Butterhead Types Research Articles

Pathogenicity Groups in Fusarium oxysporum f. sp. lactucae on Horticultural Types of Lettuce Cultivars

Isolates of Fusarium oxysporum f. sp. lactucae obtained from six localities in Japan were divided into three patho-genicity groups. Group 1 was highly pathogenic to lettuce cultivars of crisphead and red leaf types and was less pathogenic to butterhead and green leaf type cultivars. Group 2 was highly pathogenic to butterhead type and less pathogenic to crisphead and leaf types. Group 3 was less pathogenic to all lettuce types than groups 1 and 2. These results indicated pathogenic differentiation in F. oxysporum f. sp. lactucae, roughly relating to horticultural types of host lettuce cultivars.

Desempenho de cultivares de alface no Estado do Acre

Devido às condições ambientais verificadas no estado do Acre, caracterizado pela ocorrência de temperaturas elevadas e alta precipitação, as cultivares tradicionalmente utilizadas pelos produtores apresentam baixo rendimento e qualidade. O objetivo do presente trabalho foi avaliar o comportamento das novas cultivares de alface disponíveis no mercado, em termos de características agronômicas e rendimento, nas condições edafoclimáticas de Rio Branco, Acre. Para isso foram realizados dois ensaios no campo experimental da Embrapa Acre, em um solo do tipo Argissolo Vermelho-Escuro, textura argilosa. O primeiro de maio a julho de 1996 (período seco) e o segundo de dezembro de 1996 a fevereiro de 1997 (período chuvoso). Foram avaliadas as cultivares Babá de Verão, Brisa, Carolina AG-576, Elisa, Lucy Brown, Marisa AG-216, Piracicaba 65, Regina 71, Tainá, Simpson, Vanessa e Verônica, sendo que 'Regina 71' e 'Elisa' foram incluídas apenas no ensaio do período seco. O delineamento experimental foi o de blocos casualizados, com três repetições. No período seco, as cultivares Simpson, Lucy Brown e Regina 71 apresentaram os maiores pesos médios (373; 362 e 341 g, respectivamente) e produções comerciais de 49,8; 48,3 e 45,5 t/ha, respectivamente. Em geral, as cultivares dos tipos lisa sem cabeça e lisa com cabeça apresentaram maior índice de ataque de nematóide (Meloidogyne javanica) quando comparadas às do tipo crespa. No ensaio realizado no período chuvoso, as cultivares Marisa AG-216, Verônica, Lucy Brown, Brisa, Tainá e Piracicaba-65 apresentaram os maiores pesos médios e produções comerciais. Entretanto, as médias obtidas foram bem inferiores às verificadas no ensaio do período seco, variando de 164 a 198 g para o peso médio, e 21,9 a 25,9 t/ha para produção comercial. Dentre as cultivares avaliadas no período seco, Regina 71 (lisa, sem cabeça) e Carolina AG-576 (lisa, com cabeça) destacaram-se entre as do tipo lisa, apresentando folhas de tamanho uniforme e bem arranjadas. Entre as de folha crespa solta destacaram-se as cultivares. Verônica e Marisa. A cultivar Lucy Brown do tipo americana (crisp head) também foi bastante produtiva.

Evaluation of the Effect of Seed Treatments, Bactericides, and Cultivars on Bacterial Leaf Spot of Lettuce Caused by Xanthomonas campestris pv. vitians.

As a part of a broader program for management of bacterial leaf spot, the effects of lettuce-seed treatments, greenhouse application of bactericides, and cultivars were evaluated. Seed artificially inoculated with Xanthomonas campestris pv. vitians was treated with bactericides or heat treated and evaluated for the incidence of contaminated seed and seed germination. Seed soaked in 1% sodium hypochlorite for 5 and 20 min had an incidence of contaminated seed of less than 10%. Dry-heat (1 h), hot-water (50°C, 2 h), and organic-acid treatments significantly reduced seed germination. Considering both the effects on incidence of contaminated seed and seed germination, the best treatments were soaking the seeds in 1% sodium hypochlorite for 5 or 20 min. Copper sulfate, alone or mixed with Zineb or Dithane, failed to control the disease and caused phytotoxicity. All of the other bactericides significantly reduced the severity of bacterial leaf spot. However, the differences among bactericide efficacy were too small to allow comparison between the different forms of copper used, as well as the effect of adding manganese and zinc (Dithane) or zinc alone (Zineb) to the copper product. Nevertheless, copper hydroxide alone, mixed with Zineb or mixed with Dithane, and basic copper sulfate reduced disease severity by 86.89, 78.67, 80.42, and 81.82%, respectively, without causing phytotoxicity. For the two years of cultivar evaluation, no significant difference in mean disease severity was observed among the cultivars. Based on disease incidence, the most susceptible cultivar was Bellagreen. Cvs. Ideal cos, Grand Teton, Great Lakes, Paris Island, Ithaca, and Optima showed intermediate susceptibility, and the least-susceptible cultivars were Waldmann's and Grand Rapids, both green-leaf type. There was no significant difference between the three romaine (cos) cultivars and between the two crisphead cultivars, but a significant difference was observed between the two butterhead types, Bellagreen and Optima, which had 80.04 and 48.01%, respectively, of their leaves diseased at the time of harvest.

