Evaluation of the tolerance of Cucurbitaceae genotypes to water deficit at the seedling stage

A comparative assessment of various species of the Cucurbitaceae family for water deficit was carried out at the “Maritsa” Vegetable Crops Research Institute – Plovdiv during the period 2022-2023. The aim of our study was to characterize different species of Cucurbitaceae family and evaluate them for drought tolerance at the seedling stage. In order to analyze the physiological response of cucurbit crops to drought, a vegetation experiment was carried out with the following genotypes from the Cucurbitaceae family: Lagenaria siceraria (Molina) Standl. (Long gourd): Lagenaria siceraria (Molina) Standl. (Local population) (Common gourd) Cucurbita maxima Duch. ("Plovdivska 48/4") (White pumpkin); Cucurbita moschata Duch. (Muskatna 51-17); and Luffa cylindrica Roem. (Local population). The experiment was conducted under controlled conditions in a greenhouse. Plant genotypes were grown under three contrasting levels of irrigation: optimal irrigation rate of 100% (Control); reduced irrigation rate of 50% and no irrigation for 14 days. Various screening approaches were applied, including plant growth parameters (biomass, plant height, root length, fresh weight, dry weight of plants, and leaf number; and physiological responses (chlorophyll fluorescence induction parameters and chlorophyll content index). Based on the studied biometric parameters and the analysis of chlorophyll fluorescence as well as the content of total chlorophyll in drought plants in the seedling phase, the local population of long gourd (L. siceraria) is characterized as more tolerant followed by the common gourd. Susceptibility is shown by Cucurbita moschata variety "Muskatna 51-17", followed by Cucurbita maxima "Plovdivska 48/4".