California Wonder Research Articles

Resistance to the glasshouse whitefly (Trialeurodes vaporariorum Westw.) in sweet pepper (Capsicum annuum L.)

Fourteen cultivars, one F1-hybrid and one half-wild type (Cind) of sweet pepper were tested on resistance to glasshouse whitefly. Several mutually significant levels of resistance were found. Most resistant appeared to be ‘California Wonder’, ‘Severka M’, ‘Koral’ and ‘Yolo Wonder’. During the test sweet pepper plants were infested both with whiteflies and their parasite — Encarsia formosa, which caused the blackening of whitefly puparia. The blackened puparia are easily seen, enabling an easier and more rapid evaluation of the number of puparia present.

Effect of Precooling Methods and Peduncle Lengths on Soft Rot Decay of Bell Peppers1

Abstract Thorough precooling of bell peppers (Capsicum annuum L. cv. California Wonder) to 10°C (50°F) soon after harvest delayed, but did not prevent, soft rot decay caused by Erwinia carotovora (L. R. Jones) Holland. There was little weight loss and shrivel in any of the treatments. Inoculated peppers with intact or partial peduncles had better overall visual quality and were less decayed than peppers with no peduncles.

Foliar Uptake and Injury from Saline Aerosol

AbstractPepper (Capsicum annuum L. cv. California Wonder), soybean (Glycine max L. Merrill cv. Prize), and tomato (Lycopersicon lycopersicum L. Karst. ex Farw. cv. Heinz 1350) plants were exposed to saline aerosols until incremental salt deposition levels of 0.2, 0.4, 0.6, and 0.8 mg Cl− cm−2 of horizontal surface area were achieved. Foliar necrosis became evident on the 0.4 mg Cl− cm−2 treatments after 3, 7, and 8 days on tomatoes, soybeans, and peppers, respectively, in an environmental chamber that simulated early morning dew between 0100 and 0700 PST. Severity of injury increased with increasing salt deposition and time. Foliar absorption of Na+ and Cl− was linearly related to the amount of salt deposition on leaves. No injury symptoms were apparent on any species at any salt deposition level when relative humidity (RH) was maintained at approximately 70% during the same period. Similar results were obtained in a second experiment where treated tomato, soybean, and pepper plants were compared at treatments of 70 and 100% RH during predawn hours but without dew formation. The injury at 100% RH, however, was not as pronounced as when plants were exposed to dew.

Improved Growth of Onion and Bell Pepper in Saline Soils by Two Vesicular‐Arbuscular Mycorrhizal Fungi

AbstractThe effect of 5 levels of salinity on the growth of onions (Allium cepa L. cv. ‘Early Yellow Globe’) and bell peppers (Capsicum annuum L. cv. ‘California Wonder’) inoculated with the mycorrhizal fungi, Glomus fasciculatus or Gigaspora margarita, was compared to uninoculated nonmycorrhizal controls. In soils with saturation extracts (ECe) of 1, 3, 4, 6, and 12 mmho/cm, mycorrhizal plants consistently outweighed the controls. Plants inoculated with Gl. fasciculatus, also, grew larger than those inoculated with Gi. margarita. In both onion and bell pepper, the effect of salinity on decreasing percent fresh weight was greatest in the nonmycorrhizal controls. Also, in bell pepper, decreases in percent fresh weights were less with plants infected by Gl. fasciculatus than with those infected by Gi. margarita. Thus, plants infected with mycorrhizal fungi may be more salt tolerant than uninfected nonmycorrhizal plants.

Leaf age and salinity influence water relations of pepper leaves

AbstractPlant growth is reduced under saline conditions even when turgor in mature leaves is maintained by osmotic adjustment. The objective of this study was to determine if young leaves from salt‐affected plants were also osmotically adjusted. Pepper plants (Capsicum annuum L. cv. California Wonder) were grown in several levels of solution osmotic potential and various components of the plants' water relations were measured to determine if young, rapidly growing leaves could accumulate solutes rapidly enough to maintain turgor for normal cell enlargement.Psychrometric measurements indicated that osmotic adjustment is similar for both young and mature leaves although osmotic potential is slightly lower for young leaves. Total water potential is also lower for young leaves, particularly at dawn for the saline treatments. The result is reduced turgor under saline conditions at dawn for young but not mature leaves. This reduced turgor at dawn, and presumably low night value, is possibly a cause of reduced growth under saline conditions. No differences in leaf turgor occur at midday.Porometer measurements indicated that young leaves at a given salinity level have a higher stomatal conductance than mature leaves, regardless of the time of day. The result of stomatal closure is a linear reduction of transpiration.

