Abstract
This student-led project studied the production of cilantro (greens stage) and coriander (seed stage) of Coriandrum sativum L. with the objective of developing this crop as an alternate specialty crop in Virginia. Results indicated that both fall-planted for spring harvest and spring-planted for summer harvest are possible in Virginia. Rows spaced 37.5 cm apart resulted in the superior yield of both cilantro and coriander over rows 75 cm apart. Mean cilantro fresh yields from fall-planted experiments (three cultivars during 2015 and five cultivars during 2016) varied from 3301 to 5775 kg⋅ha−1, whereas those from spring-planted experiments varied from 4971 to 11811 kg⋅ha−1. Corresponding values for dry cilantro yields varied from 274 to 1129 kg⋅ha−1 and 862 to 2280 kg⋅ha−1, respectively. Mean coriander seed yields from three fall-planted cultivars varied from 818 to 1554 kg⋅ha−1, and those from three spring-planted cultivars varied from 869 to 1277 kg⋅ha−1. The total phenolic content in cilantro was significantly greater than that in coriander seed (4.95 and 1.15 g of gallic acid equivalent per 100 g of material, respectively). The total mesophiles, yeast and mold, and coliforms from three grocery store-bought cilantro were considerably higher than those of greenhouse-grown cilantro. Even though both spring and fall plantings are possible for supplying cilantro in Virginia, fall planting for spring harvest might be more profitable for producers because of the earlier availability of locally grown cilantro.
Coriander (Coriandrum sativum L.) is a crop of worldwide importance and is more commonly used for its seed than as a fresh herb (Diederichsen, 1996; Singletary, 2016). This plant is an annual herb that is part of the Apiaceae family of plants, which also includes carrots, fennel, parsley, celery, anise, and cumin. It is commonly featured in Asian, Latin American, Caribbean, and Mediterranean cuisine. The name given to the fresh herb (leaves and stems of the plant) varies regionally, but the Spanish name “cilantro” is commonly used in the Americas (Kahn and Maness, 2010); however, it is sometimes referred to as Mexican or Chinese parsley. Coriander refers to the seeds of the plant, which are usually ground and used as a spice. However, these names are often used interchangeably (Food Source Information, 2022). In this article, cilantro refers to the green stage (leaves and stems), whereas coriander refers to the seed stage of this plant. Cilantro has been cultivated and used since ancient times. The areas that produce the most cilantro include India, China, the former Soviet Union, Mexico, South America, Central America, and the Caribbean. The United States does not produce enough cilantro to meet domestic demands; therefore, it imports substantial amounts of this herb, thus making the United States one of the top importers of cilantro in the world (Food Source Information, 2022).
Cilantro is an important import commodity. The United States imported ≈289 tons of cilantro from China, Columbia, Egypt, Germany, Israel, Singapore, Spain, and United Kingdom during Feb. and Mar. 2022 (Seair Exim Solutions, 2022). Cilantro is grown commercially by both small-scale and large-scale farming operations in almost every country of the world. Mexico is the largest exporter of cilantro. In the United States, California is the leading state for cilantro production, with more than 25,000 tons grown annually. It is also grown to a lesser extent in Arizona, Oregon, and Washington (WIFSS, 2016).
Cilantro is also in demand as a local consumer product. An informal survey of four South Asian (Indian) and three Mexican stores in the Richmond, VA area during 2014 indicated that a robust local demand existed for cilantro. The total weekly demand for cilantro in these seven stores was estimated to be ≈200 to 500 bunches (10–15 stems per bunch) per week. These bunches retail from $0.50 to $1. Vendors informally remarked that organically certified cilantro could sell for almost double the general retail price. Considerable demand for cilantro is known to exist in the Washington, DC and New York areas. Virginia farmers could easily enhance their incomes by producing and marketing cilantro in these areas.
