Document Type : Research Paper
Authors
1
Genetic and Plant Production Department, Vali-e-Asr University of Rafsanjan,, Iran
2
Genetic and Plant Production Department, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran
3
Genetic and Plant Production Department,, Faculty of Agriculture, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran
4
Genetic and Plant Production Department, Faculty of Agriculture, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran
5
Genetic and Plant Production Department, Vali-e-Asr University of Rafsanjan,
Abstract
Background and objectives: Salinity is one of the major abiotic stresses limiting crop productivities in arid regions of the world like Iran. In order to meet the food demand for growing population, utilization of marginal fields which are typically areas of lower productivity and show some extents of nutrition imbalance and salinity to grow alternate crops like promising oil crops without substantial decrease in economic value of cash crop seems a practical approach. Rocket (Eruca sativa L.) is an old native plant well adapted to warm, dry climates of the Middle East region. It can play a role in crop rotation programs as green manure and/or cover crop to conserve soils in fallow lands. Nonetheless, little is known about its response to salt stress. This study aimed to evaluate main germination characteristics and yield components of some local Eruca sativa ecotypes and identify salt-tolerant ecotypes in order to use in breeding programs.
Materials and Methods: This study was conducted as two separate experiments. In the first experiment, germination percentage and rate and seed vigor of seven ecotypes of rocket named based on the region of collection as Sirjan, Bardsir, Rigan, Shahdad, Abadeh, Dehmurd and Darjaveh were assayed in a completely randomized design with two factors and four replicates. Salinity (NaCl) treatments were control (distilled water), 3, 6, 9, 12, 15 and 18 dS/m. In the second experiment, seeds of the same ecotypes as the first experiment were sown outdoor in cement boxes filled with soil (EC=1.8 dS/m) as semi-filed condition and watered normally until 4-leaf stage when treatments applied by salinized water to achieve 4, 8 or 12 dS/m. At the end of growing season, shoot biomass, grain yield, plant height and number of capsules were measured. Some stress indices were calculated and results were discussed by correlation and biplot analysis.
Results: Final Germination percentage and rate as well as seed vigor decreased by increasing salinity in all ecotypes, although magnitude of response greatly differed among ecotypes. Germination rate and seed vigor were much more affected by the adverse effects of salinity. Based on scoring method, Sirjan, Bardsir and Darjaveh were identified as superior, inferior and moderate ecotypes in terms of salinity tolerance, respectively. In the semi-field experiment, however, responses of ecotypes to salinity were quite different to those of germination as Shahdad showed the highest grain yield and shoot biomass both in the control and 12 dS/m treatments. Shahdad also showed the highest values for STI, GMP, MP and HM while Darjave being the lowest. Biplot analysis confirmed that Shahdad was the ecotype with the highest grain yield and lowest salinity susceptibility.
Conclusion: Significant ecotypic variations were observed in terms of salinity response both in germination stage and whole plant growth, though ecotypes responded differently to salinity, indicating tolerance mechanisms may differ among developmental stages and not closely related to geographic and climatic origin of seeds. Results suggest that rocket is semi-tolerant to salinity and could be a potential subsistence crop for cultivation in some saline soils.
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