Fresh Market Tomatoes Research Articles

Grafting Tomato with Interspecific Rootstock to Manage Diseases Caused by Sclerotium rolfsii and Southern Root-Knot Nematode.

Southern blight (Sclerotium rolfsii) and root-knot nematodes (Meloidogyne spp.) cause severe damage to fresh-market tomato (Solanum lycopersicum) throughout the southeastern United States. Grafting is an emerging technology in U.S. tomato production, and growers require information regarding the resistance characteristics conferred by rootstocks. In this study, southern blight (SB) and root-knot nematodes (RKN) were effectively managed using interspecific hybrid rootstocks. During 2007 and 2008, field trials were carried out at two locations that had soils naturally infested with S. rolfsii. At the end of the growing seasons, the mean SB incidence of nongrafted plants was 27 and 79% at the two sites. SB incidence among plants grafted onto rootstock cultivars Big Power (one location only), Beaufort, and Maxifort ranged from 0 to 5%, and area under the disease progress curve (AUDPC) values were lower than for nongrafted and self-grafted controls (P < 0.01). At one location, soils were naturally infested with RKN, and all three rootstocks reduced RKN AUDPC and RKN soil populations at first harvest (P < 0.01). Big Power was particularly effective at reducing RKN galling and RKN soil populations at final fruit harvest (P < 0.01). Fruit yield was higher when resistant rootstocks were utilized (P < 0.05), and in our study grafting was effective at maintaining crop productivity in soils infested with S. rolfsii and M. incognita.

NC 1 CELBR and NC 2 CELBR: Early Blight and Late Blight-resistant Fresh Market Tomato Breeding Lines

NC 1 CELBR and NC 2CELBR are sister lines developed in a long-term breeding program in North Carolina to combine early blight and late blight resistances into adapted fresh-market tomato backgrounds. The pedigree of the two breeding lines traces back to NC 215E-1(93), a large-fruited determinate line with moderate resistance to the foliage blight phase of early blight and high resistance to the stem lesion phase of early blight (Fig. 1). NC 215 E-1(93) has a complex pedigree extending back to NC EBR-1, which has moderate foliage resistance to early blight derived from the Lycopersicon hirsutum L. (currently Solanum habrochaites S. Knapp & D.M. Spooner) source PI 126445 and NC EBR-2, which has moderate foliage resistance and a high level of stem lesion resistance to early blight derived from Campbell 1943 (Gardner, 1988). The Ph-2 gene for late blight resistance was derived from Richter’s wild tomato, and the Ph-3 gene was derived from L. 3707, a selection of the Lycopersicon pimpinellifolium L. (currently Solanum pimpinellifolium L.) line PI 365957 obtained from the Asian Vegetable Research and Development Center (AVRDC). The Ph-2 and Ph-3 genes from these small-fruited sources were backcrossed into NC 215E-1(93) to develop large-fruited lines, which were then crossed to combine the Ph-2 and Ph-3 genes into the early blight resistant background derived from NC 215E-1(93). The resultant F1 hybrid, NC 03220, was selfed, and 96 F2 generation plants were tested in growth chambers using detached leaf inoculations (Brusca, 2003) for combined resistance to isolates (Ph2-OC and Ph3-OC) that specifically overcame Ph-2 and Ph-3. Plants exhibiting a high level of resistance to inoculation with the two isolates (Ph2-OC and Ph3-OC) separately and in combination were selfed in the greenhouse, and F3 generation plants were evaluated in the field for combined resistance to early blight and late blight. Selections were made in the field for the best horticultural traits, including fruit size and smoothness combined with resistances to early blight and late blight. The field selections, 33EB-1(2004) and 45EB2(2004), leading to NC 1 CELBR and NC 2 CELBR, respectively, were derived from a single F2 plant that was homozygous for the Ph-2 and Ph-3 genes combined based on field trials in 2004 and subsequent years and verified by detached leaf inoculations in the growth chamber (Brusca, 2003).

Tolerance of Fresh-Market Tomato to Postemergence-Directed Imazosulfuron, Halosulfuron, and Trifloxysulfuron

A study was conducted to evaluate the effect of imazosulfuron, halosulfuron, and trifloxysulfuron POST-directed on six fresh-market tomato varieties. Injury 7 d after treatment (DAT) was 3% or less from all treatments, and no injury was observed 28 DAT. Imazosulfuron, halosulfuron, and trifloxysulfuron did not reduce yield relative to the nontreated check. There was no detectable herbicide effect on fruit shape and earliness. Data suggest that imazosulfuron, halosulfuron, and trifloxysulfuron can be applied POST-directed without negatively affecting yield or quality of several fresh-market tomato varieties.

