Preliminary DRIS Norms for Evaluating the Nutritional Status for Rice Crop

Abstract Purpose Accurate evaluation of plant nutritional status is essential for improving fertilizer management and enhancing rice productivity. Despite the economic importance of rice ( Oryza sativa L.) in Egypt, locally developed Diagnosis and Recommendation Integrated System (DRIS) norms are still unavailable. Therefore, this study aimed to establish preliminary DRIS norms for rice cultivated under Egyptian conditions and to identify nutrient relationships associated with variations in grain yield. Methods Field experiments were conducted during the 2021 and 2022 growing seasons at the Rice Research and Training Center, Sakha, Kafr El-Sheikh, Egypt. Grain yield and nutrient concentration data were used to classify observations into high-yielding (≥ 8 t ha⁻¹) and low-yielding (< 8 t ha⁻¹) populations. Concentrations of N, P, K, Ca, Fe, Zn, Mn, and Cu were determined in grain samples and used to calculate nutrient ratios, variance parameters, and preliminary DRIS norms. Relationships between grain yield and major nutrient ratios were further evaluated using scatter plot analysis. Results The high-yielding population exhibited greater nutritional stability and lower variability in nutrient relationships than the low-yielding population. Several nutrient ratios, particularly N/P, N/K, N/Fe, K/Fe, and Zn/Mn, showed strong discriminatory capacity between yield groups and were selected as important components of the proposed DRIS norms. High grain yields were generally associated with narrower nutrient-ratio ranges, indicating that balanced nutrient interactions were more closely related to productivity than individual nutrient concentrations. Variations in N, K, Fe, Zn, and Mn were identified as major contributors to differences in crop performance. Conclusions The preliminary DRIS norms developed in this study provide a useful framework for nutritional diagnosis of rice under Egyptian production conditions. The results highlight the importance of nutrient balance in determining crop productivity and demonstrate the potential of DRIS as a decision-support tool for fertilizer management. Further validation across different cultivars, environments, and growing seasons is required before large-scale application.