Investigation on Some Physiological Traits of Tritipyrum Lines in Response to Salinity Stress

Soil salinity is one of the largest global challenges especially in the arid and semi-arid regions. It adversely and severely affected agricultural production and consequently food security. The new cereal, tritipyrum, is an artificial hexaploeid wheat (2n=6x=42, AABBEbEb) derived from crossing between Triticum durum (2n=4x=28, AABB) and Thinopyrum bessarabicum (2n=2x=14, EbEb) species that has good potential to be used as a seed or forage plant. The aim of present research was evaluating saline tolerance of new primary different tritipyrum lines through assessing some agronomical traits and ion distribution in plant under mild and severe salinity stress conditions.  

Materials and Methods:

A split-plot hydroponic experiment based on completely randomized block design with two factors and three replications was carried out at Shahrekord University in 2020. The NaCl salinity stress was considered as the main factor with 3 levels (0, 100, 200 Mm) and the genotypes were considered as sub plots with 8 levels. Genotypes included three primary tritipyrum lines (Ka/b, La/b, St/b), three combined tritipyrum lines (i.e. F4, F5 and F6 generations of a combined (Ka/b) (Cr/b) lines), as well as one durum wheat (cv. Creso) and a promising triticale line (Ma45). Different salinity stress levels were imposed from three leaf stage till maturity via irrigating the plants by appropriate saline water. The leaf surface area, fertile florets per spike, 1000-grain weight, grain yield, biological yield as well as concentration of Na+ and K+ and Ca++ ions in both root and aerial parts of genotypes were measured. 

Results and Discussion:

There were significant differences between genotypes in the case of all measured traits. Regardless of salinity levels, tritipyrum line (ka/b) (cr/b) (F6) had the highest amount of biological yield, grain yield, concentration of K+ and Ca++ and K+/Na+ ratio in shoot and the least amount of Na+ in shoot. With increase in salinity level from 0 to 200 mM, flag leaf area, number of fertile florets, 1000 grain weight, biological yield, grain yield and amount of K+ and Ca++ in both root and shoot were significantly reduced in almost all genotypes and concentration of Na+ was increased. At 200 mM salinity, all of the three combined tritipyrum lines had significantly higher amount of biological yield and K+ concentration in shoot and less amount of Na+ in shoot than durum wheat and triticale. Shoot Na+ concentration had negative significant correlation with flag leaf area and 1000 grain weight. In the other hand, positive correlation was observed between shoot K+ concentration and flag leaf area, number of fertile florets, 1000 grain weight and grain yield. At 200 mM salinity, the highest and lowest shoot K+/Na+ ratio were observed in tritipyrum line F5 and durum wheat, respectively. On average, root sodium concentration in tritipyrum lines was higher than that of wheat and triticale while shoot sodium concentration in tritipyrum lines was less than that of the two other genotypes. 

Conclusion:

Results of our experiment suggest that hindrance in the transfer of Na+ from root to the aerial parts is probably one of the mechanisms that used by tritipyrum lines to cope with the high NaCl concentrations.