2019 ASHS Annual Conference

The objective was to evaluate yield of ginger, galangal and turmeric propagules produced under two photoperiods in a greenhouse environment. Propagules included micropropagated plantlets (“tc”) or rhizomes [“ownrhiz”; second generation tc harvested after ~1 year of growth, or commercial sources of Hawaiian-grown rhizome (“rhiz”)] of several ginger, galangal, blue, yellow and white turmeric genotypes. Plants were grown from April, 2018 in 2.78 L pots and then transplanted in June 27 into 14.5 L containers filled with a blend of pine bark, Canadian Sphagnum peat moss, perlite and vermiculite. Long day photoperiods were provided in one greenhouse from July 6 onwards with night interruption lighting from 10 pm to 2 am using incandescent lamps at 1.32 µmol∙m^-2∙s^-1, with 26.8 ± 3.9°C day and 21.4 ± 2.1°C night temperatures, and 8.4 ± 3.8 moles.m^-2.d^-1 daily light integral (DLI). In a separate natural day greenhouse, day and night temperature were 26.6 ± 3.1°C and 21.3 ± 2.6°C, respectively, with 9.1 ± 3.6 moles.m^-2.d^-1 DLI. Within each greenhouse, containers were arranged in a randomized complete block design with three blocks (benches) and six replicate pots per propagule type. Plants were harvested between Jan and Feb, 2019. Under both natural and long days yields (rhizome fresh mass) were similar (on average 0.89 and 0.95 kg per container, respectively). Under natural days, ginger "ownrhiz" and galangal “tc” had the highest yields (1.44 and 1.31 kg, respectively). Ginger Bubba baba and turmeric Black had significantly lower yields (0.46 and 0.47 kg, respectively). While “rhiz”-grown ginger had more yield (1.44 kg) than “tc” ginger (0.96 kg), there was no difference between turmeric Yellow “ownrhiz” (0.68 kg) and Yellow “tc” (0.62 kg). Under long days, there were no significant differences on yield for ginger type. Yields ranged from 1.1 kg in ginger “tc” to 1.5 kg in ginger “ownrhiz”. Ginger Bubba baba “rhiz” had higher yield (1.2 kg) than when grown under natural days (0.5 kg). However, yield was significantly different for turmeric types. White “tc” had the highest yield (1.1 kg), while yellow “ownrhiz” had the lowest yield (0.5 kg) which was not different from yellow “tc” (0.6 kg). An additional experiment is underway evaluating the same set of propagule types grown in the field under full-sun or shade. Overall, research showed differences in yield depend upon genotype, plant material, and environmental conditions, and an economic analysis is needed to identify the most efficient production conditions.