Journal of Crop Production and Processing

Mendeley  

Zotero  

Amiri M, Majidi M M, Saeidi G. Effects of Drought and Salinity Stresses on Some Agronomic Traits and Selection of Recombinant Inbred Lines (RILs) of Safflower. Journal of Crop Production and Processing 2025; 15 (4) :17-34
URL: http://jcpp.iut.ac.ir/article-1-3369-en.html

Extended Abstract:
Introduction: Abiotic stresses, such as salinity and drought, significantly reduce plant performance, posing a major challenge to agricultural productivity. To address this, scientists have turned to global gene banks and cross-species approaches to enhance genetic diversity and develop adapted cultivars to these stresses, particularly in the face of climate change. Safflower (Carthamus tinctorius L.), a valuable oilseed crop, has experienced a genetic bottleneck due to prolonged natural and artificial selection, limiting its adaptability to abiotic stresses like drought and salinity. This diminished genetic diversity has constrained the crop's ability to thrive under such adverse conditions. To counteract this, a breeding programwas launched to reintroduce lost genetic diversity through interspecific hybridization and the evaluation of diverse global germplasm. This study focused on assessing 36 safflower genotypes, including recombinant inbred lines (RILs) derived from crosses among three safflower species, determining their performance under drought and salinity stress, and finally identyfing genotypes with enhanced stress tolerance, offering potential solutions for sustainable agriculture in challenging environments.

Materials and Methods: In this study, 9 recombinant inbreed lines (RILs) that were obtained from crossing of three species C. tinctorius, C. palaestinus, and C. oxyacanthus along with these three 3 parental species as well as 2 common domestic varieties (Kooseh, Padideh) and 22 worldwide genotypes, totally 36 genotypes, were evaluated under three environmental conditions (90% moisture depletion), normal (50% moisture depletion) and salinity stress (ECw=20dSm-1). Various agromorphological traits were measured and analyzed These analyses provided insights into the phenotypic variability and stress responses of the genotypes, enabling the identification of the key traits associated with tolerance to drought and salinity.

Results and Discussion: The findings of our study revealed a high genetic variation among the recombinant lines and cultivated safflower genotypes. The broad-sense heritability was above the average for most of the traits across all three environmental conditions, indicating a strong genetic potential of genotypes for selection. Notably, the number of seeds per head exhibited the highest heritability (89%) under normal, drought, and salinity conditions, followed by seed oil contentand the number of heads per plant.The correlation analysis identified plant height, number of seeds per head, and thousand- seeds weight as the most influential yield components, due to their strong positive correlation with seed yield. The stress tolerance index (CSI) and yield stability index (YSI) demonstrated a significant relationship with seed and oil yield, highlighting genotypic stability for these traits under stress conditions. The results showed that the average stress tolerance index of recombinant inbred lines (RILs) under salt stress conditions was higher than that of foreign cultivars. Stress tolerance indices serve as useful tools for identifying superior genotypes under both normal and stress conditions. This index is a linear combination of four significant indices and does not require specialized software, making it easy to use. Plotting this index alongside grain yield per plant under stress versus normal conditions helps identify high-yielding genotypes that are also tolerant to environmental stresses. Among the evaluated genotypes, G52, G43, G65, 61TP, and 8TP were identified as stress-tolerant varieties under salinity and drought stress conditions, exhibiting acceptable yields across all three environments: normal, salinity stress, and drought stress. Conversely, the Kooseh variety (check genotype) performed well under normal and drought conditions, but it showed a significant yield reduction under salinity stress, whereas Padideh (another check genotype) had consistently lower performance across all conditions.

Conclusion: The genetic bottleneck phenomenon has eliminated a significant portion of safflower's diversity through thousands of years of natural and artificial selection. The current study was conducted to evaluate 36 selected recombinant genotypes derived from interspecific crosses and exotic safflower genotypes that had been previously selected from diverse germplasm over past years. This study revealed high genetic diversity between cultivated safflower genotypes and recombinant lines. The broad-sense heritability for most traits exceeded average levels in all three evaluated environments (normal, drought, and salinity), indicating the genetic potential of this germplasm for safflower improvement and development of new cultivars. Correlation analysis identified plant height, head number per plant, seed number per head, and 1000-seed weight as key yield-influencing traits. Recombinant lines from interspecific crosses showed superior yield stability compared to foreign cultivars, with genotypes G52, G65, G43, G51, 61TP and 8TP exhibiting the best performance across all environments and high stress tolerance. For saline conditions, lines 61TP and 8TP are particularly recommended due to their excellent salinity stress performance and tolerance indices, while control varieties showed limited stress adaptability, with Kooseh performing well only in normal/drought conditions and Padideh yielding poorly in all environments.The stress-tolerant genotypes in this study have a significant potential for enhancing safflower productivity in drought-prone and saline environments, contributing to sustainable agricultural practices in regions affected by these stresses due to climate change.