Avaliação de classificadora de cilindros divergentes para tomate "Carmen"

As normas de classificação garantem o mesmo padrão para produtores, atacadistas e consumidores finais, facilitando a comercialização, agregando valor ao produto e diminuindo as perdas. O objetivo deste trabalho foi avaliar uma classificadora de tomates in natura por diâmetro, por meio de cilindros rotativos divergentes com diferentes velocidades de rotação. Foram realizados ensaios para avaliar a eficiência da classificação, conformidade da classificação por diâmetro com a norma do PROGRAMA BRASILEIRO PARA A MODERNIZAÇÃO DA HORTICULTURA (2003) e incidência de danos mecânicos em tomates "Carmen". Os cilindros divergentes apresentaram conformidade de mistura na classificação por diâmetro, nas classes 60 e 80. Entretanto, para a classe 70, nenhum tratamento esteve em conformidade com a mistura permitida de 10% de frutos de outras classes. O conjunto de um cilindro liso e outro com helicoide de borracha a 150 rpm obteve a maior eficiência de classificação, com menor perda de massa dos tomates armazenados e atividade respiratória similar aos frutos-controle.

Determining the Optimal Timing of Fruit Harvest in Transgenic Tomato Expressing F1-V, a Candidate Subunit Vaccine against Plague

Changes in the amounts of F1-V, an antigen fusion protein and a candidate subunit vaccine against plague, and total soluble protein (TSP) in green fruit of transgenic tomato plants were investigated to identify the optimum harvest timing to maximize the F1-V yields. Two T2 progenies of the transgenic plant, ‘22.11.21’ and ‘22.11.5’, were grown. The F1-V concentration rapidly decreased at the beginning of the green stage and decreased to less than 5% of the initial concentration at the late green stage in ‘22.11.21’. The F1-V concentration also decreased as fruit size increased in ‘22.11.5’, but the pattern of the decrease was linear and different from that in ‘22.11.21’. The concentration of TSP also decreased with fruit growing in both plants. When calculated on a whole fruit basis, the F1-V content linearly decreased with increasing fruit size in ‘22.11.21’. In ‘22.11.5’, the F1-V content per fruit also tended to decrease from the middle to late green stage. Based on these observations, collecting small green fruits without pruning was proposed as a harvest practice that may maximize the F1-V yields. Thus, the optimum protocols for harvesting and pruning for plant-made pharmaceutical production may be substantially different from those currently used in commercial hydroponic greenhouses for fresh market tomato.

Effect of irrigation management on yield and quality of tomatoes grown in different soilless media in a glasshouse

Global warming and resulting drought is the most important constraint affecting plant production in the Mediterranean Region. Therefore, effective management of scarce water resources is of paramount importance in this region. This research was conducted to determine the optimal irrigation strategy for drip irrigated fresh market tomato grown in different soilless culture in a glasshouse in the Mediterranean Region of Turkey. Volcanic ash, peat and their mixture were used as growth media. Four different irrigation levels (WL1=75%; WL2=100%; WL3=125% and WL4=150% of Class A Pan evaporation) and two watering frequencies (once and twice daily applications) were evaluated. Highest yield and fruit number were obtained from the ash+peat mixture (1:1) with twice a day watering at WL4 irrigation level. Soluble solids of tomato fruit decreased with increasing available water. The highest irrigation water use efficiency (IWUE) value of 121.4 kg m-3 was obtained from once a day irrigation WL1 irrigation level with peat+ash (1:1). IWUE decreased in all treatments as the amount of irrigation water increased. Key words: Peat, volcanic ash, substrate, drip irrigation, class A Pan, irrigation water use efficiency.

Characterization of Curtoviruses Associated with Curly Top Disease of Tomato in California and Monitoring for These Viruses in Beet Leafhoppers.

