Effect of plant growth regulators, fruit thinning, boron and calcium on growth indexs and seed yield of watermelon nuts

Watermelon nuts is widely cultivated in Khorasan Razavi for its edible seed production. Two experiments were therefore, conducted to increase seed production in Bahonar University of Kerman Research Station in 2013 and 2014. In first year, the effects of gibberellic acid (0 and 50 mg/l) and fruit number (1, 2 and 3 fruits /plant) were studied in 4 populations. In second year, the effects of 24- epibrassiniolide (0, 0.5 and 1 micromolar), gibberellic acid (0 and 50 mg/l), Boron (0, 0.1 and 0.2%) and calcium (0 and 0.2%) were studied in one population (Japoni) on growth and seed production. Results from first year experiment revealed that GA increased  the plant lenght (417 cm) compared with control (363 cm). the maximum of fresh biomass (1805 gr) and chlorophyll index (57.5) with application of gibberellic acid in Japony population was observed. Three fruits remained per plant produced more volume (12545 ml/plant) and weight (12223 gr/plant) of the fruit and seed weight (304 gr/plant )  in Japony population. Howevere, the results from second year experiment showed that in treatments containing Br 0.5, 0.1% boron and 0.2% calcium,  highest leaf relative water content (67%) and lowest leaf ion leakage (30%) was found. Moreover,  treatment combination of 0.5 micromolar Br, 0.1% boron, 0.2% calcium and 50 mg/l GA was the most effective treatment for increasing of shoot fresh weight (2490 gr/plant), leaf chlorophyll content (28.2 mgr/gr fresh weight), fruit volume (8486 ml/plant) and weight (8342 gr/plant) and seed weight (228 gr/plant), such that this treatment produced 3 ton/ha seed yield, compared with control which was about 1 ton/ha. This treatment is recommended for watermelon seed production.