Factors Limiting Germination in Triploid Watermelon

Abstract

Seedless watermelon, a major crop in Texas, grows from sterile triploid seeds. The triploid seed varieties have poor germination rates and are typically more expensive. Identifying techniques that increase vigor and rates of germination could decrease the amount of labor and cost of cultivation required to grow seedless watermelons. To identify the cause of low vigor, the seeds underwent stress tests using modified State Seed Laboratory germination techniques to measure sensitivity to moisture and reduced gas exchange. Triploid seeds also have embryo deformations in high frequency, which were hypothesized to play a role in low vigor. The seeds were germinated on blue blotter paper in 9 cm petri dishes with punched holes to allow for greater gas exchange. Seeds were inspected for deformations upon germination, and seeds that failed to grow were inspected at the end of each repetition. It was found that increased levels of water diminished rates of germination in triploid varieties, but had no significant effect on the diploid control variety. Testing in elevated gas exchange conditions promoted germination rates in triploid varieties significantly. The rate of deformation in triploid seed embryos did not alter the seeds rate of germination. High sensitivity to limited gas exchange appears to play a larger role in germination success of triploid seeds than the deformations originally identified. This explains the poor vigor from seeds planted directly into the soil and calls for techniques that allow for greater gas exchange to promote germination.