Processing Tomato Cultivars Research Articles

The effect of zinc fertilization on yield and quality of commercial processing tomato (Solanum lycopersicum L.) cultivars

Objective: In this study, conducted in two production seasons, the effects of zinc fertilization on yield and fruit quality of processing tomato varieties (H-1015, Lalin and Kendras) were investigated. Material and Method: Material consisted of ‘H-1015’, ‘Lalin’, and Kendras’ processing tomato varieties. The study consisted of 3 different treatments; zinc applied plots, zinc-free plots and control. Results: The results showed that zinc application to H-1015 and Lalin cultivars gave the highest yield values compared to zinc-free and control treatments in both production seasons. While the differences between the pulp colour values L* and a/b were found to be insignificant in both years, the differences between the values of a* and b* were found to be significant in both years. Similarly, zinc fertilization had no positive effects on the TA and lycopene contents of the varieties. The differences between the fruit pH values of the varieties were found to be significant. While the differences among the Brix values were found to be significant only in 2018, the variety H-1015 showed the highest Brix values in both testing years. Conclusion: Zinc fertilization is proposed to obtain a high yield in processing tomatoes.

Monitoring for a new I3 resistance gene-breaking race of F. oxysporum f. sp. lycopersici (Fusarium wilt) in California processing tomatoes following recent widespread adoption of resistant (F3) cultivars: Challenges with race 3 and 4 differentiation methods.

Fusarium wilt, caused by Fusarium oxysporum f. sp. lycopersici (Fol), causes losses in tomato production worldwide, with major impacts on Californian tomato processing. Single-gene resistance is the primary management tool, but its efficacy has been compromised following the emergence of two successive resistance-breaking races, which, in California, emerged within 12years of resistance deployment. Fol race 3-resistant (F3) processing tomato cultivars (containing the I3 resistance gene) were deployed in the state starting in approximately 2009. The emergence of a new resistance-breaking race (which would be called race 4) is imminent, and early detection will be critical to delay the spread while new resistance is sought. The detection of Fol race 4 is challenged by the lack of validated, rapid, and accurate diagnostic tools. In evaluating in planta phenotyping methods, this study found that rapid seedling phenotyping is not reliable and generates false positives for nonpathogens. Longer (10weeks) mature plant assays are the most reliable, but may not be sufficiently timely. As an additional challenge, based on field and greenhouse studies, Fol race 3 can cause symptoms in resistant F3 cultivars at frequencies greater (30%) than expected for off-types (<2%). We developed a three-F3 cultivar in planta assay to overcome the challenges this posed to differentiating Fol race 3 and Fol race 4. Using the assay, we determined that all putative resistance-breaking cases were Fol race 3; Fol race 4 was not detected in these early survey efforts. These results highlight the need for developing rapid Fol race 4 detection tools and a better understanding of the factors underlying inconsistent I3 gene expression in Fol race 3.

Impact of Plant Growth-Promoting Rhizobacteria Inoculation on the Physiological Response and Productivity Traits of Field-Grown Tomatoes in Hungary

Drought-tolerant plant growth-promoting rhizobacteria (PGPR) may promote plant development under limited water supply conditions, when plant’s water demand is not completely satisfied under rain-fed conditions or when irrigation water availability is limited. The aim of this study was to examine the effects of two inoculation treatments (B2: Alcaligenes sp. 3573, Bacillus sp. BAR16, and Bacillus sp. PAR11 strains and B3: Pseudomonas sp. MUS04, Rhodococcus sp. BAR03, and Variovorax sp. BAR04 strains) and compare those to a control (B0) without artificial inoculation on chlorophyll fluorescence, leaf chlorophyll content (SPAD value), canopy temperature, and the yield of the processing tomato cultivar H-1015 F1 grown under field conditions. The young seedlings of the hybrid tomato variety H-1015 F1 were immersed in 1% of B2 or B3 products (BAY-BIO, Szeged Hungary) for 5 min. Inoculated and untreated seedlings were grown under three irrigation treatments [regular irrigation (RI), deficit irrigation (DI), and no irrigation (I0)], to reveal the effect of PGPR under different levels of water stress. In the dry year (2018), higher canopy temperature and chlorophyll fluorescence (Fv/Fm) were measured during flowering in plants treated with bacteria than in untreated plants. In the stage of flowering and fruit setting, the B3 treatment led to a significant decrease in the Fv/Fm value, canopy temperature remained high, and the SPAD value was statistically the same in all treatments. Under limited water supply, in most cases, PGPR led to a significantly greater total yield but more unripe green berries compared to untreated plants. Under moderate water shortage (dry year + deficit irrigation), the B3 treatment resulted in 26% more ripe, marketable fruit and 49% less unripe fruit compared to the B2 treatment. On the other hand, in the wet year (2020), the bacterial treatments generally did not affect physiological properties, though the B2 treatment produced a higher marketable yield while the amount of green and diseased fruits did not differ statistically, compared to the B3 treatment under deficit irrigation. Based on our study, we recommend the application of the B3 PGPR product as it positively affected key physiological processes, leading to a higher marketable yield particularly under water shortage.

