Response of Organic Biostimulants and Silicon to Growth, Yield and Quality of Tomato under Soil Salinity Conditions

Abiotic stresses strongly affect plant growth, nutrient composition and quality of production; final crop yield can be really compromised if stress occurs in plants’ most sensitive phenological phases. The present field study was conducted to evaluate the effect of biostimulants on improvement of tolerance and yield of tomato plants exposed to salinity. The tomato field soil condition with pH- 8.7 and EC- 4 dS m-1 was recorded. After the first fruit set of tomato, Organic biostimulant (Organic mix with high concentration of carboxylic acids, containing calcium oxide (CaO), ammonium ligninsulfonate and Zinc) were given by soil drenching and Orthosilicic acid as silicon source by foliar spray at every 10 – 15 days interval. The treatments include Organic biostimulant at 0.3ml/plant & 0.6ml/plant, Orthosilicic acid at 0.2% and 0.4%. The observations were taken during greener and red ripening stage. The biostimulants positively affected the plant height and chlorophyll fluorescence. Biostimulants were allowed to maintain the lower level of electrolyte leakage and osmotic potential within the plant. The activities of catalase (CAT) and superoxide dismutase (SOD) enzymes increased with the increases in salinity: biostimulants thereby kept the lower the level of reactive oxygen species. Under saline conditions due to the ionic imbalance, potassium and calcium content in both the shoots and roots were recorded lower, whereas the sodium content was found to be higher than the control plants. Similarly, a significant increase in total soluble solids and firmness of the fruit was recorded in tomato fruits. Yield characters like fruit number per plant, single plant yield, single fruit weight and flower to fruit ratio were positively affected by the application of biostimulants. The organic biostimulant and Orthosilicic acid administered at a greater dose appeared to be the most effective in our investigation.

Field Evaluation of CRISPR-Driven Jointless Pedicel Fresh-Market Tomatoes

Clustered regularly interspaced short palindromic repeats (CRISPR)-driven traits are commonly introduced into tomato (Solanum lycopersicum) in less than a year. Although CRISPR technology is highly suitable for rapid incorporation of new traits into plants with superior breeding backgrounds, the usefulness of these traits must be demonstrated prior to large-scale distribution of any new variety possessing them. The jointless pedicel trait is crucial for stem-free harvest of tomato fruits and is therefore an essential requirement for developing low-labor tomato varieties. We aimed to evaluate the effect of CRISPR-driven jointless pedicel trait on the yield and horticultural traits of fresh-market tomatoes. We conducted field trials during three consecutive seasons using three related genotypes of two elite fresh-market tomatoes, namely a jointed pedicel tomato, a CRISPR-driven jointless pedicel mutant of the jointed pedicel tomato, and a conventionally-bred jointless pedicel near isogenic line (NIL) to the jointed pedicel tomato. Field evaluations confirmed that the total and medium-, large-, or extra-large-size fruit yields of the CRISPR-driven mutants were not statistically different for those corresponding to their backgrounds and that the fruit yield stratified by fruit size might be varied under different growth conditions. We did not observe any negative correlation between the genotype and the fruit/abscission joint detachment force for any of the genotypes under study.

Biological and Molecular Characterization of a Jumbo Bacteriophage Infecting Plant Pathogenic Ralstonia solanacearum Species Complex Strains

A jumbo phage infecting Ralstonia solanacearum species complex strains, designated RsoM2USA, was isolated from soil of a tomato field in Florida, United States, and belongs to the family Myoviridae. The phage has a long latent period of 270 min and completed its infection cycle in 360 min with a burst size of approximately 32 particles per cell. With a genome size of 343,806 bp, phage RsoM2USA is the largest Ralstonia-infecting phage sequenced and reported to date. Out of the 486 ORFs annotated for RsoM2USA, only 80 could be assigned putative functions in replication, transcription, translation including 44 tRNAs, and structure with the main structural proteins experimentally confirmed. Phylogenetic analyses placed RsoM2USA in the same clade as Xanthomonas phage XacN1, prompting a proposal of a new genus for the two jumbo phages. Jumbo phage RsoM2USA is a lytic phage and has a wide host range, infecting each of the three newly established Ralstonia species: R. solanacearum, R. pseudosolanacearum, and R. syzygii, and significantly reduced the virulence of its susceptible R. solanacearum strain RUN302 in tomato plants, suggesting that this jumbo phage has the potential to be developed into an effective control against diseases caused by R. solanacearum species complex strains.

