Future Prospects - Genetics, Genomics and Breeding of Crop Plants - page 322

itself across the northern tier of the US, and from new maize and soybean
cultivars that are adapted to northern environments.
Other factors in addition to displacement to less fertile regions also
contributed to static or intermittent decreased yields. Small, but noticeable
yield declines were occasionally observed during the hybrid sunflower era
when significant new traits were introduced into hybrids. When NuSun ®
hybrids, with mid-oleic fatty acid composition, were first introduced into
the US early in the first decade of the millennium, a yield “drag” was
perceived by some producers. This was quickly overcome in the subsequent
years by commercial breeders such that current NuSun ® hybrids outperform
most traditional high-linoleic hybrids. A similar transitional period is
currently in progress with herbicide resistant sunflower hybrids. In the
future, parallel transient decreases in yield followed by rapid recovery can
be expected when major nonyield genetic improvements are made to
sunflower. Sunflower that has been genetically modified (GMO) to
incorporate genes from other species for useful new agronomic traits would,
if introduced into commercial cultivation, likely follow a similar path.
Irrigation, as expected, increases yields dramatically. Company-
sponsored sunflower yield contests have not typically been offered in the
US, but anecdotal evidence from producers suggests that yields of over 4,500
kg ha -1 are possible for irrigated oilseed sunflower hybrids under optimum
fertilization. Such a yield is three-fold higher than the average US yield in
recent years. Market reality suggests, however, that large-scale irrigation of
sunflower is unlikely in the future. Producers with an irrigation option are
more likely to put other lucrative crops such as maize under irrigation, and
to utilize sunflower under dryland conditions due to its superior ability to
capture available moisture. Thus, in many countries, if formerly productive
regions of sunflower cultivation were to re-establish themselves as major
growing areas, the average annual yield of sunflower would increase
dramatically. However, this is not likely in the near future due to increased
attention to maize and soybean production worldwide.
10.3 Impact of Advances in Sunflower Genomics
The past decade has been marked with milestones in sunflower genomics
research that included the construction of linkage maps using various
molecular markers, such as RFLP, RAPD, AFLP, SSR, TRAP, and InDel
(insertion/deletion), the establishment of genetic transformation methods,
and the sequencing of thousands of ESTs (expressed sequence tags) of the
cultivated sunflower and its related species. These milestones have an
enormous impact on addressing problems in both fundamental biology
and applied genetic improvement of this crop.