Submitted to: Proceedings Sunflower Research Workshop
Publication Type: Proceedings
Publication Acceptance Date: March 15, 1995
Publication Date: N/A
Interpretive Summary: Roots provide the life line between the plant and the soil. They play a major role in transporting water and nutrients for survival. The number of roots, rooting patterns and rooting depth are important characteristics needed for sunflower to survive. It is also important to know at what temperature roots growth is maximum. The problem is that we do not know what the rooting characteristics and responses of sunflower roots are to temperature. We have a large pool of germplasm from which to select for rooting characteristics including the wild species which have several species with variable rooting systems which allow them to survive in unique environments. Two cultivated hybrids and three interspecific sunflower genotypes were evaluated in the laboratory for root growth patterns and their response to temperature. Maximum root growth occurs at bout 75-80 degrees F. Very little root growth takes place at 50-65 degrees F, while no growth occurs at 100 degrees F. Root growth appears to be genotype specific and temperature specific within genotype. The specific response may account for the adaptability of some hybrid and interspecific germplasm to different environmental conditions. Sufficient variability appears to exist in root growth but the next step will be to correlate the rooting responses in the laboratory to rooting responses in the field.
Technical Abstract: Roots play a major role in maintaining the water supply to plant tissues. Initiation and development of roots can be critical to the growth and productivity of crop plants. While we have some information about rooting depth in sunflower, we lack information about early root growth and their response to temperature. Root growth characteristics of primary and lateral roots of two hybrids, 894 standard height and 471D semi-dwarf, plus three interspecific hybrids were evaluated in laboratory studies using the polyethylene growth pouch system. Early growth was evaluated from 10 to 40 degrees C at 5 degree increments after 10 days of growth. Genotypes appeared to be temperature specific for maximum primary root growth. Averaged over all temperatures, primary and lateral root growth was maximum at 25-30 degrees C. Generally, very little root growth took place at 10, 15, or 40 degrees C. Semi-dwarf hybrid 471D had the greatest primary and lateral root growth with 205 cm, as well as highest number of lateral roots, root density, and root weight. Interspecific genotypes had similar growth patterns to cultivated hybrid 894. Temperature dependent root growth information will be useful in crop modeling for sunflower. There appears to be a temperature specific response in laboratory evaluated sunflower, but further studies are needed to correlate these studies with rooting responses under field conditions.