On-farm evaluation of potato genotypes for yield and late blight resistance in Malawi.

Potato production in Malawi is characterized by low yields with poor quality tubers. To some extent this has been attributed to use of low yielding varieties and poor quality seed tubers. In attempt to address the situation there is a potato variety development program whose overlying objective is to identify high yielding varieties, tolerant to major diseases and insect pests that are also adaptable to local environmental conditions. During the 2012-13 rain fed season, potato clones introduced from breeding programs from International Potato Center (CIP)-Peru, CIP-Kenya and Scotland were evaluated in a uniform yield trial (UYT) for yield and resistance to Late Blight. Two sets of on-farm trials were implemented at Mpalare (Dedza District) and Tsangano (Ntcheu District). The experimental trials were arranged in RCBD with three replications. All the recommended crop management practices were followed in addition to spraying Dithane M45 against Late Blight. Data was collected following the CIP laid procedures. Results from the first set of trials implemented at both sites, showed significant yield difference (P<0.001) across sites. Mpalare site produced high mean yield of 13.09 t/ha while Tsangano had a mean yield of 6.98 t/ha. There were also significant yield differences (P<0.05) among testing clones at the two sites. The highest yielding clone at Mpalare was Atlantic (15.60 t/ha) which had also the lowest Late Blight infestation of 10%. At Tsangano site, the highest yield was recorded from Red Pontiac (10.86 t/ha). The lower yields at this site may partly be attributed to relatively high incidence of Late Blight which averaged 25%. The second set of trials was implemented at Mpalare site showed significant yield differences (P<0.05) among the clones. The highest and lowest yields recorded from clones Desiree (23.02 t/ha) and Pukara-inia (10.8 t/ha). There was also relatively low Late Blight incidence which averaged 15%. The lowest infestation was recorded from Desiree (10%). Out of the 12 clones evaluated, 8 clones (Desiree, Pure-inia, Karu-inia, Pehuenche, Pukara-inia, 396033.102, Red Pontiac and Epicure) produced yields of more than 10 t/ha which is the current acceptable benchmark yield. Importantly, almost all the clones produced large sized tubers with more than 75% of total yield comprising of tubers with >35mm diameter. These results confirm the superiority of these clones and suggest their high potential to be released as varieties upon undergoing further multi-location evaluation as well as passing through the variety release committee of Malawi.