How to maintain gynoecious cucumber lines? A TIP for BREEDER.

Cucumber is a highly cross-pollinating crop with a significant level of heterosis. Plant breeders are exploiting this heterosis by developing hybrid cultivars that yield higher than open-pollinating varieties (OPVs) and are generally preferred by the farmers. The first step of the hybrid development process is to develop inbred lines (homozygous lines developed from continuous selfing up to 5 or 6 generations).
A cucumber plant may express monoecious, gynoecious, gyno-monoecious, androecious, andro-monoecious, or hermaphrodite sex. There would arise a constraint in selfing a gynoecious cucumber plant (that bears only pistillate flowers). This problem can be overcome by spraying different chemical solutions. Silver nitrate (AgNO3) is one of the most common solutions being sprayed at a dose rate of 3mM for artificially inducing male flowers in cucumber. The solution is usually sprayed after the emergence of the first true leaf. This solution is applied three times with an interval of a week. Other solutions such as gibberellic acid and silver thiosulphate can also be used but these are not as effective as AgNO3.