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New Mexican chile peppers were harvested at weekly intervals beginning 105 days after planting (DAP), and evaluated for ethylene (C2H4) production, respiration rates, chlorophyll content, beta-galactosidase activity, polygalacturonase (PG) activity, and fruit firmness. Physiological changes were most apparent in peppers harvested 139-154 DAP. Beta-galactosidase activity increased rapidly beginning 147 DAP, and reached a peak of 24.5 mmol·gfw-1 when peppers were harvested 160 DAP. Polygalacturonase was not detectable at any stage of maturation. Fruit firmness was greatest (35.8 N) at 139 DAP and decreased significantly at 160 DAP. Carbon dioxide production and chlorophyll content were highest in young pods harvested 105 DAP, and decreased steadily thereafter. Ethylene production peaked (0.185-0.202 nl·gfw-1·h-1) in peppers harvested between 146-154 DAP.
Individual onion (Allium cepa L.) bulbs were evaluated for pungency by measurement of enzymatically produced pyruvate and by flavor perception. In four separate experiments, pyruvate values were highly and significantly correlated to mean sensory ratings. Correlation coefficients (r) were 0.92, 0.84, 0.95, and 0.79, and regression coefficients (R2) were 0.84, 0.71, 0.91, and 0.62. The high correlations indicate that pyruvate analysis can be used as a reliable selection technique for pungency in onion breeding programs.
Onions (Allium cepa L.) with ≥18% bulb dry weight are dehydrated and used for spices and food ingredients. Bulb weight characteristics and water-soluble carbohydrates (WSC) of two commercial dehydrator cultivars, GS02 and GS04, and a breeding population, NM9335, were studied before and after maturity to observe phenotypic traits that may be useful for selection during breeding programs, and to study dehydrator onion carbohydrate physiology. At maturity, NM9335, GS02, and GS04 bulbs had 11.9 ± 0.33%, 18.6 ± 0.27%, and 19.4 ± 0.40% dry weight, respectively. Mature GS04 plants had 76.5 ± 0.01% of whole plant dry weight in bulbs, which is an extraordinarily high crop harvest index. NM9335 bulbs had higher fresh (hydrated) weight than bulbs of GS04 and GS02, but bulbs in all populations accumulated similar amounts of dry weight. Bulb percent dry weight before maturity did not indicate percent dry weight at maturity in the high-solids commercial onion cultivars. Bulb percent dry weight declined slightly after maturity in all populations. Glucose, fructose, and sucrose were relatively low, and fructans with degree of polymerization ≥6 were relatively high in GS04, but the converse was observed in NM9335. Relative amounts of GSO4 bulb fructan increased sequentially, in order of rank, from DP4 to DP6, but the converse was observed for NM9335.
The β-carotene and total carotenoid content of different Capsicum fruit types and species were analyzed using HPLC. This information is useful for breeding high carotenoid chiles (New Mexican type) for the food industry, and also provides nutritional data for the range of fruit types within the Capsicum genus. Fresh fruit from 25 accessions and dried fruit from 39 accessions were evaluated in 1996 and 1997. β-carotene levels varied from 0 to 16.6 mg/100 g fresh weight, and carotenoid levels were from 0.1 to 89.6 mg/100 g in red ripe fruit in 1996. The range of values for β-carotene was similar in 1997, but a wider range in total carotenoids (0.4 to 117.3 mg/100 g fresh weight) was observed. Fresh fruit (100 g) of the cultivars `Greenleaf Tabasco', `Pulla', `Guajillo', `NuMex Conquistador', `Ring-O-Fire', and `Thai Dragon' contained greater amounts of β-carotene than the RDA for vitamin A for the average adult. For dried Capsicum entries, New Mexican, aji, pasilla, ancho, and guajillo types had the highest levels of β-carotene. In 1996, β-carotene levels among the dried Capsicum germplasm ranged from 0 to 739.2 μg/g dry weight, and carotenoid levels were from 21.3 to 6,225.9 μg/g. Values were higher in 1997, and ranged from 23.7 to 1,198.1 μg/g dry weight for β-carotene and from 76.9 to 10,120.6 μg/g for total carotenoids. A pasilla type (C. annuum) had the highest total carotenoid content among the dried entries in both years.
Macadamia is a rapidly developing global crop; however, limited cultivation history and size of the industry means many challenges remain to support sustained productivity and profitability of this industry. This paper summarizes oral and poster presentations, and subsequent papers included in this volume, delivered at the 2017 International Macadamia Research Symposium, held in Hilo, HI, in September of that year. This was the first international meeting of macadamia researchers since 1992. The 28 oral and seven poster presentations covered propagation technology, tree physiology, soils and nutrition, pollination, pest and disease, orchard management, genetics and breeding, product development, and new production regions. Notable messages were that micrografting of macadamias is commercially viable; planting density and girdling could increase early yield per hectare; resource availability may limit cross-pollination yield; and yield production of individual branches is not independent. Integrated pest management was described to develop pest-resilient farming systems and manage felted coccid; an international collaborative approach was proposed for effective disease management and early detection; and the concept of integrated orchard management was used to translate research outputs into a common language for grower adoption. In the areas of breeding and genetic resources, research demonstrated that modern macadamia cultivars are two to four generations from wild but do not capture all wild diversity; progress was reported on the Macadamia Genome Project to produce the first macadamia reference genome; and advances in phenotypic selection and cultivar development were described.
