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Lettuce (Lactuca sativa) is a high-value crop cultivated worldwide. Harvested lettuce acreage in New Mexico, USA, trails the leading lettuce production states (California, Arizona), but growers in New Mexico are interested in expanding their production. For New Mexico farmers to increase lettuce production to reach new markets, information on heat-tolerant cultivar performance is needed. This study was conducted to evaluate six lettuce cultivars described as heat tolerant by seed suppliers or other sources. In 2020 and 2021, we assessed two butterhead types, ‘Anuenue’ and ‘Mikola RG10’; two green leaf types, ‘Muir’ and ‘Tropicana’; and two romaine types, ‘Parris Island Cos’ and ‘Sparx’, in the Jose Fernandez Garden at the New Mexico State University Heritage Farm in Las Cruces, NM. To determine which cultivars and types of lettuce are better suited for southern New Mexico, we measured these variables: marketable harvest weight, number of days from transplant to first bolt, and number of days from transplant to 50% bolted. In 2020, ‘Sparx’, a romaine-type lettuce, had, on average, 32% higher yield compared with the other lettuce types. In 2021 both romaine-type cultivars, Sparx and Parris Island Cos, produced 19% more marketable yield than the other lettuce cultivars. In 2020, ‘Sparx’ was the last to bolt and to reach the 50% bolted stage, whereas in 2021 ‘Mikola RG10’ and ‘Muir’ were the last cultivars to bolt and reach the 50% bolted stage. These results suggest that ‘Sparx’ would be a good potential candidate for farmers in southern New Mexico. ‘Mikola RG10’ and ‘Muir’, butterhead and green leaf type, respectively, demonstrated slower bolting in 2021, indicating they may be useful cultivars for extending lettuce harvest in New Mexico.

Fruit architecture and morphology-related traits are among the determinants of fruit diversity and are major contributors to yield and yield potential in chile pepper (Capsicum spp.). This study aimed to characterize 105 genotypes of a Capsicum diversity panel consisting of cultivars, breeding lines, landrace, and wild species belonging to twelve different pod (fruit) types, for 32 morphometric Tomato Analyzer (TA) descriptors. Hierarchical cluster analysis grouped the genotypes into eight clusters based on the TA descriptors. A multivariate principal component analysis yielded two principal components, PC1 and PC2, which explained 53.24% and 10.11% of the variation in fruit diversity, respectively. The basic measurements—namely, perimeter, area, width midheight, maximum width, height midwidth, maximum height, and curved height were the most discriminating descriptors with a maximum contribution to the overall fruit shape. There was a strong, positive correlation for basic measurements and fruit shape index, whereas blockiness was negatively correlated with distal angle macro. Additive genetic effects and high heritability for the fruit traits were observed. Results of this study will provide valuable information to breed high-yielding chile pepper cultivars based on fruit morphology traits.

Background Chile peppers (Capsicum spp.) are among the most important horticultural crops in the world due to their number of uses. They are considered a major cultural and economic crop in the state of New Mexico in the United States. Evaluating genetic diversity in current New Mexican germplasm would facilitate genetic improvement for different traits. This study assessed genetic diversity, population structure, and linkage disequilibrium (LD) among 165 chile pepper genotypes using single nucleotide polymorphism (SNP) markers derived from genotyping-by-sequencing (GBS). Results A GBS approach identified 66,750 high-quality SNP markers with known map positions distributed across the 12 chromosomes of Capsicum. Principal components analysis revealed four distinct clusters based on species. Neighbor-joining phylogenetic analysis among New Mexico State University (NMSU) chile pepper cultivars showed two main clusters, where the C. annuum genotypes grouped together based on fruit or pod type. A Bayesian clustering approach for the Capsicum population inferred K = 2 as the optimal number of clusters, where the C. chinense and C. frutescens grouped in a single cluster. Analysis of molecular variance revealed majority of variation to be between the Capsicum species (76.08 %). Extensive LD decay (~ 5.59 Mb) across the whole Capsicum population was observed, demonstrating that a lower number of markers would be required for implementing genome wide association studies for different traits in New Mexican type chile peppers. Tajima’s D values demonstrated positive selection, population bottleneck, and balancing selection for the New Mexico Capsicum population. Genetic diversity for the New Mexican chile peppers was relatively low, indicating the need to introduce new alleles in the breeding program to broaden the genetic base of current germplasm. Conclusions Genetic diversity among New Mexican chile peppers was evaluated using GBS-derived SNP markers and genetic relatedness on the species level was observed. Introducing novel alleles from other breeding programs or from wild species could help increase diversity in current germplasm. We present valuable information for future association mapping and genomic selection for different traits for New Mexican chile peppers for genetic improvement through marker-assisted breeding.

