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The objectives were to 1) compare growth and yield of different ginger (Zingiber officinale) and turmeric (Curcuma longa) propagules grown under two photoperiods (Expt. 1); and 2) evaluate whether their growing season could be extended with night interruption lighting (NI) during the winter (Expt. 2). In Expt. 1, propagules included 1) micropropagated tissue culture (TC) transplants, 2) second-generation rhizomes harvested from TC transplants (2GR), and 3) seed rhizomes (R). Plants received natural short days (SDs) or NI providing a total photon flux density (TPFD) of 1.3 µmol·m⁻²·s⁻¹. Providing NI increased number of new tillers or leaves per plant, rhizome yield (i.e., rhizome fresh weight), and dry mass partitioning to rhizomes in both species. There was no clear trend on SPAD index in response to photoperiod or propagative material. Although TC-derived plants produced more tillers or leaves per plant, 2GR ginger and R turmeric produced a higher rhizome yield. In Expt. 2, seed rhizomes of ginger and turmeric were grown under five treatments with different photoperiods and/or production periods: 1) 20 weeks with NI (20NI), 2) 24 weeks with NI (24NI), 3) 28 weeks with NI (28NI), 4) 14 weeks with NI + 10 weeks under natural SDs (24NISD), and 5) 14 weeks with NI + 14 weeks under natural SDs (28NISD). NI provided a TPFD of 4.5 µmol·m⁻²·s⁻¹. Lengthening the production period and providing NI increased rhizome yield and crude fiber content in both species. SPAD index decreased when plants were exposed to natural SDs at the end of the production period (NISD treatments). Results demonstrate the potential to overcome winter dormancy of ginger and turmeric plants with NI, enabling higher rhizome yield under natural SDs.

Domestic production of ginger (Zingiber officinale) and turmeric (Curcuma longa) rhizomes is increasing. The objective of this study was to compare growth and rhizome yield of these crops using different container volumes and planting densities. Two greenhouse experiments that lasted 28 weeks each were conducted. In Expt. I, one sprouted rhizome of a single ginger variety (Bubba Blue) and four turmeric varieties (Hawaiian Red, BKK, White Mango, and Black) were transplanted into either small (1.5 gal) or large (13.3 gal) round containers. In Expt. II, either one or three sprouted rhizomes of two ginger varieties (Bubba Blue and Madonna) and two turmeric varieties (Indira Yellow and Hawaiian Red) were transplanted into either large (13.3 gal) or medium (3.9 gal) round containers. In Expt. I, there were an increase in plant growth and yield with increasing container volume, as both crops produced more than double the shoot, root, and rhizome fresh weight (FW) when grown in large compared with small containers. In Expt. II, rhizome yield of ginger was 44% higher in medium than large containers, and container volume did not affect yield in turmeric. Total dry weight (DW) was higher in plants grown in the larger container volume in both species in Expt. I, and turmeric only in Expt. II. However, ginger in Expt. II had an 18% higher plant DW in the medium compared with the large container. The higher density in Expt. II increased yield and biomass production per container compared with the lower density, regardless of variety and container volume. Overall, net revenue per container was higher in Expt. II than Expt. I because of the higher rhizome yield. In Expt. I, the higher yield of ginger compared with turmeric increased sales revenue of this species, despite a lower sales price per kilogram. In contrast, the higher yield of turmeric in Expt. II resulted in higher sales revenue and net revenue per container compared with ginger. Based on our results, medium containers could be used to minimize material and space costs for ginger and turmeric production under the conditions evaluated in our study.

The overall goal was to evaluate fertilizer options for greenhouse producers, with or without a plant growth regulator (PGR) application, to improve subsequent performance of container-grown annuals. Petunia (Petunia × hybrida) was the model container-grown crop in simulated production and consumer environments. The first experiment at two locations (New Hampshire and Florida) compared strategies using water-soluble fertilizer [WSF (17N–1.8P–14.1K)], controlled-release fertilizers (CRF), and slow-release fertilizers (SRF) that were either applied throughout or at the end of the 8-week production phase [point of shipping (POS)] for petunia rooted cuttings grown in 8-inch azalea containers. In the subsequent simulated “consumer” phase, container plants were irrigated with clear water (no fertilizer) for 6 weeks. Plant performance [number of flowers, SPAD chlorophyll index, dry weight, and tissue nitrogen (N)] at the end of the consumer phase was improved by top-dressing at POS with either CRF or granular organic fertilizer (both at 2.74 g/container N), or preplant incorporation of either a typical CRF at 4.12 g/container N or a CRF with an additional prill coating to delay initial release (DCT) at 2.74 g/container. There was no carry-over benefit from applying a liquid urea-chain product (1.37 or 2.74 g/container N) or top dressing with granular methylene di-urea (2.74 g/container N), or 400 mg·L^–1 N (0.2 g/container N) from a liquid organic fertilizer at POS. The consumer benefit of applying 400 mg·L^–1 N (0.2 g/container N) from a WSF at POS was increased by supplementing with 235 mg·L^–1 magnesium (Mg) and 10 mg·L^–1 iron (Fe). A second experiment in 10-inch-diameter pots evaluated the effect on consumer performance from providing 200 or 400 mg·L^–1 N of WSF with the PGR paclobutrazol, at the final 1 L/pot irrigation at POS. Application of 3 mg·L^–1 paclobutrazol delayed leaf yellowing and reduced plant height, width, and shoot dry weight during the consumer phase, resulting in a more compact growth habit and higher plant quality compared with plants that received no PGR, regardless of WSF treatment. Addition of supplemental 235 mg·L^–1 Mg and 10 mg·L^–1 Fe to the high rate of WSF and PGR did not improve consumer performance compared with other treatments that included a PGR. Overall, the first experiment demonstrated that the most effective fertilizer strategies require a CRF or SRF that will release nutrients throughout the consumer phase, and that impact of liquid fertilizer options is limited because of lower N supply per container. A single application at POS of a high rate of WSF with supplemental Mg and Fe may have short-term benefits, for example while plants are in a retail environment. Growers should consider combining a residual fertilizer with a PGR application for premium, value-added container annuals.