1a.Objectives (from AD-416):
Develop a high-throughput process to screen for nitrogen uptake efficiency (NUpE), characterize the genetic variation for NUpE in wild and cultivated diploid potato species, and determine the influence of photoperiod on NUpE and tuberization efficiency. Interspecific crosses will also be made for future genetic studies on the inheritance of NUpE and the development of molecular markers associated with NUpE.
1b.Approach (from AD-416):
Genotypes of Solanum chacoense (chc) will be grown under different N regimes in tissue culture and root parameters measured. These same genotypes will be grown in the greenhouse under long- and short-day photoperiods. Plants will be harvested 100 days after planting, and partitioned into above-ground biomass, roots and tubers, and analyzed for total N. The correlation between root parameters from tissue culture plantlets and greenhouse-grown plants will be calculated. Relative response to photoperiod will also be determined as the ratio of roots:tubers produced under short-day to the ratio of roots:tubers produced under long-day growing conditions. Crosses will be made between phu-stn and chc.
Commercial potatoes have a shallow rooting system and much of the nitrogen applied as fertilizer is lost either through leaching, causing groundwater contamination, or volatilization as potent greenhouse gasses. Several wild potato species have a much greater rooting system and ARS and the University of Florida are evaluating different techniques to accurately assess root biomass on a large number of plants so as to improve selection efficiency for this important trait. Experiments are underway to characterize root biomass in tissue culture, pots, and field-grown plants and determine the correlations among these traits. This information will result in high through put methods for identifying nitrogen uptake efficient plants to facilitate breeding for this important trait.