Strawberry Breeding Program Research Articles

Marker-assisted Pyramiding of Charcoal Rot Resistance Loci in Strawberry

Macrophomina phaseolina, the causal agent of charcoal rot, is one of the most destructive soil-borne pathogens that affect the global strawberry industry. Resistant cultivars are critical for ensuring the profitability of strawberry production without the protection historically provided by methyl bromide. Previously, three loci, namely, FaRMp1, FaRMp2, and FaRMp3, associated with quantitative resistance to Macrophomina phaseolina have been identified and validated across diverse populations and environments. Among those, the locus with the largest effect, FaRMp3, was initially detected in crosses with an exotic Fragaria ×ananassa selection. We introgressed the favorable FaRMp3 allele into elite germplasm in the University of Florida strawberry breeding program already segregating for FaRMp1 and FaRMp2 and confirmed its phenotypic effects across various genetic backgrounds. Subsequently, we developed a high-throughput genotyping assay to facilitate the transfer and selection of FaRMp3 in breeding populations via marker-assisted selection. Given that three quantitative trait loci (QTL) contribute to partial resistance to Macrophomina phaseolina, stacking them within a single genotype presents a potential strategy for enhancing resistance. We screened 564 individuals that segregate for favorable alleles at all three QTL to assess their effects singly and in combination across multiple genetic backgrounds and production seasons. Inoculated field trials revealed that the three QTL cumulatively enhanced resistance levels, and that two-way QTL combinations including FaRMp3 provide increased protection against the pathogen. Pyramiding all three loci achieved the strongest resistance and could provide substantial economic value to the strawberry industry.

Emerging Sensory Methodologies to Support Strawberry Breeding and Future Prospects Combined with Augmented Reality

Strawberry production has been continually increasing worldwide, but this growth has often resulted in a lack of taste, favoring yield and plant adaptability instead. However, in recent decades, consumer focus has shifted towards more flavorful fruits. Consequently, the application of new sensory methodologies for consumers in strawberry breeding programs is becoming essential. This review provides an overview of new rapid consumer-based sensory methodologies and a brief summary of their potential applications when combined with Augmented Reality technology. These advancements aim to better understand and meet consumer needs, offering breeders valuable tools for their future work.

Updates on Strawberry DNA Testing and Marker-Assisted Breeding at the University of Florida

ABSTRACT Developing new strawberry varieties with high level of disease resistance and superior fruit quality is critical for strawberry production. Despite the complexity of the octoploid strawberry genome, recent advances in genomics and DNA sequencing technologies have allowed us to identify causal sequence variants associated with specific phenotypes. These have enabled the development of new and improved DNA markers for integration in marker-assisted breeding (MAB) efforts. The use of MAB has significantly improved the efficiency of stacking loci responsible for disease resistance and fruit quality characteristics. The “Strawberry DNA Testing Handbook” is currently accessible in the Genome Database for Rosaceae and has been an essential resource for the national and international strawberry research community. Based on the information provided in the handbook, the UF strawberry breeding program implemented seedling selection from 2021 to 2023, retaining 25.3%, 19.2%, and 37.9% of seedlings for further evaluation in each respective year. In this report, we provide updates on DNA markers associated with disease resistance and fruit quality traits. Additionally, we demonstrate the practical implementation of these markers in high-throughput marker-assisted selection and their potential to enhance strawberry breeding.

Exploring the genetic basis of resistance to Neopestalotiopsis species in strawberry.

