Tissue-cultured, virus-tested (TC) plantlets of sweetpotato (Ipomoea batatas var. batatas) cultivars Okinawan, LA 08-21p, and Murasaki-29 were obtained from Louisiana State University Agricultural Center. The objectives of field trials conducted at the Kula Agricultural Park, Maui, HI, were to compare yield and pest resistance of 1) ‘Okinawan’ obtained from a commercial (C) field with TC ‘Okinawan’ and 2) TC Okinawan with the aforementioned TC cultivars. Trials were planted Oct. 2015 and Aug. 2016 and harvested 5 months later. Storage roots were graded according to State of Hawai’i standards, and marketable yields included Grades AA, A, and B. In addition, injuries due to sweetpotato weevil (Cylas formicarius elegantulus) or rough sweetpotato weevil (Blosyrus asellus) were estimated. In both trials, fresh and dry weights of marketable storage roots of TC ‘Okinawan’ were nearly twice those from commercial planting material. In both trials, marketable fresh weights differed among the three TC cultivars; however, significant interactions were found, indicating that yields of cultivars differed between years. In the first field trial, ‘LA 08-21p’ had fresh marketable yields 1.6 to 1.7 times greater than TC ‘Okinawan’ and Murasaki-29, respectively. In the second trial, fresh marketable yields of TC ‘Okinawan’ and ‘LA 08-21p’were similar and 1.7 to 1.5 times greater than that of ‘Murasaki-29’, respectively. In both trials, ‘LA 08-21p’ had greater sweetpotato weevil injury than did the other two cultivars. Interestingly, in the second year, TC ‘Okinawan’ had greater rough sweetpotato weevil injury than did the other cultivars. Our results indicate that tissue-cultured planting materials increased marketable yields of TC ‘Okinawan’ compared with C ‘Okinawan’ sweetpotato and that the other TC cultivars did not produce greater yields than TC Okinawan.
Susan C. Miyasaka, Sharon Motomura-Wages, Ishakh Pulakkatu-Thodi, Michael J. Melzer, Christopher A. Clark, Don R. LaBonte and Arthur Q. Villordon
Susan C. Miyasaka, Marisa Wall, Don LaBonte and Alton Arakaki
Twelve sweetpotato (Ipomoea batatas var. batatas) accessions/cultivars/landraces (entries) were evaluated for yield, resistance to pests, and quality in five field trials planted at Pepe`ekeo, Hawai‘i Island, and replicated over time with blocks planted on May and Oct. 2014, Feb. and July 2015, and Jan. 2016. Plots were harvested at 4.5 to 6 months after planting. In the first two field trials, local entries planted were ‘Okinawan’, ‘Mokuau’, and ‘Kona B’, as well as PI 531094, ‘Beauregard’, PI 573309, PI 573330, ‘Darby’, ‘Pelican Processor’, and ‘Picadito’. Yields of ‘Mokuau’ and ‘Kona B’ were low and were replaced in the latter three field trials with ‘Murasaki-29’ and ‘LA 08-21p’ from Louisiana State University (LSU) AgCenter, Baton Rouge. At harvest, storage roots were graded according to State of Hawai‘i standards and marketable yields included grades AA, A, and B. Then, injuries of storage roots due to infestations of sweetpotato weevil (Cylas formicarius elegantulus) in each category were estimated. Finally, sugar concentrations, anthocyanins, and β-carotene contents were measured in storage roots. Marketable fresh weight yields of entries differed significantly, with ‘LA 08-21p’ having the greatest marketable yield. However, ‘LA 08-21p’ also had the greatest incidence of damage due to sweetpotato weevil, perhaps because of its growth habit as a tight cluster of storage roots located close to the soil surface. Entries also had significantly different sugar concentrations (fructose, glucose, sucrose, maltose, and total sugars). Concentrations of sucrose ranged from 25 to 68 mg·g−1 fresh weight and were greater than those of monosaccharides analyzed. ‘Beauregard’ had the highest sucrose concentration and total sugars. Purple-fleshed cultivars Okinawan and LA 08-21p contained total monomeric anthocyanins that ranged from 34 to 37 mg/100 g dry weight. Orange-fleshed cultivars Beauregard and Darby contained β-carotene that ranged from 5485 to 8302 µg/100 g fresh weight. These results provide yields of storage roots, susceptibility to sweetpotato weevils, and amounts of antioxidants in purple- and orange-fleshed sweetpotato cultivars to growers interested in producing new sweetpotato cultivars.