Date of this Version
Thesis (M.S.)—University of Nebraska—Lincoln, 1972. Department of Agronomy.
Researchers have reported that tall grain sorghum will outyield short grain sorghum within the same isogenic line (15, 23).With this fact in mind, we then logically question why the taller line outyields the shorter.Since these isogenic lines are genetically the same except for the desired character of height, to what can we attribute this increased yield?Could it be the crop canopy as influenced by height, or could it be the root system?
When we reduce the plant height, we, in essence, merely shorten the intermodal dimensions of the plant.Does this dwarfing also reduce the size of the plant’s root system?Will this dwarfing reduce the number of lateral and fibrous roots? If so, reduction of the lateral and fibrous roots in both number and length could reduce the plant’s efficiency in obtaining essential nutrients and water.
The purpose of this study was to examine the possibility of differences existing in the root systems of 3 dwarf and 2 dwarf RS 610 hybrid grain sorghums.If differences were found to occur, this could be a factor in yield differences.
Two methods of approach were utilized.The first involved the actual examination of the sorghum root systems in the field.This required the establishment of a technique of taking selective samples of roots from plants grown in the field under production conditions.The second approach was to utilize the same isogenic lines under controlled conditions in a greenhouse.The entire plants could be compared in this manner.
The utilization of soil coring techniques for comparative study of root systems seemed to be a workable system.The soil coring procedure showed the extent of the development of the root system in the field without total root extraction.This technique could also be utilized to analyze the effects of soil matrix problems on root extension and development.
The major disadvantages to this method are several.The soil coring technique destroys adjacent plants in the plot area if truck or tractor mounted coring machines are utilized.The comparative study of root systems with this method requires a soil survey in order to secure an area of uniform soil profile.This method usually requires at least two men to secure the samples in the field.The washing of the soil cores is a long and often tedious process when a great many samples are taken.
Advisor: Max D. Clegg