Water deficit is a major constraint on pepper (Capsicum annuum) yield, yet the genetic architecture of reproductive-stage drought tolerance remains poorly resolved. We phenotyped a Balkan C. annuum diversity panel (n = 133) and an interspecific backcross inbred line (BIL) population (n = 76) under well-watered (WW) and water-stress (WS) conditions. WS was applied from anthesis of the second truss as a stepwise reduction in irrigation volume relative to WW (30% for 7 days, then 60% thereafter), maintained for 90 days across the reproductive period. We assessed yield components, soluble solids, and stress-tolerance (STI) and stress-susceptibility (SSI) indices. Genome-wide association study (GWAS) identified 104 SNP-trait associations (P < 1×10-5), and QTL mapping detected 38 significant QTLs (1,000 permutations, α = 0.01), with the QTL intervals defined at LOD ≥ 8. Integrating GWAS and QTL mapping under WS revealed overlapping loci on chromosomes 5 and 6, harboring two consensus intergenic SNPs associated with yield components and soluble solids. Haplotype analysis linked chromosome 5 alleles to higher fruit number and soluble solids. At chromosome 6, the G allele at SNP 6_28348737 was enriched in tolerant lines for fruit number. These regions harbor candidate genes for reproductive development and stress response, including GREEN RIPE-LIKE1 (GRL1), CYP77A19, Endoglucanase-like, and FLOWERING PROMOTING FACTOR 1 (FPF1), possibly through cis-regulatory variation. Together, these results advance understanding of the genetic basis of pepper yield under drought and identify candidate breeding markers.
This study evaluates the effects of the biological products “Trichodermin” (Trichoderma viride, strain Trv1, titer 1×10⁸ c/mL), “Extrasol” (Bacillus subtilis, titer 1×10¹⁰ CFU/mL), and a bacterial formulation based on Enterobacter cloaceae (titer 1×10¹⁰ CFU/mL) on biometric parameters, productivity, early yield, and the immune response of greenhouse-grown pepper (Capsicum annuum, cv. “Piruet F1”) to white mold infection. The experiments were conducted from 2021 to 2023 at the Maritsa Vegetable Crops Research Institute, Plovdiv, in an unheated steel-glass greenhouse. Pepper plants were cultivated under a 90/60/40 cm spacing scheme. The biological products were applied via pre-sowing seed soaking for 4 hours in undiluted mother solutions, followed by two soil treatments (10 mL/10 L water per 20 m²) — after transplanting and during mass flowering. The results demonstrated the positive effects of Bacillus subtilis, Enterobacter cloaceae, and Trichoderma viride on plant biometric parameters, disease resistance, and yield. Treated plants showed an increase in plant mass by 14%–23%, root mass by 21%–32%, and leaf mass by 24%–36%. Total yield increased by 23%–28%, while early yield improved by 12.5% with “Extrasol”, 19% with Enterobacter cloaceae, and 24% with “Trichodermin”. Artificial infection with Sclerotinia sclerotiorum using the decapitation method confirmed that the biological products enhanced the immune response in pepper plants. The reduction in necrosis caused by white mold was 56% with “Trichodermin”, 44.8% with “Extrasol”, and 35.5% with Enterobacter cloaceae. Keywords: antagonists, Capsicum annuum, growth stimulation, non-specific induced resistance, productivity, Sclerotinia sclerotiorum
The review summarizes practical experiences in using mutation breeding for crop improvement in South-Eastern Europe (SEE) and Central Asia (CA), demonstrating that mutation breeding can be a field-validated, effective approach for developing climate-resilient crops. Drawing on coordinated research conducted within national breeding programs and international initiatives supported by FAO/IAEA, applied methodologies, trait-evaluation strategies, and concrete breeding outputs in cereals, legumes, and industrial crops are presented. The use of gamma irradiation, fast neutrons, and chemical mutagens has successfully generated stable mutant lines stable mutant lines with enhanced traits, such as increased thousand-grain weight in wheat, altered oil quality in sunflower, and improved drought tolerance in common bean and sesame. The integration of classical pedigree selection with modern breeding tools such as high-throughput phenotyping, molecular and biochemical markers, and doubled-haploid technology has enabled earlier and more efficient identification of superior genotypes in mutation breeding programs. The review underscores the practical relevance of mutation breeding in contemporary pipelines to maintain yield stability and quality under adverse environmental conditions.
