Plant Segregation and Pollen Characteristics of Highland Papaya (Vasconcellea Pubescens A.DC.) Based on Sex Types

Highland papaya (Vasconcellea pubescens A.DC.) is a member of the family Caricaceae and native to Ecuador. The plant’s introduction and cultivation were successful in specific highland areas of Indonesia but with limited growing areas. V. pubescens has monoecious and dioecious characteristics and allows fruit production from female dioecious and monoecious plants. This plant is valuable, and the knowledge about its sex pattern, though still limited, is crucial for its efficiency, productivity, and development. Hence, the presented study aimed to explain the patterns of plant segregation, as well as, pollen morphology and germination based on sex in V. pubescens. The investigations began by recognizing the total population of V. pubescens in its cultivated area for grouping and mapping according to sex. Observations on the pollen characteristics, such as, morphology and germination, used light microscopy and a Scanning Electron Microscope (SEM). The results revealed that the basis for plant segregation pattern depended on sex in male and female dioecious and monoecious plants of V. pubescens (1:5:1). In both sexes, the pollen morphological characteristics showed that the unit of monads, prolate spheroidal, radial, tricolporate, isopolar, reticulate, and P/E index of male dioecious pollen was 0.70, while monoecious was 0.52. Anthers and pollen grains from the male plant were round, but those of monoecious elongate more. However, no significant differences occurred among the sexes for pollens. The pollen grains from male flowers on male dioecious plants showed faster germination than monoecious individual plants, having a difference of 25.14 days.