n2africa - putting nitrogen fixation to work for smallholder farmers in africa symbiotic...
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N2Africa - Putting nitrogen fixation to work for smallholder farmers in Africa
Symbiotic effectiveness of rhizobia and its effect on smallholder soyabean productivity in Zimbabwe
*Tatenda T Kainga 1, Sheunesu Mpepereki 1, Paramu L Mafongoya 1,Talkmore Mombeyarara 2,
Name Organisation1 University of ZimbabweAddress: P O Box MP167, Mt Pleasant, Harare, ZimbabweE-mail: [email protected], [email protected] , [email protected],ac.zw,[email protected] Phone: +263 772 646 772, +263 772 220 934, +263 773 100 818
Name Organization 2 International Centre For Tropical Agriculture
Address: P O Box MP228 Mt Pleasant, Harare, ZimbabweE-mail: [email protected] Phone: +263 772 572 727
Materials and methods
Study site description and Experimental design and treatmentsThe study was carried out in three districts of Zimbabwe, namely Mudzi, Mhondoro and Murewa which fall in three agro-ecological regions (II, III and IV) differentiated by rainfall distribution and temperature patterns (Fig 1)
Fig 1:Map showing the study area, i.e. the districts and wards in which field trials where carried out in Zimbabweexperimental design -Randomized Complete Block Design with two factors-variety and strain with three replicates
2 sites 25*40 m2 where selected from each district based on willingness of farmer, availability of land, soil type, cropping history and management of land
Each site- 3 blocks-16 sub-plots 3*4 m2 /block, 7 strains used to inoculate 2 varieties- SC Saga (specific) and TGX (promiscuous)
Basal Compound L (5% N, 18% P2O5, 10%K2O and 0.25% Boron) at 150Kg/ha at planting
Descriptive Statistics on biomass and grain yield were done using Genstat version 14
Background
The authors are grateful to CIAT-N2Africa for the funding and to AGRITEX for their collaboration
ReferencesAbaidoo, R.C., H.H. Keyser, P.W. Singleton, K.E. Dashiell and N. Sanginga. (2007) Population size, distribution and symbiotic characteristics of indigenous Bradyrhizobium spp. that nodulate TGx soyabean genotypes in Africa. Mpepereki, S. 2010 Technology adoption by smallholder farmers: lessons from the soyabean research/promotion program in ZimbabweGiller, K.E., Murwira, M.S., Dhliwayo, D.K.C., Mafongoya, P.L and Mpepereki SSoyabeans and sustainable agriculture in Southern Africa
Acknowledgements
Results and Discussion
Fig 2: soyabean grain yield for each of the three agro-ecological zones (a) shows grain yield attained from SC Saga a local hybrid specific variety (b) shows grain yield attained from TGX an imported hybrid promiscuous variety from Malawi
Fig 3: biomass yield attained at 50% flowering when biomass production as well as nitrogen fixation is at its peek (a) shows biomass yield attained by SC Saga and (b) shows biomass yield attained by TGX variety
Fig 4: Photo and (a) shows roots of two plants, the one on the left was inoculated with MAR1305 and the one on the right was inoculated with MAR1515 (b) shows a table with the mean scores attained after nodule scoring of the strains
There was a significant interaction between the agro- ecological region, strain and variety. There was a significant grain and biomass yield difference between the strains (p<0.001). The two varieties produced the highest grain and biomass yields after inoculation with strain MAR1305 producing yields ranging from 0.9-1.68 t/ha and 0.5-3 t/ha respectively as compared to the negative control and the reference strain MAR1491(commercial strain). Yields attained were in the order natural region2> natural region4>natural region3 in relation to the fertility of the fields used.ConclusionVarieties inoculated with MAR 1305 &MAR 1306 perform better than those inoculated with MAR 1491 in terms of grain and biomass yield. Also management of the land and the crop is important to ensure maximum benefits from inoculation
Soyabean has great potential to improve food, nutritional and income security of smallholder. Demand for soyabean in these areas has grown over the years (Mpepereki, 2010, Giller et al., 2011)
Picture 1:soyabean fields (a) soyabean crop on good soil and good management (b)soyabean crop on poor soil and poor management. Both field crops were inoculated using standard rate Native rhizobia populations are low and absent in these smallholder areas, hence there is need to inoculate to achieve favorable biomass and grain yields (Abaidoo et al., 2007)
New soil environments with low fertility- low pH, low organic matter soils also be explored to meet the soyabean increased demand.
This study aims to evaluate indigenous and exotic rhizobial strains and to identify promising soyabean- rhizobium combinations for smallholder cropping environments by measuring total nitrogen fixed, biomass and grain yield
a
MAR1305 MAR1306 MAR1326 MAR1494 MAR1497 MAR1515 neg-cntrl pos-cntrl0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1 MUREWA-NRII
MHONDORO-NRIII
CHIBVURA-NRIV
rhizobial strain
gra
in y
ield
t/h
a
MAR1305MAR1306MAR1326MAR1494MAR1497MAR1515 neg-cntrl pos-cntrl0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1MUREWA-NRII
MHONDORO-NRIII
CHIBVURA-NRIV
rhizobial strain
gra
in y
ield
t/h
a
neg-cntrl MAR 1305
MAR 1306
MAR 1326
MAR 1494
MAR 1497
MAR 1515
pos-cntrl0
500
1000
1500
2000
2500
3000
3500
4000MUREWA-NR II
MHONDORO-NR III
MUDZI-NR IV
rhizobial strain
bio
mas
s yi
eld
kg
/ha
neg-cntrl MAR 1305
MAR 1306
MAR 1326
MAR 1494
MAR 1497
MAR 1515
pos-cntrl0
500
1000
1500
2000
2500
MUREWA-NR II
MHONDORO-NR III
MUDZI-NR IV
rhizobial strain
bio
mas
s yi
eld
kg
/ha
a
b
Table 1: mean scores of strains in the different agro- ecolocical zones
TREATMENT
MEAN SCORE SC SAGA MUREWA NRII
MEAN SCORE TGX MUREWA NRII
MEAN SCORE SC SAGA MHONDORO NRIII
MEAN SCORE TGX NRIII
MEAN SCORE SC SAGA MUDZI NR IV
MEAN SCORE TGX NR IV
NEG-CNTRL 6.93 5.53 6.8 6.87 4.07 4.33
MAR1305 7.13 13 12.2 11.8 9.13 9.27
MAR1306 10.53 12.33 12.07 12.73 4.07 6.47
MAR1326 8.13 12.33 12.07 12.2 7.13 11.07
MAR1494 6.07 9.27 8.2 9.27 7.4 9.73
MAR 1497 4.6 9.27 4.4 9.2 - -
MAR1515 4.47 11.93 5 11.8 - -
POS-CNTRL 12.2 11.8 11.6 12.6 - -