Aggressive strains of Neopestalotiopsis sp. have recently emerged as devastating pathogens of strawberry (Fragaria × ananassa Duchesne ex Rozier), infecting nearly all plant parts and causing severe outbreaks of leaf spot and fruit rot in Florida and globally. The development of host resistance is imperative due to the absence of fungicides that effectively inhibit Neopestalotiopsis sp. growth on an infected strawberry crop. Here, we analyzed 1578 individuals from the University of Florida's (UF) strawberry breeding program to identify and dissect genetic variation for resistance to Neopestalotiopsis sp. and to explore the feasibility of genomic selection. We found that less than 12% of elite UF germplasm exhibited resistance, with narrow-sense heritability estimates ranging from 0.28 to 0.69. Through genome-wide association studies (GWAS), we identified two loci accounting for 7%-16% of phenotypic variance across four trials and 3 years. Several candidate genes encoding pattern recognition receptors, intra-cellular nucleotide-binding leucine-rich repeats, and downstream components of plant defense pathways co-localized with the Neopestalotiopsis sp. resistance loci. Interestingly, favorable alleles at the largest-effect locus were rare in elite UF material and had previously been unintentionally introduced from an exotic cultivar. The array-based markers and candidate genes described herein provide the foundation for targeting this locus through marker-assisted selection. The predictive abilities of genomic selection models, with and without explicitly modeling peak GWAS markers as fixed effects, ranged between 0.25 and 0.59, suggesting that genomic selection holds promise for enhancing resistance to Neopestalotiopsis sp. in strawberry.

Evolutionary analysis of TIR- and non-TIR-NBS-LRR disease resistance genes in wild strawberries.

NBS-LRR genes (NLRs) are the most extensive category of plant resistance genes (R genes) and play a crucial role in pathogen defense. Understanding the diversity and evolutionary dynamics of NLRs in different plant species is essential for improving disease resistance. This study investigates the NLR gene family in eight diploid wild strawberry species to explore their structural characteristics, evolutionary relationships, and potential for enhancing disease resistance. We conducted a comprehensive genome-wide identification and structural analysis of NLRs across eight diploid wild strawberry species. Phylogenetic analysis was performed to examine the relationships between TIR-NLRs (TNLs), Non-TIR-NLRs (non-TNLs), CC-NLRs (CNLs), and RPW8-NLRs (RNLs). Gene structures were compared, and gene expression was profiled across different NLR subfamilies. Additionally, in vitro leaf inoculation assays with Botrytis cinerea were performed to assess the resistance of various strawberry species. Our analysis revealed that non-TNLs constitute over 50% of the NLR gene family in all eight strawberry species, surpassing the proportion of TNLs. Phylogenetic analysis showed that TNLs diverged into two subclades: one grouping with CNLs and the other closely related to RNLs. A significantly higher number of non-TNLs were under positive selection compared to TNLs, indicating their rapid diversification. Gene structure analysis demonstrated that non-TNLs have shorter gene structures than TNLs and exhibit higher expression levels, particularly RNLs. Notably, non-TNLs showed dominant expression under both normal and infected conditions. In vitro leaf inoculation assays revealed that Fragaria pentaphylla and Fragaria nilgerrensis, which have the highest proportion of non-TNLs, exhibited significantly greater resistance to Botrytis cinerea compared to Fragaria vesca, which has the lowest proportion of non-TNLs. The findings of this study provide important insights into the evolutionary dynamics of NLRs in strawberries, particularly the significant role of non-TNLs in pathogen defense. The rapid diversification and higher expression levels of non-TNLs suggest their potential contribution to enhanced disease resistance. This research highlights the value of non-TNLs in strawberry breeding programs aimed at improving resistance to pathogens such as Botrytis cinerea.

'SAROM' ȘI 'IREAL', SOIURI NOI DE CĂPȘUN

Since 1980, the strawberry breeding program developed at the Research Institute for Fruit Growing Pitesti, Romania has released seven short-day cultivars of interest for temperate climate environments. The latest released cultivars, 'Sarom' and 'Ireal' are late cropping season ones (second decade of June) with large fruit size (more than 25 g) and total yield per plant of over 600 g. Fruits are firm flesh and excellent flavour. Plants have compact habit with high vigour, and fruits are well presented on long braces providing increased picking efficiency. They are characterized with high plant resilience to diseases and high fruit quality.

