ARET, Annual Report 2001, p. 14-9.

Preliminary yield trial of granville wilt resistant breeding lines

ARET, Agricultural Research and Extension Trust, Lilongwe, Malawi
The performance of twenty-three lines selected at Chiwale Estate in 1999/2000 was compared with two checks, KE1 and C371G, in a 5 x 5 simple lattice with two replicates at Makoka Valley Estate. Plot size was 24 plants gross and 20 plants net at an intra and inter row spacing of 0.6 metre and 1.2 metre respectively. All other cultural practices were according to the current recommendations for production of flue-cured tobacco. Field data collected to compare the performance of the varieties included leaf length and width, plant height at topping and after harvest, leaf count at topping, and scores of all diseases observed during the course of crop growth. Root galling by nematodes was recorded after final harvest. The varieties were rated for alternaria and root galling. Post harvest data were recorded for yield, grade distribution and gross earning per hectare were calculated based on a three-year average of prices indices provided by the trade. Other derived variables included; leaf area and internode length. Eight lines were significantly more resistant to Alternaria brown spot than both controls. All the top yield and gross earning performers were more resistant to nematodes than KE1 but had similar scores as those for C371G. Seven of the twenty five lines AF11-02, AF2-01, AF15-07, AF15-08, AF15-10 and AF12-02 produced double the of KE1 and these lines had large leaf area with 18-19 leaves per plant and 5 to 6 cm internode length. The severity of alternaria and root-knot nematode was low to select lines resistant to these diseases.