Volume 14, Issue 4 (12-2023)                   2023, 14(4): 67-84 | Back to browse issues page


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Agricultural and Horticultural Science Research Department, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization, Mashhad, Iran.
Abstract:   (720 Views)
Abstract
Drought is one of the most important abiotic stresses that affects the growth and production of crops. Therefore, the need to breed cultivars that have high compatibility and low water demand is strongly felt. This study was conducted to evaluate the effect of irrigation levels on cultivars and promising lines of cotton, to use the stress tolerance and susceptibility indices for identification and selection of drought tolerant genotypes, as well as to compare cotton promising lines (KD-92-11, KD-92-17 and KD-92-19) with control cultivars of Aria and Ghoze Ghermez (which are suitable for cotton growing areas in Khorasan and Isfahan provinces). For this purpose, an experiment was performed according to the split-plot design with three replications under four irrigation levels (normal, 25, 50 and 75% deficit irrigation compared with normal) in 2020 at Kashmar. The results showed that the irrigation level had a significant effect on all traits except for keel percentage and earliness. The trait of single boll weight decreased by 7, 24 and 32% at the irrigation levels of 25, 50 and 75%, respectively, compared to the normal regime. In the same conditions, the total yield also decreased by 3, 34 and 48%, respectively. There was a significant difference between genotypes in terms of all studied traits (except for keel percentage and earliness) and drought tolerance and susceptibility indices, which indicates high genetic diversity among the genotypes and can be effective in improving selection in the breeding programs. Mean comparison of traits in the four irrigation levels showed that with the reduction of irrigation levels from 25 to 75%, the average of all traits decreased and the greatest decrease was observed in the 75% moisture regime. In each of the four irrigation levels, control cultivars were superior to promising lines in terms of single boll weight, second harvest yield, and total yield. However, in terms of the traits of keel percentage, early maturity, number of vegetative and reproductive branches, and number of open bolls, the promising lines were superior to the control cultivars. In each of the three moisture stress regimes, the control cultivars of Ghoze Ghermez and Aria did not show any difference in stress tolerance, but compared to hybrids, the promising lines had between 5 and 25% more stress tolerance in terms of various traits.
Background and Objective: Drought is one of the most important abiotic stresses that limit the growth and production of agricultural plants and affects all morphological, physiological, biochemical and metabolic aspects of plants (Blum, 2011). Changing the cultivation pattern and identifying heat and drought tolerant plant species and cultivars with high adaptability and low water requirements are among the main objectives of plant breeding in arid and semi-arid regions of the world. Cotton, as a strategic plant and the most important fiber plant, is one of the most important agricultural plants that provides the connection between the two sectors of agriculture and industry and plays a valuable role in the economy of some countries. It shows greater tolerance to abiotic stresses than other major crops. However, extreme environmental conditions such as drought are severe threats to the sustainability of cotton crops in dryland agriculture and affect the growth, productivity, and quality of cotton fibers (Barzali et al., 2016). This study was conducted to evaluate the effect of irrigation levels on cultivars and promising lines of cotton, to identify and select the drought-tolerant cultivars, and to compare the cotton lines with control cultivars.
Methods: In this study, three promising lines resulting from the crossing of Herbaceum and Arboreum species (KD-92-11, KD-92-17 and KD-92-19) along with two diploid control cultivars (Aria and Ghoze Ghermez) were cultivated according to the split-plot design with three replications at four irrigation levels (normal or control, 25, 50 and 75% deficit irrigation compared with normal) in 2020 at the field of the Research and Training Station of Agriculture and Natural Resources in Kashmar. Then, in order to select for drought tolerance, a set of morphological traits (height, number of vegetative and reproductive branches, number of opened and closed bolls, and crown diameter) and agricultural traits (single boll weight) along with yield, earliness and keel percentage were measured. Some drought tolerance and susceptibility indices were also calculated based on the yield of genotypes under normal and drought stress conditions.
Results: Drought stress had a significant effect on all traits except for keel percentage and earliness. There was a significant difference between the studied genotypes in terms of all traits (except for keel percentage and earliness) and indices, which indicates high genetic diversity among the genotypes. The mean comparison showed that with the reduction of irrigation level from 25 to 75%, the average of all traits decreased, and the greatest decrease was observed in the 75% moisture regime. In all four moisture regimes, control cultivars were superior to the lines in terms of single boll weight, the yield of the first cut, the yield of the second cut, and total yield. However, in terms of the other traits, promising lines were superior to the control cultivars. In all three moisture stress regimes of 25, 50, and 75%, the control cultivars of Ghoze Ghermez and Aria did not show any difference in stress tolerance, but compared to the lines, they had more drought tolerance.
Conclusions: Based on the results of this study, there was high genetic diversity between the studied genotypes, which can be used in the breeding programs. Drought stress negatively affected all traits and reduced their diversity. Most significant decrease was observed in the 75% moisture regime. In all of the moisture environments, control cultivars were superior to promising cotton lines in terms of yield and single- boll weight. However, promising lines were superior to control cultivars regarding the remaining traits. Moreover, in all three moisture stress regimes, the control cultivars of Ghoze Ghermez and Aria did not show any difference in terms of stress tolerance, but compared to the promising lines (KD-92-11, KD-92-17, and KD-92-19), they showed more drought tolerance.
References:
1. Barzali, M., Alishah, O., Mali, M., 2016. Evaluation of drought stress effects on some seed germination and seedling growth characteristics in Tetraploid cultivars and domestic masses (Diploid) of cotton. Iran. J. Cot. Res. 4(1), 2746.
2. Blum, A., 2011. Plant Breeding for Water-Limited Environments, Springer, New York.
Full-Text [PDF 1417 kb]   (162 Downloads)    
Type of Study: Research | Subject: Plant water relations
Received: 2023/10/15 | Accepted: 2023/12/30 | Published: 2024/03/12

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