Prediction of Soluble Solids and Lycopene Content of Processing Tomato Cultivars by Vis-NIR Spectroscopy.

Tomato-based products are significant components of vegetable consumption. The processing tomato industry is unquestionably in need of a rapid definition method for measuring soluble solids content (SSC) and lycopene content. The objective was to find the best chemometric method for the estimation of SSC and lycopene content from visible and near-infrared (Vis-NIR) absorbance and reflectance data so that they could be determined without the use of chemicals in the process. A total of 326 Vis-NIR absorbance and reflectance spectra and reference measurements were available to calibrate and validate prediction models. The obtained spectra can be manipulated using different preprocessing methods and multivariate data analysis techniques to develop prediction models for these two main quality attributes of tomato fruits. Eight different method combinations were compared in homogenized and intact fruit samples. For SSC prediction, the results showed that the best root mean squared error of cross-validation (RMSECV) originated from raw absorbance (0.58) data and with multiplicative scatter correction (MSC) (0.59) of intact fruit in Vis-NIR, and first derivatives of reflectance (R2 = 0.41) for homogenate in the short-wave infrared (SWIR) region. The best predictive ability for lycopene content of homogenate in the SWIR range (R2 = 0.47; RMSECV = 17.95 mg kg–1) was slightly lower than that of Vis-NIR (R2 = 0.68; 15.07 mg kg–1). This study reports the suitability of two Vis-NIR spectrometers, absorbance/reflectance spectra, preprocessing methods, and partial least square (PLS) regression to predict SSC and lycopene content of intact tomato fruit and its homogenate.

Diversity and Pathogenicity of Pythium Species Associated with Reduced Yields of Processing Tomatoes (Solanum lycopersicum) in Victoria, Australia.

Yield decline associated with poor crop establishment, stunting, wilting, and diminished root systems was reported in processing tomato crops in Victoria, Australia. During surveys between 2016 and 2018 Pythium species were isolated by soil baiting and by culturing from the diseased roots and collars of plants exhibiting these symptoms. Eleven species of Pythium were identified based on cultural characteristics and phylogenetic analysis with ITS, Cox-1, and Cox-2 gene sequences. None of the 11 Pythium species had been reported previously from processing or fresh tomatoes in Australia. Pythium dissotocum was the most abundant and widespread species isolated during surveys in each of two growing seasons. In pathogenicity tests, these Pythium species ranged from nonpathogenic to highly aggressive. P. aphanidermatum, P. ultimum, and P. irregulare were consistently the most aggressive species, causing serious damage or death at the pregermination, postgermination, and later stages of plant growth. Five processing tomato cultivars varied significantly in their susceptibility to Pythium disease. These results suggest that Pythium species could be contributing to yield loss in processing tomatoes in Victoria both in the crop establishment phase and through the season.

