Degree
Doctor of Philosophy (PhD)
Department
School of Plant, Environmental and Soil Sciences
Document Type
Dissertation
Abstract
Phosphorus (P) is essential for plant growth and is often a major limiting nutrient in agriculture. In sweetpotato (Ipomoea batatas), studies on the role of P on storage root yield have been limited because of the lack of response and inconsistent results across cultivars and years. Growing evidence shows that current phosphate (Pi) fertilizer rates can be reduced while maintaining productivity. Newly published molecular evidence shows differential expression of phosphate starvation response genes among sweetpotato cultivars, further supporting the hypothesis of cultivar-specific Pi sensitivity. The research herein sought to characterize root system architecture and yield response to Pi availability in greenhouse and field conditions. It has been shown that plants modify root system architecture to optimize Pi scavenging when P becomes limiting. The results show cultivar-specific variation in root system architectural adaptations in response to Pi availability, supporting the current hypothesis of cultivar-specific variation in response to Pi availability. It also helps to clarify the molecular evidence by filling in gaps in describing cultivar-specific Pi sensitivity. Results from split-root experiments designed to simulate variation in localized Pi availability corroborate the hypothesized cultivar variation in Pi sensitivity and complement the evidence implicating known P-responsive genes in the phosphate starvation pathway. Results from the field studies support molecular and physiological evidence that sweetpotato tolerates low Pi in a genotype-specific manner. A separate field study investigating the possible role of nitrogen in modulating cultivar response to Pi availability failed to show this hypothesized relationship; instead, it provided evidence that current sweetpotato cultivars tolerate Pi levels considered critical in other crops. The lack of significant yield response to P fertilization in most cultivars suggests that the current P fertilizer recommendations could be reduced without compromising sweetpotato yield. This adjustment could lead to significant cost savings for producers while reducing P losses to the environment.
Date
3-20-2025
Recommended Citation
Gregorie, Jeffrey Cole Denis, "Variation in Response to Phosphorus Among Sweetpotato (Ipomoea batatas L.) Cultivars" (2025). LSU Doctoral Dissertations. 6698.
https://repository.lsu.edu/gradschool_dissertations/6698
Committee Chair
Arthur Villordon
Included in
Agricultural Science Commons, Agriculture Commons, Agronomy and Crop Sciences Commons, Biology Commons, Bryology Commons, Plant Biology Commons
