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The pollen longevity of the material was estimated by observing the number
of seed recovered on emasculated spikes of T. aestivum var. Chinese
Spring after pollination with pollen stored (under greenhouse conditions)
for various periods of time. Anthers about to dehisce were tapped onto clean microslides, and the pollen was collected with a brush and transferred to the stigmas of the emasculated plants of Chinese Spring. Pollinations were made with the pollen from the microslides after zero, five, ten, fifteen, thirty and sixty minutes. Approximately 30 florets were pollinated for each storage time in each line. The percentage of seed set is shown in Table 2. Some rye pollen was still viable following storage for 30 minutes whilst no sets were obtained from the florets pollinated with wheat pollen stored for only five minutes. None of the addition lines had any viable pollen after five minutes storage also but some seed was set with pollen from the amphiploid after this period of time. It is possible that pollen longevity is controlled by several factors ; however, it is clear that even if simply inherited, the extended pollen longevity of rye is not fully epistatic to the short viability period found in wheat. It is possible, also, that significant differences in pollen longevity in periods of time of less than five minutes may be observed. Experiments are being made to investigate this possibility. In a visual comparison of the extrusion of anthers in these lines the estimated length of the anther visible outside the floral parts at the time of dehiscence was taken as an index of extrusion. In rye the entire anther was extruded prior to anthesis ; however, no difference was observed in the extrusion of anthers between wheat, the amphiploid or any of the addition lines. Again it is probable that the anther extrusion of rye is not epistatic to the closed pollination mechanism of wheat. From the results obtained in these preliminary studies it would appear that it may be impracticable to attempt the cytogenetic transfer of these desirable characters from rye to wheat for utilization in hybrid-wheat-breeding programs. It is possible that these characters of large anther size, anther extrusion and pollen longevity which are found in other members of the Triticinae may be controlled by genetic mechanisms that would allow their introduction into T. aestivum. Some of these possibilities are being examined. Literature cited BITZER, M. T. and F. L. PATTERSON 1967. Pollen dispersal and cross pollination of soft red winter wheats. Crop Sci. 7 : 482-484. CAHN, E. 1925. A study of fertility in certain varieties of common wheat with respect to anther length and amount of pollen in parents and offspring. J. Amer. Soc. Agron. 17 : 291-595. JOPPA, L. R., F. H. MCNEAL and M. A. BERG 1968. Pollen production and pollen shedding of hard red spring (Triticum aestivum L. em THELL.) and durum (T. durum DESF.) wheats. Crop Sci. 8 : 487 -490. (Received March 3, 1970) |
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