Plantain cultivars (Musa spp. AAB) grown at different altitudes demonstrate cool temperature and photoperiod responses relevant to genetic improvement

Abstract

Knowledge of plant development in plantains is needed to manage seasonal variation in production and better match critical development phases with appropriate seasons. Plantains have juvenile, mid-vegetative and floral phases leading up to flowering (bunch emergence). We examined whether the juvenile phase showed a cool temperature response, whether the mid-vegetative phase was sensitive to photoperiod and how these phases were related to growth of lateral shoots (suckers) up to flowering. We examined published data of an experiment of five plantain cultivars grown at four altitudes, and therefore temperatures (1000m, 24°C to 2200m, 16°C) within 1° latitude of the equator in the Democratic Republic of Congo. Four of the five cultivars showed a cool temperature response in the juvenile phase. Plants grown in cool temperatures (16°C) ended the juvenile phase after producing 7 leaves. In warmer climates (24°C) 15 leaves were produced before the juvenile phase ended. All five cultivars demonstrated a high capacity to respond to photoperiod in the mid-vegetative phase. There were detectable differences in capacity of the cultivars to respond to photoperiod, Ps. ‘Vuhindi’ had the least capacity (Ps=90) and ‘Musilongo’ and ‘Vuhembe’ the greatest (Ps=145). Across altitudes, suckers began to appear above ground at just after the end of the juvenile phase and there was a strong positive linear correlation (r2=0.97) between the calculated phyllochron (10–27 days) and the proportion of lateral buds that grew into suckers. With a phyllochron of 10 days about 10% of the lateral buds present on the plant produced lateral shoots up to flowering. At 27 days, from 40% to 80% of the lateral buds produced suckers depending on the cultivar. The responses of the juvenile phase to low temperature and the mid-vegetative phase to photoperiod in Musa spp. opens the opportunity to alter plant development and produce cultivars better suited to the climates where they are currently grown and to extend this range.