| چکیده انگلیسی مقاله |
Extended Abstract
Introduction: Melon (Cucumis melo L.) is an annual plant from Cucurbitaceae family and has a very high diversity in Iran and the world. The Khatooni variety is a melon variety widely cultivated in Khorasan Razavi Province, north-east of Iran. The growth and yield of agricultural crops are affected by environmental stresses. Drought stress is one of the most critical environmental stresses that limit crop production, particularly in arid and semi-arid regions. Salicylic acid has diverse physiological roles in plants, including improving plant growth and photosynthesis. Some researches have indicated that watermelon growth and yield may increase by applying salicylic acid under drought stress conditions. Another criterion for improvement in using water resources is the use of superabsorbent polymers. Bentonite has the ability to absorb water and minerals and prevent the leaching of minerals in the soil. Therefore, the aim of this study was to evaluate the role of salicylic acid and bentonite and investigate their interaction in mitigating drought stress and increase the quality and yield of melon.
Materials and Methods: In order to investigate the effect of bentonite superabsorbent and salicylic acid on Khatooni melon under drought stress conditions, a split factorial experiment based on a randomized complete block design with four replications was performed in two years. Irrigation factor was applied at 3 levels: 100, 80 or 60% of water requirement. Foliar spraying of salicylic acid was done at 70 or 100 ppm when the fruits had a diameter of 10 cm, and repeated after 20 days. Bentonite was applied at two levels (0 and 0.15% by weight per ha). Bentonite was mixed with the upper 30 cm of the soil depth. In each experimental unit, the distance between plants was 70 cm on each row and the rows distanced 3 m apart. In order to prevent water penetration between adjacent plots a 6 m distance was considered between experimental units, i.e. plots. Stem length, leaf area, chlorophyll content, relative water content, total soluble solids, and fruit yield were measured. Minitab software was used for statistical analysis. Comparison of means was performed using Duncan's multiple range test at a 5% probability level, and Excel software was used to draw the graphs.
Results and Discussion: A decreasing trend in stem length with increasing drought stress was observed in the studied treatments (Table 2). Mean comparison of triple interaction effects showed that the application of bentonite and salicylic acid in different irrigation treatments increased stem length (Table 2). The lowest stem length (194.36 cm) was obtained in the presence of 60% water requirement, absence of bentonite and salicylic acid, indicating a 31.2% decrease compared to the control (in the presence of 100% water requirement, absence of bentonite and salicylic acid). The highest stem length (346.89 cm) was recorded in the presence of 100% water requirement, bentonite application, and 100 ppm of salicylic acid, i.e. a 22.7% increase in stem length compared to the control. With increasing drought stress, leaf area decreased, so that in severe stress (60% water requirement) and moderate stress (80% water requirement) conditions, leaf area decreased by 28.47% and 23.76%, respectively, compared to the control. Results showed that with increasing drought stress, the content of chlorophyll a, b and total chlorophyll significantly decreased. The lowest amount of chlorophyll a, b and total chlorophyll was recorded in the presence of 60% water requirement and absence of salicylic acid, i.e. 26.0, 36.6 and 28.6% decreases, respectively, compared to the control (in the presence of 100% water requirement and absence of salicylic acid). With increasing drought stress, the relative leaf water content decreased significantly. In each irrigation treatment by bentonite application and salicylic acid, the relative leaf water content increased. The highest (88.19%) and the lowest (75.95%) relative leaf water content was recorded in the combined treatment of 100% water requirement, bentonite and 100 ppm of salicylic acid and the combined treatment of 60% water requirement, without bentonite and salicylic acid, respectively. With increasing drought stress, the amount of total soluble solids increased. No significant difference was observed between 80% and 60% water requirement treatments. However, the highest amount of total soluble solids was recorded when the melon plants were exposed to the 60% water requirement treatment. The results showed that with increasing drought stress, fruit yield decreased significantly. Under each of the irrigation treatments fruit yield increased significantly in the presence of bentonite and salicylic acid, particularly 100 ppm salicylic acid.
Conclusions: Based on the results of this research, it can be concluded that under water deficit conditions, using bentonite and salicylic acid are capable to mitigate the effects of drought stress on melon plants, mainly through reducing water consumption, leading to increased fruit yield and quality. |
| نویسندگان مقاله |
حسین نستری نصرآبادی | H. Nastari Nasrabadi
, Department of Horticultural Science and Landscape Architecture, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran and Assistant Professor, Department of Horticulture Science and Engineering, Faculty of Agriculture and Animal Science, University of Torbat-e Jam, Torbat e Jam, Khorasan Razavi, Iran.
گروه علوم باغبانی و مهندسی فضای سبز، دانشکده کشاورزی، دانشگاه فردوسی مشهد، مشهد، ایران و گروه علوم و مهندسی باغبانی، مجتمع آموزش عالی تربت جام، تربت جام، خراسان رضوی، ایران.
حسین نعمتی | H. Nemati
Department of Horticultural Science and Landscape Architecture, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
گروه علوم باغبانی و مهندسی فضای سبز، دانشکده کشاورزی، دانشگاه فردوسی مشهد، مشهد، ایران.
محمد کافی | M. Kafi
Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
گروه آگروتکنولوژی، دانشکده کشاورزی، دانشگاه فردوسی مشهد، مشهد، ایران.
حسین آروئی | H. Aroiee
Department of Horticultural Science and Landscape Architecture, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
گروه علوم باغبانی و مهندسی فضای سبز، دانشکده کشاورزی، دانشگاه فردوسی مشهد، مشهد، ایران.
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