All-Union Institute of Plant Industry, Leningrad, U.S.S.R.
1. Biochemical and physiological studies have shown that preliminary pollination with a limited amount of pollen from the maternal form causes an activation of the metabolic processes resulting in an increased inflow of nutritional material as well as other substances into the style and stigma.
2. Such preliminary pollination with limited amount (about 20 grains) of pollen from the maternal species followed by the application, 3 hours later, of pollen from the paternal species resulted in the production of plants, with new combinations of characters, which form valuable breeding material.
3. The application of pollen from the paternal parent in unlimited quantity immediately after emasculation and again the next morning, followed by a mixture of equal parts of maternal and paternal pollen on the third day also resulted in progeny exhibiting a combination of the characters of the two parents.
4. The removal of all but few buds to be used in hybridisation from the maternal parent increases the percentage of boll set and, thus, increases the possibility of getting hybrids.
5. Usually, when a mixture of pollen from two different species is applied to the stigma of one of the species, the pollen of the maternal parent successfully effects fertilization whereas the alien pollen is unsuccessful. The technique described by us has, however, given different results.
6. Under natural conditions, pollen grains (whether of the same species or from alien species or even different genera) once they reach the stigma are able to affect the characters of the progeny. Presumably they do so by influencing the formative processes in the plants.