SEvaluation of processing tomato cultivars for resistance against Tomato yellow leaf curl Thailand virus and high yield production

ISHS IX International Scientific and Practical Conference on Biotechnology as an Instrument for Plant Biodiversity Conservation (physiological, biochemical, embryological, genetic and legal aspects) sEvaluation of processing tomato cultivars for resistance against Tomato yellow leaf curl Thailand virus and high yield production

Resistance to bacterial spot (Xanthomonas gardneri) on foliage and fruit of commercial processing tomato cultivars

Bacterial spot of tomato (Xanthomonas gardneri Šutić) is an economically important disease of processing tomatoes in Ontario, Canada, resulting in premature defoliation and fruit damage. Breeding efforts for host resistance focus on assessments of foliar health as opposed to fruit health but anecdotal reports from industry suggest a poor relationship between fruit and foliar resistance. To investigate this, nine commercial cultivars were inoculated at the vegetative (foliar experiment) or reproductive (fruit experiment) stages in replicated field experiments from 2016 to 2018. In the foliar experiment, the standardized area under the disease progress curve (sAUDPC) for defoliation was 51% to 54% higher for ‘TSH18’ than ‘H9706’, ‘Hypeel 696’, and ‘H3406’, but equivalent to ‘CC337’. Fruit disease incidence was 49% and 47% lower for ‘CC337’ than ‘TSH18’ and ‘H9706’, but equivalent to ‘H3406’ and ‘Hypeel 696’. Fruit disease severity was 63% and 60% lower for ‘CC337’ than ‘H9706’and ‘H3406’, respectively, but equivalent to ‘TSH18’ and ‘Hypeel 696’. However, in the fruit experiment, fruit disease incidence was equivalent among cultivars, while the disease severity index for ‘H9706’ (3.4) was higher than ‘Hypeel 696’ (0.7). Furthermore, rank correlation analysis between sAUDPC and fruit disease variables failed to meet the criteria for a significant and strong relationship (r ≥ 0.8 or ≤ −0.8 and P ≤ 0.05). Additional research is needed to better understand the mechanisms of fruit infection by X. gardneri. In the meantime, scientists should consider the limitations of assessing only foliar damage as an evaluation method for bacterial spot management tools in tomato.

Contrasting processing tomato cultivars unlink yield and pollen viability under heat stress.

Climate change is causing temperature increment in crop production areas worldwide, generating conditions of heat stress that negatively affect crop productivity. Tomato (Solanum lycopersicum), a major vegetable crop, is highly susceptible to conditions of heat stress. When tomato plants are exposed to ambient day/night temperatures that exceed 32 °C/20 °C, respectively, during the reproductive phase, fruit set and fruit weight are reduced, leading to a significant decrease in yield. Processing tomato cultivars are cultivated in open fields, where environmental conditions are not controlled; therefore, plants are exposed to multiple abiotic stresses, including heat stress. Nonetheless, information on stress response in processing tomatoes is very limited. Understanding the physiological response of modern processing tomato cultivars to heat stress may facilitate the development of thermotolerant cultivars. Here, we compared two tomato processing cultivars, H4107 and H9780, that we found to be constantly differing in yield performance. Using field and temperature-controlled greenhouse experiments, we show that the observed difference in yield is attributed to the occurrence of heat stress conditions. In addition, fruit set and seed production were significantly higher in the thermotolerant cultivar H4107, compared with H9780. Despite the general acceptance of pollen viability as a measure of thermotolerance, there was no difference in the percentage of viable pollen between H4107 and H9780 under either of the conditions tested. In addition to observations of similar pollen germination and bud abscission rates, our results suggest that processing tomato cultivars may present a particular case, in which pollen performance is not determining reproductive thermotolerance. Our results also demonstrate the value of combining controlled and uncontrolled experimental settings, in order to validate and identify heat stress-related responses, thus facilitating the development of thermotolerant processing tomato cultivars.