Construction of a strawberry breeding core collection to capture and exploit genetic variation

BackgroundGenetic diversity is crucial for the success of plant breeding programs and core collections are important resources to capture this diversity. Many core collections have already been constructed by gene banks, whose main goal is to obtain a panel of a limited number of genotypes to simplify management practices and to improve shareability while retaining as much diversity as possible. However, as gene banks have a different composition and goal than plant breeding programs, constructing a core collection for a plant breeding program should consider different aspects.ResultsIn this study, we present a novel approach for constructing a core collection by integrating both genomic and pedigree information to maximize the representation of the breeding germplasm in a minimum subset of genotypes while accounting for future genetic variation within a strawberry breeding program. Our stepwise approach starts with selecting the most important crossing parents of advanced selections and genotypes included for specific traits, to represent also future genetic variation. We then use pedigree-genomic-based relationship coefficients combined with the ‘accession to nearest entry’ criterion to complement the core collection and maximize its representativeness of the current breeding program. Combined pedigree-genomic-based relationship coefficients allow for accurate relationship estimation without the need to genotype every individual in the breeding program.ConclusionsThis stepwise construction of a core collection in a strawberry breeding program can be applied in other plant breeding programs to construct core collections for various purposes.

Evaluation of some Selections Obtained in the Strawberry Breeding Program

The strawberry (Fragaria x ananassa Duch.) is a fruit species of interest to growers and consumers due to the early ripening of the fruits, high yields and special nutritional qualities (high content of minerals and vitamins). The paper evaluates the performance of 14 selections from Romanian strawberry breeding and a Romanian cultivar ('Premial') of strawberry under field conditions during 2021-2023. The characteristics evaluated are: phenological data, yield (g/plant), average fruit weight (g), firmness (N), shape, color, soluble solid content and pH. Based on the data obtained, from the 14 selections, it was proposed to introduce into next stages for evaluation those that recorded over 500 g/plant and over 20 g/fruit, namely: '16-3-188', '16-2-12', '16-3-170', '16-3-123'.

Genetic Variability And Correlation Studies For Growth, Yield And Quality In Strawberry (Fragaria Ananassa Duch.)

The traits viz., fruit nutritional quality, yield, day neutral nature to be improved in strawberry and hence the present study was undertaken to identify the nature of variability present in the promising advanced strawberry genotypes and to detect the association among yield and yield component traits in strawberry (Fragaria × ananassa Duch.). Fourteen advanced genotypes were evaluated to study genetic variation and the relationship between yield and its components using a randomized complete block design during the year 2021. The results showed significant variance among genotypes of all traits. The phenotypic coefficient of variation (PCV) for all the characters was slightly higher than the genotypic coefficient of variation (GCV), which signified the presence of environmental influence to some degree in the phenotypic expression of characters. The leaf area index had the highest PCV (30.71) and GCV (30.82). The genetic advance was recorded maximum for fruit yield per plant (228.24), whereas genetic advance as a percent of mean was highest for leaf area index (63.05) followed by shelf life of fruits (61.95). The highest heritability (h2, 95.22) was coupled with higher genetic advance (228.24) estimated for fruit yield per plant, which indicated that the character is controlled by additive genes and therefore further improvement could be brought by selection. Being octoploid, the inheritance of traits is complex in strawberry and the identified heritable traits in the study would be helpful for strawberry improvement breeding programs. Fruit yield was significantly and positively associated with most of the characteristics except flowering duration, fruiting duration, and volume of fruit at both genotypic and phenotypic levels; therefore, these are important prerequisites to formulate a successful strawberry improvement program.

Determination of volatile profiles of woodland strawberry (Fragaria vesca) during fruit maturation by HS-SPME GC-MS.

