Sorghum Research
The major focus of sorghum research program in the semi-arid regions of Kansas is increased yield potential through the development of elite parental lines with drought resistance (pre-flowering and post-flowering resistance), herbicide tolerance, cold/heat tolerance, non lodging and diseases resistance (Fusarium stalk rot, charcoal rot, anthracnose, and ergot). Besides, insect resistance (green bug) and forage quality are the next priority areas. The program also evaluates exotic germplasm to find new genetic sources for use in the development of improved lines. Collaborative research efforts will be made on molecular breeding for the traits of economic importance with special emphasis on exotic germplasm characterization and development of mapping population for QTL and association mapping analyses for the graduate research programs.
Sorghum Breeding: The sorghum-breeding program develops improved parental lines with major emphasis on developing lines with increased yield, improved tolerance to environmental stresses particularly on pre and post flowering drought and cold tolerance and herbicide tolerance. Next priority is on the development of lines with disease (charcoal rot and fusarium wilt) and insect (green bug) resistance. The program also evaluates exotic germplasm to find new genetic sources for priority traits for use in the development of improved lines.
Pre and post-flowering drought tolerance: Adaptation of sorghum to the range of environmental conditions in semi arid tracts has resulted in the evolution of extensive genetic variation for drought tolerance in sorghum (Blum 1979; Doggett 1988). However, water stress taking place at both pre-flowering and post-flowering stages of development and has the most adverse effect on yield during and after anthesis. Hence, productivity enhancement under drought conditions is a challenging task, because of the un-predictable nature of most periods of drought stress prevailing in sorghum growing areas in Kansas and gaps in our knowledge of drought biology. These difficulties arise from the diverse strategies adopted by sorghum plants themselves to combat drought stress depending on the timing, severity and stage of crop growth. Hence, research focus at this centre will be primarily on the development of drought tolerant parents using conventional breeding methods and through estimating the genetic parameters and character association for some valuable morpho-physiological traits, which have been extensively utilized for screening of pre and post flowering drought tolerance.
Cold Tolerance: Sorghum is sensitive to low-temperature stress in the range of 20° to 0° C and suffers chilling injury when subjected to non-freezing temperatures below 10-15° C (Peacock, 1982). Development of cold tolerant sorghum lines is one of the priority traits to take advantage of early season moisture, minimum tillage and longer growing period. It helps to expand the area of coverage and to increase the possibility of two crop seasons for producers. Enhanced germination and emergence at low temperatures would facilitate early planting and adaptation to cooler season between the end of April and May in Kansas. Research emphasis on focusing important cold tolerance seedling traits like emergence percentage, emergence index, seedling height, shoot and root dry weight and vigor score are being made in collaboration with physiologist which would result tolerant lines for further hybrid development.
Herbicide tolerance: Research has shown that heavy weed infestations can reduce grain sorghum yields by 50 percent. In addition, weeds may decrease grain quality, increase insect and disease pressure, and increase harvest difficulty. In our projects, segregating progenies are being evaluated in collaboration with weed specialist for selecting acetolactate synthase (ALS) and acetyl coenzyme A carboxylase (ACC) herbicides tolerance lines in sorghum.
Non lodging and diseases resistance: Charcoal rot [caused by Macrophomina phaseolina (Tassi) Goidanich] incidence is much higher when the plants are exposed to prolonged drought and high stress during grain development. Fusarium stalk rot (caused by Fusarium spp.) is typically more severe when drought and high temperature stress occurs during grain development followed by wet, cool conditions near physiological maturity. Research emphasis is on development of post-flowering tolerant genotypes not affected by late-season drought which helps to reduce susceptibility to stalk rot diseases.
Greenbug: The greenbug is the most widespread insect pest of sorghum. Several biotypes of the greenbug presently exist and with each new biotype, the fewer sorghum lines with resistance are available. Exotic germplasm will be continuously screened in collaboration with entomologist for the identification of resistance/tolerance sources and to use the same for further breeding programs.
Virus complex: The major viruses attacking sorghum include johnsongrass mosaic virus, maize dwarf mosaic virus, sugarcane mosaic virus, and sorghum mosaic virus. These diseases account for 2-5% loss in grain yield each year. Our pathologist have already identified a resistance source to aforesaid virus complex and research effort is underway to use the same for introgressing the trait to other breeding lines and thus into hybrids.