Effects of para-aminobenzoic acid on bacterial speck symptom development and Pseudomonas syringae pv. tomato populations in tomato leaves

Para-aminobenzoic (PABA) is reported to induce resistance against a range of plant pathogens in different crops in a salicylic acid-dependent manner. However, factors affecting its efficacy are not well understood. Foliar PABA applications on tomato seedlings reduced lesion incidence caused by Pseudomonas syringae pv. tomato (Pst) in a dose-dependent manner in distal leaves up to 18 mM under controlled environment conditions, but only three out of six commercial processing tomato cultivars tested showed a response to PABA. Leaves in direct contact with 9 and 18 mM PABA of both PABA-responsive and PABA-nonresponsive cultivars showed phytotoxicity. In a PABA-responsive cultivar, one, two and three PABA applications were equally effective at reducing lesion incidence in distal leaves, but the duration of control only persisted for approximately 7 days. Although PABA application reduced lesion incidence in distal leaves, the Pst population in leaves was unaffected. Lesions on PABA-treated plants were larger than nontreated plants, and thus the proportion of leaf surface area with lesions was unaffected by PABA treatment. In in vitro assays, 18 and 72 mM PABA produced zones of inhibition against Pst 15 and 50% larger than the ethanol control, demonstrating direct antimicrobial effects of PABA. PABA application did not affect symptom development in a mixed infection of Pst or Xanthomonas spp. in one field experiment with a PABA-responsive cultivar. Further research is needed to understand why PABA was unsuccessful in the field before it is to be used as a practical disease management tool for foliar bacterial diseases of tomato.

Mechanical resistance, biometric and physicochemical characteristics of tomato cultivars for industrial processing

In order to help the choice and recommendation of cultivars with the greater mechanical resistance of fruits, this research aimed to determine the mechanical resistance and biometric and physicochemical characteristics of tomato cultivars for industrial processing. Eleven processing tomato cultivar fruits cultivar were used (IT761, H9992, H9553, AP533, Advance, N901, BR-Sena, U2006, HY26, HY37 and HY68). Tomatoes firmness was influenced by several factors, including thickness, epidermal cell shape, and internal structures. In general terms, fruits more resistant to compression and puncture presented low longitudinal diameter (55-59 mm), cross-sectional diameter (42-45 mm), scar diameter (5.8-6.6 mm), pericarp thickness (5.9-7.7 mm), fresh weight (56 - 70 g), volume (61-77 cm3) and ash (0.34-0.40 g 100 g-1), and high moisture content (96.2-96.6 g 100 g-1), and pectin content (0.39-0.47 mg 100 g-1). The fruits showing a better mechanical resistance come from AP533, IT761, HY37 and H9992 cultivars, which should be recommended for cultivation in order to reduce losses during harvest, bulk handling and transportation.

Effect of fertilizers and compounds resistance inducers in the agronomic performance of cultivars of processing tomato

The Brazilian processing tomato production is concentrated in the state of Goias and accounts for 60% of the national production with average productivity of 87 t ha(‑1), which is above the national average of 70 t ha(‑1). However, both fall short of the real productive potential world that reaches 120 t ha(‑1). This difference is due, among other factors, to the agronomic complexity that is closely related to the high nutritional requirements and to the management of agrochemicals combined with various diseases that affect the culture. The aim of this study was to evaluate the effect of fertilizers with possible phytosanitary action and resistance inducers in the agronomic performance of processing tomato. The experiment was performed in the Agua Limpa Farm, property of the University of Brasilia, using randomized blocks in factorial scheme (8×2), four replicates, eight treatments, two processing tomato cultivars, ‘AP533’ and ‘IPA-6’, and 16 plants plot(‑1). The treatments were: control, potassium phosphite, silicon, biofertilizers, calcium sulfate, biofertilizer, acibenzolar-s-methyl and a chemical mixture of chlorothalonil + copper oxychloride. The spraying was done weekly, up to a total of 10 applications. At the end of the cycle, the harvest was performed with counting and weighing fruit evaluating the estimated yield, yield plant(‑1), number of fruits per plot and the incidence of blossom-end-rot in fruit; these data were subjected to analysis of variance. All treatments showed higher productivity than the national average. The organo-mineral treatment had the highest productivity over against a high rate of blossom-end-rot in the hybrid. The highest yield plant‑1 was obtained with organo-mineral and biofertilizer treatment for ‘AP533’ and silicon, potassium phosphite and organo-mineral for ‘IPA-6’. The treatment acibenzolar-S-methyl and calcium sulphate obtained the lower blossom-end-rot rate. These treatments are promising for improving the nutrition of tomato and reducing pesticide use while maintaining productivity.

