Lulo (Solanum quitoense Lam.) reproductive physiology: A review

Lulo is an important fruit crop, which is considered the “golden fruit” of the Andes. It belongs to the Solanaceae family with two main geographical varieties, quitoense, which is spineless and septentrionale, bearing thorns. Flowers occur on inflorescences that bear both female-sterile (staminate) and hermaphroditic flowers. Once flowering starts, plants bear buds, flowers, and fruits at different maturity stages throughout the year. Pollen grains are monads and tricolporate. Lulo phenology is influenced by environmental factors such as temperature, altitude and precipitation. More research is required to understand the role of photoperiod. Lulo is mainly pollinated by bumblebees, and insects in the Andes. Self-pollination appears to occur in lulo, but this requires confirmation. Fruit growth and development depends on environmental conditions. Lulo fruit has a sigmoid growth pattern. Hybridization is essential to obtain pest and disease resistant plants. Hybridization programs have been carried out mainly in Colombia and Ecuador acheiving successful hybrids resistant to Fusarium, nematodes and other diseases. Germplasm collections are essential for maintaining lulo diversity and traits of economic and productive relevance. These are key factors in breeding and hybridization programs. More research is required in all aspects of the reproductive biology of lulo in the tropics. This review is sought to stimulate more research in lulo and to provide the basis for understanding the complexity of its reproductive biology.