نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 دانشجوی دکتری فیزیولوژی تولید و پس از برداشت گیاهان باغبانی، دانشکده کشاورزی، دانشگاه شهید چمران اهواز، اهواز، ایران
2 گروه علوم باغبانی، دانشکده کشاورزی، دانشگاه شهید چمران اهواز، اهواز، ایران
3 گروه علوم و مهندسیﺧﺎک، دانشکده کشاورزی، دانشگاه شهید چمران اهواز، اهواز، ایران.
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objective: Drought is one of the environmental stresses that significantly affects plant growth, impacting morphological and physiological characteristics. This stress can lead to a reduction in photosynthesis, transpiration, and stomatal conductance, ultimately resulting in decreased crop yield. Plant growth-promoting bacteria (PGPB) are recognized as a factor in enhancing plant resistance to drought stress. The objective of this study was to evaluate the simultaneous effect of inoculation with various strains of PGPB and foliar application of potassium nitrate on the growth characteristics and gas exchange of lime (Citrus aurantifolia) to enhance drought resistance.
Materials and Methods: In this study, the effect of PGPB at five levels (Enterobacter cloacae E1, Bacillus subtilis CS1, Enterobacter cloacae R33, a consortium of the three mentioned strains, and a control with no bacterial inoculation) along with foliar application of potassium nitrate at two levels (0 and 20 grams per liter) under three different irrigation regimes (40%, 70%, and 100% evapotranspiration potential) was evaluated on the growth characteristics and gas exchange of one-year-old lime seedlings (Mexican lime). The dry weight of the aerial parts and leaf area were measured once at the end of the experiment, while other parameters were collected at three time points: 60, 120, and 180 days after the start of the experiment. This study was conducted as a factorial experiment in a completely randomized block design with three replications, totaling 90 experimental units.
Findings: The results showed that drought significantly reduced the gas exchange and growth characteristics of lime seedlings. Inoculation with PGPB along with the foliar application of 20 grams per liter of potassium nitrate improved the dry weight of the aerial parts under the highest drought stress, with a 36.5% increase compared to the control. The highest leaf area, measuring 1111 square meters, was observed in plants inoculated with the R33 strain and treated with 20 grams per liter of potassium nitrate. Inoculation of lime seedlings with the bacterial consortium along with the foliar application of 20 grams per liter of potassium nitrate resulted in a 61.2% increase in seedling height and a 16.6% increase in leaf number under the highest drought stress level. At the end of the experiment, the photosynthesis rate decreased by 29.9% compared to the start. Foliar application of 20 grams per liter of potassium nitrate and inoculation with PGPB improved photosynthesis. Specifically, photosynthesis in plants inoculated with Bacillus subtilis CS1 and the three-strain consortium, along with foliar application of 10 grams per liter of potassium nitrate, increased by 56.1% and 43.8%, respectively, compared to plants without potassium nitrate application and no bacterial inoculation under the same irrigation regime. Under the highest stress level, the 40% evapotranspiration potential irrigation regime, inoculation with the three-strain consortium along with foliar application of 20 grams per liter of potassium nitrate improved stomatal conductance by 333.3% compared to untreated plants. Additionally, transpiration in plants inoculated with Bacillus subtilis CS1 increased by 138.7% compared to the control. Sub-stomatal carbon dioxide concentration also increased by 69.4% in plants inoculated with Enterobacter cloacae R33 and treated with potassium nitrate compared to the control.
Conclusion: The findings indicated that drought had significant negative effects on the growth characteristics and gas exchange of lime seedlings. In this experiment, foliar application of 20 grams per liter of potassium nitrate along with inoculation with Bacillus subtilis CS1, Enterobacter cloacae R33, and the three-strain consortium is suggested as the best treatment combination, leading to improved growth indices and gas exchange. This combination could be used as an effective strategy in managing drought stress to mitigate the adverse effects of drought on lime plants.
کلیدواژه‌ها [English]
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