Two Distinct Soil Disinfestations Differently Modify the Bacterial Communities in a Tomato Field

Reductive soil disinfestation (RSD) and soil solarization (SS) were evaluated based on environmental factors, microbiome, and suppression of Fusarium oxysporum in a tomato field soil. Soil environmental factors (moisture content, electric conductivity, pH, and redox potential (RP)) were measured during soil disinfestations. All factors were more strongly influenced by RSD than SS. 16S rRNA amplicon sequencing of RSD- and SS-treated soils was performed. The bacterial communities were taxonomically and functionally distinct depending on treatment methods and periods and significantly correlated with pH and RP. Fifty-four pathways predicted by PICRUSt2 (third level in MetaCyc hierarchy) were significantly different between RSD and SS. Quantitative polymerase chain reaction demonstrated that both treatments equally suppressed F. oxysporum. The growth and yield of tomato cultivated after treatments were similar between RSD and SS. RSD and SS shaped different soil bacterial communities, although the effects on pathogen suppression and tomato plant growth were comparable between treatments. The existence of pathogen-suppressive microbes, other than Clostridia previously reported to have an effect, was suggested. Comparison between RSD and SS provides new aspects of unknown disinfestation patterns and the usefulness of SS as an alternative to RSD.

Determination of The Prevalence and Population Development of Tomato Leafminer [Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae)] in Tomato (Lycopersicon esculentum Mill.) Planting Areas of Sanliurfa Province

This study was carried out to determine the extensity, development of population and the state of damage of tomato leaf miner (Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae)) in total eight tomato fields located in the villages of Goktepe of Central Sanliurfa, Meteler of Birecik, Kepirce of Bozova, Yalcinkaya of Ceylanpinar, Ovacik of Hilvan, Kucuk Yucelen of Siverek, Aligor of Suruc and Ciftciler of Viransehir in 2011. To determine the extensity of tomato leaf miner each of the 5 districts in the village tomato field was checked by observation whether adult or larvae found in fields T. absoluta. The result showed that tomato leaf miner was common in all the districts. The highest density of tomato leaf miner adult population quantities were 630, 800, 400, 965, 211, 600, 215 and 96 pcs/week in Goktepe of Central Sanliurfa, Meteler of Birecik, Kepirce of Bozova, Yalcinkaya of Ceylanpinar, Ovacik of Hilvan, Kucuk Yucelen of Siverek, Aligor of Suruc and Ciftciler of Viransehir, respectively. Tomato leaf miner harmed the fruits, particularly total in 1st and 2nd harvest of tomato (the end of August- the beginning of September) , if precautions were not taken. Moreover, it was recorded that if the adult population was quite dense in the fields study conducted, there aren’t any undamaged leaves and fruits from T. absoluta.

Sown Wildflowers Enhance Habitats of Pollinators and Beneficial Arthropods in a Tomato Field Margin

We evaluated the capacity of selected plants, sown along a processing tomato field margin in central Greece and natural vegetation, to attract beneficial and Hymenoptera pollinating insects and questioned whether they can distract pollinators from crop flowers. Measurements of flower cover and attracted pollinators and beneficial arthropods were recorded from early-May to mid-July, during the cultivation period of the crop. Flower cover was higher in the sown mixtures compared to natural vegetation and was positively correlated with the number of attracted pollinators. The sown Glebionis coronaria, Coriandrum sativum, Anethum graveolens, and Fagopyrum esculentum attracted mainly wild bees, which were the most abundant pollinating insects. In the natural vegetation, Rapistrum rugosum attracted mainly honeybees, while Asteraceae, Convolvulaceae, and Apiaceae species attracted wild bees. Beneficial arthropod abundance and diversity were higher in the sown mixture. Tomato flowers were visited by a small number of wild bees. Their number was not affected by the distance from the field margin, indicating no distraction effect from the sown or natural vegetation flowering plants. Our results suggest that selected flowering plants can improve the field margin habitats for pollinating insects and beneficial arthropods, but more work is needed to elucidate the effect on crop pollination.

