نوع مقاله : مقاله پژوهشی
عنوان مقاله English
نویسندگان English
Introduction
Chickpea (Cicer arietinum L.) is one of the most important rainfed legumes in the western regions of Iran; however, its production is severely constrained by late-season drought stress. Drought stress disrupts photosynthetic processes and reproductive growth by reducing the availability of essential nutrients. Salicylic acid, as a plant growth regulator, enhances drought tolerance. Furthermore, mycorrhizal fungi such as Glomus intraradices, through the extension of their hyphal network, facilitate the uptake of water and low-mobility elements such as phosphorus (P), thereby improving stress resilience. Given the decisive role of cultivar selection in yield performance, this study was conducted to evaluate the interactive effects of salicylic acid and mycorrhizal inoculation on the morphophysiological characteristics, yield, and nutrient acquisition of two rainfed chickpea cultivars under the climatic conditions of Lorestan province.
Materials and Methods
The experiment was carried out during the 2021–2022 growing season at the Beyranvand Research Station (northeast of Khorramabad, altitude 1660 m, cold semi-arid climate with an average annual rainfall of 250 mm). The expriment was arranged as a split-plot factorial based on a randomized complete block design with three replications. The main factor consisted of salicylic acid at four levels (0, 0.5, 1.0, and 1.5 mM). Subplot factors included two chickpea cultivars (Lorestan local and the Goksu cultivar) and two mycorrhizal inoculation levels (inoculation with Glomus intraradices and non-inoculated). Seeds were hand-planted in December. Mycorrhizal inoculum was incorporated into the root-zone soil, before sowing, and salicylic acid was applied as a foliar spray at the pre-flowering stage. Measured traits included plant height, number of pods per plant, number of seeds per pod, 100-seed weight, grain yield, biological yield, leaf area index (LAI), canopy temperature, leaf chlorophyll index (SPAD), plant nitrogen and phosphorus concentration, and seed protein content. Data were analyzed using SAS software (version 9.4, SAS Institute Inc.). Analysis of variance (ANOVA) was performed, and treatment means were compared using Duncan’s multiple range test (α = 0.05).
Results and Discussion
Analysis of variance revealed that the salicylic acid × mycorrhiza interaction had a significant effect on number of pods per plant, number of seeds per pod, canopy temperature, leaf chlorophyll index, plant nitrogen and phosphorus concentrations, and seed protein content. The highest number of pods per plant (26.30) and seeds per pod (2.15) were recorded in the 1.5 mM salicylic acid × mycorrhiza treatment. Moreover, the highest leaf chlorophyll index (17.08) was observed in the Goksu cultivar treated with 1.5 mM salicylic acid and mycorrhiza, which was twice the minimum value (8.18 in the untreated local seed, 0 mM salicylic acid, no mycorrhiza). The combined application of 1.5 mM salicylic acid and mycorrhiza increased plant nitrogen concentration (40.38%), plant phosphorus concentration (4.16 mg.kg-1) which was more than double the lowest value (19.82% and 1.98 mg.kg-1) respectively. The lowest canopy temperature (23.45 °C) was also recorded under the 1.5 mM salicylic acid × mycorrhiza treatment, showing a significant reduction compared to the control (31.53 °C). The main effect of salicylic acid was significant on plant height, 100-seed weight, and grain yield; the application of 1.5 mM salicylic acid resulted in the highest plant height (42.07 cm), 100-seed weight (38.06 g), and grain yield (2022 kg.ha⁻¹), which were increases of 26.6%, 30.5%, and 56%, respectively, over the control. Mycorrhizal inoculation alone also increased grain yield to 1864 kg ha⁻¹. The Goksu cultivar was superior to the local seed in terms of plant height (39.03 cm vs. 37.52 cm) and leaf area index (2.08 vs. 1.85), but no significant difference in grain yield was detected between the two cultivars.
Conclusion
Based on the results obtained from this experiment, it was established that the main effects of salicylic acid application and mycorrhizal inoculation individually increased grain yield. Mycorrhiza, through the expansion of its hyphal network, improves phosphorus uptake, which provides the energy required for nitrogen fixation and chlorophyll synthesis. Salicylic acid appears to improve nitrogen metabolism and prevent protein degradation under drought conditions by enhancing nitrate reductase activity and modulating antioxidant responses. Furthermore, the synergy between these two factors reduced canopy temperature (which improve plant water status) and increased the chlorophyll index (enhanced photosynthetic capacity), thereby promoting the translocation of photosynthates to the grain. Although the Goksu cultivar was superior in certain vegetative traits, its grain yield was similar to local seed, which is likely attributable to the greater adaptation of the local seeds to the region’s rainfed conditions. In conclusion, the foliar application of 1.5 mM salicylic acid combined with soil inoculation with the mycorrhizal fungus Glomus intraradices can be recommended as a low-input, environmentally sustainable strategy to increase grain yield (up to 56%), protein content (up to 37%), and nutrient uptake in rainfed chickpea under cold semi-arid conditions similar to those of Lorestan province.
کلیدواژهها English
