Final version of Tropical Legumes II Project Report for Phase 1 - icrisat

At TSBF-CIAT in Kenya, a study was conducted to assess the nodulation and nitrogen fixation of a set
of nine indigenous Bradyrhizobium strains inoculated on three promiscuous soybean varieties grown
under greenhouse conditions. Seedlings of three promiscuous soybean varieties (TGx 1895-33F, TGx
1895-49F and TGx 1740-2F) were each inoculated with 3 ml each (10 8 cell mL -1 ) of pure indigenous
Bradyrhizobium strains (TSBF 404, TSBF 101, TSBF 131, TSBF 531, TSBF 534, TSBF 331, TSBF 442,
TSBF 344, TSBF 3360). Negative and positive (98 kg per ha N equivalent) controls were also included.
The seedlings were grown in 2 kg sand filled polybags, kept at field capacity by alternate day watering
with double distilled water and Broughton solution in a greenhouse at approximately 12/12 light and
25 o C/32 o C. Seedlings were harvested at R1 growth stage for each of the genotypes and nodule number
and shoot biomass recorded. All samples were dried to constant weight for 48 hrs at 70 o C. Shoot
dry weight (SDW) was recorded as it is used as proxy for nitrogen fixation. There was no interaction
between strains and varieties on shoot dry weight (Figure 11-4).
Shoot dry weight (g)ht t
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
bc
b
cd
b
b
b
b
b
b
cd
0.2
0.1
d
0
TSBF 404
TSBF 101
TSBF 131
TSBF 531
TSBF 534
TSBF 331
TSBF 442
Bradyrhizobium strains
TSBF 344
TSBF 336A
USDA 110
Control
Figure 11-Shoot dry weight of three promiscuous soybean varieties grown in sand under greenhouse conditions
However, there was a highly significant (P