Aroma is an important agronomic trait for strawberries, and the improvement of fruit flavor is a key goal in current strawberry breeding programs. Fragaria vesca (also known as woodland strawberry) has become an excellent model plant with exquisite flavor, a small genome size, and a short life cycle. Thus, the comprehensive identification of fruit volatiles and their accumulation pattern of F. vesca strawberries are very important and necessary to the fruit aroma study. This study examined the volatile profile changes from the fruits of three F. vesca genotypes during maturation using the headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME GC-MS) with multivariate analysis. A total of 191 putative volatile compounds were identified, while 152, 159, and 175 volatiles were detected in 20-30 dap fruits of Hawaii 4 (HW), Reugen (RG), and Yellow Wonder (YW), respectively. Aldehydes and alcohols predominated in the early time point while esters were predominant during the late time point. Ketones were the dominant compounds from F. vesca strawberries fruits at the ripe stage. Certain genotype-characteristic volatiles were identified, including eugenol, γ-octalactone, and δ-decalactone were only detected in YW, and mesifurane was found in HW. RG and YW showed very similar volatile compositions, but YW presented a greater number of volatiles and RG yielded a higher content. Differences in the volatile composition may be primarily due to genetic relationships. The metabolic changes that occurred during fruit ripening and characteristic volatiles will be a useful reference for future strawberry volatile studies. This article is protected by copyright. All rights reserved.

Bioinformatics and Expression Analysis of the Chitinase Genes in Strawberry (Fragaria vesca) and Functional Study of FvChi-14.

Plant chitinases (EC 3.2.1.14) are pathogenesis-related (PR) proteins and are well studied in many plant species. However, little is known about the genomic organization and expression of chitinase genes in strawberries (Fragaria vesca). Here, 23 FvChi genes were identified in the genome of strawberry (F. vesca) and divided into GH18 and GH19 subfamilies based on phylogenetic relationships. A detailed bioinformatics analysis of the FvChi genes was performed, including gene physicochemical properties, chromosomal location, exon-intron distribution, domain arrangement, and subcellular localization. Twenty-two FvChi genes showed upregulation after Colletotrichum gloeosporioides infection. Following the exogenous application of SA, FvChi-3, 4, and 5 showed significant changes in expression. The ectopic expression of FvChi-14 in Arabidopsis thaliana increased resistance to C. higginsianum via controlling the SA and JA signaling pathway genes (AtPR1, AtICS1, AtPDF1.2, and AtLOX3). The FvChi-14 protein location was predicted in the cell wall or extracellular matrix. We speculate that FvChi-14 is involved in disease resistance by regulating the SA and JA signaling pathways. The findings of this study provide a theoretical reference for the functional studies of FvChi genes and new candidates for strawberry stress resistance breeding programs.

Genome-wide identification and functional analysis of Cellulose synthase gene superfamily in Fragaria vesca.

The Cellulose synthase (CesA) and Cellulose synthase-like (Csl) gene superfamilies encode key enzymes involved in the synthesis of cellulose and hemicellulose, which are major components of plant cell walls, and play important roles in the regulation of fruit ripening. However, genome-wide identification and functional analysis of the CesA and Csl gene families in strawberry remain limited. In this study, eight CesA genes and 25 Csl genes were identified in the genome of diploid woodland strawberry (Fragaria vesca). The protein structures, evolutionary relationships, and cis-acting elements of the promoter for each gene were investigated. Transcriptome analysis and quantitative real-time PCR (qRT-PCR) results showed that the transcript levels of many FveCesA and FveCsl genes were significantly decreased during fruit ripening. Moreover, based on the transcriptome analysis, we found that the expression levels of many FveCesA/Csl genes were changed after nordihydroguaiaretic acid (NDGA) treatment. Transient overexpression of FveCesA4 in immature strawberry fruit increased fruit firmness and reduced fresh fruit weight, thereby delaying ripening. In contrast, transient expression of FveCesA4-RNAi resulted in the opposite phenotypes. These findings provide fundamental information on strawberry CesA and Csl genes and may contribute to the elucidation of the molecular mechanism by which FveCesA/Csl-mediated cell wall synthesis regulates fruit ripening. In addition, these results may be useful in strawberry breeding programs focused on the development of new cultivars with increased fruit shelf-life.

