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Tito P. Alcantara and Paul W. Bosland

An inexpensive, rapid, and reliable seedling screening technique was developed to identify sources of resistance to foliar blight of Capsicum annuum L. caused by the fungal pathogen Phytophthora capsici Leon. Leaf surfaces of test plants were inoculated with 500 to 1000 zoospores prepared in distilled water. Seedlings were incubated for 5 days in an easy-to-construct dew chamber and observed for symptom development. `Criollo de Morelos 334' chile seedlings, a Mexican land race resistant to root rot caused by the same fungal pathogen, were highly resistant to foliar blight. All commercial cultivars tested in this study, however, were highly susceptible. No root rot symptoms were observed in any of the foliar-inoculated plants.

Open access

John J. McGrady and Donald J. Cotter


Pregerminated (PG) chile pepper (Capsicum annuum L.) seed was fluid-drilled in gels on three dates (early to late spring). Plants grown from PG seed emerged earlier than those from dry seed, and plant growth was enhanced (including earlier flowering), but the fruit yields were not affected. In the first planting date in cold soils, PG slowed emergence and the hypocotyls tended to coil within the gel. In a companion test, pre-soaking seed improved emergence, growth, and yield compared to plants from dry seed. Adding P to the soaking solution enhanced emergence, early plant growth, and plant P, but decreased fruit yields. Phosphorus added to the gel water of hydration increased seedling growth, but did not significantly affect fruit yields.

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Alejandra Nieto-Garibay and Enrique Troyo-Dieguez

Diurnal and seasonal water relations, soil humidity, transpiration, water demand, stomatal resistance, and fruit production, as well as some microclimatic parameters, were studied in a semidomesticated chile ecotype (Capsicum frutescens) under two treatments of plastic mulches, black and opaque, and compared with plants without a mulch in Baja California Sur, a Mexican semiarid state. Plants with opaque plastic mulch showed the highest chile production and total growth. The biggest transpiration rates from January to April was evidenced also by this treatment. The soil water content seemed to be determinant. Opaque plastic mulch plants had more soil moisture during the whole experiment. Plants without plastic mulch had the least chile production, with a lesser soil water content. These plants evidenced an osmotic adjustment under drought stress with low water potential, maintaining a partial turgor pressure, and stomatal regulation, in order to control the lost of water by transpiration.

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Paul W. Bosland

Chile pepper (Capsicum spp.) hybrids are normally produced by hand-emasculating the female parent and then pollinating the emasculated flower by hand. Increased yield has occurred with F1 hybrid seed, but the seed is considered too expensive by growers to be direct-seeded, a common production practice in the southwestern U.S. chile pepper industry. In ornamental flowers, when F2 hybrid seed is available, it is cheaper than F1 hybrid seed. If F2 hybrid chile pepper cultivars could manifest heterosis, and produce fruit quality acceptable to the chile pepper industry, then a less-costly alternative would be available to growers. A series of field trials with jalapeños was conducted to test F1 hybrid cultivars to their F2 progeny for yield and fruit quality. The results indicated that in some instances the F2 progeny can yield as well as the F1 hybrid parent. Therefore, F2 hybrid cultivars can be used in a commercial production system. However, if a male-sterility system is used to produce the F1 hybrid cultivar, the F2 progeny will have significantly lower yield than the F1 hybrid parent, as was the case in one accession in this trial. Nevertheless, F2 hybrid cultivars are an additional way to supply high yielding hybrid cultivars to growers.

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M. Pilar Bañados, Carolina Alvarez, and Alejandra Soto

To evaluate the effect of the time of primocane tipping on harvest date of `Heritage' red raspberry in the central valley of Chile (southern hemisphere), we tipped primocanes at three dates during the 1996–97 growing seasons: in Nov. 1996 (PN), Dec. 1996 (PD), and Jan. 1997 (PJ). Tipping was done manually at a 1.10-m height. Harvest date, fruit quality, and yield component was evaluated in the control and three tipping dates. A difference of 75 days on the initiation of harvest date was detected among treatments. Harvest date initiation was on 20 Jan. for the control with no tipping and for PN, 3 Mar. for PD, and 4 Apr. for PJ. Fruit of the PN treatment was smaller and lighter than the rest of the treatments; however, little differences in soluble solids, acidity, and pH were detected among treatments. Primocane lateral number was 14 for the control treatment and decreased to seven in tipped primocanes. Lateral length increased largely with tipping treatments: 7.8 cm in the control, 30 cm in PN, 29 cm in PD, and 42 cm in PJ. Fruit per lateral ranged between 6.2 in control and 12.2 in PD. Yields estimation for the fall production were 8.5 t/ha in the control, and increased to 12 t/ha estimated for the PJ treatment. The time of primocane tipping had an important effect on `Heritage' red raspberry harvest date, lateral length, and estimated yield.

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Reddy R. Chinthakuntla, Frank Matta, Rao S. Mentreddy, Umesh Reddy, Padmavathi Nimmakayala, Daniel Peterson, and Om Prakash Vadhwa

Chilepepper (Capsicum spp.) is the third most important vegetable crop in the United States. The market value of chile peppers for spices and condiments exceeds $650 million per year. With a growing Hispanic population across the United States, the demand for high yielding, good quality cayenne pepper continues to increase. In order to fulfill this niche market, a study has been initiated to develop pepper varieties that combine high yield potential with superior agronomic traits, including insect and disease resistance, and fruit characteristics, using molecular marker assisted breeding/selection. In preliminary trials, several F1 generations were created through inter- and intra-specific crosses among 220 germplasm lines belonging to six Capsicumsp. in the greenhouse. Selected F1 progeny, parent lines, and selected accessions were planted in single-row field plots the following summer. The crossing success was higher within species than between. The genotypic variation was significant for all parameters examined. The average percent germination (81.1) of F1 progeny was 32% and 45% higher than that of the parent lines and selected accessions, respectively. The F1 progeny were shorter in height; more vigorous in growth, flowered early, and with fewer, but heavier, fruits per plant out-yielded the parent lines and accessions by 50% and 120%, respectively. The study showed a marked heterosis in F1 progeny compared to the parent lines and accessions. Microsatellite genotyping to estimate genetic diversity and validation of markers that are linked to various traits is in progress and will be discussed in the presentation.

