Curd, seed yield and disease resistance of cauliflower are enhanced by oligosaccharides

Oligosaccharides have been demonstrated as promoters for enhancing plant growth across several crops by elevating their secondary metabolites. However, the exploration of employing diverse oligosaccharides for qualitative trait improvements in cauliflower largely unknown. This study was intended to uncover the unexplored potential, evaluating the stimulatory effects of three oligosaccharides on cauliflower's curd and seed production.

Two experiments were initiated in the early (15 September) and mid-season (15 October). Four treatments were implemented, encompassing a control (water) alongside chitosan oligosaccharide (COS 50 mg.L^-1) with a degree of polymerization (DP) 2-10, oligo galacturonic acid (OGA 50 mg.L^-1) with DP 2-10 and alginate oligosaccharide (AOS 50 mg.L^-1) with DP 2-7.

Oligosaccharides accelerated plant height (4-17.6%), leaf number (17-43%), curd (5-14.55%), and seed yield (17.8-64.5%) in both early and mid-season compared to control. These enhancements were even more pronounced in the mid-season (7.6-17.6%, 21.37-43%, 7.27-14.55%, 25.89-64.5%) than in the early season. Additionally, three oligosaccharides demonstrated significant disease resistance against black rot in both seasons, outperforming the control. As a surprise, the early season experienced better growth parameters than the mid-season. However, performance patterns remained more or less consistent in both seasons under the same treatments. COS and OGA promoted plant biomass and curd yield by promoting Soil Plant Analysis Development (SPAD) value and phenol content. Meanwhile, AOS increased seed yield (56.8-64.5%) and elevated levels of chlorophyll, ascorbic acid, flavonoids, while decreasing levels of hydrogen per oxide (H₂O₂), malondialdehyde (MDA), half maximal inhibitory concentration (IC₅₀), and disease index. The correlation matrix and principal component analysis (PCA) supported these relations and findings. Therefore, COS and OGA could be suggested for curd production and AOS for seed production in the early season, offering resistance to both biotic and abiotic stresses for cauliflower cultivation under field conditions.