indicated that only P5-01PR151-1 would be classified as postflowering drought resistant as B35 (rating 1.6) the resistant check based on the stay-green rating 2.2. Although some progenies were carrying stay-green QTLs, they were considered as post-flowering drought susceptible. The elite line B1 significantly produced more grain yield (5283 kg ha'^) than most of the progenies. Grain yield is a complex trait that is influenced by genetic and environmental factors. Severe losses can be caused by drought, a common stress in most sorghum growing regions. Two hundred seventy-four Restriction Fragment Length Polymorphic markers covering the sorghum genome were used to identify the main-effect QTLs in the 98 recombinant inbred lines evaluated under water stress conditions at Lubbock during 1993 and 1994, and under stress and no-stress conditions in Halfway during 1994. Significant (P<0.05) differences were detected between the parents B35 and Tx7000 and among the RILs for all phenotypic traits measured. The analysis detected 7 main-effect QTLs for grain yield under stress and non-stress conditions in Lubbock and Halfway. Under stress, 3 main-effect QTLs collectively explained 52.3% of the phenotypic variation with significant allelic effects for 2 QTLs from Tx7000.Item Heterosis, backcross analysis, and breeding potential of one exotic cultivar for grain yield in sorghum (Sorghum bicolor (L.) Moench)(Texas Tech University, 2002-05) Teme, NiabaLian Tang Ai, a Chinese landrace cultivar donor parent and Tx2783, an elite US restorer parental line and, the recurrent parent, were used to develop BC2 derived lines which were evaluated for grain yield potential. The hypothesis of this research was that some of the BC2 derived lines themselves could have higher grain yield potential in BC2F2 and in hybrid combination with ATx623, respectively, than Tx2783 and the hybrid of ATx623xRTx2783. Grain yield of the derived lines and their hybrids grain yield was normally distributed. Five (3.7%) and 46(32.4%) derived lines (P=0.05) produced significantly higher grain yield than the recurrent parent in limited and fully irrigated combined analysis trials, respectively. In the combined analysis of fully irrigated trials, 132(89.2%) hybrids produced significantly higher grain yield than the recurrent parent hybrid. In the combined full irrigation trials, the average heterosis values was 50% over the midparent, heterosis of the best hybrid over the best parent was 60.2%, the best parent over the mid-parent was 78.0% and the worst hybrid had 23.3% over the mid-parent. Highest heterosis of the best hybrid over the best parent was 90.5% at Halfway 2001. Under full irrigation trials, five, four and nine derived lines, respectively, from Lubbock 2000, 2001 and Halfway 2001, were among the top 10% highest grain producing derived lines while four hybrids from Lubbock 2000, 2001 and Halfway 2001 were consistent in producing high grain yield across environments. Across irrigation levels, four derived lines and two hybrids produced consistently and significantly higher grain yield than the recurrent parent and its hybrid. Three high grain yielding derived lines produced high grain yield in hybrids and were significantly superior to the recurrent parent and its hybrids. Five hybrids from the combined limited trials and 7 hybrids from Lubbock 200l fully irrigated trial produced significantly higher grain yield than the standard commercial hybrid check. When using fully irrigated combined analysis, however, no hybrid produced significantly more grain than the standard commercial hybrid. Other derived lines and hybrids had erratic grain yield distribution. Higher grain yield was expressed at Halfway than at Lubbock. There was a significant low and negative correlation between grain yield and maturity in general. Grain yield of derived lines did not accurately predict well their respective hybrid grain yield in individual environments (trials). However, across environments in full irrigation combined trials, grain yield of derived lines was positively and highly correlated to grain yield of hybrids (r=0.419). Introgression of useful yield genes from Lian Tang Ai into Tx2783 was a success. However, genotype by environment interaction made the selection for high yielding and widely adapted derived lines for hybrid productivity a difficult task.Item Photosynthetic variation in sorghum genotypes(Texas Tech University, 1978-05) Leeton, Barbara SmithNot availableItem Sorghums resistant to the Banks grass mite, Oligonychus pratensis (Banks)(Texas Tech University, 1976-05) Foster, David GlennNot availableItem The yield and chemical composition of four sorghum genotypes as influenced by time and rate of nitrogen application.(Texas Tech University, 1975-05) Sung, Frankie Jih-MjnNot available