نوع مقاله : مقاله پژوهشی
نویسندگان
1 محقق، بخش تحقیقات جنگلها و مراتع، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان لرستان، سازمان تحقیقات، آموزش و ترویج کشاورزی، خرم آباد، ایران
2 استادیار پژوهش، بخش تحقیقات حفاظت و حمایت، مؤسسه تحقیقات جنگلها و مراتع کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران
3 استادیار پژوهش، بخش تحقیقات جنگلها و مراتع، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان لرستان، سازمان تحقیقات، آموزش و ترویج کشاورزی، خرم آباد، ایران
4 محقق، بخش تحقیقات حفاظت و حمایت، مؤسسه تحقیقات جنگلها و مراتع کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران
5 استادیار پژوهش، بخش تحقیقات جنگلها و مراتع، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان لرستان، سازمان تحقیقات، آموزش و ترویج کشاورزی، خرم آباد، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objective: The Astragalus genus is one of the largest plant genera and has a wide distribution worldwide. These plants cover approximately 25% of the pastures in Iran. In recent years, a number of these species have begun to decline, leading to gradual drying and death. Deterioration typically starts due to a combination of various factors that alter the conditions and environment of the plants ultimately resulting in infection by pathogenic agents, the most important of which are fungi. The purpose of this research was to identify the fungal factors responsible for drying and deterioration in the Astragalus grasslands in the Tang Sayad area of Chaharmahal and Bakhtiari province as well as to investigate the extent of drying and dieback at different altitudes and slopes.
Methodology: Samples were collected from the roots, stems, and crowns of infected or decaying plants at various stations and subsequently transferred to the laboratory. Parts of the crown, stem and roots of the infected plants were separated and cultivated. After isolating and purifying the pathogenic agents, the isolates were identified based on their morphological and microscopic characteristics using identification keys. Moreover, the virulence of the isolated fungi on detached host branches was evaluated based on recommended methods by inoculating the pathogenic fungi onto healthy branches of uniform diameter from the same species and assessing the resulting lesion size. Additionally, to assess the percentage of damage at three different heights and in two directions (north and south slopes), a factorial design based on a completely randomized block design was employed. The percentage of dieback damage on these plants was recorded, and the data were analyzed using Excel and SPSS statistical software.
Results: In total, six fungal species and genera were isolated and identified from the tissues of Astragalus plants: Fusarium sp., Trichothecium roseum, Nattrassia mangiferae, Verticillium dahliae, Phoma sp., and Penicillium sp.. These fungi were classified into three groups based on the severity of their pathogenicity. The results also indicated that the differences observed in the damage suffered by the plants due to wilt on the northern and southern slopes at each elevation level were highly significant (P < 0.01). Additionally, the effect of elevation on the percentage of dieback damage noted on the northern slope was statistically significant across three elevation ranges (P ≤ 0.01). However, the effect of elevation on the percentage of wilt damage observed on the southern slope across the three elevation ranges was not statistically significant (P > 0.05). The lowest percentage of damage was recorded on the northern slope at elevations above 2500 meters (19.83 ± 2.60), while the highest percentage of damage occurred on the southern slope at elevations between 2300 and 2400 meters (61.00 ± 4.39).
Conclusion: Among the identified fungi, some serve as significant pathogenic agents that affect a wide range of plants, while others act as secondary pathogens, becoming harmful only when plants are under stress. This latter group has gained importance in recent years, as it impacts many plants experiencing decline. Additionally, some fungi are very weak pathogens that primarily function as saprophytes, targeting dead and decaying tissues and contributing to the decomposition of deteriorating plant tissues. Furthermore, the percentage of wilt damage at different elevations was statistically significant among the declining plants on the northern slope, whereas it was not statistically significant on the southern slope.
کلیدواژهها [English]
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