Document Type : Research Paper
Authors
1
Graduate Ph.D., Department of Plant Production and Genetics, Faculty of Agriculture, Maragheh University, Maragheh, Iran
2
Professor, Department of Plant Production and Genetics, Faculty of Agriculture, Maragheh University, Maragheh, Iran
3
Associate Professor, Department of Plant Production and Genetics, Faculty of Agriculture, Maragheh University, Maragheh, Iran
4
Research Professor, Dryland Agricultural Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Maragheh, Iran
Abstract
Introduction
Today, wheat production as the most important crop in the word has been affected by increasing climate changes. In this regard, it is very important to investigate the physiological and agronomic reactions of resistant and sensitive wheat genotypes to drought stress under variable rainfall conditions, along with identifying the relationships between the characteristics of resistance and sensitivity to this stress. For this purpose, the current research was conducted with the aim of investigating the conditions of rainfed and supplemental irrigation, on the physiological characteristics and traits related to wheat yield.
Materials and methods
This research was conducted to investigate the effect of full dryland conditions and supplemental irrigation on biochemical processes and yield of bread wheat in two resistant genotypes with sutable yield (4 and 33) and two sensitive genotypes with poor yield (30 and 40) genotypes. From the two-year surveys of this crop, there were 49 genotypes that were implemented in the form of randomized complete block design in the form of split plots with three replications in the field of Dryland Agricultural Research Institute in Iran- Maragheh. Supplemental irrigation was done after planting and during the booting stage. In this study, the activity of antioxidant enzymes, oxidative damage, biochemical characteristics, yield and yield components were measured in order to identify differences in genotypes. Statistical analysis of data and comparison of averages were done with SAS software and LSD test at the probability level of one and five percent, respectively.
Research findings
According to the degree of sensitivity, the investigated genotypes showed great differences in response to drought stress, such that the activity level of antioxidant enzymes was higher in rainfed conditions than in supplemental irrigation conditions. Meanwhile, genotype 4 had the highest enzyme activity and the lowest amount of hydrogen peroxide and malondialdehyde in rainfed conditions, and genotype 40 had the lowest enzyme activity and the highest amount of these compounds in supplemental irrigation conditions. In terms of proline, genotype 4 showed the highest amount of proline in rainfed conditions and genotypes 30 and 40 showed the lowest amount in supplemental irrigation. The yield and yield components of the examined genotypes also showed a similar trend in this direction as a result of the internal changes of the plant. In this way, unlike genotypes 30 and 40, genotypes 4 and 33 produced the highest values in the two components of the number of spikes per unit area and the number of seeds per spike under supplemental irrigation conditions. Also, the weight of 1000 kernels of these genotypes had a similar trend, although with a lower slope. Of course, examining the changes in chlorophyll values in these genotypes as well as their enzyme activity can justify the mentioned process.
Conclusion
The examination of the findings of this research showed that despite the effects of the treatments on the examined genotypes, the genotypes resistant to drought stress, with the production of proline, maintaining the capacity of chlorophyll and intensifying the activity of antioxidant enzymes, showed a better performance in the mentioned stress conditions and after that, in these conditions, they had less performance reduction. Indeed, preventing the increase of hydrogen peroxide and malondialdehyde in them can support and complement the above result and help to have higher performance in variable rain conditions. In this research, among the yield components, the number of seeds in the spike, followed by spikes per unit area, had the most direct effect on grain yield. This approach can justify the need to focus more on the above components in field examinations, in order to achieve optimal yield easier and faster.
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