Curly top disease is caused by a complex of curtoviruses (family Geminiviridae), and it continues to plague tomato production in California. To better understand the etiology of curly top of tomatoes in California, polymerase chain reaction (PCR)-based methods were developed and used to characterize the curtoviruses involved, and to monitor for these viruses in the beet leafhopper vector, Circulifer tenellus. From 2002 to 2008, 86 processing and fresh market tomato fields in the Central Valley of California were surveyed for the incidence of curly top symptoms. Representative samples with curly top symptoms were collected from the surveyed fields, as well as from another 24 fields. The incidence of curly top symptoms in most fields ranged from trace (<1%) to low (1 to 5%); however, in 2002, 2003, and 2008, some fields had medium (5 to 20%) or high (>20%) incidences. PCR with general and species-specific primers was used to establish that the predominant species associated with tomato curly top disease were Beet mild curly top virus (BMCTV) and, to a lesser extent, Beet severe curly top virus (BSCTV). The incidence, relative amount, and species of curly top virus in leafhoppers, collected at monthly intervals by the California Department of Food and Agriculture (CDFA) personnel during 2003 to 2008, was also determined. The predominant species detected were BMCTV and BSCTV. The highest incidences of curly top in tomato fields were associated with high populations of leafhoppers (e.g., in 2003 when populations were two times greater than average) having high incidences and levels of curly top virus early in the growing seasons (e.g., March to May 2003 and 2008). Detection of curly top virus in leafhoppers early in the growing season was consistent with acquisition of virus from reservoir hosts in the foothills. However, continued detection of curly top virus in leafhoppers throughout the growing season and development of curly top in late-planted fresh market tomatoes were consistent with the presence of inoculum sources (e.g., weeds or crop plants) in the agricultural areas of the Central Valley. Geographical locations or "hotspots" having higher proportions of curly top virus-positive leafhoppers were identified, which may reveal areas having high concentrations of curly top virus reservoir hosts. The application of these molecular tools has provided new insight into curly top of tomato in California, and may lead to improved curly top management.

Population dynamics of arthropods associated with early-season tomato plants as influenced by soil surface microenvironment

Two field studies were conducted in the San Joaquin Valley (SJV) of California in order to describe the association of arthropods and possible virus diseases with the plant canopy of early-season, bush-trained, fresh-market tomato ( Lycopersicon esculentum L. cv. Shady Lady) over three soil surface microenvironments. The experimental treatments were based on alterations to planting bed surfaces, as follow: 1) soil covered with silver metalized, light-reflective plastic mulch; 2) soil covered with biological mulch consisting of killed, chopped, cool-season cover crop residues [mixture of triticale ( X Triticosecale Wittm.), rye ( Secale cereale L. cv. Merced), and common vetch ( Vicia sativa L.)]; or 3) bare soil (not covered) – the SJV standard tomato production practice. In both studies, the predominant arthropods encountered in all treatments were the aphid species Aphis craccivora Koch, Macrosiphum euphorbiae Thomas, and Myzus persicae Sulzer; the western flower thrips ( Frankliniella occidentalis Pergande), and the false chinch bug ( Nysius raphanus Howard). These are all considered to be pests of cultivated tomato plants. Spiders were the most prevalent arthropod predator group recovered from foliage samples. All monitored arthropods, except spiders, were most abundant in tomato plants grown over the conventional, bare soil surface, and least abundant (P < 0.05) in plants grown over the silver plastic mulch. Spider numbers were highest in plant foliage over the biological mulch. Other arthropods commonly found on tomato plants in the SJV, including leafhoppers, whiteflies, various caterpillars, and predaceous taxa, were not commonly nor consistently encountered. This was likely due to the early-season timeframe of these studies. Similarly, foliar virus disease symptoms, which were originally targeted for monitoring, were virtually nonexistent. The only arthropod pest species encountered which consistently caused economically important damage to tomato fruit was N. raphanus. In both experiments, tomato fruits grown over the reflective plastic mulch had significantly less (69.5% and 39.7%, respectively) damage due to this pest than those over bare soil. The biological mulch gave inconsistent, intermediate damage reductions. Results from these two field studies showed that reflective plastic bed mulch suppressed populations of a variety of tomato canopy-associated arthropod taxa in early-season plantings, as compared to conventional, bare-soil beds. The biological bed mulch results were more inconsistent, but gave indications that killed cover crop residues, as well as the light-reflective plastic, may be of value in integrated pest management programs for fresh-market tomato production.

