ABSTRACT
Watermelon (Citrullus lanatus) is an important cucurbit crop, accounting for 7% of the worldwide area devoted to vegetable production. Commercial varieties of watermelon include diploid seed watermelon and triploid seedless watermelon: triploid seedless watermelon is one of the most successful examples of an artificially induced polyploid crop. The triploid seedless watermelons have many advantages relative to homozygous diploid watermelon, such as high yield, strong tolerance and good quality traits. Tetraploid watermelons are used as parental lines in triploid breeding, and are always obtained by treating newly emerged diploid seedlings with colchicine. The early identification of tetraploid plants may require morphological, cytological and even molecular techniques in the process of induced tetraploidy in watermelon. Tetraploids should be evaluated directly for green rind pattern, high seed yield, and other traits such as abundant fertility and high combining ability. Useful tetraploid inbred lines should produce triploid hybrids with excellent yield and quality for the market type and production area of interest. Commercial production of elite triploid hybrids is done by hand in locations where labor is inexpensive, or by bee pollination in isolation blocks. Cultivation of triploid seedless watermelons is similar to seeded watermelon, but there are three major differences: germination difficulties, transplanting requirement, and necessity of planting pollenizer varieties. Due to the advantages of polyploid watermelon, triploid seedless watermelon breeding and cultivation is becoming more and more popular, and has great future potential.
