Assessment of Rooting Capability and Rootstock Potentials of Some Turkish Bottle Gourd (Lagenaria siceraria) Accessions Used as Rootstocks for Watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai]

Grafting practice has been common agricultural application in fruit-bearing vegetables in several countries. Since scion can be grafted on rootstock seedling with or without root in Cucurbitaceous crops, rooting capabilities of rootstocks during healing processes has critical importance. Rooting characteristics of some commercial hybrid rootstocks and eight Turkish bottle gourd accessions (Lagenaria siceraria) was studied when they were used as rootstocks for watermelon in splice grafting method. The study was carried out at three steps. At the first step, gourd seedling cuttings were prepared by cutting one cotyledon and growing point and roots then they were transplanted into irrigated rooting media consist of peat and perlite (2:1 v:v) under high air humidity and low light intensity conditions in a plastic tunnel covered with shading material (post graft care unit). Root formation capability of the cuttings was evaluated three weeks after transplanting. Crimson Tide watermelon cv. was grafted onto gourd genotypes without root by splice grafting method, and they were transplanted in growth media (2:1 v:v) in post graft care unit at the second stage of the experiment. At the third stage, rootstock effect of the bottle gourd accessions on plant growth parameters was investigated. Rooting performance (1-5 scale), root characteristics (length, thickness, fresh and dry weight) and graft compatibility rate (%) were determined three weeks after grafting. Rootstocks effect of different local bottle gourd accessions on leaf number and area, plant length, and fresh and dry weight of shoots and roots were investigated at the last stage of the study. While bottle gourd accessions showed significant variation in rooting capabilities after grafting, root characteristics, graft compatibility and plant growth (leaf number, leaf area and biomass accumulation), it was found out that local calabash accessions presented similar rootstock performance with commercial hybrid rootstocks. The survival rate of grafted plants ranged from 84% to 100%. All grafted combinations produced significantly higher biomass than ungrafted control plants. A number of local bottle gourd accessions produced higher leaf number, leaf area, dry root weight and shoot dry weight than commercial rootstocks were three, five, six and six, respectively.