Potassium and Boron Nutrition Enhance Fruit Quality in Midwest Fresh Market Tomatoes

The tomato fresh fruit market has rigorous quality standards that can be challenging to meet, particularly under highly variable climatic conditions. Information is required about the influence of nutritional regime on tomato fruit and the interaction of potassium (K) and boron (B) in particular. A field experiment was conducted in 2002 and 2003 to evaluate the effects of K and B on yield and quality of fresh market tomatoes cv. ‘Mountain Spring’ at a southwest Michigan site with well‐drained soil (Alfisol Hapludalf, Oakville fine sand). Treatments applied during fruit development included three fertigation regimes (1N:0.8K, 1N:1.7K, and 1N:2.5K) in the presence and absence of a weekly foliar spray of B (300 mg⋅L−1 B). Increasing K concentration in the fertilizer increased K content in leaf tissue, but in some cases reduced tissue calcium (Ca) and B. Fruit quality was influenced by nutrition, as the greatest rate of K was associated with increased crack susceptibility as indicated by a fruit bioassay and a 14% increase in incidence of the defect “shoulder check” in field‐grown fruit compared to less rates of K nutrition. Boron foliar spray increased tomato marketable yield and fruit quality, reducing shoulder check incidence by 50% compared to zero‐B‐treated plants in 2003. Because of yield and quality improvements, B was a cost‐effective treatment as shown by partial budget analysis, whereas increasing K nutrition did not provide consistent economic benefits. Moderate K rates were associated with the greatest marketable yield, and the 1N:1.7K plus foliar B nutrient regime produced the greatest quality fruit. Overall data were consistent with the need to carefully evaluate K and B nutrition in tomatoes, in the context of soil type, yield potential, fruit quality, and nutrition regime.

A trade model to evaluate the impact of trade liberalisation on EU [European Union] tomato imports

The complexity of the Euro-Mediterranean trade liberalisation is difficult to represent in trade models because of the range of instruments still constraining trade as well as the special characteristics of the major traded fruits and vegetables (product differentiation and seasonality). This paper proposes a trade model to assess the impact of trade liberalisation in the fresh tomato market, taking into account trade measures that are defined on a seasonal basis, such as tariff-rate quotas and entry prices. Simulations are carried out in monthly periods. The model considers imports from different sources as imperfect substitutes, following a non-linear Armington-type approach. Different policy scenarios have been run, considering various types of changes in the trade policy for tomatoes, changes that would arise from a new multilateral trade agreement. Model results indicate that, as far as EU producers are concerned, considering tomatoes as a sensitive product would be the less dramatic scenario. By contrast, entry price elimination would have noteworthy consequences on EU producers.

Variations in tomato (Lycopersicon esculentum) cultivars grown under heat stress

Tomato (Lycopersicon esculentum Mill) is considered as important and economic agricultural crop all over the world. For improving the yield and yield attributes, varieties are often produced and evaluated under different growth condition. In the study presented morphological (growth and yield parameters), biochemical (oil, moisture content and radical scavenging activity) and molecular diversity (RAPD and ISSR) of eleven freshmarket tomato (L. esculentum) cultivars (Aledo VF, Carmeuco 201M, Castle-rock, Falkon, Money Maker, Peto 86, Red Star, Super Marmande, Super Queen, Super Strain B, and UC97–3) were analyzed under heat stress in Egypt to assist breeders in selecting heat tolerant cultivars and nutritional quality. Cultivars Aledo, Peto86 and Red Star were found to have the most vigorous growth habit, while cv. Super Queen has the most significant average fruit weight, yield/plant and total yield/m2 under heat stress. For nutritional quality cv. Super marmande and cv. Aledo showed the highest oil content while cv. Aledo and cv. Money Maker showed the highest radical scavenging activities (RSA). Molecular polymorphism among cultivars was detected using two molecular markers systems, RAPD (random amplified polymorphic DNA) and ISSR (inter-simple sequence repeat), providing further facilities for molecular comparison.

