Differential effects of commercial and local Iranian pumpkin rootstocks on growth, yield, and postharvest quality of grafted cucumber (Cucumis sativus L.)

This study investigated the effects of grafting cucumber ( Cucumis sativus L. cv. Saba hybrid) onto a commercial Cobalt rootstock ( Cucurbita maxima × Cucurbita moschata ) and a local pumpkin ( Cucurbita moschata ) landrace from Zanjan province (named Zanjan) on plant growth, yield, and postharvest fruit quality. The study was conducted in a greenhouse using a completely randomized design with four replications. Various quantitative and qualitative indices were measured in grafted and non-grafted plants and subsequently, the data were analyzed using ANOVA followed by Tukey’s HSD test ( p ≤ 0.05). Relative to non-grafted plants, grafting response varied with respect to the rootstocks. Grafting onto Cobalt rootstock significantly increased chlorophyll content (from 1.22 to 1.69 mg g −1 FW; + 39.0%), plant height (from 392.3 to 429.0 cm; + 9.4%), fruit number (from 35.5 to 54.8 fruits per plant; + 54.4%) and total yield (from 2.46 to 3.89 kg per plant; +57.9%), while reducing postharvest weight loss (17.6%) and firmness decline (39.2%). However total soluble solids measured at post-storage did not followe same trends and were highest in the local Zanjan rootstock-grafted plants, indicating variable postharvest responses with respect to the rootstocks. Although the Zanjan rootstock showed a significant increase in root volume (20.6%), it was not superior to the commercial rootstock for most yield-related traits. In contrast, leaf size and sensory quality were reduced in both rootstock-grafted plants; however, the flavor of the fruits remained within an acceptable range for consumers. Overall, the Cobalt rootstock-grafted plants demonstrated a more favorable balance between yield improvement and postharvest performance, therefore, cucumber grafting onto commercial rootstocks (i.e., Cobalt) can be considered a useful strategy to enhance the yield and postharvest quality of greenhouse cucumbers.