MODELING THE IMPACT OF LOW LIGHT INTENSITY ON STORAGE ROOT DEVELOPMENT USING CASSAVA-OPENSIMROOT MODEL

Light intensity is one of the major factors that determine the amount of carbon substrate yielded from photosynthesis. Plants exposed to unfavorable light intensity always show less CO2 fixation and a decrease in plant dry weight. In cassava, low light intensity was reported to affect not only above-ground plant development but also storage root (SR) formation. However, the insightful study of carbon assimilation and allocation resulting in lowered SR production is not yet present. For this purpose, Cassava-OpenSimRoot (MeOSR), a functional-structural plant model (FSPM) developed in our laboratory, was employed to simulate cassava plant growth as well as SR development under different light intensity conditions. Simulation suggested that photosynthesis under a low light environment generated less photoassimilate, then lowered the overall carbon budget for plant development. The limiting carbon substrates first affected shoot growth and later led to insufficient carbon allocated for storage root bulking. The results were corresponding to the simulated root architecture that showed smaller numbers of thickening roots and shorter lateral roots under the low light condition. Our simulated results also showed that an insufficient carbon budget at the early stage of plant development has a large impact on cassava storage root formation. Modeling crop growth via MeOSR enabled us to investigate the dynamics of shootroot carbon partitioning under variable light conditions and its effect on overall plant growth and SR formation.