نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری دانشگاه آزاد اسلامی واحد گرگان، گرگان، ایران.
2 دانشیار گروه تولیدات گیاهی، دانشکده علوم کشاورزی و منابع طبیعی، دانشگاه گنبدکاووس، گنبدکاووس، ایران.
3 دانشیار بخش تحقیقات گیاهپزشکی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان گلستان، سازمان تحقیقات، آموزش و ترویج کشاورزی، گرگان، ایران.
4 دانشگاه فدرال لاوراس، میناس گرایس، برزیل
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Objective
Black shank disease, caused by Phytophthora nicotianae, is one of the most important soilborne diseases of tobacco worldwide and causes causing substantial yield losses. This study aimed to evaluate the resistance of commercial tobacco cultivars to P. nicotianae under greenhouse conditions and to assess the efficacy of novel and conventional fungicides for disease control under natural infection conditions.
Materials and Methods
For resistance evaluation, eight commercial tobacco cultivars, along with resistant (K346) and susceptible (K326) controls, were assessed under greenhouse conditions using the collar inoculation method. Disease severity was recorded, and the area under the disease progress curve was calculated. Analysis of variance, principal component analysis, and hierarchical cluster analysis were employed to differentiate the cultivars. To assess fungicide efficacy, a field experiment was conducted in a randomized complete block design with three replications using the K326 cultivar under natural infection conditions. The effectiveness of four fungicides—Elite (2.5%), Ridomil MZ (2%), Orvego (0.7%), and Beltanol (0.5%) was compared with an untreated control.
Results
Results indicated that cultivars K394, NC60, Bel61-10, and K346 were resistant to the disease. Cultivars NC100 and MN944 showed moderate tolerance, whereas TC100, Coker 347, and K326 were highly susceptible. The first principal component (PC1) accounted for over 97% of the total variance and clearly distinguished resistant from susceptible cultivars. The Iranian cultivar TC100 was highly susceptible, with a disease severity of 93.75%. Regarding fungicide efficacy, Elite and Ridomil provided the best disease control, with efficacies of 77.4% and 67.7%, respectively. These fungicides also significantly (P < 0.01) increased dry leaf yield (up to 5,265 kg/ha), plant height, fresh and dry leaf weight, gross income, nicotine content, and nutrient elements compared with the control.
Conclusion
This study highlights the need to integrate resistant cultivars (e.g., K394 and NC60) with effective fungicides (particularly Elite and Ridomil) in an integrated management program for black shank disease. The findings provide a basis for breeding programs and management recommendations in northern Iran. Given the potential emergence of new races, continuous monitoring of pathogen populations and diversification of control strategies are essential.
کلیدواژهها [English]
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