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The globalization of the economy, increased ethnic diversity, and a greater demand for healthy and more diverse food production has increased the demand for tropical fruits. There is a lack of formal experimentation to determine yield performance and fruit quality traits of lychee (Litchi chinensis) cultivars. Six lychee cultivars (Bosworth-3, Brewster, Groff, Mauritius, Kaimana, Salathiel) grown on Mollisol and Inceptisol soils were evaluated for 8 years at the Adjuntas Agricultural Experiment Station of the University of Puerto Rico (UPR-Adjuntas) and La Balear farm, Adjuntas, Puerto Rico, respectively. At UPR-Adjuntas and La Balear, cultivar Groff had a significantly higher production (257,296 fruit/ha) of total fruit than other cultivars, whereas Salathiel had the lowest. However, total fruit production of ‘Groff’ was not significantly different from ‘Kaimana’ and ‘Bosworth-3’at La Balear. At UPR-Adjuntas, cultivars Groff and Bosworth-3 had significantly higher number of marketable fruit than the rest of the cultivars averaging 171,760 fruit/ha. At La Balear, ‘Kaimana’ had a higher number of marketable fruit, but it was not significantly different from ‘Groff’, ‘Bosworth-3’, and ‘Mauritius’, averaging 291,360 fruit/ha. At both sites, individual fruit weight of marketable fruit was higher in ‘Kaimana’ than the rest of the cultivars. However, at La Balear, there were no significant differences between ‘Kaimana’ and ‘Mauritius’. At both locations, cultivars exhibited erratic production patterns, which were characterized by lower production during 1 or 2 successive years following heavy cropping. At current farm gate prices and fruit yield reported in this study, cultivars Groff, Bosworth-3, and Kaimana can generate a good income for growers, and allow them to diversify crops as part of their farm operations.

Plantain (Musa balbisiana AAB) is a tropical rhizomatous perennial plant in the genus Musa spp., closely related to banana (Musa acuminata AAA). It is an important cash crop and staple for inhabitants in many parts of the world, including various ethnic groups in the United States. Black leaf streak disease (BLSD) or black sigatoka, caused by Pseudocercospora fijiensis (formerly Mycosphaerella fijiensis), is responsible for significant losses of this crop due to the high susceptibility of the most economically important cultivars. BLSD does not immediately kill plantain plants, but it causes severe leaf necrosis, which 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 a BLSD-resistant cultivar, FHIA-21, against Maricongo, a standard commercial cultivar with no BLSD tolerance, at two locations in Puerto Rico on Ultisol (Corozal site) and Oxisol (Isabela site) soils. Total number of fruit and bunch yield were significantly higher at Isabela, with BLSD severity being significantly lower at this location. Average fruit production of ‘FHIA-21’ was significantly higher than that of ‘Maricongo’ at both locations, with fruit yields of 122,522 and 99,948 fruit/ha at Isabela and Corozal, respectively. Overall, fruit of ‘FHIA-21’ were significantly longer and had greater diameters than those of ‘Maricongo’. At Isabela, the mean bunch fruit weight was significantly higher for ‘FHIA-21’, but both cultivars exceeded the minimum local marketable fruit weight criterion of 270 g. At both locations, the numbers of functional leaves present at flowering and at harvest were significantly higher for ‘FHIA-21’ than for ‘Maricongo’, indicating more availability of photosynthetic area for ‘FHIA-21’ during the fruit-filling period. There were no significant differences between cultivars regarding the concentration of starch and soluble sugars for green fruit. Regarding ripe fruit, ‘FHIA-21’ had a significantly higher concentration of soluble sugars and less starch. In this study, ‘FHIA-21’ had good resistance against BLSD and, if accepted by consumers, is a viable alternative to current commercial cultivars. We also conclude from this study that the expression of the Banana streak virus (BSV) in planting material of this cultivar remains an unknown threat in yield decline of ‘FHIA-21’.

