Abstract:
It is well known that the parasitic weed Striga asiatica (L.) Kuntze can be suppressed by Striga-tolerant sorghum
(Sorghum bicolor L. Moench) cultivars, Desmodium intortum (Mill.) Urb. (greanleaf desmodium), and by fertilization
with nitrogen. The study objective was the assessment of Striga control provided by integration of Desmodium density,
timing of sorghum-Desmodium intercrop establishment, and nitrogen fertilization. Growth responses and yield of three
sorghum cultivars were measured in three pot experiments. A soil naturally infested with Striga was used, and that
part of the soil which served as uninfested control was chemically sterilised. Striga numbers and growth were affected
significantly by sorghum cultivars, sorghum-Desmodium intercrop ratios, timing of the sorghum-Desmodium association,
as well as by their interactions. Desmodium caused 100% suppression of Striga emergence when Desmodium
was established in the 1:3 sorghum-Desmodium ratio at seeding of sorghum. Total control of Striga was also achieved
with the 1:1 sorghum-Desmodium ratio when Desmodium was transplanted 30 days before sorghum seeding. However,
these two treatments also caused significant reductions in sorghum yield. In contrast, 100% Striga control and a
dramatic increase in sorghum yield were achieved with 100 kg N ha −1 in the 1:1 sorghum-Desmodium intercrop. Compatibility
of sorghum and Desmodium was evident at the 1:1 sorghum-Desmodium intercrop established at sorghum
seeding. Overall, the Ethiopian cultivars Meko and Abshir showed better agronomic performance and higher tolerance
to Striga than the South African cultivar PAN 8564. It is recommended that the N× Desmodium× sorghum interaction
be investigated under field conditions.