Changes in yield components, morphological, physiological and fruit quality traits in processing tomato cultivated in Italy since the 1930’s

Yield of processing tomato (Solanum lycopersicum L.) increased (∼ 50%) in Italy since the 1930’s. The aim of this work was to assess the changes in yield components associated with morphological, physiological and fruit quality traits in processing tomato cultivars cropped in Italy from the mid-1930s until nowadays, introduced by breeding in six representative cultivars. Marketable yield showed an increase of 0.6% per year of release since the 1930’s. The highest marketable yield was obtained in modern cultivars due to a higher harvest index, fruit number and the ratio between ripe fruit and total fruit in comparison with the old ones. However, no single trait drove the highest marketable yield in modern cultivars. In fact, both morphological (smaller plant height and leaf area index) and physiological (accelerated plant senescence, higher leaf nitrogen status, and lower potential plant water and chlorophyll contents) traits contributed to increase marketable yield in modern cultivars. Moreover, total plant dry weight (shoot + fruit) of a single plant decreased, whereas its total fruit fresh weight and fruit dry matter content were stable and not correlated with the year of release, thus suggesting that a higher sink strength and homogeneity of fruit ripening were also involved in the highest marketable yield showed by modern cultivars. A great effort of breeders was done in the improvement of important fruit quality traits required by Italian canning industries. Fruit colour and Brix yield were positively correlated with the year of release, while viscosity and total carotenoids were negatively correlated with the year of release. However, no improvement was achieved for important traits such as soluble solids content, fruit dry weight and total fruit yield, which instead should be considered in the future breeding programmes, to improve both yield and quality of processing tomato.

Management of Fusarium oxysporum race 3 in processing tomatoes with chemical and biofungicides and cultivar resistance

Fusarium wilt race 3 of tomato (Solanum lycopersicum), caused by the soil fungal pathogen Fusarium oxysporum f. sp. lycopersici race 3 (F3), has increased in both incidence and severity in the San Joaquin Valley, CA, production areas over the past decade. A limited number of chemical and biological fungicides (biofungicides) are registered and claim suppression of Fusarium. Trials were conducted in central California in 2016-17 to evaluate the efficacy of fungicides and biofungicides applied as transplant drenches on controlling F3 in resistant and susceptible processing tomato cultivars. The trials were located in commercial fields with low to severe levels of F3. Serenade Soil (Bacillus subtilis) and Regalia (extract of Raynoutria sachalinensis) biofungicides were applied at label recommended rates, equivalent to 10 L ha(-1). Fludioxonil (40.3%) and fluopyram (41.5%) fungicides were applied at rates equivalent to 0.41-0.82 and 0.25 kg a.i. ha(-1), respectively. Initial applications were made to the plants immediately before transplanting. Treatment design was a randomized block with 4 replications; Fisher’s protected LSD was used for comparison tests. Susceptible cultivars ‘H5608’ and ‘H8504’ had significantly (p<0.05) higher F3 infection as compared to the F3 resistant cultivars ‘BP16’ or ‘BP141’. Both fludioxomyl and fluopyram fungicides significantly reduced the number of Fusarium infected plants 70 days after planting in susceptible cultivars, but 50-93% were infected regardless of fungicide treatment at harvest. In 2017, yields increased approximately 21% with ‘H5608’ when fungicides were used. However, in 2016 the fungicide treatments increased yield for the resistant cultivar ‘BP141’. The biofungicides did not provide yield benefits nor suppressed the onset of Fusarium wilt in any year/location. Cultivar resistance, regardless of fungicide treatment, gave excellent suppression of F3 and good yield performance in fields with and without F3.