Evaluation of some selected soil properties of a drip irrigated tomato field at different moisture regimes in South-Western Nigeria

Soil properties are important to the development of agricultural crops. This study determined some selected soil properties of a drip irrigated tomato (Lycopersicon esculentum M.) field at different moisture regime in South-Western Nigeria. The experiment was carried out using Randomized Complete Block Design with frequency and depth of irrigation application as the main plot and sub-plot, respectively in three replicates. Three frequencies (7, 5 and 3 days) and three depths equivalent to 100, 75 and 50% of water requirement were used. Undisturbed and disturbed soil samples were collected from 0-5, 5-10, 10-20 and 20-30 cm soil layers for the determination of some soil properties (soil texture, organic matter content, bulk density, infiltration rate and saturated hydraulic conductivity) were determined using standard formulae. Soil Water Content (SWC) monitoring was conducted every two days using a gravimetric technique. The soil texture was sandy loam for all the soil depths; average value of soil organic matter was highest (1.8%) in the 0-5 cm surface layer and decreased with soil depth; the soil bulk density value before and after irrigation experiment ranged from 1.48 and 1.73 g/cm3 and 1.5 and 1.76 g/cm3, respectively; there was a rapid reduction in the initial infiltration and final infiltration rate. Saturated hydraulic conductivity show similar trend although the 20-30 cm layer had the lowest value (50.84 mm/h); the SWC affect bulk density during the growing season. The study showed that soil properties especially bulk density and organic matter content affect irrigation water movement at different depth..

Nanopore sequencing of tomato mottle leaf distortion virus, a new bipartite begomovirus infecting tomato in Brazil

During a survey in a tomato field in Luziânia (Goiás State, Brazil), a plant showing mottling, chlorotic spots, and leaf distortion was found. A new bipartite begomovirus was found by Nanopore sequencing, and the full DNA-A sequence was confirmed by Sanger sequencing. The highest nucleotide identity match of this DNA-A genome (2596 bases) was 81.65% with tomato golden leaf deformation virus (HM357456). Due to the current species demarcation criterion of 91% of nucleotide identity (DNA-A), we propose it as a new member of the genus Begomovirus, named Tomato mottle leaf distortion virus.

Integrated Genomic and Greenhouse Assessment of a Novel Plant Growth-Promoting Rhizobacterium for Tomato Plant

Plant growth promoting rhizobacteria (PGPR) can display several plant-beneficial properties, including support to plant nutrition, regulation of plant growth, and biocontrol of pests. Mechanisms behind these effects are directly related to the presence and expression of specific genes, and different PGPR strains can be differentiated by the presence of different genes. In this study we reported a comprehensive evaluation of a novel PGPR Klebsiella variicola UC4115 from the field to the lab, and from the lab to the plant. The isolate from tomato field was screened in-vitro for different activities related to plant nutrition and growth regulation as well as for antifungal traits. We performed a functional annotation of genes contributing to plant-beneficial functions previously tested in-vitro. Furthermore, the in-vitro characterization, the whole genome sequencing and annotation of K. variicola UC4115, were compared with the well-known PGPR Azospirillum brasilense strain Sp7. This novel comparative analysis revealed different accumulation of plant-beneficial functions contributing genes, and the presence of different genes that accomplished the same functions. Greenhouse assays on tomato seedlings from BBCH 11–12 to BBCH > 14 were performed under either organic or conventional management. In each of them, three PGPR inoculations (control, K. variicola UC4115, A. brasilense Sp7) were applied at either seed-, root-, and seed plus root level. Results confirmed the PGP potential of K. variicola UC4115; in particular, its high value potential as indole-3-acetic acid producer was observed in increasing of root length density and diameter class length parameters. While, in general, A. brasilense Sp7 had a greater effect on biomass, probably due to its high ability as nitrogen-fixing bacteria. For K. variicola UC4115, the most consistent data were noticed under organic management, with application at seed level. While, A. brasilense Sp7 showed the greatest performance under conventional management. Our data highlight the necessity to tailor the selected PGPR, with the mode of inoculation and the crop-soil combination.

Predicting tomato field-yield using continuous monitoring of young tomato water status

To address the challenge of predicting tomato yields in the field, we used whole-plant functional phenotyping to evaluate water relations under well-irrigated and drought conditions. The genotypes tested are known to exhibit variability in their yields in wet and dry fields. The examined lines included two lines with recessive mutations that affect carotenoid biosynthesis, zeta z2083 and tangerine t3406, both isogenic to the processing tomato variety M82. The two mutant lines were reciprocally grafted onto M82 and multiple physiological characteristics were measured continuously, as well as before, during and after drought treatment in the greenhouse. A comparative analysis of greenhouse and field yields showed that the whole-canopy stomatal conductance (gsc) in the morning and cumulative transpiration (CT) were strongly correlated with field measurements of total yield (TY: r2 = 0.9 and 0.77, respectively) and plant vegetative weight (PW: r2 = 0.6 and 0.94, respectively). Furthermore, the minimum CT during drought and the rate of recovery when irrigation was resumed were both found to predict resilience. Keywords: drought tolerance, functional genomic mapping, functional phenotyping, physiological trait, time-series measurements, tomato, yield prediction, yield-prediction models