Effect of waterlogging at the three-leaf stage stress on the growth and some physiological characteristics of bread wheat (Triticum aestivum L.)

Wheat is one of the most important crop plants in the world. waterlogging stress causes serious damage to the wheat crop wheat crop worldwide annually, and it is likely that these damages are increasing with climate change. In many cases, waterlogging stress occurs for various reasons in the initial stages of the growth of this plant. There are many reports about the existence of differences in waterlogging stress tolerance in different cultivars and genotypes of wheat, but so far these differences have not been fully exploited. This research was designed and carried out to investigate the effect of waterlogging stress on the dry matter yield of shoot system, the concentration of photosynthetic pigments, the activity level of antioxidant enzymes, the concentration of malondialdehyde and carotenoid content.

Floods will increase as a result of climate change and in some areas will have a negative impact on wheat production. plants are obligate aerobic organisms and they need to absorb oxygen from their surroundings to complete their life cycle, growth, reproduction and competition. with 215 million hectares, wheat has the largest area of cultivated plants in the world, waterlogging stress usually damages winter wheat during Seedling establishment and tillering. a field experiment in the form of a split plot design, based on randomized complete blocks in 3 replications accomplished. Stress was applied at the three-leaf stage and at three levels, control (no waterlogging stress), mild stress (48 hours) and severe stress (120 hours) as the main factors. Cultivars and genotypes were also included as secondary factors. Plants were cultivated in pots and grown in open space (outdoor), the water level was maintained about five centimeters above the soil level during the stress period.

Mild and severe waterlogging stress resulted in a decrease of 14.06 and 38.37 percent of shoot dry matter, respectively, which was significant in all cultivars and genotypes. Different cultivars and genotypes showed different responses to waterlogging stress. to better understand the reasons for these differences, among 11 cultivars and 10 genotypes, Mehrgan and Sarang cultivars and ms 93-16 and ms 93-6 genotypes were selected to study some physiological traits. waterlogging stress led to a decrease photosynthetic pigments , an increase in the malondialdehydeconcentration and an increase in the antioxidant enzymes activity ,and in these cases, the differences between these cultivars and genotypes were obvious. there were also differences between severe stress and mild stress, for example, in all studied cultivars, only severe stress could lead to a significant increase in peroxidase enzyme activity, but in the case of catalase, mild stress tolerant cultivars also led to a significant increase.

In general, cultivars that had a higher level of antioxidant enzyme activity when faced with waterlogging stress were able to pass through the stress period with less damage to the cell membrane structure (according to the concentration of malondialdehyde) and photosynthetic pigments and showed a lower percentage reduction in dry matter. Mehrgan cultivar had the highest dry matter yield compared to other cultivars and genotypes in all three stress levels, despite the severe decrease in shoot system dry matter yield.