Kochia pollen dispersion was measured during 24 and 48 h periods from a kochia population in an 8- by 10-m area in the center of a 1.6 ha fallow field. Pollen counts from traps at 50- and 100-cm heights declined rapidly with increasing distance from the pollen source. Pollen deposition was highest along the prevailing wind direction: up to 23 pollen grains cm–2 were recovered 50 m from the pollen source along the southeast (SE) vector. Nonlinear regression analysis of pollen deposition along the SE vector was used to estimate that 99.9% of shed pollen would be deposited within 154.4 m of the source. Viability of pollen from greenhouse- and field-grown plants was measured using staining and germination assays. of four pollen stains tested, only 1,2,3-triphenyl tetrazolium chloride gave consistent results and did not stain heat-killed pollen. Depending on environmental conditions, kochia pollen remained viable from less than 1 d to 12 d. Length of kochia pollen viability was shortest under high temperatures (22 and 28 C) and low relative humidity (7 and 32%). Less than 0.5% germination was observed in 1.1% agar media with various additions; however, up to 17.8% germination was observed after incubation at 28 C in 100% relative humidity.

Introduction. Investigation of pollen performance is essential in breeding experiments or artificial pollination procedures, especially in a crop such as chestnut, some genotypes of which are characterized by male sterility. Our study was carried out to determine the pollen germination rate and the pollen tube growth of some European chestnut genotypes. Materials and methods. Seven Turkish advanced chestnut selections (SE3-12, SE18-2, SE21-2, SE21-9, 552-8, 552-10 and 554-14), and a cultivar (Sariaslama), growing in two different locations, were studied in the central Black Sea region of Turkey in 2006. For this purpose, in vitro pollen germination tests were performed on media with four different concentrations of sucrose [(0, 5, 10 and 15)%]. Results and discussion. The pollen germination rates of the eight genotypes studied were significantly different due to the sucrose concentrations. The best pollen germination rate was found in the 554-14 chestnut genotype (35.80%). The best sucrose concentration for a high germination rate and pollen tube growth was 10%. For the same genotype, the results varied due to the two different study locations (Terme and Fatsa). A linear relationship between the sucrose concentrations and pollen tube length was found to be significant in most genotypes. The longest pollen tube length was found in the 554-14 genotype (74 mm).

Using monoclonal anti-calmodulin antibodies in conjunction with confocal scanning laser microscopy we have analysed the spatial variations in the distribution pattern of calmodulin (CaM) during the sequential events of pollen hydration, germination and tube growth in Nicotiana tabacum. These immunocytochemical observations have been complemented by immunochemical studies wherein the anti-calmodulin antibody raised against pea CaM recognises a polypeptide of c. 18 kDa in the pollen extracts. Digitisation of confocally acquired optical sections of immunofluorescence images reveals that in hydrated pollen a high level of CaM is consistently present in the region of the germinal apertures. Subsequently, with the onset of germination a high CaM concentration was found associated with the plasma membrane of the germination bubble and in the cytoplasm in its vicinity, while in the vegetative cytoplasm a weak diffuse and intense punctate signal was registered. CaM immunostain was also detected in association with the plasma membrane of the tube tips in both short and long pollen tubes. Furthermore, the cytosol of the tubes invariably manifested an apically focused CaM gradient. We were, however, unable to detect any vacuolar association of CaM in the older regions of the pollen tubes. Although punctate immunostain was obvious across the pollen tube numerous punctate structures were invariably present in the extreme tip. The possible implications of these findings in development of cell polarity, polarised growth, maintenance of calcium homeostasis and CaM interactions with other mechanochemical motor proteins in effecting propulsion of organelles during pollen hydration, germination and pollen tube growth are discussed.