Improvement of Salinity Stress Tolerance in Onion and Watermelon for Resilient Crop Production in Southern United States

Commodities

Practices

Climate change and soil salinization continue to threaten global food security, particularly in arid and semi-arid regions such as the southern United States, including Texas. Declining waterflow and recharge, coastal water intrusion, increased fertilizer runoff and deposits, and wastewater from oil/gas production are increasing salinity in arable land and irrigation water. Salinity stress is one of the most significant abiotic factors limiting the yield and quality of salt-sensitive crops such as watermelon (Citrullus lanatus) and onion (Allium cepa). Therefore, developing salt-tolerant cultivars is essential for sustaining productivity under such challenging conditions. This project aims to screen 150 diverse accessions of watermelon and onion, each collected from global sources, to identify salt-tolerant genotypes. Plants will be grown in controlled conditions in a greenhouse under high-salinity conditions. We will evaluate salt responses based on salt uptake in leaf tissues through sodium and chloride ion analyses, growth performance, biomass, and key physiological and biochemical traits such as relative water content, membrane stability, proline levels, and antioxidant enzyme activity. Following phenotypic assessment, we will apply genotyping-by-sequencing to identify single-nucleotide polymorphisms (SNPs) across all accessions. We will then integrate the phenotypic and genotypic data to conduct genome-wide association studies (GWAS) and discover SNP markers and quantitative trait loci (QTL) linked to salinity tolerance. The resulting markers and QTLs will support in selection breeding of resilient onion and watermelon cultivar crops with improved salt-tolerance. This research is vital for supporting sustainable and efficient production in Texas, one of the largest onion and watermelon-producing states.

This project is designed to address the urgent need for salt-tolerant onion and watermelon cultivars by leveraging phenotypic screening and genomic tools. The specific objectives of this research are as follows:

1. Screen 150 genetically diverse accessions of onion (Allium cepa) accessions of watermelon (Citrullus lanatus) each, quantify salinity stress, and identify salt-tolerant genotypes
2. Genotyping-by-sequencing and genome-wide association mapping of watermelon and onion accessions to discover high-density single-nucleotide polymorphisms and candidate genes markers across the genomes
3. Disseminate the research findings to growers and the scientific community through conference presentations and manuscript publications

Through these objectives, the project seeks to enhance genetic improvement strategies for two economically important but salt-sensitive crops and to contribute directly to climate-resilient agricultural systems. The outcomes will support sustainable crop production in saline soil and help ensure long-term food security in regions increasingly affected by soil salinization.