Origin

‘NuMex Las Cruces’ originated from a hybridization between two of the most prominent cultivars, Large Red Thick and Mesilla, grown in southern New Mexico. ‘Large Red Thick’ is an open-pollinated cultivar that in southern New Mexico is favored because of its early maturity date (≈70 d) and has large fruits. ‘Mesilla’ is an F₁ hybrid that has high yield but is late-maturing (≈90 d). The two parents were hybridized to combine the earliness and large fruits of ‘Large Red Thick’ with the high yield of ‘Mesilla’. At hybridization, selecting for curly top resistance was not planned. Beginning with the F₂ progeny, single plant selection using phenotypic recurrent selection with pedigree breeding for earliness, desirable fruit shape, and size, yield, and ease of destemming was accomplished. After five generations of selfing, seed from the single plant selection, New Mexico Breeding Line 03C477-4, was increased under insect-proof cages (Bosland, 1993). This increased seed became ‘NuMex Las Cruces’ and was used in subsequent field plot trials. In 2005, a year with high curly top incidence in northern Mexico and southern New Mexico, including the Las Cruces area (Velasquez-Valle, et al., 2008), it was serendipitous that in the replicated yield trial plots, ‘NuMex Las Cruces’ was observed to have significantly less curly top symptoms as compared with the other cultivars and breeding lines in the trial. Therefore, ‘NuMex Las Cruces’ was advanced as not only a high-yielding cultivar, but as a curly top-resistant cayenne cultivar.

Description and Performance

‘NuMex Las Cruces’ is a high-yielding, high-heat cayenne pepper with a maturity similar to that of ‘Large Red Thick’, an early-maturing cayenne cultivar (Fig. 1). Replicated trials were conducted at the Leyendecker Plant Science Research Center 5 km south of Las Cruces, NM. Data for fruit size and yield were based on a randomized complete block design with four replications containing up to 30 plants each over 3 years. The plants were grown using standard growing practices commonly found in southern New Mexico (Bosland and Walker, 2005). The plots were harvest three times. Table 1 shows the yields for each harvest with the percentage that the yield represented. To calculate means for fruit quality traits, 10 randomly selected fruit from each plot were used. In replicated trials in 2005, 2006, and 2007, ‘NuMex Las Cruces’ fruit length (17.2 cm) was not significantly different from ‘Large Red Thick’ and ‘Mesilla’ (data not shown). Fruit width of ‘NuMex Las Cruces’ is most similar to ‘Mesilla’ (2.6 cm), and both are wider than ‘Large Red Thick’ (Table 1). Individual pod weight for ‘NuMex Las Cruces’ at 25.4 g is between ‘Large Red Thick’ and ‘Mesilla’ (Table 1). Hand removal of the pedicel and calyx was rated “easy” (personal observation), and ripe mature pod color of ‘NuMex Las Cruces’ was scarlet (Munsell color rating: 7.5R 3/12). In limited field testing, ‘NuMex Las Cruces’ was conducive to hand or machine-harvesting (personal observation).

Table 1.A 3-year mean for yield, fruit heat, fruit weight, and fruit width of ‘Large Red Thick’, ‘Mesilla’, and ‘NuMex Las Cruces’ at the Leyendecker Plant Science Research Center.

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The heat level of ‘NuMex Las Cruces’ was determined by a reverse-phase high-performance liquid chromatography system with fluorescence detectors (Collins et al., 1995). ‘NuMex Las Cruces’ at 17,400 Scoville Heat Units (SHU) is significantly hotter than ‘Large Red Thick’ (12,900 SHU) or ‘Mesilla’ (13,200 SHU). ‘NuMex Las Cruces’ is well suited for the cayenne mash industry for hot sauce production as a result of its high heat level.

‘NuMex Las Cruces’ average yield over the 3-year period was 50% higher than ‘Large Red Thick’, the standard open-pollinated cultivar grown in the southern New Mexico production area. ‘NuMex Las Cruces’ yielded as well as the high-yielding F₁ hybrid ‘Mesilla’ (Table 1).

In 2010, another year of high curly top virus incidence in the Las Cruces, NM area, ‘NuMex Las Cruces’ had 67% less curly top incidence than ‘Large Red Thick’ and 75% less curly top incidence than ‘Mesilla’. Besides field observations of curly top virus resistance, ‘NuMex Las Cruces’ was tested under controlled conditions at the USDA-ARS-Northwest Irrigation and Soils Research Laboratory. Nine plants of ‘NuMex Las Cruces’ (resistant) and ‘Large Red Thick’ (susceptible) were inoculated with the three most common Curtovirus species (BCTV, BSCTV, and BMCTV) by placing six viruliferous beet leafhoppers in a clip cage per plant. A non-inoculated plant served as the control. The plants were evaluated 3 months later for the presence of Curtovirus species by polymerase chain reaction (PCR) amplification of the replication-associated protein gene using species-specific primers and methods described previously (Strausbaugh et al., 2008). For samples that did not produce an amplicon using the species-specific primers, we developed an internal standard to prove inhibitors of PCR were not present as described previously (Strausbaugh et al., 2008). No detectable virus was found in the leaves of the inoculated plants of ‘NuMex Las Cruces’ and the non-inoculated checks, whereas the inoculated ‘Large Red Thick’ had BSCTV and BMCTV present. The inheritance of curly top virus resistance within ‘NuMex Las Cruces’ is not known. The open-pollinated nature of ‘NuMex Las Cruces’ may explain why the cultivar is not 100% resistant, or alternatively, a situation similar to the VAT gene in melon (Cucumis melo L.) may be occurring (Klingler et al., 2001). The VAT gene, a single dominant gene, produces both an antixenosis and an antibiosis response in the melon plant. Genetic studies to determine the inheritance of curly top resistance in ‘NuMex Las Cruces’ are underway and will be reported later.

Availability

Commercial seed amounts of ‘NuMex Las Cruces’ can be obtained by contacting Jurado Inc., Las Cruces, NM 88007; (575) 525-0034. A seed sample (30 seeds) is available from the Chile Pepper Institute, New Mexico State University, P.O. Box 30003, MSC 3Q, Las Cruces, NM 88003. The Chile Pepper Institute can be contacted at http://www.chilepepperinstitute.org, hotmail@nmsu.edu, or phone: (575) 646-3028.