Interactive Effects of Genotype, Irrigation, and Fertilization on Physiological, Biometric, and Biochemical Traits of Runner Bean (<em>Phaseolus coccineus</em> L.)

Phaseolus coccineus L. (runner bean) stands out for its high nutritional value, richness in bioactive compounds, and broad genetic diversity—traits that make it a valuable candidate for crop improvement and integration into sustainable agricultural systems, particularly under the changing climate conditions. In this context, this study aimed to assess the individual and combined effects of three runner bean cultivars (Cozia1, Cozia2, and Cozia3), two irrigation regimes (2000 and 2500 m³·ha⁻¹), and three fertilisation strategies (chemical, organic, and unfertilised) on key physiological, morphological, and biochemical parameters. The field experiment was conducted over two consecutive growing seasons using a randomized block design with three replications. The results showed that genotype had the most significant influence on the majority of traits, highlighting its dominant role over fertilization and irrigation. Among cultivars, Cozia2 was highly responsive to fertilisation and irrigation variation, showing both the highest and lowest values for pod number, seed weight, and seeds per pod depending on treatment. Under chemical fertilization and 2500 m³·ha⁻¹ irrigation, Cozia2 achieved the highest grain yield (3427.60 kg·ha⁻¹) and pod number (48.13), while Cozia1 combined with chemical fertilization under 2000 m³·ha⁻¹ irrigation recorded the highest total phenolic content (0.47 mg GAE·100 g⁻¹ d.w.). Notably, the highest photosynthetic assimilation rates were observed in Cozia2 × IR2 × UF and Cozia3 × IR1 × OR combinations. These findings therefore highlight the necessity of choosing optimal genotype-input combinations to enhance yield, quality, and resource efficiency in runner bean production.