CHARACTERIZING A CUCUMBER POLLEN STERILE MUTANT - INHERITANCE, ALLELISM, AND RESPONSE TO CHEMICAL AND ENVIRONMENTAL-FACTORS

A new sterile mutant designated pollen sterile (PS) found in pickling cucumber (Cucumis sativus L.) is characterized by normal corolla in st aminate and pistillate flowers, normal fertility in the female, and ab sence of pollen in otherwise normal-appearing staminate flowers. All F 1 plants from PS x male fertile (MF) sib-matings were MF, and F2 proge ny segregated 3 MF : 1 PS. Sib-matings of PS segregates with sister MF segregates produced either 1 MF : 1 PS ratios or all normal plants. T hus, PS is controlled by a single recessive gene. The PS gene is not a llelic to apetalous (ap), but was shown to be allelic to male sterile- 2 (ms-2) and is designated ms-2PS. It was not possible to determine po ssible allelic relationships between ms-2PS and ms-1 because of strong nude and female sterility of the available ms-1 material F1 generatio ns from gynoecious--PS and monoecious-PS crossed with monoecious, gyno ecious (silver-ion treated), and hermaphroditic parents produced no PS plants and sex types did not influence PS levels in F2 progenies, ind icating it is not possible to maintain the PS mutants through crosses with different cucumber sex types. It was not possible to change the e xpression of PS by applying cytokinin, IAA, or GA3, and there were no changes in response to temperature and fertilizer treatment. Unlike gy noecy, which is responsive to some external factors, PS is unresponsiv e. The results suggest that the use of PS in cucumber F1 hybrid seed p roduction is not practical. Chemical names used: indole acetic acid (I AA), gibberellin (GA3).