Introduction:Water availability is a crucial factor for crop performance in greenhouse tomato production, affecting both yield development and fruit composition traits. This study examined how deficit irrigation alters the relationship between yield and quality in tomatoes and whether foliar application of seaweed-derived biostimulants impacts these responses. Methods:A greenhouse experiment was carried out under two different irrigation levels, characterized by soil moisture contents of approximately 23-27% under optimal watering and 12-15% under reduced watering, using treatments based on extracts of Laminaria digitata and Ascophyllum nodosum, applied separately and together. Yield components, temporal yield dynamics, and concentration-related compositional traits were evaluated, and integrative PCA and concentration-index analyses were performed. Results:Reduced irrigation altered the yield structure by increasing fruit number and decreasing average fruit weight, while total yield showed limited variation among treatments. At the same time, concentration-related traits, including dry matter, soluble solids, vitamin C, and titratable acidity, were consistently higher under reduced irrigation. Biostimulant effects were dependent on the irrigation regime. Under optimal irrigation, treatment effects were limited, whereas under reduced irrigation, some treatments were associated with higher yields, primarily due to differences in fruit number during the main production peak. However, these yield responses were not consistently aligned with changes in compositional traits. Temporal yield analysis further showed that treatment effects under reduced irrigation were expressed mainly through modifications in the timing and intensity of peak production rather than through uniform effects across the entire production cycle. Integrative PCA and concentration-index analysis indicated that compositional enhancement and yield performance were only partly associated under reduced irrigation, suggesting a partial decoupling between productivity and fruit quality responses. Discussion:Overall, the results show that the irrigation regime is the main factor influencing yield-quality relationships in greenhouse tomato, while biostimulant treatments add extra, context-dependent variability. These findings emphasize the importance of evaluating both yield components and compositional traits together when analyzing crop responses under limited water availability.
Tomato brown rugose fruit virus (Tobamo virus fructirugosum, ToBRFV), poses a significant threat to tomato crops worldwide. While fertilizers do not affect viral spread, their proper usage can improve crop quality, enhance resilience and mitigate symptoms severity. The present study aimed to assess the impact of mineral nutrition on three different tomato varieties infected with ToBRFV:Monalbo, Mobaci and Momor. The varieties differ in the absence or presence of Tomato mosaic virus (ToMV) resistance genes (Tm1 and Tm22). Plants were mechanically inoculated at the first true leaf stage and grown until flowering under four different fertilization treatments (0x, 0.5x, 1x, and 2 × times the optimal dose), alongside a control group of non-inoculated plants. Plant growth parameters, macronutrient (Na, Mg, Ca, K) accumulation, chlorophyll contentand total phenolic content were evaluated. ToBRFV infection was confirmed in the three tested varieties 30 days post-inoculation, with distinct symptoms and changes in morphology, chlorophyll levels and phenolic content. The findings suggest that fertilization improved growth performance in ToBRFV-inoculated tomato plants as shown by increased biomass, height, and leaf number. While macronutrient accumulation remained largely unaffected by infection status, chlorophyll content and total phenolic content were significantly influenced by both fertilization and viral infection. Chlorophyll content remained lower in ToBRFV-inoculated plants, whereas total phenolic content increased in inoculated plants under “0.5x” and “1x” fertilization treatments, with the highest levels at “0x” and the lowest at “2x”treatment. These findings highlight the complex interaction between viral stress and mineral nutrition, suggesting that low fertilization may enhance defense-related phenolic responses, while higher fertilization supports vegetative growth.
