Inhibition of Viviparous Sprouting on Melon Seeds Using High Level of Potassium Fertilization or Abscisic Acid Application

The present experiments were undertaken in order to clarify the effects of a high potassium fertilization level on the occurrence of viviparous sprouting in melon fruit. Melon (Cucumis melo L. group) plants of two susceptible lines and one resistant line to viviparous sprouting were used at two different potassium concentrations. A high potassium fertilization level (12.0 mmol·L) resulted in a marked decrease of the occurrence of viviparous sprouting in the susceptible lines, and in the increase of the endogenous ABA content. No significant differences were observed in the seed number per fruit, the seed weight, and the percentage of seed germination at a high level of potassium fertilization. Further experiments were conducted in order to analyze the effects of exogenous ABA treatment at a low potassium fertilization level (1.5 mmol·L) on the occurrence of viviparous sprouting in melon fruit. At 25 days after pollination, ABA solution at different concentrations was sprayed on the fruits of the susceptible melon line grown at two different potassium fertilization levels. Even at a low potassium fertilization level, exogenous ABA application inhibited the occurrence of viviparous sprouting and increased ABA contents both in juice samples around the placenta and in the seeds. ABA treatment, however, led to a significant decrease in the seed number per fruit and in the percentage of seed germination, as a result of a marked increase in the ABA content and potassium absorption.