A multi-omics framework reveals strawberry flavor genes and their regulatory elements.

Flavor is essential to consumer preference of foods and is an increasing focus of plant breeding programs. In fruit crops, identifying genes underlying volatile organic compounds has great promise to accelerate flavor improvement, but polyploidy and heterozygosity in many species have slowed progress. Here we use octoploid cultivated strawberry to demonstrate how genomic heterozygosity, transcriptomic intricacy and fruit metabolomic diversity can be treated as strengths and leveraged to uncover fruit flavor genes and their regulatory elements. Multi-omics datasets were generated including an expression quantitative trait loci map with 196 diverse breeding lines, haplotype-phased genomes of a highly-flavored breeding selection, a genome-wide structural variant map using five haplotypes, and volatile genome-wide association study (GWAS) with > 300 individuals. Overlaying regulatory elements, structural variants and GWAS-linked allele-specific expression of numerous genes to variation in volatile compounds important to flavor. In one example, the functional role of anthranilate synthase alpha subunit 1 in methyl anthranilate biosynthesis was supported via fruit transient gene expression assays. These results demonstrate a framework for flavor gene discovery in fruit crops and a pathway to molecular breeding of cultivars with complex and desirable flavor.

Transcriptomic and Metabolomic Analyses Provide Insights into the Formation of the Peach-like Aroma of Fragaria nilgerrensis Schlecht. Fruits.

Fragaria nilgerrensis Schlecht. is a wild diploid strawberry species. The intense peach-like aroma of its fruits makes F. nilgerrensis an excellent resource for strawberry breeding programs aimed at enhancing flavors. However, the formation of the peach-like aroma of strawberry fruits has not been comprehensively characterized. In this study, fruit metabolome and transcriptome datasets for F. nilgerrensis (HA; peach-like aroma) and its interspecific hybrids PA (peach-like aroma) and NA (no peach-like aroma; control) were compared. In total, 150 differentially accumulated metabolites were detected. The K-means analysis revealed that esters/lactones, including acetic acid, octyl ester, δ-octalactone, and δ-decalactone, were more abundant in HA and PA than in NA. These metabolites may be important for the formation of the peach-like aroma of F. nilgerrensis fruits. The significantly enriched gene ontology terms assigned to the differentially expressed genes (DEGs) were fatty acid metabolic process and fatty acid biosynthetic process. Twenty-seven DEGs were predicted to be associated with ester and lactone biosynthesis, including AAT, LOX, AOS, FAD, AIM1, EH, FAH, ADH, and cytochrome P450 subfamily genes. Thirty-five transcription factor genes were predicted to be associated with aroma formation, including bHLH, MYB, bZIP, NAC, AP2, GATA, and TCP family members. Moreover, we identified differentially expressed FAD, AOS, and cytochrome P450 family genes and NAC, MYB, and AP2 transcription factor genes that were correlated with δ-octalactone and δ-decalactone. These findings provide key insights into the formation of the peach-like aroma of F. nilgerrensis fruits, with implications for the increased use of wild strawberry resources.

Productivity of strawberry genotypes in the south and southwest mesoregion of Minas Gerais

