Development and characteristics of the ‘Desert Dew’. (A) Pedigree and breeding history. ‘Desert Dew’ (initially named MTX851) was selected from the F4 generation of a cross between ‘Zac-Heart’ and ‘Micro-Tom’, followed with field trials. (B) ‘Desert Dew’ plant growth in the field. (C) Young fruit cluster. The fruits are light green to white and develop a pointed tip; both the peduncle and pedicel are robust. (D) Harvested plant with mature fruits. A ‘Desert Dew’ plant heavily loaded with mature fruit at harvest, with the plant cut and inverted to display the fruit. (E) Mature, vine-ripened fruit cluster. Bar = 2.5 cm.
Comparison of yield and quality traits for ‘Ground Jewel’, ‘Ground Dew’, and ‘Desert Dew’. (A) Number of fruits produced per plant. (B) Single fruit weight. (C) Yield per plant. (D) Brix readings. GJ = ‘Ground Jewel’, GD = ‘Ground Dew’, DD = ‘Desert Dew’.
Violin plots showing the variation in yield and quality traits between ‘Desert Dew’ grown at Minnesota Agricultural Experiment Station (MAES) the University of Arizona Maricopa Agricultural Center (MARC).
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‘Desert Dew’ is a new dwarf tomato variety selected from a cross between ‘Zac-Heart’ and ‘Micro-Tom’, originating from the same selection pool as ‘Ground Jewel’ and ‘Ground Dew’. Previously known as MTX851, ‘Desert Dew’ boasts high fruit yield, a determinate growth habit, compact size, short life cycle, and elevated vitamin C content. The fruits are red, plum-shaped, and feature a pointed tip. The vitamin C content of ‘Desert Dew’ is 34.6 mg per 100 g of fresh weight, significantly higher than the average 19.1 mg per 100 g in typical red tomatoes grown in the United States. This cultivar has demonstrated strong field performance across various locations and shows promise for reducing agricultural water usage due to its short life cycle.
The recent tomato breeding programs in the United States at the University of Minnesota and Arizona State University have focused on developing dwarf tomato cultivars through traditional crosses and phenotypic selection. The aim is to select traits such as dwarfism, short life cycle, high yield, and improved nutritional value and flavor, making these cultivars suitable for farming and gardening in extreme environments, including short-season locations, patios, deserts, and even space farming.
We grew 30 F1 plants under greenhouse conditions from an initial cross between ‘Zac-heart’ and ‘Micro-Tom’. ‘Zac-heart’ was selected from the F3 population after selfing the ‘Big-Zac’ hybrid, resulting in stable, ‘Brandywine’-like large heart-shaped fruits for four additional generations. ‘Big-Zac’ was bred by Minnie Zaccaria of New Jersey, USA, and the hybrid seeds were purchased from Totally Tomatoes (cat. #00087). The female parent plant for the initial cross was ‘Micro-Tom’, developed by researchers at the University of Florida (Scott and Harbaugh 1989). ‘Micro-Tom’ produces small, round cherry-sized fruits, which makes it unsuitable as a field or greenhouse crop due to the small fruit size. However, because of its miniature dwarf plant characteristics, ‘Micro-Tom’ has become one of the most used model systems for plant research (Shikata and Ezura 2016).
A total of 137 F2 plants were grown in a greenhouse, and more than 20 phenotypes were selected to screen for dwarf and short-season cultivars. Field selection began at the F4 generation, focusing on a small number of breeding lines with desirable traits. The field population size for each line of interest varied from 30 to 1000 plants, with off-type individuals being less than 1 in 100. All released inbred lines were further maintained for at least three more generations, with off-type rates consistently below 1%. Among these selected lines are MTX851 (now ‘Desert Dew’), MTX097 (‘Ground Jewel’), and MTX104 (‘Ground Dew’) (Murphy et al. 2021). ‘Desert Dew’ is the result of field selections from the initial pool of phenotypic variation and is the third official release (Fig. 1)
Citation: HortScience 60, 5; 10.21273/HORTSCI18325-24
‘Desert Dew’ exhibits determinate growth habits. Mature plants are dwarf in stature, presenting a small, bushy appearance and spreading in a cycle with an approximate diameter of 30 to 45 cm, reaching no more than 30 cm in height. The fruit set is dense, eventually comprising the majority of the aboveground biomass (Fig. 1C).
