S01 - Session P10 - Pollen germination and behavior of a set of lemon cultivars

Authors: Fernando Córdoba López, Monserrat Moreno Verdú, Marta Rabadán Mínguez, Carmen Rodríguez Sánchez, Margarita Pérez-Jiménez, Olaya Pérez-Tornero *

Characterizing pollen performance is especially relevant for some economically significant species of Citrus . However, little is known about the self- or cross-incompatibility in lemon, which are very important traits in terms of the breeding of this citrus species. In the present study, pollen-pistil interaction was characterized on 5 lemon cultivars ('Fino 49', 'Verna 51, 'Fino 95', 'Eureka' and 'Lisbon') in several experiments. First, in vitro germination was assessed under five temperature regimes (10, 15, 20, 25 and 30°C) as part of a pollen viability analysis. Then, an in vivo experiment (self- and cross-pollination) among the lemon species was performed to check for self- or intercompatibility and characterize the influence of the pistilar genotype. Although pollen viability was high in all of the cultivars, germination was strongly affected by temperature. Very low germination percentages were obtained at the lowest temperature of 10°C, while pollen of the lemon cultivars showed their maximum germination percentages at 25°C. These results were verified in the field. In the self- and cross-pollination experiments, the number of pollen grains germinating on the stigma increased with time from pollination. Nine days after treatment, under field conditions, pollen tubes reached the base of the style in most of the combinations, except for self-pollinated 'Fino 95'. Altogether, pollen tubes growth along the style was faster in the cross-pollination treatments. Pollen tubes inside the ovary were observed from the sixth day and were at their maximum on the twelfth day in all the treatments. 'Lisbon' and 'Fino 95' were the cultivars with the highest number of pollen tubes in the ovary in self-pollination, while 'Fino 49' x 'Fino 95', 'Fino 95' x 'Fino 49', and 'Fino 49' x 'Eureka' were the cross-pollination combinations with the maximum number of pollen tubes in the ovary.