Rootstocks effect on plant nutrition concentration in different organs of watermelon grafted onto various rootstocks

In this study carried out in 2009 and 2010 growing seasons, the effect of rootstocks on plant nutrition partitioning in grafted watermelon onto four gourd rootstocks was investigated. Ferro, RS841 (Cucurbita maxima x C. moschata) and Argentaio and Macis (Lagenaria hybrid) were used as rootstocks. Crimson Tide and Crisby watermelon cultivars were used as scion. Grafted and ungrafted seedlings were produced by a commercial seedling company. Plants were grafted by one cotyledon grafting techniques. Experiment was conducted in Alata Horticultural Research Institute in Mersin. The grafted plants were planted under low tunnel in early spring and regular cultural practices for watermelon were applied. Plant nutrition concentrations were determined in leaf, fruit rind, fruit flesh and seeds. Leaf sample was taken at flowering stage, rind, flesh and seed sample were taken from fully mature fruit. Nitrogen concentration was determined by modified Kjheldahl methods. Phosphorous concentration was determined by vanadomolybdophosphoric acid method. K, Ca, Mg, Fe, Mn, Zn and Cu concentration of samples were determined by atomic absorption spectrofotometry. Plant nutrient concentration in leaf, rind, flesh and seed were significantly affected by rootstocks. Increase in concentration of N, P, K, Ca and Mg in leaf was not observed in grafted plant while ungrafted plant had higher concentration of Fe, Mn, Zn and Cu in their leaf. Ca concentration in rind of fruits from grafted watermelon was higher than ungrafted control plant except Macis/Crimson Tide and Argentario/Crimson Tide graft combinations. Plant nutrition content of fruit flesh was significantly affected by rootstocks and scion. Magnesium, Fe, Zn and Mn concentration of seed was not significantly influenced by rootstocks and scion while other plant nutrient content was significantly affected rootstocks and scion