Cover Crops and Organic Mulch to Improve Tomato Yields and Soil Fertility

Cover crops and organic mulches (OMs) have been reported as a means to reduce inputs and increase soil quality. A field experiment was conducted to elucidate the effects of summer cover crops and organic compost on winter fresh market tomato (Lycopersicon esculentum Mill.) yields and quality. Cover crops were sunn hemp (Crotalaria juncea L.), velvetbean (Mucuna pruriens var. utilis), cowpea (Vigna unguiculata L.), and sorghum sudangrass [Sorghum bicolor × S. bicolor var. sudanense (Piper) Stapf.], and compost was applied at 25, 50, and 75 t ha−1. Sunn hemp accumulated up to 190–319 kg ha−1 of N, which was greater than that by sorghum sudangrass (38–110 kg ha−1). The tomato total marketable yields increased 49–82 and 71–85 t ha−1, respectively, in 2 yr. The application of OM at 75 or 50 t ha−1 increased tomato yields compared with that at 25 t ha−1. Yields of extra‐large tomato fruits, especially at the first harvest during the early winter, were improved by growing sunn hemp or applying the composts. However, no interaction between cover crops and OM was observed for tomato marketable yields or quality. Soil organic C increased when OMs were applied compared with the plastic mulch (PM), whereas total soil N and organic C:N ratio were unaffected by any treatment. These results suggest that either the production of cover crops, especially sunn hemp, or the application of compost at high rates can improve winter fresh market tomato yields and quality and advance organic farming.

Incorporating pest management into the design of multiple goal-oriented cropping systems

Dan O. Chellemi born in the USA in 1959. Research Plant Pathologist, U.S. Department of Agriculture, Agricultural Research Service (USDA, ARS). 1982, B.S. Plant Science, U. of Florida; 1986, M.S. Plant Pathology, U. of Hawaii-Manoa; 1990, Ph.D., Plant Pathology, U. of California-Davis. 1990 Post-Doctoral Researcher, U.S. Forest Service, Coweeta, North Carolina; 1991–96 Assistant Prof., and 1996–97 Associate Prof., U. of Florida, Plant Pathology Department, North Florida Research & Education Center, Quincy, FL, USA; 1997–present, Lead Scientist, USDA, ARS research project ‘Alternatives to methyl bromide soil fumigation for vegetable and floriculture production’; 2007–present, Project Coordinator, USDA, ARS AreaWide Pest Management Project for Methyl Bromide Alternatives. Publications: Over 50 published papers in peer-reviewed journals, four peer-reviewed book chapters. Research: Current research involves the development and implementation of pest management systems designed to minimize environmental disruption and reduce chemical inputs while remaining technically feasible and economically viable. Research accomplishments include the evaluation of bacterial wilt-resistant tomato genotypes using a regional approach, the adaptation of soil solarization to the integrated management of soilborne pests of tomato under humid conditions, development of an alternative, low-input production system for fresh market tomatoes, and the characterization of land and crop management effects on the stability of soil fungal and bacterial communities. Phytoparasitica (2009) 37:101–103 DOI 10.1007/s12600-008-0016-1

EFFECT OF FIELD MANAGEMENT PRACTICES ON DISEASE DEVELOPMENT, SOIL CHEMISTRY AND YIELD IN ORGANIC TOMATOES

The effects of different strategies for transition to organic tomato production on timber rot (Sclerotinia sclerotiorum), early blight (Alternaria solani) and Septoria leaf spot (Septoria lycopersici) incidence and severity, soil chemistry and yield were studied. The four cropping strategies considered were 1) low input cover crop/fallow, 2) low input perennial mixed hay, 3) moderate input field vegetables, and 4) high input extended season vegetables under high tunnels. Each was considered with and without compost applications. Each cropping strategy was carried out for 3 years, and then all plots were cropped to fresh market tomato, cultivars Florida 47 and Mountain Spring in the fourth year. Annual applications of composted dairy manure during the 3-year transition and prior to tomato planting resulted in significantly less timber rot and early blight in high tunnels, and Septoria leaf spot in open field plots under the mixed hay transition strategy, than in the non-amended plots. Tomatoes in the mixed hay transition strategy tended to have less Septoria leaf spot than those in the open fallow and vegetable transitions. Septoria leaf spot was significantly higher in Mountain Spring than in Florida 47 in open-field plots. Transition strategy generally did not affect soil fertility, but, in all cases, compost amendment significantly increased soil C, N and other nutrients. Compost amendment in the each cropping strategy significantly increased total and marketable yield for green to pink and light red to red maturity stages of both cultivars. The high-tunnel vegetable cropping strategy significantly increased to total and marketable yield for both cultivars. There were no significant differences among cultivars in the total and marketable yield.

Effects of Partial Rootzone and Controlled Deficit Irrigation on Growth, Yield and Peroxidase Activities of Tomatoes (Lycopersicon esculentum Mill.)