Genotypic response of lettuce cotyledons to regeneration in vitro

Twenty-two lettuce ( Lactuca sativa) genotypes belonging to different morphological groups were screened for their response to regeneration in tissue culture. A shoot regeneration medium, consisting of SH salts and vitamins, supplemented with 0.1 mg 1 −1 IAA, 0.5 mg 1 −1 kinetin, 0.05 mg 1 −1 zeatin, 30 g 1 −1 sucrose and 7 g 1 −1 bacteriological agar at pH 5.8 was used. Response in tissue culture measured by callus production, root and shoot regeneration was generally found to be statistically dependent on the genotype of lettuce used. Callus and shoot indices were generated for all genotypes as indicators of performance. The use of Bronze Mignonette as a standard genotype enabled batches of genotypes to be compared in successive experiments. This approach detected minor variations among experiments and allowed the culture performance of all genotypes to be ranked. No correlation was observed between callus index and shoot index, and the variation in performance of genotypes was not statistically linked to their morphological groups. Genotypes that showed good shoot regeneration in tissue culture included: Bambino and Iceberg (crisphead types); Cobham Green and Sweet Butter (butterhead types), Simpson Elite (leaf type), and Rosalita and Paris White (cos types).

水耕法による外生アスコルビン酸ナトリウムのサラダナへの導入

The effects of administering 1000 and 2000 ppm sodium ascorbate (NaAs) to roots of lettuce (butter head type) just prior to harvest for 24 hr on the foliar L-ascorbic acid (AsA) content were studied. The results were as follows.1. The water absorption ability of the roots was lowered by increasing NaAs concentration such that plants exposed to 2000 ppm withered.2. When roots were exposed to 1000 and 2000 ppm NaAs, the AsA contents of the leaves increased 3.5 and 4.7 times over those of the control plants. The AsA content in the lettuce leaves kept at 5°C for 3 days after treatment did not decrease significantly and the appearance of leaves from the treated plants was similar to that of the control.3. The K, Ca and Mg contents of leaves from the treated plants were similar to those of the control, which suggests that the mineral content in the leaves was unaffected by the treatment.Although the production of lettuce (butter head type) with abundant L-ascorbic acid content was shown to be possible, there are still some problems to be solved before this method can be put into practical use.

545 PB 087 SUMMER LETTUCE PRODUCTION POTENTIALS FOR HIGHER ELEVATIONS

Greenhouse grown transplants of 23 lettuce varieties were produced in 1” diameter speedling flats, seeded May 1, transplanted to the field in early June when plants were 4 weeks of age. Transplants were grown in a commercial potting media of peat-vermiculite-perlite. Loose leaf, butterhead, crispbead or iceberg and cos types were included, field-planted at the Elam Swarey farm in Burkes Garden, Tazewell County, Virginia, at an elevation of 3,400 ft. above sea level. No crisphead (iceberg) varieties were found to be satisfactory in yield or quality for area conditions. Of loose leaf varieties, `New Red Fire' and `Red sails' were judged highly adapted for high elevation summer production at sites above 2,000' elevation and/or for fall production at lower Piedmont and coastal areas for October and November harvests. `Tiara', a dark green loose leaf was judged the best of its type in this test. Of the cos types, `Pyramid' and `Ideas' were best adapted to high elevation summer production or lower elevations fall production. Of the butterhead types, `Condor' and `Encore' were suited to higher elevations, `Condor' showing more heat tolerance.