Dragon fruit (Hylocereus sp. and Selenicereus sp.), also referred to as pitahaya or pitaya, is a member of the Cactaceae family and native to the tropical forest regions of southern Mexico, Central America, and northern South America. Its fruit is becoming increasingly popular as consumers seek healthy and more diverse food products. The crop adapts to different ecological conditions ranging from very dry regions to wet ones receiving more than 3500 mm of rainfall per year. U.S. commercial production of dragon fruit occurs mainly in Florida, southern California, and Hawaii. As growers learn more about this crop and how productive it can be, the acreage planted is likely to increase. Twelve dragon fruit cultivars grown on an Oxisol soil were evaluated for 5 years under intensive management at Isabela, PR. There were significant differences in number and weight of fruit per hectare among years. Cultivars exhibited an increase in fruit number and yield from 2010 to 2013 and then leveled off or declined. There were significant differences among cultivars for number of fruit and yield per hectare. Cultivars N97-17 and N97-15 produced significantly more fruit averaging 74,908 fruit/ha. Significantly higher fruit yield was obtained by cultivars N97-17, N97-20, N97-22, and NOI-13 averaging 17,002 kg·ha⁻¹. Cultivar Cosmic Charlie had the lowest fruit yield, averaging only 25.1 kg·ha⁻¹. Individual fruit weight was significantly higher in cultivars N97-20 and NOI-13 with fruit weight averaging 346.3 g. Cultivars NOI-16, N97-18, and Cosmic Charlie had significantly higher fruit soluble solids than others, averaging 17.4%. Some of the cultivars used in this study have shown horticultural potential and may serve as new planting material for growers.

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.

Little is known about the adaptability of lychee (Litchi chinensis) to acidic soils high in aluminum (Al). A 2-year greenhouse study was conducted to determine the effects of various levels of soil Al on dry matter production, plant growth, and nutrient concentration in shoots of lychee cultivar rootstock seedlings (maternal half-sibs) of cultivars Brewster, Bostworth-3 (Kwai May Pink), and Kaimana. Soil Al treatments were statistically different for all variables measured in the study but not rootstock seedlings. Total leaf, stem, and root dry weights significantly decreased at soil Al concentrations ranging from 0.42 to 12.69 cmol·kg⁻¹. Increments in soil Al resulted in a significant reduction in the concentration of leaf calcium and phosphorus and a significant increase in leaf Al in cultivar rootstock seedlings. The concentration of leaf potassium, magnesium, iron, zinc, and boron were in the optimum range for lychee, whereas leaf nitrogen and manganese concentrations were above optimum. The results of this study demonstrated no cultivar rootstock seedlings differences for dry matter production in lychee trees grown under Al stress and demonstrate that lychee is highly susceptible to acid soils.

Research on sapodilla (Manilkara zapota) has been very limited. A field study was conducted to determine the yield potential, fruit quality traits, leaf nutrient composition, and scion/rootstock compatibility of ‘Prolific’ sapodilla grafted onto 16 sapodilla rootstock seedlings. For this purpose, seedlings (maternal half-sibs) of cultivars Adelaide, Arcilago, Aruz, Blackwood, Blocksberg, Guilbe, Hanna, Jamaica-1, Larsen, Mendigo-1, Gallera, Morning Star, Russel, Prolific, Timothe, and Vasallo-1 were used as rootstock seedlings and evaluated during 7 years of production at Isabela, PR. Year showed a significant effect on the number of fruit per hectare, yield, individual fruit weight, fruit length and diameter, and total soluble solids. Rootstock seedlings had a significant effect on the number of fruit per hectare, yield, and individual fruit weight but had no effect on other fruit traits. The year × rootstock interaction was not significant for any of the variables measured in the study. Rootstock seedlings ‘Timothe’, ‘Vasallo-1’, ‘Larsen’, and ‘Aruz’ had the highest 7-year mean for number and the yield of fruit averaging 4479 fruit/ha and 1245 kg·ha⁻¹, respectively. ‘Timothe’ and ‘Vasallo-1’ significantly out yielded the ‘Prolific’ rootstock seedling. The number of fruit per hectare and corresponding yield obtained in this study were very low probably as the result of wind exposure, the presence of the fungus Pestalotia causing floral necrosis, or both. Scion/rootstock incompatibility was not the cause of the low yield performance of grafted trees. The average individual weight of fruit was 282 g and ranged from 264 to 303 g. Averaged over rootstock seedlings, leaf tissue nutrient concentration did not vary greatly over time. Moreover, tissue nutrient concentration was similar before and after fertilization events.