Study on Induction and Characterization of Tetraploid Plants in Pumpkin

In order to explore the method of inducing the tetraploid plants and expand the new resources in pumpkin,the seeds of diploid pumpkin( C. maxima Duch.) M10-13-09 were soaked in 2. 0 mg / m L concentration of colchicine and 0. 05 mg / m L concentration of Oryzalin to successfully induce tetraploid plants. The morphological and physiological difference between diploid and tetraploid were investigated. The results indicated that Oryzalin was more efficient to induce tetraploid than colchicine,and their mutation rates were 0. 83% and 0. 33% respectively.Compared with diploid pumpkin,the growth period of tetraploid was prolonged and the plant characterized by small and thick leaves,descended female flower node position,thicker filament,and woolly dark corolla. The tetraploid fruit peel became dark with wide ribs. The transverse and longitudinal diameter of tetraploid seeds was 1. 0 cm and1. 2 cm,increased 66. 7% and 20% than that of diploid. The diploid seeds germination ability became more poor with dark color and number of seeds decreased from 122. 0 to 30. 3 per fruit. The photosynthetic rate( Pn) and transpiration rate( Tr) increased 90% and 20%. The bleeding intensity and root activity of tetraploid pumpkin were higher than those of diploid plants. The total flavonoids content of tetraploid fruits increased 50%.