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Strawberries (Fragaria ×ananassa) are being produced increasingly in indoor vertical farms, where the light quality of sole-source lighting is a primary factor that influences the outcomes of crop production. Far-red (FR) light (700–750 nm) has been shown to promote plant responses such as leaf expansion, biomass accumulation, and flowering in some long-day plant species. However, the impacts of including FR light in sole-source lighting on strawberries have not been fully understood. This study investigated the impacts of FR light on the growth and development of long-day strawberries ‘Albion’ and ‘Monterey’ in an indoor vertical farm. We hypothesized that the addition of FR light under a long photoperiod would promote leaf expansion, biomass accumulation, flowering, and fruit production in long-day strawberries. Bare-root strawberry plants were grown in a deep-water-culture hydroponic system at an air temperature of 22 °C and an 18-hour photoperiod using 90 μmol⋅m^–2⋅s^–1 of blue (peak = 455 nm) + 250 μmol⋅m^–2⋅s^–1 of red (peak = 660 nm) light-emitting diodes (LEDs) with or without adding 50 μmol⋅m^–2⋅s^–1 of FR (peak = 730 nm) LEDs. After 5 weeks of lighting treatments, additional FR light increased the leaf area and shoot dry mass of strawberry ‘Monterey’ by 74% and 73%, respectively, and the number of crowns per plant of strawberry ‘Albion’ by 33%. However, FR light did not influence flowering time in either cultivar. Adding FR light increased the number of fruit harvested per plant by 36%, the total fruit yield by 48%, and the total soluble solids of fruit by 12% in strawberry ‘Albion’, but not in ‘Monterey’. In both cultivars, FR light did not affect the individual fruit mass. Our results suggest that the addition of FR light in sole-source lighting can promote leaf expansion, biomass accumulation, fruit yield, and fruit quality in at least some long-day strawberry cultivars.

Because hydroponic operations in the United States can be certified as organic, and because the price of chemical fertilizers has increased, there is an increasing interest in using organic fertilizers and beneficial microorganisms for controlled-environment agriculture. However, there is a scarcity of information regarding their effectiveness and application methodologies. We investigated the effects of inoculating Azospirillum brasilense and Rhizophagus intraradices and using organic fertilizers on growing lettuce (Lactuca sativa ‘Cherokee’) and tomato (Solanum lycopersicum ‘Red Robin’) young plants in an indoor vertical farm. Seeds were sown in rockwool substrate, with A. brasilense (1.05 × 10⁸ colony-forming units⋅L⁻¹) or R. intraradices (580 propagules⋅L⁻¹) applied weekly via subirrigation. Seedlings received chemical fertilizer, organic fertilizer derived from corn steep liquor and fermented fish by-products, and food waste-derived organic fertilizer at 100 ppm total nitrogen every 2 or 3 days. They were grown indoors at 23 °C under light-emitting diode lighting at a photosynthetic photon flux density of 200 μmol⋅m⁻²⋅s⁻¹ with an 18-hour photoperiod. Lettuce under organic fertilizers had 75% lower shoot fresh mass and 64% less shoot dry mass compared with lettuce under chemical fertilizer. Similarly, tomato seedlings with organic fertilizers had fewer leaves, 75% less shoot fresh mass, and 67% less shoot dry mass. In both lettuce and tomato, the macronutrient and micronutrient concentrations in plant tissues were generally similar regardless of fertilizer treatments, but nitrogen use efficiency and nitrogen uptake efficiency were lower under organic fertilizers compared with those under chemical fertilizer. The inoculation of A. brasilense or R. intraradices showed limited effects on plant nutrient uptake, nutrient concentrations, and seedling growth in both lettuce and tomato. Further research is necessary to optimize application methods for organic fertilizers and beneficial microorganisms to fully harness the benefits of sustainable alternative fertilizers in soilless and hydroponic crop production.

Cultivation of grafted tomatoes has been sharply increased in recent years. Millions of grafted seedlings were grown in California as well as other parts of the world, and the need for high quality grafted tomato seedlings is also rapidly growing. Since the price of grafted plug seedlings are 3–4 times higher than the nongrafted ones, production and commercial distribution of double-stemmed plugs, even though slightly more expensive than the single-stemmed plugs, will greatly cut down the expenses needed to purchase grafted seedlings. Several methods of producing double-stemmed grafted plug seedlings are presented and the advantages as well as the disadvantages of these methods will be fully discussed. Brushing or painting lanolin paste containing thidiazuron at 100–500 ppm to the lower node of the decapitated scion is effective in fast-growing cherry, whereas inducing double stems from the cotyledonary node of grafted scions appeared to be more practical for ordinary tomatoes for table use. Methods of grafting, especially in relation with machine grafting, will be discussed.

Washing oriental melon (Cucumismelo var. makuwa Makino) is a standard procedure because it facilitates the precise elimination of defective fruit, such as fruit having internal decay symptoms, and also facilitates easier handling of fruit by the elimination of gummy substances on the fruit surface. In most fresh fruits and vegetables, however, washing has never been recommended unless it is related to other practices, such as waxing or immediate processing. Harvested oriental melons were placed in a big water tank and washed with a brush machine immediately before grading, using an automatic grader. Fruit that had sunk down to the bottom of the tank were discarded, as they were premature-fermented fruit with no commercial value. Fruit, intact or washed, were treated with 1-MCP at 0.5–2.0 ppm for 12 hours and stored at room temperature for 3 weeks. Flesh firmness, soluble solids contents, fruit petiole color, and changes of surface suture color were measured to evaluate storability of the fruit. The washed fruit exhibited poor skin color and early suture-browning as compared to the non-washed fruit, regardless of 1-MCP pretreatment. 1-MCP treatment was also effective in maintaining fresh fruit quality as compared to the non-treated fruit. 1-MCP effects were, however, more pronounced in relatively smaller and less mature fruit as compared to the fully mature fruit. 1-MCP was also effective in maintaining white suture color, the most important visual factor currently used for quality evaluation in oriental melon.

Double-stemmed seedlings (DSS) will be favored by the growers because they can save the expense needed to purchase commercial seedlings. This is also true with grafted tomatoes since the price of grafted tomato seedlings is about 2 times higher than non-grafted ones. The plug seedling growers will also benefit from the increased demand for DSS if the production cost for DSS can be maintained at appropriate level. Two stem cuttings having two expanded leaves were taken from a seedling when the seedling had four expanded leaves and rooted in 32-cell trays filled with commercial soil mix. Lower stem cuttings having first and second leaves produced well-balanced DSS even without any plant bioregulator treatment whereas up upper stem cuttings having third and fourth leaves resulted in single-stem seedlings with very limited outgrowth of axillary shoot from the third node. DSS can be obtained from the decapitated seedling stump by outgrowth of axillary shoots from the cotyledonary nodes, but the quality and uniformity were inferior to other seedlings. Pinching off the tips of seedlings thus leaving three expanded leaves per seedling and application of plant bioregulators to the decapitated seedlings were also effective for producing DDS. Application of thidiazuron (TDZ) in lanolin paste to the second node was most effective even though whole plant spray with TDZ or BA was also partially effective. Subsequent growth characteristics of these seedlings will be further discussed.