Field trial results for all three lines are summarized in Table 1 and Figs. 2 and 3. On average, ‘Desert Dew’ produced a similar number of fruits per plant compared with ‘Ground Dew’ and smaller number of fruits compared with ‘Ground Jewel’ (Fig. 2A). However, the fruits of ‘Desert Dew’ are larger, contributing to a significantly higher yield than ‘Ground Jewel’ and ‘Ground Dew’ (Murphy et al. 2021; Table 1, Fig. 2B and C). The shape and color of ‘Desert Dew’ fruits are similar to those of ‘Ground Dew’. Young fruits of both cultivars are light green to white while growing in greenhouse and field conditions. Each plum-shaped fruit develops a pointed tip, which we believe enhances self-pollination during greenhouse growth in a genetically determined manner (Chen et al. 2015; Song et al. 2022).
Citation: HortScience 60, 5; 10.21273/HORTSCI18325-24
Citation: HortScience 60, 5; 10.21273/HORTSCI18325-24
We conducted field trials for ‘Desert Dew’ at two US locations: the Minnesota Agricultural Experiment Station (MAES) on the St. Paul Campus of the University of Minnesota and the University of Arizona Maricopa Agricultural Center (UAMAC) in the Arizona desert. Field preparations varied between Minnesota and Arizona according to local agricultural extension practices. ‘Desert Dew’ shares similarities with ‘Ground Jewel’ and ‘Ground Dew’, developing flower buds by the third week after germination. Transplanting 2-week-old seedlings is optimal for maximizing yield.
In Minnesota, trials followed Murphy et al. (2021) protocols, using 60-cm-wide rows with biodegradable plastic mulch and drip irrigation. Rows were spaced 1.2 m apart to accommodate tractor access, with no fertilization and watering as needed (two to three times per season). Two-week-old seedlings (14 d after germination) were transplanted in early June, and fruits began ripening 42 to 45 d after transplanting. In Arizona, 30-cm-wide rows with ditches on both sides for flood irrigation were used, with fertilizer applied before transplanting and at 4 weeks. Seedlings were transplanted during the last week of March, and fruits ripened 40 to 42 d after transplanting.
A comparison of ‘Desert Dew’ grown in Minnesota (data collected from 12 randomly selected plants at MAES in 2017) and Arizona (data collected from 11 randomly selected plants at UAMAC in 2021) showed that ‘Desert Dew’ grown at UAMAC produced fewer fruits, which were larger and exhibited greater size variation (Fig. 3). In contrast, plants grown at MAES produced more fruits per plant, with less size variation and higher overall yield (Fig. 3). Additionally, ‘Desert Dew’ in Arizona matured 2 d earlier than those in Minnesota.
Yield data were collected from 10 to 20 randomly selected plants. Canopy closure for ‘Desert Dew’ requires ∼40,000 plants per hectare (16,000 per acre).
