Stress-Tolerant Cassava: The Role of Integrative
Ecophysiology-Breeding Research in Crop Improvement
ABSTRACT
This review highlights an integrative multidisciplinary eco-physiological, breeding and agronomical research on the
tropical starchy root crop cassava conducted at CIAT. Laboratory and field studies have elucidated several physiological/biochemical
mechanisms and plant traits underlying the high productivity in favorable conditions and tolerance
to stressful environments, such as prolonged water stress and marginal low-fertility soils. Cassava is endowed with
inherent high photosynthetic capacity expressed in near optimal environments that correlates with biological productivity
across environments and wide range of germplasm.Field-measured photosynthetic rates were also associated with
root yield, particularly under prolonged drought. Extensive rooting systems and stomatal sensitivity to both atmospheric
humidity and soil water shortages underlie tolerance to drought. The C4 phosphoenolpyruvate carboxylase (PEPC) was
associated with photosynthesis and yield making it a selectable trait, along with leaf duration, particularly for stressful
environments. Germplasm from the core collection was screened for tolerance to soils low in P and K, resulting in the
identification of several accessions with good levels of tolerance. Cassava has a comparative advantage against major
tropical food and energy crops in terms of biological productivity. Results also point to the importance of field research
versus greenhouse or growth-chamber studies. In globally warming climate,the crop is predicted to play more role in
tropical and subtropical agro-ecosystems. More research is needed under tropical field conditions to understand the
interactive responses to elevated carbon dioxide, temperature, soil fertility, and plant water relations.
Keywords: Abiotic Stress; Agriculture; Breeding; Climate Change; Cultivars; Drought; Ecophysiology; Food Security;
Modeling; Nutrients; Photosynthesis; Productivity; Semiarid; Soils; Storage Roots; Water Stress; Yield