A critical issue related to cilantro is the microbial load. Between 2000 and 2020, at least 43 cilantro-associated outbreaks were reported to the Centers for Disease Control’s National Outbreak Reporting System; these outbreaks caused 970 illnesses, 75 hospitalizations, and no deaths. Implicated pathogens have included Salmonella, Shiga toxin-producing Escherichia coli, Shigella, norovirus, and Cyclospora cayetanensis (Food Source Information, 2022). During 2015, the U.S. Food and Drug Administration banned cilantro imports from the Puebla region of Mexico. This alert, which included fresh intact and chopped cilantro, allowed officials in the United States to detain without physical inspection any cilantro shipments from the Puebla region from 1 April through 31 Aug. 2015.
Consumers are increasingly interested in the consumption of antioxidants. It is well known that herbs and spices such as C. sativum possess antioxidant activity (Singletary, 2016). During recent years, consumers have been enhancing their diets with antioxidants because they have been shown to reduce DNA damage induction (Sasaki et al., 2002). Wangensteen et al. (2004) reported that the addition of coriander to food would increase the antioxidant content and may have potential as a natural antioxidant, thus inhibiting unwanted oxidation processes. This has led to an increasing interest in natural food additives, such as spices or spice extracts, which can function as natural antioxidants in addition to seasoning the food. Therefore, we were interested in the characterization of antioxidants in C. sativum produced in Virginia.
Even though preliminary information indicated that C. sativum can be grown in Virginia, commercial production of this crop in Virginia is nonexistent. Therefore, the objectives of our studies were to identify cilantro and coriander yields, suitable cultivars, and optimal row spacing for commercial production. Given the recent incidences of contamination with human pathogens in imported cilantro, we also wanted to investigate microbial loads in locally produced cilantro and cilantro available in grocery stores. Additionally, our objectives included the characterization of antioxidants in cilantro.
Materials and Methods
Four experiments were conducted during 2015 to 2017 with the following details:
Fall-planted, spring-harvested cilantro.
Cilantro in Expt. 1 was planted on 1 Dec. 2015 and harvested on 12 Apr. 2016; coriander was harvested on 22 July 2016. Cilantro in Expt. 2 was planted on 14 Oct. 2016 and harvested on 13 Apr. 2017; coriander was harvested on 6 July 2017.
Spring-planted, summer-harvested.
Cilantro in Expt. 3 was planted on 26 May 2016 and harvested on 6 July 2016; coriander was harvested on 2 Aug. 2016. Cilantro in Expt. 4 was planted on 10 Apr. 2017 and harvested on 21 June 2017; coriander was harvested on 24 July 2017.
Cultivars.
Three coriander cultivars (Santo, Santo Monogerm, and Marino-Organic) were used for Expts. 1 and 3, whereas five coriander cultivars (Calypso, Marino-organic, Santo, Santo-Monogerm, and VSU-COR) were used for Expts. 2 and 4. Seeds for all cultivars were purchased from Johnny’s Selected Seeds (Winslow, ME), except for VSU-COR, which is a selection from an unnamed cultivar that is popular for home production among Indian immigrants in Virginia.
All cultivars were planted in the field using a randomized complete block design with four replications. The soil type was Abel sandy loam (fine loamy, mixed, thermic Aquatic Hapludult). Each plot consisted of four rows with interrow spacing of either 37.5 or 75 cm for Expts. 1 and 3; only row spacing of 37.5 cm was used for Expts. 2 and 4. Approximately 100 seeds were planted in each 3-m-long row with an Almaco research planter (Nevada, IA). The experimental area received a preplant-incorporated treatment of trifluralin herbicide (Treflan 4EC; DowElanco, Indianapolis, IN) at a rate of 1 L⋅ha−1 active ingredient. These plots received 250 kg⋅ha−1 of 10N–4.4P–8.3K, as used during previous studies (Rangappa et al., 1997).
For cilantro harvests, a 1-m row length was harvested from one of the middle rows of each plot and fresh yields were recorded immediately. A sample of the fresh harvest was dried in a commercial drier at 65 °C for 72 h to record dry weights. For the coriander harvest, a 2-m row length was harvested from the remaining middle row and the seed yield was recorded.
