Plant growth promoter enhanced photosynthesis and fruit quality in strawberry. A cultivar-specific multivariate analysis

Abstract

Spring protected strawberry production in northern China is constrained by elevated temperatures and narrowed diurnal range, yet cultivar-specific management strategies remain undefined. To identify optimized foliar treatments for three cultivars (Benihoppe, Yuexiu, White Snow Princess), plants were sprayed with S-abscisic acid (S-ABA), amino acids, jasmonate, or 5-aminolevulinic acid (5-ALA) at 10, 50, and 100 mg · L⁻¹. Growth, photosynthetic, and fruit quality traits were analyzed using two-way ANOVA, stepwise regression, OPLS-DA, and PLS-SEM. Cultivar was dominant for most traits. Optimal responses were achieved with 50 mg · L⁻¹ 5-ALA for Benihoppe, S-ABA or 10 mg · L⁻¹ 5-ALA for Yuexiu, and 10 mg · L⁻¹ 5-ALA for White Snow Princess. PLS-SEM identified vegetative growth as the central driver of fruit colour (0.922) and fruit quality (0.845), while photosynthesis exerted a significant direct negative effect on growth (−0.709), revealing a resource-based tradeoff under elevated spring temperatures. Stepwise regression confirmed that 5-ALA promoted total soluble solids (TSS) accumulation more strongly than cultivar effects for Benihoppe, whereas high concentration (100 mg · L⁻¹) suppressed fruit weight. These findings support cultivar-specific precision management, emphasizing growth promotion over photosynthetic enhancement to sustain fruit quality under spring stress.