Based on the feedback received from 65 participants who tasted different varieties at state fairs, in the class, or at home (home gardeners who conducted trials of the three varieties in their own home gardens), we analyzed the nutritional composition of ‘Desert Dew’ fruits compared with ‘Ground Jewel’ and ‘Ground Dew’ (Table 2). On average, pH value for fresh fruits ‘Desert Dew’, ‘Ground Jewel’, and ‘Ground Dew’ were measured as 4.3, 4.2, and 4.1, respectively. The nutritional analysis was conducted by EMSL Food Chemistry Laboratory (Cinnaminson, NJ, USA). Per 100 g of fresh red tomato, ‘Desert Dew’ contains 1.63 g of sugar, 0.81 g of protein, and 34.6 mg of vitamin C—higher than the corresponding levels found in both ‘Ground Jewel’ and ‘Ground Dew’ (Table 2). For comparison, the average US red tomato contains 19.1 mg of vitamin C per 100 g (Beecher 1998; Hedges and Lister 2005), which is lower than any of the three new breeding lines, particularly ‘Desert Dew’. With a vitamin C content of 34.6 mg per 100 g, ‘Desert Dew’ offers ∼81% more vitamin C than the average red tomato grown in the United States, a notable increase. A study of nine tomato cultivars grown in Slovakia found that the variety with the highest vitamin C content contained 21.51 mg per 100 g (Valšíková-Frey 2017). Although vitamin C content can vary depending on growing conditions (Liptay et al. 1986) and developmental stages (Matteo et al. 2010), most tomato varieties fall within the average range (Matthews et al. 1973; Watada et al. 1976). Notably, some nonred tomato varieties, such as ‘Indigo Apple’, have been reported to contain up to 39.55 mg per 100 g of raw fruit (https://www.saferbrand.com/articles/which-tomatoes-are-the-healthiest-to-grow; data from Baker Creek Heirloom Seeds, Mansfield, MO, USA, rareseeds.com). Among high-yield, red tomato varieties, however, ‘Desert Dew’ stands out for its high vitamin C content.
Tomatoes are among the most popular vegetables cultivated in both gardens and farm fields. However, these plants face challenges in cold or hot, dry locations where the growing season is relatively short for most available tomato varieties. ‘Desert Dew’ was bred alongside other varieties, such as ‘Ground Jewel’ and ‘Ground Dew,’ to meet the needs of growers in high latitude, altitude regions, and deserts with short growing seasons, offering improved nutritional values (Murphy et al. 2021). The gene regulating dwarf trait in tomatoes was previously analyzed as DWARF gene (Averello, et al. 2024; Marti et al. 2006; Shimada et al. 2001). The trait that fruits of ‘Desert Dew’, ‘Ground Jewel’, and ‘Ground Dew’ all develop pointed tip and was reported as gene “n,” which was comprehensively analyzed by Song et al. (2022), who renamed it POINTED TIP (PT). We observed that pointed-tip fruits are less susceptible to calcium deficiency or blossom-end rot, which aligns with findings from previous research (Barten et al. 1994).
The Arizona desert presents a unique growing environment with a short growing season, characterized by hot, dry summers from mid-May to September and winter frost from December to February. Tomato varieties that are not tolerant of these extreme conditions often experience flower bud and young fruit drop, leading to significant reductions in productivity and yield. The optimal tomato growing season in the greater Phoenix area occurs in the spring, from early March to mid-May. There is also some potential for production in the fall, from September to November, although this season is generally less favorable than spring. Nonetheless, both growing seasons remain relatively short.
‘Desert Dew’ performed well during our spring field trials. Notably, from transplanting to harvest, ‘Desert Dew’ required only 8 weeks, ∼4 weeks shorter than most other tested cultivars. This reduction in growing time translates to significant cost and resource savings, particularly in terms of water use. For example, our field trials in Arizona, we applied flood irrigation every 10 d. Because of their short life cycle, all three dwarf tomato varieties required only six cycles of flood irrigation to reach full harvest. In contrast, conventional varieties required nine cycles of flood irrigation before reaching growth limitations, with extreme summer heat limiting the spring crop and frost limiting the fall crop. The high nutritional values of ‘Desert Dew’, especially its elevated vitamin C content, make it a promising candidate for enhancing other nutritional traits, such as increasing vitamin D production through gene editing (Averello et al. 2024).
The potential applications of ‘Desert Dew’ extend beyond traditional agriculture. Its adaptability makes it a promising candidate for home gardeners and small-scale desert farming, where water conservation is crucial. The fresh fruits are aimed to be used in salads or as a snack. The shortened life cycle allows for reduced irrigation needs, making it suitable for cultivation in arid regions. Furthermore, its efficient growth characteristics position ‘Desert Dew’ as an ideal option for space farming initiatives, where resource limitations are a significant concern. Overall, ‘Desert Dew’ shows great promise for farmers and home gardeners in regions with short growing seasons, high latitudes, or high altitudes and in areas like the Sonoran Desert that experience hot, dry summers and chilly winters.
