Growth and yield of plantain cultivars at four sites of differing altitude in North Kivu, Eastern Democratic Republic of Congo.

Abstract

Abstract The Congo Basin is an important centre of diversity for plantain. Plantain is mainly grown below 1200 m above sea level (masl). However, some plantain cultivars can be found up to 2200 masl in the highlands along the Albertine Rift Valley in North Kivu. This study assessed the effect of altitude on plantain growth and yield at four sites in North Kivu (Mavivi, 1066 masl; Maboya, 1412 masl; Butembo, 1815 masl; Ndihira, 2172 masl). Five plantain (AAB genome group) cultivars commonly grown in North Kivu were assessed at each site. The cultivars were three from the 'French' clone set - 'Nguma', 'Vuhindi' and 'Vuhembe', and two 'False Horn' cultivars - 'Kotina' and 'Musilongo'. Fifteen vigorous sword suckers of each cultivar obtained from farmers' fields were planted in three replications of five plants, at each site. Growth and yield parameters were assessed over a period of 2.5 years. The same parameters were also assessed in 20 farmers' fields in Butembo, Maboya and Mavivi for 'Musilongo' and 'Kotina', while 'Vuhembe' was assessed at only one farm in Ndihira. At the experimental sites, plant height, pseudostem circumference and bunch weight generally decreased with an increase in altitude, while first crop cycle duration, time from flowering to harvest and mean number of suckers increased with altitude. At the flowering stage, the average parent plant height across the five cultivars varied significantly by site and was 239 cm at Maboya, 251 cm at Butembo, 258 cm at Ndihira and 316 cm at Mavivi. First crop cycle duration across all plantain cultivars ranged from 15.6 months at Mavivi to 28.8 months at Ndihira, while time from flowering to harvest ranged from 4.4 months at Mavivi to 7.9 months at Ndihira. The number of suckers per parent plant at flowering across the five cultivars increased from two at Mavivi to seven at Ndihira. The average bunch weight was significantly higher at the lowest site compared with the highest. The cultivars 'Kotina' and 'Vuhembe' seemed to be adapted to both low and higher altitude sites. A large number of partially developed and hence non-harvestable bunches were observed at Ndihira and, to a lesser extent, at Butembo. In addition, a significant increase in total rachis length was observed at Ndihira. Although there is a 400 m altitude difference between Maboya and Butembo, no significant difference was observed in bunch weight. The altitude effect is most probably overshadowed by the clayey and compact soil that reduced yield at Maboya. Similar growth and yield trends were observed in farmers' fields for plant height at flowering, time from flowering to harvest and bunch weight. These findings indicate that an increase in altitude and the corresponding lower temperatures negatively influence plant growth, first crop cycle duration and yield, while positively influencing suckering.