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  • Author or Editor: Sofía Gómez x
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Biostimulant products have various reported benefits for plant production in the field or using hydroponic systems in protected structures. However, limited information is available describing their potential use for indoor farming applications. Considering that lettuce (Lactuca sativa) is one of the most popular crops produced in commercial indoor farms, the objective of this study was to compare growth and quality of lettuce grown indoors using nine biostimulant products derived from humic substances, amino acids, hydrolyzed proteins, or seaweed extracts. ‘Monte Carlo’, ‘Fairly’, and ‘Lalique’ lettuce were grown hydroponically for 30 to 33 days under a daily light integral, day/night temperature, relative humidity, and carbon dioxide concentration of ≈13 mol·m‒2·day‒1, 22/21 °C, 70%, and 800 µmol·mol‒1, respectively. There were no positive effects from using any of the biostimulant products evaluated in our study as growth (leaf area, leaf number, shoot diameter, and shoot and root dry weight), yield (shoot fresh weight), and quality (bolting, tipburn index, leaf color, and SPAD index) of treated plants were generally similar to those from the untreated control. Applications from one seaweed extract caused slight negative growth effects, possibly due to phytotoxicity. Cultivar differences showed that Fairly plants had the highest susceptibility to tipburn and bolting, and none of the biostimulant products countered these symptoms. Overall, the products evaluated provided marginal advantages for indoor hydroponic lettuce production.

Open Access

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.

Open Access

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.

Open Access