Therefore, the PMGF values presented in this work should be treated as upper-bound estimates in subsequent forms of population modeling requiring PMGF as an input parameter.
While we recognize the inherent difficulties in modeling PMGF, consideration must be given to the cumulative effects of the factors outlined in this letter before making generalized conclusions regarding PMGF in wheat such as those made by Gustafson et al.
Time and distance may be employed together to limit PMGF.
However, there are no studies directly comparing PMGF from different plot sizes under similar environmental conditions, and the effect of plot size cannot be assessed here.
The male-sterile border was a part of the practical model we evaluated, and our results are insufficient to establish whether such bordering is indeed effective in reducing PMGF in maize.
The influence of humidity on PMGF may perhaps be understood on a population basis, where the proportion of viable pollen grains in a population available for dispersal is reduced more quickly under arid than under more humid conditions.
In sum, Davies has done us a considerable and lasting service by integrating PMG and SLG in PMGF I.
With Lobel and Page's Fragmenta Poetarum Lesbiorum out of print for some time, and with PMG and SLG now out of print, Oxford has left us with only Page's Lyrica Graeca Selecta (1968) as an alternative to PMGF.
The eventual fate and persistence of the gene(s) delivered to the recipient crop populations as a result of PMGF are variable, depending partly on what is done with the harvested grain and partly on physiological and ecological factors.
In this paper, we define PMGF to include all such seed regardless of viability and fertility because it could produce detectable genetic material in the seed of the recipient population.
Several studies have been conducted to measure PMGF in commercially available spring and winter wheat cultivars (Table 1).
The extent of PMGF in wheat is low, largely because wheat is predominantly (>99%) self-pollinating (Harrington, 1932).