The aim of the experiment was to examine the application of partial rootzone drying and deficit irrigation on growth and plant development of tomatoes. Potted fresh market tomatoes (Lycopersicon esculentum Mill.) in pots were subjected to partial root zone drying (PRD) and controlled deficit irrigation (CDI) under glasshouse conditions. Roots of plants were remained attached to plants and half the volume divided in one plant and the other half planted in the other adjacent pot. The treatments were: well-watered continually maintained close to field capacity in both pots (control), CDI50 (half the amount of water in control divided equally to both pots with each watering), PRD50 (half the amount of water in control applied to one pot while water was withheld from the other pot until soil water declined to 50-70% the field capacity and then water was applied to the other pot), PRD25 (half the amount of water in control was applied to one pot while water was withheld from the other pots until soil moisture declined to 25-50% field capacity and then water was applied to the other pot) and CDI25 (quarter amount of water in control divided equally to both pots with each watering). Imposing water deficit reduced fruit yield up to 18% in PRD50 and 33% in CDI50 which coincided with an impairment of fruit expansion. The percentage of fruit dry matter and osmotic potential increased in both PRD and CDI compared with the control. The incidence of blossom end rot increased in both CDI and PRD25 compared with the control and PRD50 treatments. Cell wall peroxidase in the epidermal layer of fruit may have a role in cessation of fruit expansion towards fruit maturity under reduced water availability.

Caracterização de genótipos de tomateiro resistentes a begomovírus por marcador molecular co-dominante ligado ao gene Ty-1

O objetivo deste trabalho foi avaliar genótipos de tomateiro, quanto à resistência a begomovírus, e caracterizar, por meio do marcador molecular SSR-47, híbridos de tomate de mesa portadores do alelo de resistência ao begomovírus Ty-1, com potencial comercial. Os 24 híbridos experimentais, heterozigotos no loco Ty-1, depois de infectados via enxertia, apresentaram sintomas intermediários, em comparação aos identificados pelas linhagens homozigotas Ty-1/Ty-1 e pelos genótipos suscetíveis Ty-1+/Ty-1+, o que indica a dominância incompleta do alelo Ty-1. Esses híbridos foram considerados como parcialmente tolerantes a begomovírus. Os híbridos experimentais TEX-246, TEX-261, TEX-253, TEX-256, TEX-262, TEX-252, TEX-251 e TEX-268 aliaram médias elevadas de produção total e de massa média dos frutos; e os híbridos TEX-246, TEX-253, TEX-256, TEX-262 e TEX-252 apresentaram valores elevados também para meia-vida da firmeza e foram, portanto, considerados competitivos em comparação aos padrões comerciais usados como testemunhas. O marcador molecular SSR-47 foi eficiente em caracterizar genótipos portadores do alelo Ty-1. A infecção do begomovírus, induzida via enxertia, manifestou sintomas, nos genótipos testados, condizentes com os resultados obtidos com o marcador molecular SSR-47.

U.S. Production Trends and the Impact of the Florida Fresh Market Tomato Industry to the Economy of Florida

FE749, a 6-page fact sheet by John J. VanSickle and Alan W. Hodges, describes trends in tomato production and provides estimates for the total regional impacts of the Florida tomato industry using IMPLAN input output modeling system. Includes references. Published by the UF Department of Food and Resource Economics, September 2008.

Tomato yield, biomass accumulation, root distribution and irrigation water use efficiency on a sandy soil, as affected by nitrogen rate and irrigation scheduling