In the past, many ornamental chile pepper (Capsicum annuum) cultivars had to be pinched or sprayed with a uniconazole foliar application to achieve a dwarf, semidwarf, or compact plant habit. This study compares 12 currently available commercial ornamental pepper cultivars considered to be compact, and introduces 13 new ornamental pepper cultivars that do not require pinching or a uniconazole foliar spray to accomplish the desired dwarf or semidwarf plant habit. All 25 cultivars evaluated in this study were given either a dwarf or semidwarf classification based on industry standards. Of the 25 cultivars evaluated, 12 originate from and are commercially available and bred by various breeding programs, whereas 13 are new cultivars bred by the New Mexico State University Chile Pepper Breeding Program with the goal of having dwarf or semidwarf growth habits. Data indicate that the 13 new ornamental chile pepper cultivars did not require pinching or a chemical foliar spray to develop a dwarf or semidwarf plant habit and have the potential for commercial container production in the greenhouse and nursery industries.

Breeding for capsaicinoid content is one of the major objectives for chile pepper breeding programs due to its culinary, agricultural, and medicinal uses. The objectives of the current study were to determine the Scoville Heat Units (SHU) of select New Mexico State University (NMSU) chile pepper varieties and ‘superhot’ genotypes using high-performance liquid chromatography, and to verify the feasibility of using capsaicinoid content as a taxonomic indicator for the ‘superhot’ varieties. Significant variation (P

Controlled abscission of floral structures is an important horticultural technique that has many applications throughout the growing season. A novel use of chemical abscission in chile pepper (Capsicum annuum) is the removal of open flowers and fruit for the production of breeder seed. For efficiency of abscising flower buds, open flowers, and fruit of ornamental chile peppers, two foliar spray treatment levels, 1000 and 2000 ppm ethephon were tested. Ornamental chile peppers were chosen because they are prolific flower and fruit producers, making removal of potentially cross-pollinated fruit and open flowers laborious. Flower bud and flower number were reduced with both 1000- and 2000-ppm ethephon treatments, while fruit number decreased only with 2000-ppm ethephon treatment. ‘NuMex Easter’ was more sensitive to ethephon treatment as compared with ‘Chilly Chili’ and ‘Riot’. Ethephon had no negative impacts on end of the season growth index, mature fruit number, and seed number. We found ethephon can reduce numbers of flower buds, open flowers, and fruit with no long-term effect on mature fruit and seed number, making it a useful tool for the production of breeder seed in chile pepper breeding programs.

Chile peppers (Capsicum sp.) are one of the most important spices in the world and a significant vegetable, providing substantial amounts of vitamins A and C. Chile peppers are also used as a medicinal and lachrymator plant because of the characteristic burning sensation they cause when consumed by mammals. This sensation is caused by capsaicinoids that are alkaloids produced in vesicles inside the fruit. A novel class of chile peppers known as “super-hots” having greater than 1 million Scoville heat units have generated much interest. We compared the morphological structure of fruit pericarp and placental tissue of “super-hot” chile peppers to those of jalapeno and bell pepper. Most chile peppers including jalapenos, only produce the capsaicinoids in secreting vesicles found on the placenta. We report on the novel discovery that these “super-hot” chile peppers have developed accessorial vesicles on the pericarp tissue in addition to the vesicles on the placental tissue, thus leading to exceedingly high Scoville heat units for these plants.

This study established the heat levels for several high-heat chile pepper (Capsicum chinense) varieties (Trinidad Moruga Scorpion, Bhut Jolokia, Trinidad Scorpion, Douglah Trinidad Chocolate, and Trinidad 7-pot Jonah) to determine which variety has the highest average measured heat level and the relatedness of the chile peppers using molecular analysis. In replicated trials with appropriate controls at Las Cruces, NM, results show two ‘Trinidad Moruga Scorpion’ chile pepper plants reached more than two million Scoville heat units (SHU). This is the first confirmation of chile pepper fruit measuring more than two million SHU. A large range of heat levels was observed among the field plots—further supporting strong environmental effects on chile pepper pungency. ‘Trinidad Moruga Scorpion’ was significantly hotter than ‘Bhut Jolokia’, but ‘Trinidad 7-pot Jonah’, ‘Douglah Trinidad Chocolate’, and ‘Trinidad Scorpion’ did not differ significantly from ‘Bhut Jolokia’. Molecular analysis with randomly amplified polymorphic DNA (RAPD) markers confirmed that the accessions are genetically unique. ‘Trinidad Moruga Scorpion’ belongs to the species C. chinense and is not the same chile pepper as ‘Bhut Jolokia’.