Oriental and Mediterranean Fruit Flies: Fumigation of Papaya, Avocado, Tomato, Bell Pepper, Eggplant, and Banana with Phosphine12

Infestations (1- to 3-day-old eggs and larvae) of the oriental fruit fly, Dacus dorsalis Hendel, or the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), were eliminated from packaged papayas, Carica papaya L., by low-temperature (12.8°C) fumigation with phosphine generated from ½ of a FUMI-CEL®. There were no survivors from 103,880 oriental fruit flies after an exposure of 4940 ppm-h. Where fumigations were done at 12.8° or 18.5°–26.1°C and 80% RH (ambient), mortality varied both with the natural logarithm of the concentration and treatment time because of the variable rates of phosphine generated. Time influenced efficacy more than concentration. The residues of phosphine in the fumigated papayas were 0.08 ppb after low-temperature fumigation and an exposure of 7600 ppm-h. These residues dissipated to trace levels after 2 days of storage at 12.8°C. Residues were 1.0–1.4 ppb after fumigation at ambient and an exposure of 7700–9100 ppm-h. These residues decreased to 0.18–0.3 ppb after 1 day of storage. Residues of 1.3 ppb on the carton and the polyethylene foam sheet dissipated to levels ranging from trace to 0.4 ppb. Papayas and 10 Hawaiian varieties of avocado, Persea Americana Mill., were not injured by low-temperature fumigation, but fumigated avocados ripened faster than unfumigated avocados. ‘California Wonder’ bell peppers, Capsicum annuum L. var. annuum, ‘apple’ and ‘Williams Hybrid’ bananas, Musa paradisiaca ssp. sapientum (L.) O. Ktze., ‘N-52’ and ‘Anahu’ tomatoes, Lycopersicon esculentum Mill., and 5 varieties of avocado were uninjured after fumigation for 12–63 h and exposures of 5500–20,000 ppm-h at ambient. ‘Black Beauty’ eggplant, Solanum melongena L., tolerated 5500 ppm-h.

Separation of chlorosphyll and carotenoid pigments of capsicum cultivars

A system of thin-layer chromatography on cellulose and column chromatography of mixed pigment bands on columns of magnesium oxide—Hyflo Super-Cel (1:1, w/w) and alumina was developed for the separation of chlorophyll, carotene and xanthophyll pigments in capsicum cultivars. A total of twenty six pigments were separated and identified in Large Green and Golden California Wonder cultivars, during maturation and ripening. Cellulose thin layers and up to four solvent mixtures enabled chromatographic separation without degradation of chlorophylls nd xanthophylls. Carotenoid hydrocarbons which travelled as one streak behind the solvent front on thin layers were separated on magnesium oxide—Hyflo Super-Cel and alumina columns.

Effects of Phosvel and Sevin on Green Peach Aphid Populations, 1974

Abstract ‘California Wonder’ pepper plants were trans-planted on May 10‘74. The plots consisted of a single row of peppers, 25-feet in length, buffered on either side by an untreated guard row. The plants were spaced 12-inches within the row. The treatments were arranged in a randomized complete block design with 3 replications. The soil was a Norfolk “A” loamy sand. All spray treatments were mixed in 1.0 gallon of water and applied at the rate of 25 gal/A with 40 psi. Treatments were applied with a wheelbarrow-type sprayer using CO2 for spray discharge. The spray boom was equipped with drop nozzles and the row was covered by 3 nozzles. Plots were sprayed May 31; Jun 12, 26; Jul 2, 10, 18, 24; and Aug 16 and 27. Peppers were harvested on Jul 23, 31; Aug 7, 12, and 19.

Within-day Changes in the Polyribosome Content and in Synthesis of Proteins in Leaves of Capsicum annuum L

Capsicum annuum cv. California Wonder was grown in controlled environment with a 12-hour photoperiod. The polyribosome content of leaves varied from 60 to 72% of total ribosomes with the highest level occurring in the middle of the photoperiod and the lowest in the middle of the dark period. The variation was accounted for by changes in the content of large polyribosomes (hexamers and larger). There was no indication of an immediate effect on polyribosome content of light-on or light-off.The synthesis of proteins at two times in the 24-hour cycle was compared using a dual isotope technique. Statistically significant results were obtained that suggested that protein(s) with molecular weights of 26,000 daltons were preferentially synthesized in the photoperiod compared to the dark period. No evidence was found for the differential synthesis of proteins within the photoperiod.

Inheritance of resistance to fruit rot (Phytophthora capsici Leon.) and induction of resistance in bell pepper (Capsicum annuum L.)