The strawberry is a perennial plant of temperate climate belonging to the Rosaceae family, much appreciated for presenting a fleshy and succulent receptacle as an edible part. Among small fruits, in Brazil it represents the species of greatest economic expression. The breeding of the strawberry aims to meet the demands of the market, mainly regarding the quality of the fruit required by consumers. Thus, the selection of genotypes that have good quality, productivity and adaptation is extremely important for the development of culture in the country, as well as for making seedlings available at lower prices. The objective of this work was to evaluate the agronomic performance and productivity of experimental strawberry genotypes in the city of Alfenas, Minas Gerais. For this, the experiment was carried out in the premises of the José do Rosário Vellano University (UNIFENAS), Alfenas-MG, in an experimental area of the Olericulture and Experimentation Sector (21025'45''S, 45056'50 "W, 880 m altitude). The experimental design used was completely randomized, with eleven treatments, distributed in seven experimental genotypes, namely MDA01, MDA06, MCA 119, MFA444, MDA19, MDA11 and MDA23, and four commercial cultivars taken as control, being them Pircinque, Albion, Aromas and Festival, in eight repetitions. The following characteristics were evaluated total production per plant (grams of strawberries per plant-1), average weight of fruits per plant (grams/fruit-1), total number of fruits per plant and number of stolons (seedlings) per plant. The experimental genotypes that showed the highest total productivity and average fruit weight were MDA01, MDA23 and MDA19. These materials are presented as promising for the strawberry breeding program in the region and should be reevaluated under other edaphoclimatic conditions and/or used as parents in new crossings for the next stages of the program.

Genetic Variability and Structure of Fragaria nilgerrensis Schlecht. Germplasm in Sichuan Province

Fragaria nilgerrensis Schlecht. (wild strawberry) is widely distributed in Southwest China, characterized by stress tolerance and the fruits of a notable peach aroma. So far there is only limited knowledge of variability and genetic structure in this species. Using AFLP markers, we investigated the genetic variability of 37 plants of F. nilgerrensis sampled in six main mountain areas of Sichuan Province and analyzed their genetic structure. Genetic similarity according to Nei and Li was used for cluster analysis based on UPGMA method and Agglomerative Hierarchical Clustering. Stratification of plants into more distinctive genetic groups was determined using Bayesian structure analysis. Six primer combinations produced a total of 1302 fragments of which 818 (62.8%) were polymorphic. Bayesian analysis showed the 37 plants of F. nilgerrensis grouped into five distinctive genetic groups. Most of the plants from the same mountain area clustered into the same genetic group, indicating each area as an area with the unique genetic profile. The genetic parameters analyzed here indicate a huge genetic variability of F. nilgerrensis in Sichuan Province. Our results provide reference data for surveying and protecting the germplasm resources of F. nilgerrensis that could be used in strawberry breeding programs.

Shape, firmness and fruit quality QTLs shared in two non-related strawberry populations

The cultivated strawberry (Fragaria x ananassa) is an octoploid species (2n = 8x = 56), appreciated widely for its fruit. There have been very few studies on fruit quality traits, which are known to be mostly polygenic and environmentally dependent. To identify higher genetic variability, two non-related populations were genotyped: an F1 population cross between ‘FC50’ and ‘FD54’ and an F2 population cross between ‘Camarosa’ and ‘Dover’, hybridizing both with IStraw35k and IStraw90k SNP arrays, respectively. The F1 genetic map was constructed with 14595 SNPs and the F2 map with 7977 SNPs. High collinearity was observed when comparing one genetic map with the other and on comparing both with the octoploid genome. To assess fruit variability, both populations were phenotyped for shape, firmness, taste and other fruit traits over the 2016−2019 period. With QTL analyses, 33 stable QTLs were mapped in the ‘FC50xFD54’ population, and three hotspot regions were found for shape traits in LG3A, LG4D and LG6D. In the ‘21AF’ population, only eight stable QTLs were detected. Despite that, two major and stable QTLs were mapped in the same interval of confidence for both populations. A shared fruit shape ratio QTL which explained around 25 % of trait variance was mapped in LG3A, and a shared firmness QTL explaining 26.9 % of trait variance in LG7C. For the first time, two QTLs were discovered in LG3A and LG4A for a phenotype neck without achenes. When analysing two different mapping populations, in addition to finding specific QTL regions for the studied traits, a narrowing down of the interval of confidence for the shared QTLs is achieved. As a result of this study, a new set of SNPs for fruit firmness and shape is now available for use in MAS in strawberry breeding programs.

