| Anther size and pollen longevity in wheat/rye addition
lines R. S. ATHWAL and G. KIMBER Department of Genetics, University of Missouri, Columbia, Missouri, U.S.A. The development of hybrid wheat requires the solution of many problems in addition to those associated with the exploitation of heterosis. It would, for example, be advantageous to use, as male parents, lines which had large numbers of pollen grains, or lines that extruded their anthers prior to dehiscence, or lines with pollen of extended longevity. BITZER and PATTERSON (1967) have reported that seed set in wheat is directly related to the amount of wind-borne pollen. The amount of windborne pollen has been shown to be related to anther extrusion and anther size (JOPPA, MCNEAL and BERG 1968), whilst CAHN (1925) indicated that anther size may be simply inherited and directly related to the number of pollen grains per anther. Therefore, it is possible that increases of these parameters (anther size, anther extrusion and pollen longevity) may assist in the development of hybrid wheat. Variation in these characters is uncommon, possibly due to the fact that Triticum aestivum is usually self fertilized. A possible source of variation may be found in a related out-pollinating species such as rye. This note reports investigations of pollen longevity, anther size and extrusion in wheat, rye, a wheat/rye amphiploid and six addition lines derived from the amphiploid. The material, which was provided by Dr. E. R. SEARS, consisted of T. aestivum var. Chinese Spring, Secale cereale var. Imperial, the amphiploid of these species, and six of the seven possible addition lines, each with 21 pairs of wheat chromosomes and a single pair of rye chromosomes, except line E which had only one rye chromosome, designated 5R, 2R, C, D, E and 3R. In the investigations of anther size the length of mature anthers selected just prior to dehiscence from the primary floret of the middle spikelet on the first tiller was taken as proportional to anther volume. Four anthers, fixed in Carnoy's solution, were measured from each of four plants of the types listed above. The mean of the sixteen measurements on the four plants of each line was taken as the mean anther size of that line. From Table 1, where these measurements are listed, it is clear that rye has anthers approximately twice as long as wheat. The length of the anthers of addition lines 5R, D and 3R were significantly smaller than the anthers of all other addition lines. None of the other addition lines (2R, C and E) or the amphiploid had anthers that were significantly larger than T. aestivum. The anthers of rye were significantly larger than those of any other lines. This indicates that the small anther size of T. aestivum is epistatic in these lines to the larger anther size of S. cereale. |
| --> Next |