DNA polymorphisms in Oryza sativa L. and Lactuca sativa L. amplified by arbitrary primed PCR

Thirty-five rice (Oryza sativa L.) varieties, including 18 japonica, 5 javanica and 12 indica subspecies and 12 lettuce (Lactuca sativa L.) varieties were identified taxonomically, using PCR with originally designed 21 RAPD (Random Amplified Polymorphic DNA) primers and 8 sequence-specific primers, used for amplifying four specific DNA fragments. Use of these primers revealed polymorphisms among varieties in rice and lettuce and facilitates DNA fingerprinting. Dendrograms of both species based on polymorphisms were constructed and genetical relationships were established. In rice, half the number of amplified bands were polymorphic and almost all varieties differentiated. However, differentiation of minor genetic alterations among somaclonal variants or mutants and their mother varieties was not feasible. In L. sativa, 47% of the amplified fragments were polymorphic and all 12 varieties were differentiated. Some of the PCR fragments were variety or type specific, which could be used for indicators for type-selection. The dendrogram obtained showed differentiated clusters of crisphead, leaf and butterhead type, findings in good accord with the classification based on the genetic background.

The Level of Field Resistance to Bremia lactucae in Lettuce (Lactuca sativa) Cultivars Carrying the Resistance Gene Dm11

AbstractForty‐one lettuce cultivars (butterhead type), carrying race‐specific resistance gene Dm11 in combination with some others, were studied for field resistance to Bremia lactucae. Significant differences in the level of field resistance were revealed. Most of the cultivars under study were highly susceptible under field conditions. There are evident relationships between combinations of race‐specific Dm genes and field resistance. The cultivars with gene combinations Dm2, Dm3 and Dm11 are susceptible. A very high level of field resistance was detected in the cultivars with combination of genes Dm5/8, Dm6 and Dm16 (cvs. ‘Celia’, ‘Katanga’ and ‘Musette’). This is in close link with their Lactuca serriola origin and a high level of field resistance in progenitors.

Prevention of Lettuce Tipburn by Supplying Air to Inner Leaves

Growing environments were controlled to prevent or reduce lettuce tipburn, a physiological disorder in inner developing leaves around a growing point caused by calcium deficiency. Lettuce (Lactuna sativa, L.) of butter head type was grown by hydroponics in a controlled-environment room which had heaters, humidifiers, a refrigerator, electric lamps, and a CO2 control apparatus. With air pumps and flexible pipes, room air was blown onto inner developing leaves totally or partially enclosed by the outer leaves. After transplanting, lettuce plants were exposed to various air supply conditions. Air temperature and RH were 24 C and 85%, respectively, in the light period, and 20 C and 85% in the dark. The PPF was 264 mmol m2sl, and light period was 14 hours. The CO2 concentration was 1500 mmol mol1. Temperature of the nutrient solution was constant at 20 C, pH was 5.8-6.2, and EC was 150 mS/m. The effects of various conditions on tipburn development were studied in relation to growth rate. Air supply to inner leaves prevented tipburn completely up to 60 g f.w., though tipburn occurred at approximately 15 g f.w. in the control. All-day air supply was more effective in preventing tipburn than air supply in the light period or the dark period alone. Air supply to inner developing leaves was proved effective in preventing tipburn without sacrificing a rapid growth rate. The reason for the effect was an increase in transpiration from the leaves encouraged water and calcium uptake by the root and increased calcium concentration in the leaves.

`Valprize': A Butterhead Lettuce Cultivar for Southern Texas

Lettuce production in the Lower Rio Grande Valley (LRGV) of southern Texas has fluctuated from a high of 1882 ha in 1979 to a low of 564 ha in 1986. Since 1986, production has rebounded to just > 1000 ha in 198990 season, with mostly crisphead type cultivars. There are three planting periods: midSeptember to early October; mid-October to mid-November; and late November to midDecember. Each planting period requires specifically adapted cultivars to maintain shipments from November through April. Butterhead types are occasionally integrated into the cropping system, but often fail to produce a salable product because of diseases and bolting. The purpose of our breeding program was to develop a larger butterhead lettuce adapted to the LRGV. Primary importance was placed on resistance to premature bolting and tipbum. Secondary emphasis focused on resistance to Texas races 5 and 6 of downy mildew (Bremia lactucae Regl.), which is a sporadic problem in the region. An additional objective was to enlarge the array of adapted lettuce cultivars available to growers in southern Texas. ‘Valprize’ was developed as a re-

Integrated Analysis of Growth and Light Interception in Winter Lettuce II. Differences between Cultivars