The Processing Tomato Cultivar ‘Natsunoshun’ is Susceptible to an Excess or Lack of Soil Moisture after the Flowering Stage

The Processing Tomato Cultivar ‘Natsunoshun’ is Susceptible to an Excess or Lack of Soil Moisture after the Flowering Stage

The effect of plant growth-promoting rhizobacteria on yield, water use efficiency and Brix Degree of processing tomato

Open field experiments were conducted to investigate the effects of plant growth-promoting rhizobacteria (PGPR) (Phylazonit MC®) as a biofertilizer on processing tomato cultivar var. Uno Rosso F&lt;sub&gt;1&lt;/sub&gt;, grown under three different regimes of water supply. Field effectiveness of rhizobacteria inoculation on total biomass production, yield and water use efficiency, were examined in 2015 and 2016. Seedlings were inoculated with 1% liquid solution of Phylazonit MC® (Pseudomonas putida, Azotobacter chroococcum, Bacillus circulans, B. megaterium; colony-forming unit: 10&lt;sup&gt;9&lt;/sup&gt; CFU/mL) at sowing and planting out by irrigation. There were three different regimes of water supply: rain-fed control (RF); deficit water supply (WS50) and optimum water supply (WS100); the latter was supplied according to the daily evapotranspiration by drip irrigation. Total aboveground biomass (shoot and total yield) and red fruits yield were measured at harvest in August, in both years. Total biomass changed between 32.5 t/ha and 165.7 t/ha, the marketable yield from 14.7 t/ha to 119.8 t/ha and water use efficiency (WUE) between 18.5 kg/m&lt;sup&gt;3&lt;/sup&gt; to 32.0 kg/m&lt;sup&gt;3&lt;/sup&gt;. The average soluble solids content of the treatment combinations ranged from 3.0 to 8.4°Brix. Seasonal effects were significant between the two years with different precipitation, which manifested in total biomass and marketable yield production. PGPR increased WUE only in WS50 in both years, while under drought stress and higher water supply, the effect was not clear. The effect of PGPR treatment on marketable yield, total biomass and WUE was positive in both years when deficit irrigation was applied and only in the drier season in the case of optimum water supply.

The influence of ethephon application to processing tomato plants on yield structure in relation to weather conditions during the growing period

Abstract The aim of the study was to evaluate the effect of ethephon application (Agrostym 480 SL) on the yield and yield structure of five processing tomato cultivars (Rumba, Hubal, Sokal F1 , Mieszko F1 and Polset F1 ). The experiment was carried out in the open field in the years 2009-2011 in Mydlniki near Kraków, Poland. Two weeks before harvesting, half of the plants of each cultivar were treated with Agrostym 480 SL (3 dm3 ha-1) and the other half were left as a control without spraying. Marketable yield included properly shaped and welldeveloped light red and red fruits. Non-marketable yield included pink and turning fruits, mature green and breaker fruits, and diseased fruits. A generalized linear model (GLM) for Poisson distribution with the log link function was used to determine the relationship between the years of the study and cultivar and selected values of the yield structure. The yield structure of tomato depended significantly on the weather conditions during the growing period in different years of the study, on the cultivar, and on the use of ethephon. Ethephon had a particularly beneficial effect on yield structure in the years with an unfavourable distribution of precipitation. Ethephon application in the years 2009 and 2010 had a beneficial effect on the health of tomato plants.

EFFECT OF DEFICIT IRRIGATION ON THE SUGAR AND ACID PROFILE OF PROCESSING TOMATO CULTIVARS

Water deficit on tomato taste-related components was studied in standard and high lycopene cultivars. The treatment was applied once the fruits were set to avoid drastic effects on yield. Despite applying considerable reductions in water doses down to 50% ETc, the contents of fructose, malic and citric acid remained unaffected. Only glucose concentration increased with lower irrigation doses in one of the locations used for the study. The cultivar effect has a major impact in taste-related components, which might be shaded by location effects. Deficit irrigation during the last part of the growing cycle may contribute to a better water management while offering little or positive effects on the taste profile of processing tomato cultivars.

