Tomato hybrid seed production using stored pollen grains: temperature and storage time interactions and their effects on pollen viability

Abstract

In the past decades, tomato (Solanum lycopersicum L.) hybrid seed production has been massively employed in breeding programs throughout the world. However, some important physiological factors should be considered in order to attain adequate yield in association with high physiological and genetic qualities, during hybrid seed production. Pollen viability under stored conditions is of crucial importance or hybrid seed production as well as co-hybrid development programs and collaborative shuttle breeding networks among partner research institutions/companies. The main objective of the present work was to identify the best combinations of temperature and storage time of tomato pollen grains aiming to produce hybrid seeds with high genetic and physiological qualities. Pollen grain viability of the male tomato inbred line of the hybrid 'San Vito' (San Marzano type) was evaluated after the following storage conditions: 4, -20, and -80°C in combination with 30, 60, and 120 days of pollen storage. The viability of the pollen grains was evaluated by visualizing them in vivo through stigma tissue and counting the percentage of grains with conspicuous pollen tube growth (germination). The results indicated that the best storage condition for the tomato pollen was -20°C for 60 days. Under this storage condition, the average pollen germination was around 41%. These results reinforce that storage at low temperatures might represent an alternative technique for tomato pollen conservation, assisting the hybrid seed production systems and minimizing the risk associated with the potential lack of flowering synchronization between male and female parental inbred lines.