Heirloom vegetables are becoming more appreciated by the public for their unique colors, shapes, and superior flavor unavailable in modern cultivars (Klee, 2010). The increased popularity of heirloom vegetables began in the late 20th century and has been attributed to the return to the organic, local, and ‘‘authentic’’ foods movement (Weaver, 2000). However, experimenting with and cultivating heirlooms has been a popular pastime for centuries. Even Thomas Jefferson grew heirlooms at his Monticello plantation. In his 1000-foot long garden terrace, Jefferson tended to a number of heirloom cultivars, taking meticulous notes on the growth and cultivation of each species in his Garden Kalendar (Hatch, 2012). Heirloom cultivars are ideal for home gardeners and can be used in the commercial processing industry to improve sales. A potential problem with heirloom varieties is that the consumer and the processing industry needs and desires can change through time (McLaughlin, 2010). Some heirlooms have fallen from favor because they are not widely adapted or they fail to satisfy commercial production standards or mainstream tastes (Gettle et al., 2011). These factors limit the ability of the old cultivars to compete against newer introduced cultivars whose general or specific attributes have broader appeal. So even with their perceived benefits, heirloom cultivars can be improved. Selection for improvement within an heirloom cultivar can enhance the consumer and/ or horticultural value of heirloom cultivars.

The New Mexico State University Chile Pepper Breeding and Genetics Program announces the release of ‘NuMex Heritage Big Jim’ chile pepper (Capsicum annuum L.). ‘NuMex Heritage Big Jim’ is an openpollinated, improved, New Mexican pod-type cultivar. The name was chosen to distinguish the newly selected cultivar from the original cultivar, NuMex Big Jim, while retaining its association. ‘NuMex Heritage Big Jim’ has superior flavor, a uniform and higher heat level, greater plant and pod uniformity, and higher yield as compared with the current commercially available ‘NuMex Big Jim’ chile pepper. There is a renewed interest in heirloom vegetables in the United States because of the variety of shapes, sizes, colors, and, most importantly, the flavor they provide (Creasy, 1999; McLaughlin, 2010). There is no official definition for what constitutes an heirloom vegetable. Most sources agree that heirloom cultivars, also called heritage or vintage cultivars, should be open-pollinated and have a well-established history (Harris, 2007; Iannotti, 2012). One such heirloom legacy is ‘NuMex Big Jim’. The New Mexican-type chile pepper cultivar, NuMex Big Jim, was released by New Mexico State University in 1975 (Nakayama, 1975). It is listed in the Guinness Book of Records as producing the world’s largest pepper pod at 33.75 cm (13.5 inches) long (Coon et al., 2008). Because of the large pods, the cultivar is a favorite of home gardeners and chefs for making chile relleno, a stuffed chile pepper pod. Changes have occurred to the original ‘NuMex Big Jim’ that includes yield, maturity date, plant habit, and fruit characteristics. Growers state that ‘NuMex Big Jim’ fruit is much milder than it was in the past. Also, when released in 1975, one of the complaints about the original ‘NuMex Big Jim’ was that the heat level (pungency) varied greatly from one plant to the next. It has been reported that ‘California Wonder’, another heirloom cultivar, is so variable that is should not be used as a control in experiments (Votava and Bosland, 2002). Selection within an heirloom cultivar to recreate as close as possible the original cultivar is termed a ‘‘rehabilitation’’ of the heirloom variety (Idlebrook, 2011). Therefore, a program was initiated to ‘‘rehabilitate’’ the current, commercially available cultivar NuMex Big Jim. Growers requested our breeding program to rehabilitate the commercially available ‘NuMex Big Jim’ by selecting for a more uniform heat level, maturity date, plant habit, and increased yield. A similar request was given for ‘New Mexico 6-4’ and culminated in the release of ‘NuMex Heritage 6-4’ (Bosland, 2012).