Assessment of germination and seedling development of tomato genotypes under polyethylene glycol (PEG)-induced drought

Abstract

Food security is one of the major global challenges of the twenty-first century. Crop yield is estimated to decline by 5 to 30% from 2050 onwards compared to 1990. Climate change has a major impact on crop production. Drought stress is a significant environmental factor affecting plant growth and crop productivity, and understanding its impact on tomato production is crucial for the development of drought-tolerant varieties. The experiment was carried out to find the drought tolerant genotypes. The study was conducted in two factorial completely randomized designs with three replications, subjecting tomato seeds of five different genotypes to three different polyethylene glycol 6000 induced drought stress. The observation revealed that Monoprecas showed increase in root length, shoot length, canopy spread, root spread lengthwise, root spread breadthwise, root weight, shoot weight, total biomass, root-shoot ratio, vigor index, and vigor test index with increase in PEG concentration 3% (-0.18Mpa), and then decreases with higher concentration 6% (-0.36Mpa). NGRCO9569, NGRCO9571, and Khumal 2 showed continuous increase in most of the observations with an increase in PEG concentration 3% (-0.18Mpa) and 6% (-0.36Mpa). Unlike these genotypes, Srijana showed drastic reduction in all the observations and unexpectedly increased in days of first germination and days to fifty percent germination as compared to control. Results showed these varieties were more tolerant even up to higher drought conditions up to -0.36 Mpa but Srijana were susceptible even to lower drought conditions (-0.18 Mpa). The five tomato varieties were grouped into two clusters, Srijana and NGRCO9571 genotypes in one and NGRCO9569, Monoprecas, and Khumal 2 under another based on the unweighted pair group method with arithmetic mean. The promising genotypes NGRCO9569, Khumal 2, and Monoprecas were identified as more drought tolerant and be utilized in breeding programs aimed at developing drought tolerant tomato varieties or can be recommended at areas with lower irrigation facilities. The findings highlight the vulnerability of tomato genotypes, especially the commercial and hybrid to drought stress during the early stages of growth. The variation observed among different tomato genotypes indicates the presence of genetic variability for drought tolerance, suggesting the potential for breeding drought-tolerant tomato varieties. Further research and breeding efforts should focus on identifying and utilizing drought-tolerant genetic traits in tolerant varieties NGRCO9569, Khumal 2, and Monoprecasto enhance the resilience of tomato plants to drought stress. Furthermore, breeding programs should be initiated to develop new tomato varieties with enhanced drought tolerance, incorporating the identified drought-tolerant genetic traits and genes.