‘Integrated growth analysis’ (emphasizing aspects of crop and plant structure) and ‘light conversion analysis’ (stressing the efficiency of interception and photosynthetic conversion of light) have been used to investigate the winter growth of different cultivars of butterhead and crisphead types of glasshouse lettuce. Measurements from ‘Ambassador’ (large-framed butterhead), ‘Renate’ (medium-sized butterhead) and ‘Cristallo’ (crisphead) were made, statistical progressions were fitted to the primary data and hence estimates of all the analytical components were derived. Curves for crop growth rate, like those for most other components, followed a generally similar pattern for all three cultivars. In integrated growth analysis, the biomass curve for Ambassador lay above the curves for the other cultivars. The weight advantage was initially 60 per cent and it persisted with only a small reduction (to 40 per cent) until the final harvest. Relative growth rate varied little between cultivars because differences observed in leaf area ratio were complementary to those seen in net assimilation rate. In light conversion analysis, differences in light intercepting efficiency between cultivars were not statistically significant, though Ambassador attained full interception 4 days earlier than Renate and 6 days earlier than Cristallo. Differences in light utilizing efficiency were small and non-significant except during the post-rosette stage when the value for Renate was lower than that of either Ambassador or Cristallo. Deviations around the fitted curves were correlated with fluctuations in the light regime. An assessment is made of the utility and limitations of the two procedures. It is concluded that both approaches can assist in analyzing the rate of dry matter production in crops or plant stands. Integrated growth analysis is advantageous when the need arises to treat individual and population-based attributes simultaneously, while light conversion analysis provides a means of explicitly incorporating the primary environmental variable influencing growth.

Development of a Compact Mass Spectrometer for Analysis of Gases During Plant Metabolism

A compact, dispersion-type mass spectrometer for analysis of gases of interest in the metabolism of plants has been developed. By means of a heated flexible inlet capillary 0.25mm in diameter, less than 15l/min of gas is taken from the plant-growing area using a differential pumping system (Fig. 1). Precise analysis of gases in high water-vapour pressure is performed under a constant capillary temperature of about 80°C. Ions produced by electron impact are separated according to their masses by a specially designed permanent magnetic field and simultaneously collected by independently adjustable collectors (Fig. 1). The magnetic field consists of a concave entrance field and a convex exit field. Properties of second-order aberrations are determined by the radii of the concave, and convex field, r and R, respectively and the angle of incidence, e, of the ion beam to the concave field (Fig. 2). These aberrations are minimum when r=31mm, R=50mm and e=24 degree, and three-dimensional focusing is applied clearly (Fig. 3). A mass difference such that the valley between two adjacent peaks is exactly zero is less than 1 within a mass range of 4 to 50 (Fig. 4). The advantages of this mass spectrometer in comparison with the well-known infra-red gas analyzer are:1) Such multiple gases as H2O, O2 and CO2 can be measured simultaneously.2) Several gases labeled by their stable isotopes, 13C, 15N and 18O, can be analyzed.3) The low gas consumption and short response time enables measurement of the changes in gas concentration in a small space.These characteristics have been clarified through the following experiments using this mass spectrometer:a) Distribution pattern of water vapour pressure on the surface of leaves of butter-head type lettuce and its response to sudden illumination were measured directly in the plant-growing area (Fig. 5 and 6).b) Simultaneous measurement of the photosynthesis and transpiration for a cut-leaf of butter-head type lettuce was made using the leaf chamber method (Fig. 7).c) Translocation of photosynthates from leaves to a green pepper pod using stable isotope 13CO2 was estimated by measuring the 13CO2 concentration emitted from the pod by respiration after 13CO2 feeding of the leaves (Fig. 8).

レタスにおける光, 施肥条件がアスコルビン酸含量に及ぼす影響

Effects of light and nutritional conditions on the ascorbic acid content in hydroponically grown lettuce of butterhead type (Luctuca sativa L. cv. Edogawa or Okayama) were investigated. With increasing levels of shading, the fresh weight and number of leaves decreased, the shape of leaves became narrower and ascorbic acid and sugars content decreased markedly, while nitrate nitrogen content inclined to increase. Plants grown in 1/4 strength standard nutrient solution were inferior in fresh weight and number of leaves to those grown in 1/2 strength solution. Though ascorbic acid and sugars content was higher for plants grown in 1/4 strength solution at higher light intensities, the effect of nutrient concentration gradually disappeared with increasing shading level.Diurnal changes in leaf constituents were studies on sunny and cloudy days. The contents of ascorbic acid, sugars and chlorophyll were higher in the daytime and lower during the night, while nitrate nitrogen content increased in the night time. These tendencies were more clear on the sunny day than on the cloudy day.The relations between the contents of ascorbic acid, sugars, nitrate nitrrogen etc. were discussed and possible techniques of practical use for improving the quality of hydroponically grown leaf vegetables were also discussed.

Isolation of Natural Cytokinins from Lettuce Leaves1

Abstract Cytokinins were extracted from lettuce leaves (Lactuca sativa L., butterhead type), purified by cation exchange, paper and Sephadex LH-20 column chromatography and bioassayed with tobacco callus. Compounds with chromatographic mobilities corresponding to those of zeatin and zeatin riboside were detected. The inner, developing leaves of the heads contained most of the cytokinin activity.

