Enhancing Growth of Upland Rice in Low Phosphorus Soil by Leveraging Root Morphological Traits

Abstract

Low phosphorus (P) in the upland ecosystems negatively influence rice growth and cause significant yield losses. Upland rice to effectively adapt to low P in upland agroecosystems requires a suite of novel root traits. However, studies to identify these traits in upland rice grown in low P agroecosystems have received limited attention in Kenya. In the present study, nine (9) upland rice cultivars were screened to identify root traits that support low-P soil growth in a cement tank. Upland rice cultivars showed significant (p ≤ 0.05) variation in number of root tips (NRT), number of root branching points (NBP), total root length (TRL), whole root network area (NA), average root diameter, root volume (RV), root surface area (RSA), first-order root length (FORL), and second order root length (SORL). BW01 and ITA01 recorded the highest NRT, NBP, TRL, RV, NA, RSA, FORL, and SORL, while NERICA04 had the lowest, representing 5.8, 8.0, 7.6, 6.8, 9.0, 5.8, and 9.3 differences in these traits under low P soil. NRT wassignificantly and positively correlated with NBP, TRL, NA, RV, RSA, and FORL, indicating the role of these traits in foraging for soil nutrients. Principal component analysis (PCA) showed that NRT, NBP, TRL, RSA, and SORL are important and effective root traits for selection in rice breeding under low P soil. BW01 and ITA01 recorded well-developed root systems, indicating that they are more P-efficient than the P-inefficient NERICA04 under low P soil conditions. Therefore, BW01 and ITA01 can be targeted for cultivation in P-deficient soils and used as trait donors to improve P-inefficient rice cultivars.