Small trial seed sample of ‘Desert Dew’ is available for research purposes (contact the authors).
Development and characteristics of the ‘Desert Dew’. (A) Pedigree and breeding history. ‘Desert Dew’ (initially named MTX851) was selected from the F4 generation of a cross between ‘Zac-Heart’ and ‘Micro-Tom’, followed with field trials. (B) ‘Desert Dew’ plant growth in the field. (C) Young fruit cluster. The fruits are light green to white and develop a pointed tip; both the peduncle and pedicel are robust. (D) Harvested plant with mature fruits. A ‘Desert Dew’ plant heavily loaded with mature fruit at harvest, with the plant cut and inverted to display the fruit. (E) Mature, vine-ripened fruit cluster. Bar = 2.5 cm.
Comparison of yield and quality traits for ‘Ground Jewel’, ‘Ground Dew’, and ‘Desert Dew’. (A) Number of fruits produced per plant. (B) Single fruit weight. (C) Yield per plant. (D) Brix readings. GJ = ‘Ground Jewel’, GD = ‘Ground Dew’, DD = ‘Desert Dew’.
Violin plots showing the variation in yield and quality traits between ‘Desert Dew’ grown at Minnesota Agricultural Experiment Station (MAES) the University of Arizona Maricopa Agricultural Center (MARC).
Contributor Notes
The tomato breeding program is supported by the Minnesota Agricultural Experiment Station (AES 00021031 and 00021095), the Minnesota Department of Agriculture (MDA-21782), and the generous contributions of the Fink family. Trials conducted in Arizona are sponsored by the Arizona State University School of Life Sciences and supported by the University of Arizona’s Maricopa Agricultural Center. We acknowledge the contributions of Duane McDowell, Shahzad Hussain Shah, Vincenzo Averello IV, Amy Sawyer, John Hiebel, Noah Reimer, and many other students and volunteers who played key roles in the trials and selection of ‘Desert Dew’. Special thanks to Drs. Yin Lu and Claire Milsted for their valuable feedback on the original manuscript, Dr. Fang Yu for her assistance with data analysis using R, and to the reviewers whose thoughtful comments and suggestions greatly assisted us in finalizing this paper. We also extend our gratitude to the field crew at the Minnesota Agricultural Experiment Station and the University of Arizona’s Maricopa Agricultural Center, including Tom Warnke, Steven Poppe, Clint Jones, Gilbert Harrison-Dale, Russell Noon, and the late Billy Petty, for their dedicated efforts in conducting trials.
Development and characteristics of the ‘Desert Dew’. (A) Pedigree and breeding history. ‘Desert Dew’ (initially named MTX851) was selected from the F4 generation of a cross between ‘Zac-Heart’ and ‘Micro-Tom’, followed with field trials. (B) ‘Desert Dew’ plant growth in the field. (C) Young fruit cluster. The fruits are light green to white and develop a pointed tip; both the peduncle and pedicel are robust. (D) Harvested plant with mature fruits. A ‘Desert Dew’ plant heavily loaded with mature fruit at harvest, with the plant cut and inverted to display the fruit. (E) Mature, vine-ripened fruit cluster. Bar = 2.5 cm.
Comparison of yield and quality traits for ‘Ground Jewel’, ‘Ground Dew’, and ‘Desert Dew’. (A) Number of fruits produced per plant. (B) Single fruit weight. (C) Yield per plant. (D) Brix readings. GJ = ‘Ground Jewel’, GD = ‘Ground Dew’, DD = ‘Desert Dew’.
Violin plots showing the variation in yield and quality traits between ‘Desert Dew’ grown at Minnesota Agricultural Experiment Station (MAES) the University of Arizona Maricopa Agricultural Center (MARC).