Characterization and mapping of a QTL derived from Solanum habrochaites associated with elevated rutin content (quercetin-3-rutinoside) in tomato

Consumption of flavonoids found in fruits and vegetables is linked to beneficial health outcomes. Tomato is among the most widely consumed and economically important vegetables worldwide and improvement of the nutrient content could lead to significant health benefits. Rutin, (quercetin-3-rutinoside), the main flavonol in tomato fruit, is confined to the peel. Rutin synthesis is limited by low expression of chalcone isomerase, the enzyme catalyzing the conversion of naringenin chalcone to naringenin quercetin. The wild tomato species Solanum habrochaites is a major source of new alleles to improve cultivated tomato (Solanum lycopersicum). AVRDC—The World Vegetable Center identified introgression line (IL) LA3984 containing a segment of S. habrochaites on chromosome 5 expressing high levels of rutin in full red ripe fruit. An AVRDC high rutin tomato line evaluated for 2 years and two seasons in Taiwan produced mean rutin content about four- to five-fold greater than the mean of all entries and about 11–12 times higher than the commercial fresh market and processing tomato cultivars. The quantitative trait locus (QTL) conditioning high rutin content was mapped to a 0.42 Mb segment on chromosome 5 flanked by markers c2_At3g55120/TaqI and ch05-4.883/ApaLI. Marker c2_Atg55120 overlaps with the chalcone-flavonone isomerase gene Solyc05g10320, and a second chalcone-flavonone isomerase gene is located 3,000 bp upstream from c2_At3g551220. Results of this project will facilitate breeding of high flavonoid tomato lines.

California processing tomatoes: Morphological, physiological and phenological traits associated with crop improvement during the last 80 years

Breeding has greatly increased yields of many crops, but the contributions of particular morphological, phenological and physiological traits to these higher yields are rarely well understood. In the past 50 years, California processing tomato yields per hectare have more than doubled. This study evaluated a group of important processing tomato cultivars released over the past 80 years in California. The objective was to assess how a suite of traits might be associated with genetic improvement for yield gains. A wide array of morphological, physiological and phenological traits and relevant environmental variables was evaluated in the field for a discrete set of eight cultivars originating from a common ancestor. Multivariate statistics were used to analyze the set of 95 variables to understand how cultivars became adapted to a more mechanized agronomic management while also producing higher yields. No single trait seems to have driven yield increases. Instead, distinct assemblies of traits characterize the processing tomato cultivars in different eras. For instance, certain phenological traits (early flowering and concentrated fruit set) were associated with a set of morphological traits (smaller canopies and low vegetative biomass), along with gains in physiological traits (biomass N concentration and photosynthetic rates) in modern varieties. These results provide a platform to examine new suites of traits that could be relevant for future breeding and crop improvement.

Use of introgression lines to determine the ecophysiological basis for changes in water use efficiency and yield in California processing tomatoes.

Field and greenhouse studies examined the effects of growth habit and chloroplast presence in leaf veins for their role in increasing agronomic water use efficiency and yields of California modern processing tomato (Solanum lycopersicum L.) cultivars. Five introgression lines (ILs), made with Solanum pennellii Cor. in the genetic background of cultivar M82, differ in genes that map to a region on Chromosome 5, including the SP5G gene (determinate vs. semideterminate (Det vs. SemiDet)) and the obv gene (presence (obscure) vs. absence (clear) of leaf vein chloroplasts (Obs vs. Clr)). The five ILs and M82 represented three of the four gene combinations (Det-Clr was unavailable). Det-Obs ILs had less leaf, stem and total aboveground biomass with earlier fruit set and ripening than SemiDet-Clr ILs. By harvest, total fruit biomass was not different among ILs. Photosynthetic rates and stomatal conductance were 4-7% and 13-26% higher, respectively, in Det-Obs ILs than SemiDet-Clr ILs. SemiDet-Obs ILs were intermediate for growth and gas exchange variables. The Det-Obs ILs had lower leaf N concentration and similar chlorophyll content per leaf area (but slightly higher per leaf mass) than SemiDet-Clr ILs. The Obs trait was associated with gains in leaf gas exchange-related traits. This study suggests that a more compact growth habit, less leaf biomass and higher C assimilation capacity per leaf area were relevant traits for the increased yields in cultivars with determinate growth. Developing new introgression libraries would contribute to understanding the multiple trait effects of desirable phenotypes.