Origin

In the late 1990s, the Prunus Breeding and Genetics Program began to develop a series of early ripening, yellow peach cultivars adapted to the medium chill zone (minimum chilling accumulation of 500 to 600 chilling units) of the southern United States. This work has resulted in five new peach cultivars that ripen consecutively from mid-May to late June in the medium chill zone of Texas. These cultivars have similar size but better color, fruit shape, and firmness when compared with commercial cultivars such as ‘Regal’, ‘June Gold’, and ‘Harvester’ (Tables 2 to 5; Figs. 1 and 2). ‘Royal Zest One’ (RZ1), ‘Royal Zest Two’ (RZ2), ‘Royal Zest Three’ (RZ3), and ‘Royal Zest Four’ (RZ4) resulted from crosses done between adapted breeding materials with a high-colored California cultivar. ‘Golden Zest’ (GZ) is a cross between a Californian and a Brazilian peach cultivar.

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Fruit of the Royal Zest peach series.

Citation: HortScience horts 49, 4; 10.21273/HORTSCI.49.4.506

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Fruit of the Golden Zest peach.

Citation: HortScience horts 49, 4; 10.21273/HORTSCI.49.4.506

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The Zest peaches [Prunus persica (Batsch) L.] originated in the Stone Fruit Breeding Program at the Department of Horticultural Sciences at Texas A&M University located in College Station, TX, from crosses between selections adapted to the medium chill zone (TX2293-1, ‘Victor’, ‘Agata’) and two peaches from California (‘Rich Lady’ and ‘Crimson Lady’). ‘Royal Zest One’ (RZ1, TX4B235) is a cross between a yellow-fleshed, medium-chill peach selection (TX2293-1 = ‘Flordaking’ open-pollinated) and the California cultivar Rich Lady, an early/midseason, yellow-fleshed peach that was released by Zaiger Genetics. ‘Rich Lady’ is an open-pollinated seedling from ‘Amparo’ (Zaiger et al., 1990). ‘Royal Zest Two’ (RZ2, TX4D165), ‘Royal Zest Three’ (RZ3, TX4E218), and ‘Royal Zest Four’ (RZ4, TX4E169) are sister seedlings, which originate from a cross between the yellow-fleshed California peach ‘Rich Lady’ and the early-ripening, medium-chill peach, ‘Victor’. ‘Victor’ was released by Texas A&M University for use in Spain and is a seedling from the cross between the low-chill, yellow-fleshed, midseason cultivar Tropic Beauty and the early-ripening, yellow-fleshed, medium-chill peach ‘Goldprince’. ‘Tropic Beauty’ was jointly released by the University of Florida and Texas A&M University (Rouse and Sherman, 1989) and is derived from a cross between a Florida selection Fla3-2 (K6E121 open-pollinated) and ‘Flordaprince’ (Fla2-7 × ‘Maravilha’). ‘Goldprince’ was released by the USDA breeding program in Byron, GA (Okie, 1993) and is derived from a cross between ‘Loring’ and the Georgia selection FV3-257. ‘Golden Zest’ (GZ, TX4E220C) is a bright, golden yellow, clingstone peach with nonmelting flesh. It is from a cross between the California peach cultivar Crimson Lady and the Brazilian nonmelting cultivar Agata. ‘Crimson Lady’ is a high-chill, early-ripening, nonmelting, yellow-fleshed, clingstone peach released by Bradford in 1992, which resulted from a cross between the ‘Red Diamond’ nectarine and the ‘Springcrest’ peach (Bradford and Bradford, 1992; Okie et al., 1985). ‘Agata’ (Conserva 458), a nonmelting, processing peach, was released in 1985 by the EMBRAPA Fruit Breeding Program in Pelotas, Rio Grande do Sul, Brazil (Raseira et al., 1992). It is a selection from an open-pollinated seed from the selection 682011041 acquired from Dr. Hough at Rutgers University in 1972. This selection was derived from a cross between a nonmelting selection from New Jersey (NJC95) and a nonmelting, freestone from South Africa (SN45/3).

The original plants of these new releases were first identified in 2000–02. Two-year-old and older trees of the selection were subsequently evaluated during the 2004–11 fruit growing seasons in four locations: three medium-chill sites (College Station, Fairfield, and Terrell, TX) and one higher chill location (Fowler, CA). College Station, TX (lat. 30°37′ N, long. 96°22′ W, 94 m elevation), Fairfield, TX (lat. 31°44′ N, long. 96°10′ W, 134 m elevation), Terrell, TX (lat. 32°42′ N, long. 96°11′ W, 151 m elevation), and the Fowler, CA, site (lat. 36°38′ N, long. 119°42′ W, 92 m elevation) have a chilling accumulation that is generally above 550, 750, 700, and 800 chill units, respectively, as estimated with the mean monthly temperature of the coldest month (Byrne and Bacon, 1992; Sharpe, 1970; Weinberger, 1956) (Table 1).

Table 1.

Chilling conditions at three Texas (College Station, Fairfield, and Terrell) and one California (Fowler) evaluation sites.

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^zChilling estimated with the mean monthly temperatures of the two coldest months using the equation chilling = 4280 – (68.8*Dec/Jan mean monthly temperature in °F) and chilling = 2079 – (123.8*Dec/Jan mean monthly temperature in °C). (Byrne and Bacon, 1992; Sharpe, 1970; Weinberger, 1956). Fairfield used data from Waco, Terrell used data from Dallas, and Fowler used data from the Fresno weather station. All Texas sites used data from 2000 to 2011 and the California site used data from 1975–96.

