Morphological and Physiological Development of Organic Greenhouse Grown Ginger (Zingiber officinalis, Rosc) in a Temperate Climate as Influenced by Container and Transplant Origin

Ginger (Zingiber officinale Rosc) is a spice produced from underground rhizomes. This makes it necessary to consider the size of its growing area. There is limited information on the phenological development of the plant in containerized greenhouse conditions in temperate regions where natural daylength decreases as the growing season advances. This study determined the effects of container and rhizome sources on ginger shoot growth, chlorophyll concentration, leaf chlorophyll index, transpiration rate, and rhizome yield. Ginger, from non-tissue culture (O1) and tissue culture (O2) origins, were transplanted in a greenhouse in June 2019, 2020 and 2021, and monitored in five container types of different sizes. These were (C1) plastic Supertub (113.2 L), (C2) large Sterilite box (55.3 L), (C3) small Sterilite box (36.7 L), (C4) Husky heavy duty contractor plastic clean up bags (26.3 L) and (C5) Root Trapper Grounder Squat bag (27.9 L). The results did not show consistent trends for the effects of the respective size and origin combinations on most of the morphological characteristics, and all the physiological characteristics evaluated. Increasing container size increased the shoot biomass in all studies and increased fresh rhizome yield in two of three studies in the greenhouse. The effect of transplant origin was inconclusive, with a tissue culture advantage one year and no effect the other year. During the first 5 months after transplanting, the morphological development of tillers and height increased. Leaf chlorophyll index, chlorophyll concentration and stomatal conductance varied across sampling months, and within container and rhizome origin at individual sampling dates. The development of the plants in a greenhouse with decreasing natural day length posed a challenge as some plants senesced within 5 months after transplanting. Further opportunities to arrest senescence and extend growth should be introduced as another approach to extend growth and increase rhizome yield.

Organic Ginger (<i>Zingiber officinale</i>Rosc.) Development in a Short Temperate Growing Season: Effect of Seedling Transplant Type and Mycorrhiza Application

Global warming and consumer demand for medicinal plants present an opportunity to introduce ginger growth to the US Delmarva Peninsula. High tunnel and field studies were conducted to assess the development of organic ginger (Zingiber officinalis, Rosc) seedling transplants in mycorrhiza-amended soil. Transplant types were tissue culture derived with less than three tillers (TCS1), three or more tillers (TCS2), and nontissue culture derived (NTCS1). Transplants were grown with or without mycorrhiza (2.8 g per plant) in a split plot design with soil amendments as main plot and transplant type as subplot. Data were collected for air temperatures, plant height, tiller number, leaf chlorophyll index (LCI), rhizome fresh weight, plant biomass, rhizome nutrients, and levels of As and Pb. TCS2 transplants produced significantly higher, or trended to higher rhizome yield than transplants with less than three tillers, except for year two field study. The maximum rhizome fresh weight per plant was 648.3 g for TCS2 in high tunnel in year one. Generally, TCS2 had most tillers throughout the growing season ranging from 6.9 to 25.7 tillers per plant over three studies. Mycorrhiza had no effect on ginger height, tiller number, LCI or rhizome yield. Sustained high temperatures above 37°C, plus high light in the field caused dieback and stunted shoot growth in year two. There were no consistent effects of mycorrhiza or transplant type on rhizome nutrient content. Content of total Pb, As and other elements were at safe threshold levels for rhizome consumption. These results suggest that gingers grown from TCS2 transplants with at least three tillers yielded more rhizome than those grown from S1 transplants with fewer tillers. Introduction of ginger to a short season region such as the Delmarva may require consideration of environmental condition such as high temperature and light to which seedling transplants may be exposed in summer.