Abstract:
Performances of three sorghum (Sorghum bicolor L. Moench) genotypes (Wahi,
Hakika and Pato) and inorganic soil amendments were studied under naturally Striga
asiatica [L.] Kuntze infestation for one cropping season (2015/16) in two locations,
using a split plot design laid out in a randomized complete block design with four
replications. A susceptible sorghum (Pato cultivar) was used as a bioassay to
evaluate the effectiveness of reduced rates of N under Striga infestation. At
Hombolo, 40 Kg N/ha had significantly (P< 0.05) lower emerged Striga shoots
count/m2 than all other rates of N, except at 11 WAP. Yields with 30 Kg N/ha
(0.64t/ha) was significantly (P< 0.05) lower than yields from all other rates of
nitrogen (1.08 - 1.52t/ha). At Ngamu, fertilization played no significantly (P< 0.05)
role in Striga emergence and attachment. Yields with 10 Kg N/ha (4.89t/ha) was
significantly (P< 0.05) lower than yields from all other rates of nitrogen (5.2 –
6.0t/ha). Across locations, variety Hakika had significantly (P< 0.05) fewer emerged
Striga shoots count/m2 compared with varieties Wahi and Pato. At Hombolo, Yields
on Hakika variety (0.96t/ha) was significantly (P< 0.05) lower than the yield in all
other varieties (1.21 - 1.28t/ha). At Ngamu, variety Pato gave more yields (7.21t/ha
than other varieties (2.81 – 5.95t/ha). This study showed that the most effective rates
of nitrogen; 40 and 60 Kg N/ha (Hombolo) and 50 Kg N/ha (Ngamu) should be
promoted in semi-arid areas of Tanzania where Striga poses a serious threat. Results
also showed that varieties Hakika and Wahi proved their resistance/ tolerance to
Stiga asiatica compared to variety Pato.
