Typescript, etc. / Digitized by Kansas State University Libraries

Typescript, etc. / Digitized by Kansas State University Libraries

Typescript (photocopy). / Digitized by Kansas Correctional Industries

The introduction of hybrid seed in developing countries may be in conflict with the tradition of saving seed for the next planting. This study evaluates 15 sorghum (Sorghum bicolor (L.) Moench) hybrids and their three successive generations in three environments. Under optimum conditions for all 15 genotypes segregating generations yielded as well as the F1 generation. Under moisture stress and late planting, the F2 generation showed inbreeding depression for yield and kernels per panicle. Height, panicle length and test weight were reduced and flowering was hastened for all segregating generations. Kernel weight was not affected by segregation. This study indicates that under optimal conditions it is possible to find a line among segregating generations of sorghum that is superior to its F1 hybrid.

No description available.

Call number: LD2668 .T4 1985 D59 / Master of Science

Physiological responses of six sorghum (Sorghum bicolor (L.) Moench) hybrids and their respective parental lines were evaluated under high and low soil moisture conditions at Tucson, Arizona in 1980 and 1981. Apparent photosynthesis, transpiration, diffusive resistance, and temperature differential (ambient temperature minus leaf temperature) were measured under field conditions at weekly intervals. To measure apparent photosynthesis, a small plexiglas chamber was sealed over a section of leaf blade and gas was sampled with two syringes pulled at a 30 or 60 second interval. The gas samples were injected from the syringes into an infrared gas analyzer to measure CO(,2) concentrations. Transpiration, diffusive resistance, and temperature differential were measured with a steady state porometer. Regression analysis was used to compare the physiological performance of the germplasm sources over a wide range of environmental conditions. The physiological characteristics of the highest yielding sorghum hybrid in 1980 were the most stable across all environments. This hybrid was superior to both its male and female parent for all four physiological characteristics. In 1980, this hybrid was superior to the other hybrids in temperature differential and transpiration. The superior yielding hybrid had the highest mean apparent photosynthesis and the lowest mean diffusive resistance. All hybrids had higher yields than their respective male parents under both irrigation treatments. Thirty-five days after planting, the superior yielding hybrid had the greatest leaf, stem, and root dry weights. This hybrid also had the highest relative leaf area expansion rate. Heterosis for stomatal density was not observed either year. Regression analysis proved to be an effective tool for analyzing the sorghum germplasm over a diverse range of environmental conditions. By comparing the response of an individual germplasm against the mean response of the population under numerous environmental conditions, the slope, mean, and coefficient of correlation may be used to evaluate genotype-environment interactions.

Thesis (M. Sc. (Plant Protection)) -- University of Limpopo, 2021 / Worldwide, root-knot (Meloidogyne species) nematodes are considered to be the most important and damaging genus in crop husbandry. The existence of a wide host range, over 2000 plants, and several biological races, makes the management of this nematode genus difficult with nematode-resistant crop Hybrid Sorghum Sudan grass (Sorghum bicolor × Sorghum Sundanese) has been classified as being resistant to certain Meloidogyne species and races, with a wide range of uses in crop rotation intended to manage nematode population densities. However, due to the ability of nematodes to enter chemiobiosis when gradually exposed to chemicals, this hybrid might not be effective in managing nematode population densities for the subsequent highly susceptible sweet potato (Ipomoea batatas L.) cultivars. The objective of the study was to determine whether hybrid Sorghum-Sudan grass would suppress M. javanica (Trial 1), M. incognita race 2 (Trial 2) and M. incognita race 4 (Trial 3) population densities, allowing a nematode susceptible sweet potato cv. ′Beauregard′ as successor crop to be cultivated without suffering nematode damage. The hybrid Sorghum-Sudan grass study was conducted under greenhouse conditions, with seven inoculation levels, namely, 0; 5; 25; 125; 625; 3 125 and 15 625 eggs and second-stage juveniles (J2) of each nematode species or race, arranged in randomised complete block design, with six replications and validated in time. Plant growth, foliar nutrient elements and nematodes were collected at 56 days after inoculation and prepared for analysis using standard methods. The reproductive factor (RF) at all levels was zero, whereas nematode inoculation at all levels did not have any effect on plant growth of the hybrid Sorghum-Sudan grass. However, the nematode levels affected the accumulation of nutrient elements and the quality of forage. After cultivating the susceptible sweet potato cultivar in pots xxx previously with hybrid Sorghum-Sudan grass at increasing levels of M. javanica alone, that is in Trial 1, similar results were observed with respect to RF and lack of nematode damage to plant growth. Consequently, the hybrid was suitable for use in crop rotation with sweet potato for the purpose of managing nematode population densities of thermophilic Meloidogyne species and/or races. / National Research Foundation of South Africa (NRF) and the Agricultural Research Council (ARC)