‘Red Leaf’: a new disorder in Australian strawberry plants

In 2014, several strawberry plants growing in commercial field beds in South East Queensland, Australia, displayed a reddish/maroon interveinal discolouration and decline in plant health and yield. This new red leaf disorder (RLD) has since been observed to varying extents in several commercial cultivars grown during winter production. An increase in the number of commercial plants affected by RLD has occurred since 2014. In 2019, a survey of 18 farms in South East Queensland assessed the incidence and severity of RLD symptoms. RLD was observed in up to 30% of plants in affected field blocks. Samples were screened for evidence of an association with viruses, phytoplasmas, rickettsia, and fungal and bacterial pathogens using polymerase chain reaction and high-throughput sequencing (HTS). Transmission tests, fungal isolations, and leaf nutrient analysis were also undertaken. These tests have not identified an obvious single causal agent and work is ongoing to investigate potential biotic and abiotic stress factors of this complex disorder and its epidemiology. An examination has also been conducted into whether resistance or tolerance to RLD is present in Australian cultivars and Australian Strawberry Breeding Program selections. Quantitative genetic analyses of symptom severity and RLD incidence in two field trials identified a range of tolerances to the disorder, and moderate narrow-sense heritability. Due to the significance of this disorder to the Australian winter production and potential importance to the national strawberry industry, RLD requires broader investigation to accelerate identification. © 2021 International Society for Horticultural Science. All rights reserved.

Updates on Italian strawberry breeding programs coordinated by CREA

Updates on Italian strawberry breeding programs coordinated by CREA

Önemli Çilek Genotiplerinin Tat Parametreleri Bakımından Değerlendirilmesi

Çilek dünyada ve ülkemizde eşsiz tat ve aromasından dolayı, üretimi giderek artan önemli bir meyve türüdür. Birçok meyve türünde olduğu gibi, çilek meyvelerdeki verim, tad ve diğer önemli kalite bileşenlerinin genetik yapıdan etkilendiği bilinmektedir. Bu kapsamda, özellikle son 100 yılda dünyadaki çilek ıslah çalışmaları sonucunda çok miktarda çilek çeşidi geliştirilmiştir. Bu bağlamda, Çukurova Üniversitesi bünyesinde de uzun yıllar farklı yoğunluklarda çilek ıslah çalışmaları gerçekleştirilmiştir. Bu çalışmada, bölümümüzde gerçekleşen çilek ıslah programı sonucu ön plana çıkan ‘33‘, ‘36‘ ve ‘61‘ kodlu genotipler ile Akdeniz bölgesinde yaygın olarak yetiştiriciliği yapılan ‘Fortuna‘, ‘Rubygem‘ ve ‘Festival‘ gibi ticari çilek çeşitleri geniş hasat (Ocak-Mayıs) süresi boyunca meyve SÇKM, pH, asit miktarı ile et sertliği gibi özellikler bakımından karşılaştırılmıştır. Çalışma sonucunda Akdeniz iklim koşullarında ocak ayında az miktarda ürün elde edilmiş olup, söz konusu ayda incelenen çeşit ve genotiplerde en yüksek SÇKM ve meyve et sertlik değerleri elde edilmiştir. Genotipler bakımından; ‘36‘ kodlu olan, sezon boyunca %8,0 ile %13,1 arasında değişen SÇKM değerleriyle diğerlerine göre yüksek olması yanında, nispeten düşük asit içeriğiyle de dikkat çekmiştir. Bu genotip tat bakımından güçlü yönüne rağmen, 0,63 lb/inch2 meyve et sertlik değeriyle ticari çeşitlere (1,10-1,20 lb/inch2) göre oldukça yumuşak bulunmuştur. Bütün bu bilgiler doğrultusunda, her yönüyle çok iyi bir çeşit elde etmenin fizyolojik ve genetik nedenlerden dolayı mümkün olmadığı düşünülmektedir. Bununla birlikte, çilek ıslahçıları belirledikleri temel amaçlar doğrultusundaki özellikleri en yüksek seviyelerde bünyesinde barındıran çilek çeşidi geliştirmeyi hedeflemelidirler.