Fruit rot in bell pepper caused by Phytopthora capsiciLeon. is a limiting factor in its commercial production. Crosses were made between Waxy Globe, a small fruited hot type, resistant to fruit rot and four highly susceptible bell pepper commercial cultivars (Chinese Giant, California Wonder, Osh, Kosh and Yolo Wonder). Studies of the F1's, F2's and backcrosses indicated that Waxy Globe carries a dominant gene imparting resistance to fruit rot. After three backcrosses with California Wonder, lines were obtained combining the resistance gene of Waxy Globe with the large fruit size and low capsaicin of California Wonder.

Sweet Pepers, Insect Control, 1976

Abstract ‘California Wonder’ peppers were transplanted on May 3, 1976, near Dunn, North Carolina. Plots consisted of paired rows, 200 ft long, and were replicated 3 times. A series of Furadan 10G split applications (20 + 30 lb) were made using a Demco applicator mounted on a row buster. On August 14, counts were made for European corn borer, corn earworm, and tobacco hornworm.

Visualization of Oil on Leaf Surfaces—a Technique

Tcchniques were developed to visualize deposits of emulsified oil on leaves of pepper plants, Capsicum annuum L., var ‘California Wonder’. The oil accumulating Over anticlinal walls of epidermal cells may be the oil that interferes with aphid transmission of stylet-borne viruses.

Effects of Mineral Oil on Probing Behavior and Transmission of Stylet-borne Viruses by Myzus persicae1

Electronic monitoring of probing, salivation, and feeding of Myzus persicae (Sulzer) adults on pepper leaves, Capsicum annum L., variety ‘California Wonder,’ after treatment with an 0.75% emulsion of Sunoco 7E oil revealed significant increases in preprobing time over aphids on untreated leaves, little effect on salivation, and fewer aphids ingested sap after contacting oil coated leaves. The antitransmission activity of oil was associated with oil located over the anticlinal walls of epidermal cells. This activity could be removed by absorptive dusts applied to oil treated leaves. Studies on the influence of temperature or expansion of leaf surfaces on persistence of activity of oil showed that rate of loss of activity is greater at 32° than at 24° and 16°C, and expansion of leaf areas up to 150% does not significantly reduce the effectiveness of the oil over a 6-day period following application. Young leaves treated with oil were more susceptible to infection with potato virus (PVY) than were mature leaves. Oil affected aphid transmission of a normally vectorless strain of tobacco etch virus much the same as it did an efficiently vectored strain of PVY. Previous work on effects of oil against both acquisition and inoculation of virus by aphids was verified. Protection of a leaf was limited to the surface on which oil was applied. Momentary contact between an aphid’s labium and an oil treated leaf sufficed to reduce transmission. The anti-transmission effect also resulted from a momentary contact between the labium and a surface impermeable to stylet penetration. Oil can be removed from the aphid’s labium by absorption on cellulose.

Daily changes in nitrate uptake and metabolism in Capsicum annuum

The diurnal pattern of nitrate uptake by Capsicum annuum L. cv. California Wonder in a constant environment is described by a Fourier harmonic, with the maximum uptake in the middle of the photoperiod and the minimum in the middle of the dark period. Comparison of the uptake pattern with that of nitrate reductase (EC 1.6.6.1.) activity suggests against a direct control of one process by the other. This was confirmed by the observation that the pattern of nitrate reductase activity was not altered by restricting nitrate uptake to one hour per day. Translocation of (15)N from the roots is much greater in the lightperiod than in the dark period. Reduction of (15)N in the leaves occurs in the lightperiod but very little is reduced in the dark period. Amino acid levels showed marked daily fluctuations but in the roots neither amino acids, sucrose, fructose, glucose nor malate showed fluctuations. The amino acid composition of roots and leaves differed: glutamine+glutamate were relatively more important in leaves than in roots whereas alanine was a more important constituent of roots than of leaves.

Rhythmic Nitrate Reductase Activity in Leaves of Capsicum annuum L. and the Influence of Kinetin

In the expanding leaves of Capsicum annuum L. cv. California Wonder, two of the three peaks of nitrate reductase activity associated with the light period exhibit a circadian rhythm that persists in continuous light.The spray application of kinetin to the whole shoot or to leaves other than the ones used for nitrate reductase assay causes a phase shift in the activity peaks and this has been used in preliminary investigations of the character of the mechanisms controlling the timing of the peaks.There was some indication that the rate of translocation of nitrate from the roots might be involved. The levels of nitrate moving up the stem after kinetin treatment were more dependent upon the rate of sap flow than on the concentration of nitrate in the sap. For this reason, transpiration rates in whole plants were measured after kinetin treatment but no change in pattern was seen that would correlate with the phase shift in nitrate reductase activity.The occurrence of nitrate reductase peaks in excised leaves suggested a leaf-based in addition to a root-or stem-based mechanism in the timing of nitrate reductase activity in the leaves.