Three measures of antioxidant activity were evaluated in cilantro and coriander: oxygen-radicals scavenging activity [ABTS: 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid assay)], antioxidation activity (DPPH: 2,2-diphenyl-1-picrylhydrazyl assay), and total phenolic content (TPC) according to the methods described previously (Haiwen and Parry, 2011).
A preliminary study was conducted to determine populations of several microorganisms in cilantro bought from three local grocery stores compared to those in cilantro grown in a greenhouse at Virginia State University. One fresh cilantro sample was purchased from each grocery store. Each sample portion (25 g) was homogenized in 225 ml of sterile saline solution (0.85%) using a laboratory blender (Masticator Silver; IUL Instruments, Barcelona, Spain) at high speed for 2 min. Appropriate dilutions of the homogenate were surface-plated using standard method agar for aerobic mesophile counts after incubating at 36 °C for 48 h. Yeast and mold counts were determined using acidified potato dextrose agar after incubating at 25 °C for 5 d and recorded as colony-forming units (CFU) per gram. Total coliform counts were determined using the three-tube most-probable-number evaluation with a detection limit of 3 cells/g after incubation at 36 °C for 24 to 48 h Kim et al. (2021).
Data regarding cilantro yield were available from all four experiments, but seed yield data were only available from Expts. 1 and 3. Statistical analyses were conducted to compare cultivars and row spacings as appropriate depending on the experiment. Means over four replications were compared after an analysis of variance using the PROC GLM procedure in SAS version 9.4 (SAS, 2016). Means of cultivars and row spacings were compared using Duncan’s multiple range test at a 5% level of significance.
Results and Discussion
Cilantro.
Our results indicated that fall planting of cilantro for harvest during the following spring is possible (Tables 1 and 2). Mean cilantro fresh and dry yields (means from ‘Santo’, ‘Santo-Monogerm’, and ‘Marino-organic’) from the 1 Dec. 2015 planting with the 12 Apr. 2016 harvest were 4881 and 934 kg⋅ha−1, respectively. Mean cilantro fresh and dry yields (from ‘Calypso’, ‘Santo’, ‘Santo-Monogerm’, ‘Marino-organic’, and VSU-COR) from the 14 Oct. 2016 planting with the 13 Apr. 2017 harvest were 4453 and 352 kg⋅ha−1, respectively. These results indicate that planting later in fall might be preferable to planting early in fall. ‘Santo-Monogerm’ was observed to be a superior cultivar for fall plantings with spring harvests of fresh cilantro.
Cilantro yield as effected by cultivars and interrow spacing during Expt. 1 (fall-planted and spring-harvested).
Cilantro yield as effected by cultivars during Expt. 2 (fall-planted and spring-harvested).
Spring planting of cilantro for summer harvest provided impressive results (Tables 3 and 4). The 26 May 2016 planting with the 6 July 2016 harvest had mean fresh and dry yields (means from ‘Santo’, ‘Santo-Monogerm’, and ‘Marino-organic’) of 10941 and 2058 kg⋅ha−1, respectively. The experiment planted on 10 Apr. 2017 with the 24 July 2017 harvest had mean fresh and dry yields (from ‘Calypso’, ‘Santo’, ‘Santo-Monogerm’, ‘Marino-organic’, and VSU-COR) of 5976 and 1076 kg⋅ha−1, respectively. Varietal differences for spring plantings were not significant among the three cultivars studied in 2016; however, they were significant among the five cultivars studied in 2017. However, Santo and Santo-Monogerm were observed to be consistently high-yielding cultivars. The nondescript line (VSU-COR) resulted in cilantro fresh and dry yields similar to those of ‘Santo’ and ‘Santo-Monogerm’ in 2017. A study of this line is continuing during our coriander/cilantro improvement project.
