by A.M.Z. Chamango 1, Gomonda, R.W.J. 1, Mainjeni, C.E.D. 1, Msangosoko K.R. 1 and Kumwenda, R.L.N. 1 1 Agricultural Research and Extension Trust (ARET), Private Bag 9, Lilongwe, Malawi
Introduction Objectives Materials and Methods Results and Discussion Conclusion Acknowledgement
Tobacco: important export crop for Malawi Contributes 60-70% of forex base Contributes 12% to GDP Burley: 85-90% share of all tobacco
Low yield and poor quality leaf Multiple constraints limit productivity... biotic... abiotic... socioeconomic
Root galling Firing, chlorosis and stunting Root-knot nematodes Meloidogyne spp.
Fusarium wilt (F. oxysporum f.sp nicotianae) Damage on susceptible Burley cultivar often occur together with root-knot nematodes
Granville wilt / Bacterial wilt (Rolstonia solanacearum) Damage on susceptible Flue-cured tobacco cultivar
Angular leaf spot (Pseudomonas syringae pv. tabaci Tox-)
Brown Spot (Alternaria alternata) Damage on susceptible Fluecured tobacco cultivar
Significant yield and quality losses yearly Often together with Fusarium wilt No locally-bred resistant burley cultivars Imported sources; unaffordable & unsustainable Crop rotation known to reduce nematodes, but diminishing due to small land holdings Resistance key to IPM for managing nematodes ARET initiated breeding activity in 2009/10
To develop root-knot nematode (Meloidogyne spp.) resistant burley tobacco hybrids with high yield potential and other traits acceptable by the trade Widen choice of varieties with desirable attributes and enhanced productivity through hybrid technology responding to key constraints in tobacco industry
Pioneering crosses Susceptible adapted parents crossed with root-knot nematode resistant donors in 2009/10 season Fifty F 1 hybrids generated-subjected to preliminary screening in infested hotspots
Screening hotspots Kandiya Mwimba Agronomic evaluation in rotated lands KABWAFU Kandiya Mwimba Kabwafu KANDIYA MWIMBA
Disease screening in hotspots F 1 hybrids and 4 checks ( 3 OPVs: KBM 20, KBM 33 and Mkanachikhosi) and BRK4 Design and Plot size RCBD with 3 reps 1 row x 1.2 m x 7.2m long x 12 plants x 0.6m apart No topping, de-suckering and reaping
Agronomic evaluation in rotated lands 9 promising hybrids and 4 checks (same as earlier) Design and Plot size RCBD with 3 reps 2 rows x 1.2 m apart x 7.2m long x 12 plants x 0.6m apart Cultural practices done as recommended for burley by ARET
Nematode root galls: uprooting each plant, cleaning and assessing nematode root galling at 6 WAT using a 0-10 scale (Bridge and Page 1980) Fusarium wilt infected plants assessed as percentage of row population at 6 WATP Cured leaf yield Leaf quality parameters (colour and grade out-turn) Data analysis used ANOVA in Genstat and means separated by LSD test
Nematode root gall-rating (0-10) 10 9 8 7 6 5 4 3 2 1 0 2011/12 2012/13 2013/14 P 0.001 P 0.003 P 0.001 Burley Tobacco Cultivars
10 Nematode root gall-rating (0-10) 9 8 7 6 5 4 3 2 1 0 Burley Tobacco Cultivars P=0.045
Fusarium wilt infected plants (%) 100 90 80 70 60 50 40 30 20 10 0 2011/12 2012/13 2013/14 P 0.001 Burley Tobacco Cultivars
Fusarium wilt infected plants (%) 100 90 80 70 60 50 40 30 20 10 0 Burley Tobacco Cultivar
Nematode root gall-rating (0-10) 10 9 8 7 6 5 4 3 2 1 0 Root-knot nematode Burley Tobacco Cultivar Fusarium wilt 100 90 80 70 60 50 40 30 20 10 0 Fusarium wilt infected plants (%)e
ABH 31 at Kandiya Sick plot, 2012/13 season ABH 15 at Kandiya Sick plot, 2012/13 season
Cured leaf yield (Kg/ha) 3000 2500 2000 1500 1000 500 0 2011/12 2012/13 2013/14 Burley Tobacco Cultivar P=0.033
Mkanachikhosi at Kandiya Sick plot, 2012/13 season ABH 43 at Kandiya Sick plot, 2012/13 season
2500 Cured leaf yield (Kg/ha) 2000 1500 1000 500 0 Burley Tobacco Cultivar
ABH 31 in rotated lands at Kandiya 2012-13 ABH 12 in rotated lands at Kabwafu, 2012-13
70 % Buff % Tan % Red Colour distribution (%) 60 50 40 30 20 10 0 Burley Tobacco Cultivar
40 % 1st quality % 2nd quality % 3rd quality % 4th quality % 5th quality 35 Grade out-turn (%) 30 25 20 15 10 5 0 Burley Tobacco Cultivar
ABH 12 was found to be moderately resistant to root-knot nematodes only compared to the rest of the test hybrids ABH 43 and ABH 31 consistently combined moderate resistance to rootknot nematodes and Fusarium wilt while the rest of the test hybrids proved as being susceptible
ABH hybrids gave comparable cured leaf colour distribution and grade out-turn to the check varieties; KBM 33, KBM 20, Mkanachikhosi and BRK 4. ABH cultivars demonstrated potential for producing equally acceptable leaf grades compared to varieties currently being grown in Malawi
ABH 12 was accepted for release as a burley tobacco hybrid moderately resistant to root-knot nematodes while ABH 31 and ABH 43 were accepted for release as burley hybrids moderately resistant to root-knot nematodes and Fusarium wilt in Malawi
Tobacco growers, other smallholder burley tobacco farmers and leaf merchants for their cooperation and participation during testing Co-authors for input and constructive criticism CORESTA Secretariat for the opportunity to present