Leaf Water Potential: Comparison of Pressure Chamber and in situ Hygrometer on Five Herbaceous Species1

Leaf water potential was measured on the same leaf with an in situ dewpoint hygrometer of the Neumann‐Thurtell design and with a pressure chamber, for potato (Solarium tuberosum ‘Russet Burbank’), sunflower (Helianthus annuus ‘Russian Mammoth’), pepper (Capsicum annuum ‘California Wonder’), soybean (Glycine max ‘Wells’), and oat (Avena sativa ‘Lodi’). On the average the pressure chamber measurement was within 1.5 bars of the in situ potential, although the scatter in the data was large. The comparisons showed a trend in which the pressure chamber gave lower (drier) leaf water potentials than the hygrometer in the high (wet) potential range, and higher potentials than the hygrometer in the dry potential range. This trend was most distinct in sunflowers, soybeans, and oats. Serious error in the pressure chamber measurement can result if evaporative loss of leaf water is not prevented before and during pressurization or if leaves are stored for an extended period between excision and pressurization.

Photosynthate translocation in Capsicum annuum

The leaves of Capsicum annuum L. cv. California Wonder function as efficient carbon exporting organs for a large part of their life span. Young and old leaves export the same percentage of fixed carbon (74% within 24 hours) although fixation rates per unit area of young leaves may be three times that of old leaves. A constant feature of translocate distribution is a supply to the roots and to the terminal fruit of the main axis from both the main axis leaves and branch leaves. Carbon supply to branch fruit is flexible in that main axis leaves supply carbon to the very small fruit, but the subtending branch leaves supply more as the fruit grows and the branch node becomes more self-sufficient. Fruit are capable of carbon fixation but translocation to terminal fruit from main axis leaves supplies about 7.5 times as much carbon as direct fixation.

Control of Diurnal Variations in Photosynthetic Products

Nitrate accumulates in the leaves of Capsicum annuum L. cv. California Wonder and the leaf content is dependent on the nitrate level supplied to the roots. There is no consistent diurnal periodicity in the leaf nitrate levels.Nitrate reductase activity exhibits three distinct peaks in the leaves. One in the dark period, a second at the time of the prevailing dawn, and a third 6 hours after the beginning of the photoperiod. The third peak of activity can be induced by a short period of illumination (20 minutes) which is also sufficient to induce the labeling of the amino acid fraction by (14)CO(2).

Control of Diurnal Variations in Photosynthetic Products

It has been demonstrated previously that the synthesis of amino acids from photosynthetically fixed carbon in leaves of Capsicum annuum L. cv. California Wonder occurs in the middle of the photoperiod. This paper reports experiments which identify control points regulating the carbon flow in these leaves.Estimations have been made of the levels of intermediates between 3-phosphoglycerate and pyruvate and between 3-phosphoglycerate and fructose 6-phosphate in leaves at different times in the photoperiod. Application of the Chance crossover analysis indicates that during periods of amino acid synthesis, pyruvate kinase is activated, possibly by ammonium ions. Fructose diphosphate aldolase could possibly be an additional control point, showing activation when amino acid synthesis has ceased. There was no indication of diurnal periodicity in the activity of fructose diphosphate aldolase.

The Effect of Molecular Size, Concentration in Nutrient Solution, and Exposure Time on the Amount and Distribution of Polyethylene Glycol in Pepper Plants

Pepper plants Capsicum annuum L. var. California Wonder were grown in nutrient solutions of either -3.0 or -5.0 bars osmotic potential, using polyethylene glycol with molecular weights of 400, 600, 1000, 1540, or 4000 as osmotica. Polyethylene glycol with molecular weights of 1000 or 1540 proved most satisfactory as osmotica to decrease the water potential of nutrient solutions.There was no relationship between the small amount of polyethylene glycol accumulated in the plants and the amount of water transpired. The concentration of polyethylene glycol in the expressed sap of the leaves and the total accumulated was inversely related to molecular weight of polyethylene glycol, was greater at lower osmotic potential of nutrient solution, and increased with time in solution. Except for plants grown in polyethylene glycol 4000, there was more polyethylene glycol in leaves than roots. The indications were that, when the concentration of polyethylene glycol reached a value of 1 to 2 mg per ml, any additional quantity absorbed was transferred to the leaves. The major proportion of polyethylene glycol 4000 absorbed was retained in the roots.The results of Sephadex gel chromatographs showed that the passage of polyethylene glycol through the plants did not alter the average molecular weight. This indicated that there was no selective absorption of small molecules that might be present as contaminates in the commercial product.