Effects of Temperature on the Germination and Emergence of Lettuce (Lactuca Sativa, L.) Varieties

SummaryThe response of seed germination to temperature, over the range 5-33°C, was studied for 22 varieties of the Crisp, Cos and Butterhead types of lettuce. The overall patterns of response were similar in all varieties, irrespective of the storage conditions or origin of the seed lot. The optimum temperature for germination in all varieties was between 15°C and 22°C, but there was a marked upper temperature limit for germination ranging from 25.7+0.9°C in cv Hilde to 32.8+0.9°C in cv Avoncrisp. In the main, the Crisp types germinated well at 30°C, which inhibited germination in the Butterhead types.In a field experiment where eighteen of these varieties were sown during a period of hot sunny weather, two distinct patterns of emergence were observed, apparently related to the prevailing soil temperatures and the upper temperature limits for germination of each variety. In varieties with a high upper temperature limit for germination, seedling emergence was rapid even during periods of high soil temperat...

Relationship of Turnip Mosaic Virus Susceptibility and Downy Mildew (Bremia lactucae) Resistance in Lettuce1

Abstract A mosaic disease of Lactuca sativa L. is described and the causal agent identified as turnip mosaic virus (TuMV). Extensive infection reduces the yield appreciably or may destroy entirely the value of the crop. A survey of L. sativa cultivars indicated that TuMV susceptibility is restricted to mildew resistant: crisphead types: ‘Calmar’, ‘E-4’, ‘Imperial 410’, ‘Imperial Triumph’, ‘Valrio’, ‘Valtemp’, and ‘Valverde’. Circumstantial evidence indicates that TuMV susceptibility in cv. ‘Calmar’, ‘Imperial 410’, ‘Valrio’, ‘Valtemp’, and ‘Valverde’ stems from the mildew resistant L. serriola L. (P.I. 91532). TuMV and mildew resistant cultivars are: butterhead type ‘May King’, ‘Meikoningin’, ‘Proeftuin’s Blackpool’, ‘Ventura’; leaf type ‘Red Salad Bowl’, ‘Salad Trim’; cos type ‘Valmaine’. Seed collections of L. serriola from the Santa Clara and Salinas Valleys of California produced plants that fell into 3 classifications: a) TuMV-resistant, mildew-resistant; b) TuMV-resistant, mildew-susceptible, and c) TuMV-susceptible, mildew-resistant. No plants in L. sativa or L. serriola were susceptible to both TuMV and mildew. Extreme resistance to TuMV was demontrated in L. sativa and L. serriola. TuMV-susceptible L. sativa cultivars showed differences in tolerance to symptom expression and resistance to infection. In L. serriola a resistance connected with a hypersensitivity reaction was observed. All isolates of TuMV collected were capable of infecting susceptible L. sativa cultivars. L. sativa cv. ‘Calmar’ and ‘Valverde’ systemically infected with TuMV did not transmit the virus through the seed. L. serriola systemically infected with TuMV failed to produce seed.

Recognition of lettuce mosaic virus in Japan

1) In recent years, a mosaic disease of lettuce has been recognized in the vicinity of Tokyo as one of the most destructive diseases of lettuce. Symptoms on crisp-head type varieties, Imperial 847 and Great Lakes, are conspicuous, leaves becoming distorted and frequently developing mosaic or vein-clearing. In butter-head type variety, Wayahead, very faint mosaic or vein-clearing, and in some individuals, necrotic flecks are observed.2) Twenty-three collections of mosaic lettuce plants were tested for the causal viruses by inoculating with carborundum to several indicator plants. As a result, 4 samples yielded cucumber mosaic virus, while the other 19 samples were found to contain a virus hitherto unreported from Japan.3) This virus was readily transmitted either by mechanical inoculation or by aphids, Myzus persicae and Hyperomyzus sp. It infected plants belonging to three of the eight families tested, including lettuce, zinnia, aster, Chenopodium album, C. anthelminticum, and Gomphrena globosa. The last three plants developed only local lesions. Cucumber, tobacco, tomato, petunia, bean, broad bean, cowpea, turnip, corn, etc., were not infected.4) The virus was found to be carried over in the seed of lettuce. Seed-borne infection occured at a rate of 1 to 6per cent, in varieties Imperial 847, Great Lakes, and Wayahead.5) The virus activity was lost when juice of diseased lettuce was diluted 1:500, when exposed to 60°C for 10 minutes, or when subjected to aging in vitro for 2 days.6) From these results, it has been concluded that this virus is to be identified with the lettuce mosaic virus (Marmor lactucae), known from U. S. A. and other countries.