Cilantro yield as effected by cultivars and interrow spacing during Expt. 3 (spring-planted and summer-harvested).
Cilantro yield as effected by cultivars during Expt. 4 (spring-planted and summer-harvested).
Closer row spacing of 37.5 cm was significantly superior to 75 cm for both fresh and dry cilantro yields of both fall-planted and spring-planted (closer row spacing resulted in double the fresh and dry cilantro yields) experiments. These results are in agreement with those observed in Oklahoma (Kahn and Maness, 2010), where investigators compared either four rows spaced 30 cm apart or eight rows spaced 15 cm apart and observed that closer spacing resulted in higher cilantro yields. Weed pressure was not researched during our studies, but it was observed that the closer row spacing was generally helpful to reducing weed pressure.
Coriander.
Cultivars and row spacings had significant effects on seed yield during both fall and spring plantings (Tables 5 and 6). The mean seed yield from the fall planting was 1134 kg⋅ha−1. The Santo cultivar had the highest seed yield. Similar to the cilantro yield, closer row spacing (37.5 cm) resulted in a significantly higher seed yield (≈1.6-times better) than wider row spacing (75 cm).
Coriander seed yield as effected by cultivars and interrow spacing during Expt. 1 (fall-planted and spring-harvested).
Coriander seed yield as effected by cultivars and interrow spacing during Expt. 3 (spring-planted and summer-harvested).
The mean seed yield from spring-planted and summer-harvested coriander was 1142 kg⋅ha−1. Similar to fall planting, Santo was observed to be the best-yielding cultivar for spring planting. Plants with closer row spacing (37.5 cm) during spring planting significantly outyielded (≈1.4-times more seed) those with wider row spacing (75 cm).
Antioxidants.
Because of the increasing interest in the health-related properties of C. sativum, additional experiments were conducted to determine antioxidants in both cilantro and coriander. Two measures of antioxidant concentrations (Trolox and DPPH) indicated a lack of significant differences between the cultivars evaluated (data not presented). However, Marino-organic contained a significantly higher concentration of total phenolic content than Santo-Monogerm (5.09 and 4.77 g of gallic acid equivalent per 100 g of cilantro, respectively). Cilantro contained a significantly higher concentration of total phenolic content as compared with coriander (4.95 and 1.15 g of gallic acid equivalent per 100 g of material, respectively). Wangensteen et al. (2004) also reported higher levels of phenolics in the leaves than in the seeds of C. sativum.
Microbial populations.
Total mesophiles (CFU/g), yeast and mold (log CFU/g), and coliforms (log MNP/g) from three grocery stores varied from 6.0 to 7.1, 4.5 to 5.1, and 2.6 to >4.0, respectively, whereas corresponding values of greenhouse-grown cilantro were 3.3, 3.3, and 2.0, respectively. Cilantro produced in the greenhouse had the lowest counts of mesophiles, coliforms, and yeast and mold. This indicated that the handling of cilantro from the farm through marketing/delivery channels might be responsible for increasing microbial loads on grocery store cilantro. In Virginia and other areas in the south, some greenhouses that formerly produced tobacco transplants were not fully used. These greenhouses may be used to grow of C. sativum with low/safe levels of microbes.
Our long-term goal is to develop/establish coriander as a specialty crop for Virginia farmers. Results indicated that coriander/cilantro is a potential crop in Virginia. This crop can provide a source of coriander/cilantro for use by extensive local immigrant populations around Washington, DC, and it can provide an alternative crop for Virginia farmers.
Conclusions
We concluded that that both fall and spring plantings are possible for producing cilantro and coriander in Virginia. However, fall planting for cilantro harvesting during the following spring would be more profitable for farmers in Virginia and other areas in the mid-Atlantic region because these will result in earlier supplies for harvest during the year. Most cilantro is imported from outside regions during earlier months, and local production could reduce transportation costs. The same argument could apply to spring plantings, but increasing temperatures during late spring generally induce early bolting in cilantro.
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