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The rootstock potential of 21 bottle gourds (Lagenaria siceraria) collected from the Mediterranean region (Turkey) was investigated for watermelon with regard to plant growth, yield, and fruit quality. The Crimson Tide watermelon cultivar was used as a scion and 2 commercial rootstocks (L. siceraria) were also used for comparison. In greenhouse conditions, the survival rate of grafted plants and the eff ect of rootstocks on plant growth were determined. The grafted plants were planted under low tunnels in early spring and the eff ects of the rootstocks on early yield, total yield, and fruit quality were evaluated. The survival rates of the grafted plants varied from 83% to 100%. Survival rates of those with commercial rootstocks and local rootstocks were similar. Plants grafted onto 20-02, 31-09, 31-43, 35-01, and 46-03 were more vigorous than ungrafted control plants. Compared to the control plants, grafted plants had 37% to 80% higher plant dry weight. All of the grafted plants except CT/Macis produced a higher yield than the control plants. The plants grafted onto 6 of the local rootstocks had significantly greater total yields than those grafted onto the commercial rootstocks. Among the local bottle gourd landraces tested, the 01-16, 07-45, 20-06, 31-09, 31-15, and 46-03 were found to be promising genotypes with regard to total yield. Early yield was not significantly affected by rootstock. The quality parameters of the fruits harvested from the grafted and control plants were found to be similar except for a limited number of graft combinations. It was concluded that germplasm from Turkish bottle gourds has a high rootstock potential for watermelon with regard to the investigated parameters. © TÜBİTAK.

The rootstock potential of Turkish Lagenaria siceraria germplasm for watermelon was evaluated. Among 210 accessions, 72 genotypes were selected based on morphological characteristics. Two commercial hybrid rootstocks were also used for comparison. Crimson Tide watermelon cultivar was used as a scion. Emergence rate, hypocotyl morphology, survival rate, and resistance to Fusarium oxysporum f. sp. niveum (FON) were investigated. Grafted plants were grown for 3 weeks in order to investigate the effect of rootstocks on plant growth. Leaf number, shoot dry weight, and root dry weight were determined. Emergence rate was ranked between 72% and 100% in collected genotypes. The highest graft compatibility was 99% while the lowest graft compatibility was 70%. All the grafted plants showed better performance than control plants regarding plant growth. All bottle gourd genotypes were tested against known 3 races of FON and all of them showed resistance against it. However, 9 genotypes showed yellowing but reisolation from those plants showed that yellowing was not due to FON. Crimson Sweet watermelon cv. susceptible to 3 races of FON was grafted onto 10 Lagenaria siceraria genotypes with the highest graft compatibility with watermelon. While all grafted plants showed resistance to FON, ungrafted Crimson Sweet watermelon cv. was found susceptible to 3 races of FON. The results showed that Turkish L. siceraria germplasm has powerful rootstock potential for watermelon against Fusarium wilt and it is a good resource for rootstock breeding programs. © TÜBITAK.

The emergence performance of different rootstocks and watermelon cultivars at different temperatures, and the effect of hypoctyl structure on grafting success and survival rate were investigated. Evaluated rootstocks were Cucurbita moşchata (landrace), C maxima (Arican local cultivar), Strong Tosa (C. maxima x C. moschata), P360 (C. maxima x C. moschata), Luffa cylindrica, Benincasa hispida, Lagenaria siceraria (landrace), Skopje (Landrace), and 2 Lagenaria hybrids, 216 and FR Gold. The Crimson Tide watermelon cultivar was used as scion. Emergence tests at 14 °C, 18 °C and 25 °C were carried out for all rootstocks and scion seeds in a growth chamber. Cucurbita type rootstocks showed better emergence performance at low temperatures than did other rootstocks and scion. However, B. hispida, L. cylindrica, Lagenaria type rootstocks and scion did not emerge at 14 °C and they were rotten. At 18 °C, the earliest emergence was recorded in Cucurbita type rootstocks while the latest emergence was observed in B. hispida and L. cylindrica. Rootstocks and scion did not show any difference in emergence rate at 25 °C. B. hispida and L. cylindrica had the thinnest and shortest hypocotyls which made grafting difficult. The survival rate of grafted plants was inversely correlated with the difference in diameters of scion and rootstock. At the same time survival rate was significantly affected by the rootstocks genotype. Rootstocks had different numbers of vascular bundles but the survival rate was not affected by the number of vascular bundles whereas the plant growth rate was positively affected. In general, Lagenaria type rootstocks had a higher survival rate than did other rootstocks. The hole insertion grafting technique had a significantly lower survival rate than did the approaching technique in Cucurbita type rootstocks. All graft combinations produced higher plant biomass than did the control plant, except for the L. cylindrica. The study showed that rootstock influences survival rates and plant growth in the use of grafting applications in watermelon. © TÜBITAK.

This study was carried out at the Department of Horticulture, Faculty of Agriculture, Çukurova University in spring 1999 and 2000. In the study, 46 doubled haploid lines produced by irradiated pollen technique and 10 original diploid genotypes were used as plant materials. To investigate inbreeding depression in melons, doubled haploid lines and original diploid parental lines were compared with regard to plant vigor, yield and quality. Various plant growth and fruit characteristics were determined over two years. These were plant main stem height, node number, main stem diameter, earliness and total yield, fruit weight, fruit diameter, fruit length, rind thickness, flesh thickness, diameter and length of seed cavity and total soluble solid contents. Double haploid lines showed similar results to the original diploid lines. Inbreeding depression was not observed in these materials. Great variations were noted in respect of fruit weight and fruit length. It can be concluded that homozygosity did not cause any significant adverse effects on plant vigor, yield or quality in melons.