From Traits to Parameters: Genotype and Water Regime Effects on Sugar Beet ( Beta vulgaris L.) Crop Model Parameterization

ABSTRACT

Understanding genotype × environment (G × E) interactions is essential for improving yield stability and resource use efficiency in sugar beet ( Beta vulgaris L.) under variable water availability. Field experiments with six diverse genotypes grown under two contrasting water regimes (fully irrigated vs. rain‐excluded) across two seasons were used to derive genotype‐specific parameter sets for storage root partitioning ( RP _max , k _DM ), within‐leaf partitioning ( flb , fla ), specific leaf blade area ( a _SLA ) and rooting depth dynamics ( k _zb ). Storage root partitioning was best described by a rectangular hyperbola: Maximum storage root proportion ( RP _max ) differed significantly among genotypes and between water regimes, whereas dry matter at half maximum ( k _DM ) showed no significant variation. Specific leaf blade area declined under reduced water availability and exhibited strong genotypic control. Partitioning between leaf blades and petioles varied with increasing leaf dry matter among genotypes in both intercept and slope but was not affected by water regime. Rooting dynamics were captured by an expo‐linear function with a transition to linear growth at approximately 288°Cd; genotypes differed in linear‐phase rooting speed (G4 ≈ G1 > G5 > G6 > G2 > G3). No statistically significant genotype × water regime interaction was detected for any estimated parameter, suggesting that genotype‐specific baseline parameters can be retained and, within the range of conditions tested, dynamically scaled by a common continuous water‐status modifier (ratio of actual to potential transpiration, T _act T _pot ⁻¹ ).