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L. Antonio Lizana, Jorge M. Sandoval, Manuel Pinto, and Luis Luchsinger

An experiment was set up to elucidate the causes of differences in harvest time in the adjacent grape-growing areas of Rapel and Sotaqui in the Limari Valley, Chile. Berry samples of `Flame Seedless' were collected from each area, from 10 days after last GA spray until harvest (December to February). Soluble solids (SS), titrable acidity (TA), and SS/TA ratios were analyzed and days from full bloom to harvest, growing degree days, and ambient temperatures were recorded. In Rapel, full bloom was 25 Sept.; the harvest by 16 °Brix, started on 3 Jan., and the harvest by 20:1 SS/TA ratio (min. 15.5 °Brix) on 28 Dec. (11, 16, and 24 days earlier, respectively, than Sotaqui). Degree-days (DD) at harvest (16 °Brix) were 1058 in Rapel and 837 DD in Sotaqui. In the last 50 days prior to harvest, berry acidity was always lower in Rapel, decreasing from 0.87% to 0.47%, while in Sotaqui berry acidity decreased from 1.96% to 0.86%. From 20 Dec. to 2 Jan., the acidity did not decrease significantly (1.96% to 1.84%), but in the next 3 weeks decreased to 0.68%. This difference in the rate of acid degradation is related to the increase in minimum night temperatures in this same period of berry growth. It is concluded that the minimum temperature-dependent rate of organic acid degradation is the main factor influencing the SS/TA harvest index parameter.

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Kevin M. Crosby, Justin Butcher, Kil Sun Yoo, and Daniel I. Leskovar

, TMV, and PVY ( Villalon, 1981 ). In addition, resistance to PepMoV was verified in several lines as well. These resistant lines were used as sources of potyvirus resistance genes to develop additional breeding lines. ‘TAM Mild Chile-2’ was developed by

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Luis Humberto Escobar Torres, Eduardo Alejandro Olate Muñoz, Miguel Jordan, and Marlene Gebauer

Callus induction (CI) and later shoot induction (SI) were studied in Leucocoryne purpurea, a native and endemic Chilean geophyte species. Basal leaf portions (BL), bulb basal plate (BP), and root tips (RT) from in vitro plants were used as explants. Treatments for CI included all three explants and media containing different sources and concentrations of auxins and cytokinins as plant growth regulators (PGRs). Plant material was initiated on MS basal medium (Murashige and Skoog, 1962), supplemented with vitamins, 30 g·L-1 sucrose, 6.0 g·L-1 agar and pH adjusted to 5.7 before autoclaving. The experiments were carried on a growth chamber at 24 ± 1.5 °C. CI cultures were maintained in darkness for 16 weeks, and SI for 12 weeks in a 16-hour photoperiod. BL and RT explants did not respond to any of the CI treatments. BP explants cultured on MS basal medium without PGRs also did not produce any callus. The average frequency of callus induction for BP was 78% and the average fresh weight of callus was 10.06 g/explant after 16 weeks of culture. Best treatment for CI was BP cultured on 4.52 μm 2,4-dichlorophenoxyacetic acid (2,4-D) in combination with 0.45 μm 6-benzyladenine (BA), when they were compared to 2,4-D alone or picloram as auxin source. After 16 weeks of culture, calli were transferred to SI medium, supplemented with three different concentrations of thidiazuron (TDZ), either intact or subdivided (150 mg/explant). SI treatments had a greater and significant response when the callus came from a CI medium containing auxin and cytokinin combined, in comparison to those coming from a CI medium containing auxins only.

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J.A. Anchondo, M.M. Wall, V.P. Gutschick, and D.W. Smith

Pigment and micronutrient concentrations of New Mexico 6-4 and NuMex R Naky chile pepper (Capsicum annuum L.) cultivars as affected by low Fe levels were studied under soilless culture. A custom-designed, balanced nutrient solution (total concentration <2 mm) was continuously recirculated to the plants potted in acid-washed sand (pot volume 15.6 L). Each set of plants from each cultivar received iron concentrations at 1, 3, 10, and 30 μm Fe as Fe-EDDHA. The pigments of leaves, green fruit, and red fruit were extracted with acetone and measured with a spectrophotometer. Surface color of green and red fruit was measured with a chromameter. Total concentrations of Fe, Cu, Zn, Mn, P, and K of leaf blades and red fruit were measured by inductively coupled plasma emission spectroscopy (ICP). Ferrous iron in leaf blades, and NO3-N in petioles also were determined. Iron nutrition level affected total leaf chlorophyll and carotenoid content at early season, and the level of these pigments in green fruit at second harvest. No differences in extractable or surface color of red fruit were found among iron treatments in the nutrient solution, despite variations in red fruit iron content, total foliar iron, and foliar ferrous iron. Higher levels of iron in the nutrient solution increased both ferrous and total iron of the leaves, but depressed foliar Cu and P. High iron supply also increased fruit iron, and decreased fruit Cu content. High iron levels in the nutrient solution were associated with higher concentrations of leaf pigments at early season and higher pigment concentration in green fruit.