Assessment of Phenological and Morphological Characteristics of Banana (Musa sp.) to Determine Potential for Fruit Production in Coastal Alabama

Banana (Musa sp.) cultivation has expanded beyond tropical origins and into the subtropics due largely to the development of cold-tolerant, short-cycle banana cultivars.  A study was initiated in Coastal Alabama to determine feasibility of banana fruit production and best-suited cultivars.  Thirteen banana cultivars representing four genetic groups and three groups based on plant height—dwarf, medium, and tall, were planted in Fairhope, AL on June 5, 2013.  Bananas were blocked according to plant height and were arranged using a completely randomized design with five single plant replications.  Mother plants (plants of the initial season) were subjected to winter temperatures of –l0 °C during late December 2013 and early January 2014, which were uncharacteristically low for coastal Alabama.  Mother plants succumbed; however, the first ratoon plants (R1), or suckers generated from the lateral meristems below the base of the mother plant began to emerge in early spring 2014 and exhibited vigorous growth. Cultivars ‘Cardaba’ (ABB genetic group) and ‘Gold Finger’ (AAAB genetic group) fruited in a single season, which was unexpected in a variable and extreme subtropical environment.  Data were collected at various days from the juvenile stage of R1 suckers (DFJ).  At each DFJ, ‘Cardaba’ plants were statistically larger than ‘Gold Finger’ as exhibited by taller pseudostems with thicker circumferences.  Pseudostem height: circumference ratio (HCR) of ‘Gold Finger’ was consistently lower than ‘Cardaba’ at each DFJ and therefore was theoretically less prone to lodge due to crop load or high winds.  At the time of flowering, total leaf number (TLN) of ‘Cardaba’ and ‘Gold Finger’ was 26 and 28 respectively.  Flower emergence is expected to occur at a total leaf number of 30-50.  Leaf emergence rate (LER) reached maxima in August and declined in September and October as temperatures lowered.  Leaf area index (LAI) was significantly higher for ‘Cardaba’ than ‘Gold Finger’ at 60 and 88 DFJ but was statistically similar at subsequent DFJ.  Number of leaves present (NLP) increased quadratically for both cultivars and at flower emergence, 16 and 15 leaves were present for ‘Cardaba’ and ‘Gold Finger’, respectively.  A minimum of four leaves is required to promote bunch maturity.  Flower emergence occurred at 197 and 238 DFJ for ‘Cardaba’ and ‘Gold Finger’ respectively.  These preliminary results are encouraging: Banana cultivars exhibited vigorous growth and fruiting of banana cultivars support the hypothesis that environmental conditions of Coastal Alabama are sufficient for subtropical banana fruit production.