Variability Effect of Witchweed [Striga hermonthica(Del.) Benth.]Populations on the Performance of [Sorghum bicolor) cv. ‘Abu sabeen’ in Sudan

Abstract

Field surveys and a green house experiment were conducted
during season 2009/2010 to investigate variability and host specificity of
witchweed Striga hermonthica populations. The field surveys were
conducted in S. hermonthica endemic areas in Gadarif, Gezira and
Kordofan to collect seeds from striga plants growing under their respective
hosts. A total of fifteen S. hermonthica populations were collected.
Twelve S. hermonthica populations, were collected from under sorghum
and three. were collected from under millet. Laboratory and green house
experiments were undertaken at the horticulture nursery, Faculty of
Agricultural Sciences, University of Gezira, Sudan, to test the viability
and infectivity of seeds of witchweed populations on sorghum, cultivar
“Abu-sabeen”, a highly susceptible cultivar. Data collected were
transformed as necessary and were statistically analysed. Results showed
that all S. hermonthica seed populations displayed high germination %
ranging from 87.0 % to 92.3 %, regardless of the area, location and the
host crop. Capsules per plant, shoot dry weight and underground plantlets
of emergent striga were highest on the respective host. It is noteworthy
that some of the millet striga populations displayed limited emergence at
60 days after crop emergence on sorghum and produced capsules.
S. hermonthica populations significantly reduced growth and yield of
sorghum. However, the magnitude of the damage attained by each
population was highest on the respective host, thus indicating the
existence of inter-crop specialization and probably the existence of two
strains of S. hermonthica, one specific to sorghum and the other to millet.
These findings may provide clues on the complexity of breeding sorghum