Pollination Relations of Lycopersicon esculentum in Native and Foreign Regions
, 1950. V. 4. No. 2. P. 110–122 (13).
Журнал с антэкологическими публикациями.
Rates and other features of natural cross-pollination of Lycopersicon esculentum in stations within the range of wild forms in Perú were studied by counting the number of seeds and fruits produced by male-sterile mutants and were compared with similar data previously obtained in California, where no species of Lycopersicon are native. Useful data, which were provided by two plots, both located within the range of distribution of L. esculentum, L. pimpinellifolium, and L. peruvianum, showed much higher rates of natural cross-pollination than were obtained in any tests outside the range of distribution. Mean values of 14.2 and 14.8 seeds per flower, construed to be the most useful single measure of cross-pollination, for the Peruvian plots contrast with numbers varying from 0.3 to 7.0 for 16 plots in California. Expressed as a proportion of the fertile-plant yield, the values for Peru are respectively 41.4 and 51.4 per cent and for California vary from one to 33 per cent. The interbranch and interplant variability is generally lower in the Peruvian than in the Californian data. The appearance of natural hybrids between varieties of L. esculentum and between this species and L. pimpinellifolium and also the much greater activity of insect pollen vectors observed in Peru lends support to the direct measures of natural cross-pollination. The insects visiting flowers of tomatoes were collected and the identifications by P. H. Timberlake are presented herewith. L. esculentum in the region studied is actively pollinated by two species of native solitary bees. Bees of nine other species representing diverse families were obtained in cursory collections from other species of Lycopersicon. The results are discussed in relation to (1) commercial production of F1 hybrid seed, (2) the change in breeding system during the historical transfer of L. escu-lentum to non-native areas from a facultatively cross-pollinated species to an almost exclusively self-pollinated one, and (3) the bearing of the change in pollination relations on flower form, heterosis, and appearance of mutants.