Description

These five cultivars ripen consecutively from mid-May through late June (Tables 2 to 5). RZ1 and GZ are clingstone and the rest are semifreestones or freestones. All of the new releases have large fruit size and good to excellent flavor when properly managed and thinned. The mean soluble solids for these cultivars when picked mature are similar to or better than the common commercial cultivars. RZ1, RZ2, RZ3, and RZ4 have an attractive yellow ground color with a red blush over 60% to 95% of the fruit surface depending on the cultivar and environmental conditions. GZ has nonmelting flesh, an attractive golden yellow ground color with 20% to 30% red blush over the fruit surface (Tables 2 to 5; Figs. 1 and 2).

Table 2.

Fruiting characteristics of the ‘Zest’ peaches compared with three medium-chill commercial peach cultivars at College Station, TX (2005–11).

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^zFull bloom = 60% to 80% flowers open; FDP = fruit development period, days from full bloom to ripe; Ripe date = date when 20% of the fruit is firm ripe.

^ySize ratings of diameter (mm) 0 to 9; 4 = 51 to 57, 5 = 58 to 64, 6 = 65 to 70, 7 = 71 to 76.

^xRating scale 0 to 9; 0 to 4 = unacceptable, 5 = marginal, 6 = good, 7 = very good, 8 to 9 = excellent for commercial use.

Mean separation within columns by Duncan’s multiple range test at the 5% level. Items with the same letter are not significantly different. No letters within a column indicates no significant differences. SAS statistical program used for analysis of variance.

Table 3.

Fruiting characteristics of the ‘Zest’ peaches compared with two medium-chill commercial peach cultivars at Fairfield, TX (2006–11).

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^zFull bloom = 60% to 80% flowers open; FDP = fruit development period, days from full bloom to ripe; Ripe date = date when 20% of the fruit is firm ripe.

^ySize ratings of diameter (mm) 0 to 9, 4 = 51 to 57, 5 = 58 to 64, 6 = 65 to 70, 7 = 71 to 76.

^xRating scale 0 to 9; 0 to 4 = unacceptable, 5 = marginal, 6 = good, 7 = very good, 8 to 9 = excellent for commercial use.

Mean separation within columns by Duncan’s multiple range test at the 5% level. Items with the same letter are not significantly different. No letters within a column indicates no significant differences. SAS statistical program used for analysis of variance.

Table 4.

Fruiting characteristics of the ‘Zest’ peaches compared with three medium-chill commercial peach cultivars at Fowler, CA (2004–11).

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^zFull bloom = 60% to 80% flowers open; FDP = fruit development period, days from full bloom to ripe; Ripe date = date when 20% of the fruit is firm ripe.

^ySize ratings of diameter (mm) 0 to 9, 4 = 51 to 57, 5 = 58 to 64, 6 = 65 to 70, 7 = 71 to 76.

^xRating scale 0 to 9; 0 to 4 = unacceptable, 5 = marginal, 6 = good, 7 = very good, 8 to 9 = excellent for commercial use.

Mean separation within columns by Duncan’s multiple range test at the 5% level. Items with the same letter are not significantly different. No letters within a column indicates no significant differences. SAS statistical program used for analysis of variance.

Table 5.

Fruiting characteristics of the ‘Zest’ peaches compared with three medium-chill commercial peach cultivars at Terrell, Texas (2004–11).

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^zRipe date = date when 20% of the fruit is firm ripe.

^ySize ratings of diameter (mm) 0 to 9; 4 = 51 to 57, 5 = 58 to 64, 6 = 65 to 70, 7 = 71 to 76.

^xRating scale 0 to 9; 0 to 4 = unacceptable, 5 = marginal, 6 = good, 7 = very good, 8 to 9 = excellent for commercial use.

Mean separation within columns by Duncan’s multiple range test at the 5% level. Items with the same letter are not significantly different. No letters within a column indicates no significant differences. SAS statistical program used for analysis of variance.

Although the Zest peaches bloom before ‘June Gold’ in the medium-chill zone (Table 2), they cropped consistently in the region where ‘TexRoyal’, JuneGold’, and ‘Harvester’ are grown commercially. Based on the relative bloom times of standard cultivars, these new peaches need between 500 and 600 chilling units (CU). The latest blooming releases RZ1, RZ4, and GZ require 600 CU, whereas RZ3 requires 550 CU and RZ2 requires ≈500 CU to break dormancy.

The stones are elliptical to ovate in shape. RZ1, RZ3, RZ4, and GZ have larger stones (length 31 to 36 mm, width 21 to 26 mm, thickness 16 to 19 mm) than does RZ2 (length 28 to 30 mm, width 18 to 23 mm, thickness 16 to 17 mm).

Flowers of RZ1 are non-showy, whereas RZ2, RZ3, RZ4, and GZ have showy flowers. All the new peach cultivars have five pink petals with the non-showy petals being a darker pink and smaller than the showy petals. Pollen is yellow and abundant. The trees are self-fertile.

The trees are vigorous with the typical semispreading growth habit similar to ‘TexPrince’, and ‘TexRoyal’. No observations have been made on resistance for either peach rust or bacterial leaf spot. The leaves are lanceolate with acuminate apices and crenate margins. RZ1, RZ3, and GZ have small globular petiolar glands, whereas RZ2 and RZ4 have reniform petiolar glands.

Availability

Requests for budwood should be directed to The Texas A&M University System’s Office of Technology Commercialization. These cultivars are the subject of plant patent applications.