| Popis: |
Banana (Musa acuminata AAA) is the most exported fruit worldwide and represents a major source of revenue for Central American and South American countries as well as the Caribbean region, among others. Black leaf streak disease (BLSD) or black sigatoka, caused by Pseudocercospora fijiensis (formerly Mycosphaerella fijiensis), is responsible for significant losses to this crop due to the high susceptibility of the most economically important cultivars. BLSD does not immediately kill banana plants, but it causes severe leaf necrosis that results in reduced photosynthetic area, thereby adversely impacting bunch weight and fruit production. Without cultural and chemical control, yields can be reduced by 20% to 80%, depending on severity. This study evaluated ‘FHIA-17’, a BLSD-resistant synthetic hybrid (AAAA), against ‘Grand Nain’, a standard commercial cultivar with no BLSD tolerance, at two locations in Puerto Rico on Ultisol (Corozal site) and Oxisol (Isabela site) soils where BLSD was not managed. Significantly lower bunch yield (45,990 kg·ha−1) and significantly fewer fruit (220,671 fruit/ha) were obtained at Corozal than at Isabela (53,755 kg·ha−1; 380,241 fruit/ha). Lower production at Corozal was the result of higher severity of BLSD at this location than at Isabela and to soil factors interfering with optimum nutrient uptake. Average fruit production of ‘FHIA-17’ was significantly higher than that of ‘Grand Nain’ at both locations, with bunch yields of 68,105 and 72, 634 kg·ha−1 at Corozal and Isabela, respectively. Fruit of the third-upper hand was significantly longer for ‘FHIA-17’ at Corozal but not different at Isabela; however, ‘FHIA-17’ fruit in this hand were of significantly greater diameter. Fruit in the last hand of ‘FHIA-17’ were significantly longer than in ‘Grand Nain’ at Corozal, but of significantly greater diameter at both locations. At both locations, the mean fruit weight was significantly higher in ‘FHIA-17’ than in ‘Grand Nain’. The number of functional leaves present at flowering and at harvest was significantly higher in ‘FHIA-17’ than in ‘Grand Nain’ at both locations, indicating more availability of photosynthetic area in ‘FHIA-17’ during the fruit-filling period. The harvest cycle of ‘FHIA-17’ was significantly longer than for ‘Grand Nain’. It took 315 and 204 more days in Corozal and Isabela, respectively, to harvest three cycles (mother crop and two ratoon crops) of ‘FHIA-17’ than for ‘Grand Nain’. No significant differences were found for starch and soluble sugars in green unripe or fully mature fruit among cultivars. In this long-term study, ‘FHIA-17’ showed to have good production and resistance against BLSD and is a viable alternative to current commercial cultivars. Its relative advantage of reduced production costs by not needing fungicide applications should be weighed against its longer harvest cycle to produce a fruit bunch. |
