The effect of methyl jasmonate (MeJA) in terms of its induction of inherent bioactive chemicals in sweet basil (Ocimum basilicum L.) was evaluated after MeJA was sprayed on healthy basil plants. The total phenolic content of the sweet basil significantly increased after 0.1 and 0.5 mM MeJA treatments compared with the control not subjected to MeJA. Two phenolic compounds, rosmarinic acid (RA) and caffeic acid (CA), were identified as strong antioxidant constituents of the sweet basil. Their amounts also significantly increased after the MeJA treatment. In addition, eugenol and linalool increased 56 and 43%, respectively, by the 0.5 mM MeJA treatment. Due to the accumulation of RA, CA, and eugenol, which possess strong 2,2-diphenyl-1-picrylhydrazyl (DPPH*) free radical scavenging activities, the antioxidant activity of the sweet basil extract was 2.3-fold greater than that of the control after the 0.5 mM MeJA treatment. In the DPPH* assay, the EC50 values of RA, CA, and eugenol were determined as 23, 46, and 59 microM, respectively, which indicated they were 6-, 3-, and 2.4-fold more efficient than BHT (140 microM). Besides, an unidentified HPLC peak in the methanolic extract of the sweet basil was 4.3-fold higher than that of the control after the 0.5 mM MeJA treatment.

The effect of the treatment of chitosan at various concentrations (0.01%, 0.05%, 0.1%, 0.5%, and 1%) upon sweet basil (Ocimum basilicum L.) before seeding and transplanting was investigated in aspects of the amount of phenolic and terpenic compounds, antioxidant activity, and growth of the basil, as well as the phenylalanine ammonia lyase (PAL) activity. The total amount of the phenolic and terpenic compounds increased after the chitosan treatment. Especially, the amounts of rosmarinic acid (RA) and eugenol increased 2.5 times and 2 times, respectively, by 0.1% and 0.5% chitosan treatment. Due to the significant induction of phenolic compounds, especially RA, the corresponding antioxidant activity assayed by the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging test increased at least 3.5-fold. Also, the activity of PAL, a key regulatory enzyme for the phenylpropanoid pathway, increased 32 times by 0.5% chitosan solution. Moreover, after the elicitor chitosan treatment, the growth in terms of the weight and height of the sweet basil significantly increased about 17% and 12%, respectively. Our study demonstrates that an elicitor such as chitosan can effectively induce phytochemicals in plants, which might be another alternative and effective means instead of genetic modification.

Daily light integral (DLI) describes the rate at which photosynthetically active radiation is delivered over a 24-hour period and is a useful measurement for describing the greenhouse light environment. A study was conducted to quantify the growth and flowering responses of bedding plants to DLI. Eight bedding plant species [ageratum (Ageratum houstonianum L.), begonia (Begonia ×semperflorens-cultorum L.), impatiens (Impatiens wallerana L.), marigold (Tagetes erecta L.), petunia (Petunia ×hybrida Juss.), salvia (Salvia coccinea L.), vinca (Catharanthus roseus L.), and zinnia (Zinnia elegans L.)] were grown outdoors in direct solar radiation or under one of three shade cloths (50, 70 or 90% photosynthetic photon flux (PPF) reduction) that provided DLI treatments ranging from 5 to 43 mol·m–2·d–1. The total plant dry mass increased for all species, except begonia and impatiens, as DLI increased from 5 to 43 mol·m–2·d–1. Total plant dry mass of begonia and impatiens increased as DLI increased from 5 to 19 mol·m–2·d–1. Impatiens, begonia, salvia, ageratum, petunia, vinca, zinnia, and marigold achieved 50% of their maximum flower dry mass at 7, 8, 12, 14, 19, 20, 22, and 23 mol·m–2·d–1, respectively. The highest flower number for petunia, salvia, vinca, and zinnia occurred at 43 mol·m–2·d–1. Time to flower decreased for all species, except begonia and impatiens, as DLI increased to 19 or 43 mol·m–2·d–1. There was no consistent plant height response to DLI across species, although the shoot and flower dry mass per unit height increased for all species as DLI increased from 5 to 43 mol·m–2·d–1. Guidelines for managing DLI for bedding plant production in greenhouses are discussed.

The interest in using nonchemical alternatives for growth control of horticultural crops has recently increased due to public concerns for food safety and environmental pollution. Several research teams around the world are investigating alternative growth control measures, such as genetic manipulation, temperature, water and nutrient management, mechanical conditioning, and light quality manipulation. This review discusses the recent developments in light quality manipulation as a nonchemical alternative for greenhouse plant height control.

‘TifEagle’ bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy] is a fine textured hybrid bermudagrass used for golf course putting greens in the subtropical and tropical regions of the world. The growth and performance of TifEagle and other bermudagrass often decline in reduced light environments (RLEs). This study quantified a daily light integral (DLI; mol m−2 d−1) required to maintain commercially acceptable TifEagle bermudagrass maintained under golf green conditions. Three levels of shade, none, low, and high (0, 41, and 92%), were applied to mature TifEagle bermudagrass during morning (sunrise to 1100 h) and afternoon (1500 h to sunset) hours, allowing full irradiance from 1100 to 1500 h to mimic a golf green situation where trees or structures are adjacent to, but rarely directly overhead. The study was performed for 8 wk in June to August 2001 and 2002. An average minimal DLI of 32.6 mol m−2 d−1 was needed to maintain commercially acceptable TifEagle turf quality (TQ ≥ 7). Other plant responses measured included percentage lateral regrowth (RG), total shoot chlorophyll, and total nonstructural carbohydrates (TNC). These responses declined significantly when the DLI ≤ 32.6 mol m−2 d−1 Differences in diurnal shade exposure occurred. High afternoon shade reduced TifEagle bermudagrass TQ, percentage lateral RG, shoot chlorophyll, and TNC by 3.0 rating units and 17, 39, and 27%, respectively, compared with no afternoon shade (NSA). High morning shade reduced TQ, percentage lateral RG, and shoot chlorophyll by 1.5 rating units and 11 and 16%, respectively, compared with no morning shade (NSM). Overall, afternoon shade applications were more detrimental to TifEagle bermudagrass growth and performance compared with morning shade.