Some aspects of cross-pollination in wheat (Triticum aestivum L.) 1. Pollen concentration in the field as influenced by variety, diurnal pattern, weather conditions and level as compared to the height of the pollen donor

Summary

For the large-scale production of hybrid seed the cross-fertilizing capacity of wheat must be increased. Breeding good pollinators is, therefore, a necessity. Five spring wheat varieties were examined for differences in pollen shedding capacity under normal field conditions. The examination was carried out by collecting pollen on object slides every hour from 06.00 till 20.00 h during flowering. In general, the variety Peko proved to be the best shedder of pollen, while Opal was the worst. Gaby, Jufy I and Orca were intermediate. Consistent results were hard to obtain mainly due to varying weather conditions.

It was established that pollen is released throughout the whole period of daylight. The maximum release of pollen, however, occurred from 08.00 till 11.00 h. A less pronounced and much smaller peak was noticed from about 15.00 till 18.00 h. Most pollen appeared to be released at a temperature of 16–20°C and a relative humidity of 70–75%. Although there seems to be some relationship between the diurnal pattern of the pollen release and the indicated values of these meteorological factors, one cannot say that the former is entirely determined by the latter.

It has been suggested in the literature that a male-sterile parent that is shorter than its pollinator would be most likely to produce good seed set in the hybrid wheat seed production field. Investigations showed that a greater concentration of pollen was found below the ear level of pollinator plants than at or above ear level.