New Mexican Chile peppers (Capsicum annuum L. `New Mexico 6-4') were harvested at weekly intervals beginning 20 days after flowering (DAF), and were evaluated for ethylene (C2 H4) production, respiration rates, chlorophyll content, degradative enzyme activity (cellulase, polygalacturonase, ß-galactosidase), and fruit firmness. Morphological and physiological changes were most apparent in peppers harvested 54 to 69 DAF. ß-galactosidase activity increased rapidly beginning 54 DAF and reached a peak by 89 DAF. Fruit firmness was highest (36 newtons) at 54 DAF and had decreased significantly by 69 DAF. Carbon dioxide production and chlorophyll content were highest in young pods harvested 20 DAF and decreased steadily thereafter. A climacteric increase of CO, was absent. There were two peaks in C2 H4 production: one associated with rapid fruit growth and the other with color change (61 to 69 DAF). Fruit harvested on the same day but at different developmental stages (green to red) were similar to those observed in fruit harvested over the season for the physiological characteristics tested. Separation of pepper fruit soluble proteins on SDS-PAGE demonstrated increased intensity in protein bands at 27, 35, and 40 kDa and decreased intensity of 51 kDa band as the fruit matured. Several biochemical processes appeared to be enhanced in Chile pepper fruit from 47 to 69 DAF.
Heritabilities of the pungency and single-center traits were estimated in onion breeding lines using selection response and half-sib family analyses. Pungency was determined by measuring enzymatically produced pyruvic acid in individual bulbs. After one generation of selection, pungency was lowered by 0.37 and 0.42 μmol pyruvic acid/gram fresh weight in the breeding lines 90-61-1 and 89-69-8, respectively, and realized heritabilities of 0.21 and 0.51 were estimated. Heritability estimates calculated through half-sib progeny analysis were 0.53, 0.48, and 0.25 for pungency in the breeding lines 90-61-1, 90-62, and 89-69-8, respectively. The number of single-centered onions was increased by 19% and 22% in the lines 90-62 and 89-69-8, respectively, after one generation of selection, and the realized heritability estimates were 0.37 and 0.34, respectively.
The β-carotene and total carotenoid content of either fresh or dried tissue of fruits of a total of 57 cultivars of six Capsicum species were analyzed using high performance liquid chromatography (HPLC). β-Carotene levels in ripe fruit varied from 0 to 166 μg·g-1 fresh weight, and carotenoid levels were from 1 to 896 μg·g-1 in ripe fruit in 1996. The range of values for β-carotene was similar in 1997, but that for total carotenoids was wider (4 to 1173 μg·g-1 fresh weight). Fresh fruit of the cultivars Greenleaf Tabasco, Pulla, Guajillo, NuMex Conquistador, Ring-O-Fire, and Thai Dragon contained greater amounts of β-carotene per 100 g fresh weight than the recommended dietary allowance (RDA) for vitamin A for the average adult. For dried Capsicum entries, New Mexican, aji, pasilla, and ancho types had the highest levels of β-carotene. In 1996, β-carotene levels among the dried Capsicum germplasm ranged from 2 to 739 μg·g-1 dry weight, and carotenoid levels from 111 to 6226 μg·g-1. Values were higher in 1997, ranging from 24 to 1198 μg·g-1 dry weight for β-carotene and from 187 to 10,121 μg·g-1 for total carotenoids. A pasilla type (C. annuum L.) had the highest total carotenoid content among the dried entries in both years.
Experiments were conducted to develop a clonal propagation system for agarita (Berberis trifoliata Moric.). Actively growing agarita shoots were collected from a mature plant at the Texas A&M Univ. Research and Extension Center in El Paso and successfully established on a basal medium consisting of woody plant medium (WPM) salts and Murashige and Skoog vitamins, sucrose at 30 g·L–1, and 0.8% Phytagar supplemented with 11.1 μm BA. Cytokinins (benzyladenine, kinetin, and thidiazuron), subculture period, and age of cultures were tested. The optimal shoot proliferation conditions were WPM basal medium supplemented with 5.5 μm BA and a subculture period of 4 weeks. Culture age did not affect shoot proliferation but did affect rooting. Preliminary experiments with 1.0 μm NAA resulted in nearly 100% rooting of microshoots <6 months old. Shoots from 21-month-old cultures had to be placed on a cytokinin-free medium before successful rooting. On basal medium supplemented with NAA (5.4 μm), 68% of the microshoots rooted with an average of 1.2 secondary roots per microshoot. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA); 1-naphthaleneacetic acid (NAA); N-phenyl-N′-1,2,3-thiadiazol-5-ylurea (thidiazuron or TDZ); 6-furfurlaminopurine (kinetin).