Florida is the largest producer of fresh-market tomatoes in the United States. Production areas are typically intensively managed with high inputs of fertilizer and irrigation. The objectives of this 3-year field study were to evaluate the interaction between N-fertilizer rates and irrigation scheduling on yield, irrigation water use efficiency (iWUE) and root distribution of tomato cultivated in a plastic mulched/drip irrigated production systems. Experimental treatments included three irrigation scheduling regimes and three N-rates (176, 220 and 230 kg ha −1). Irrigation treatments included were: (1) SUR (surface drip irrigation) both irrigation and fertigation line placed right underneath the plastic mulch; (2) SDI (subsurface drip irrigation) where the irrigation line was placed 0.15 m below the fertigation line which was located on top of the bed; and (3) TIME (conventional control) with irrigation and fertigation lines placed as in SUR and irrigation being applied once a day. Except for the “TIME” treatment all irrigation treatments were controlled by soil moisture sensor (SMS)-based irrigation set at 10% volumetric water content which was allotted five irrigation windows daily and bypassed events if the soil water content exceeded the established threshold. Average marketable fruit yields were 28, 56 and 79 Mg ha −1 for years 1–3, respectively. The SUR treatment required 15–51% less irrigation water when compared to TIME treatments, while the reductions in irrigation water use for SDI were 7–29%. Tomato yield was 11–80% higher for the SUR and SDI treatments than TIME where as N-rate did not affect yield. Root concentration was greatest in the vicinity of the irrigation and fertigation drip lines for all irrigation treatments. At the beginning of reproductive phase about 70–75% of the total root length density (RLD) was concentrated in the 0–15 cm soil layer while 15–20% of the roots were found in the 15–30 cm layer. Corresponding RLD distribution values during the reproductive phase were 68% and 22%, respectively. Root distribution in the soil profile thus appears to be mainly driven by development stage, soil moisture and nutrient availability. It is concluded that use of SDI and SMS-based systems consistently increased tomato yields while greatly improving irrigation water use efficiency and thereby reduced both irrigation water use and potential N leaching.

Genetics, Genomics and Breeding of Late Blight and Early Blight Resistance in Tomato

Late blight (LB), caused by the oomycete Phytophthora infestans, and early blight (EB), caused by the fungi Alternaria solani and A. tomatophila, are two common and destructive foliar diseases of the cultivated tomato (Solanum lycopersicum) and potato (Solanum tuberosum) in the United States and elsewhere in the world. While LB can infect and devastate tomato plants at any developmental stages, EB infection is usually associated with plant physiological maturity and fruit load where older senescing plants exhibit greater susceptibility and a heavy fruit set enhances the disease. At present, cultural practices and heavy use of fungicides are the most common measures for controlling LB and EB. Genetic resources for resistance have been identified for both diseases, largely within the tomato wild species, in particular the red-fruited species S. pimpinellifolium and the green-fruited species S. habrochaites. A few race-specific major resistance genes (e.g., Ph-1, Ph-2 and Ph-3) and several race-nonspecific resistance QTLs have been reported for LB. Ph-3 is a strong resistance gene and has been incorporated into many breeding lines of fresh market and processing tomato. However, new P. infestans isolates have been identified which overcome Ph-3 resistance. Recently, a new resistance gene (Ph-5) has been identified, which confers resistance to several pathogen isolates including those overcoming the previous resistance genes. Advanced breeding lines including Ph-5 alone and in combinations with Ph-2 and Ph-3 are being developed. Genetic controls of EB resistance have been studied and advanced breeding lines and cultivars with improved resistance have been developed through traditional breeding. Additionally, QTLs for EB resistance have been identified, which can be utilized for marker-assisted resistance breeding. Currently, new inbred lines and cultivars of tomato with good levels of EB resistance and competitive yield performance are being developed at the Pennsylvania State University. This review will focus on the current knowledge of both LB and EB with respect to the causal pathogens, host resistances, and genetics and breeding progresses.

Adequação de engates rápidos de aspersores como conectores de mangueira para distribuição de água em sulcos de irrigação

Como forma de reduzir as perdas de água que ocorrem na irrigação empregada na cultura do tomateiro, agricultores vêm utilizando mangueiras de forma precária na distribuição de água aos sulcos. O presente trabalho teve como objetivo estudar a adequação de engates rápidos de aspersores para serem aplicados como conectores de mangueiras por produtores irrigantes que façam uso desse sistema de distribuição de água. A primeira etapa do estudo foi avaliar, em campo, a operacionalidade do uso de mangueiras por produtores que fazem uso desse sistema. Posteriormente, quatro modelos de engates rápidos, disponíveis no mercado, foram ensaiados em laboratório, determinando-se o coeficiente de resistência, o comprimento equivalente, a curva de perda de carga e a eficiência de estanqueidade. Como resultado, apresenta-se o projeto estrutural de um sistema de conexão de mangueiras, utilizando-se do modelo de engate com melhor desempenho e recomendações quanto ao seu uso na distribuição de água. Apesar da necessidade de ensaios adicionais em campo, o sistema proposto tem potencial para otimizar a eficiência do uso da água, melhorar as condições ergonômicas do trabalhador e garantir boa rentabilidade ao produtor.