پديد آورندگان :
الداغي، مهسا دانشگاه تهران - پرديس كشاورزي و منابع طبيعي كرج - دانشكده علوم و مهندسي كشاورزي - گروه گياه پزشكي , اللهياري، حسين دانشگاه تهران - دانشكده كشاورزي و منابع طبيعي - گروه گياه پزشكي , حسيني نوه، وحيد دانشگاه تهران - دانشكده كشاورزي و منابع طبيعي - گروه گياه پزشكي , بهبودي، كيوان دانشگاه تهران - دانشكده كشاورزي و منابع طبيعي - گروه گياه پزشكي
كليدواژه :
تريكودرما , آنتاگونيست , ترجيح ميزباني , فنول كل
چكيده فارسي :
يكي از مكانيسم‌هاي عمل قارچ‌هاي جنس Trichoderma spp.، تحريك سامانه دفاعي در گياهان است. در اين مطالعه، اثر استرينTr6 Trichoderma harzianum بر ترجيح ميزباني و تخم‌گذاري سفيدبالك گلخانهTrialeurodes vaporariorum westwood در شرايط آزمايشگاهي بررسي شد. در اين راستا چهار آزمايش شامل سنجش فنول كل، بررسي اثر زمان در بروز مقاومت، انتخاب آزاد و بدون انتخاب در شرايط دمايي 2±25 درجه سلسيوس، رطوبت نسبي60-70 درصد و دوره نوري 8:16 ساعت (روشنايي:تاريكي) انجام شد. نتايج نشان داد بيش‌ترين غلظت فنول كل در گياه مربوط به زمان‌هاي3 و 4 روز بعد از تلقيح قارچ بود كه به‌ترتيب برابر با 0/003±0/3503و 0/001±0/3323 ميلي‌گرم بر گرم بود و كم‌ترين تعداد افراد بالغ پشت برگ از روي گياهاني كه 2 و 4 روز از زمان تلقيح آنها مي‌گذشت، جمع‌آوري شد كه به‌ترتيب ميانگين آنها برابر با 0/86±2/2 و0/63±2/0بود. هم‌چنين در گياهان تيمارشده به‌وسيله قارچ تريكودرما، كاهش معني‌داري در ميانگين تعداد حشرات بالغ درپشت برگ (0/66±3/4)، تخم‌هاي گذاشته شده (1/51±7/4) و ميزان قطرات عسلك توليدشده (0/28±1/0) نسبت به گياهان شاهد، مشاهده شد. يافته‌هاي اين پژوهش نشان داد كه تيمار گياه با استرين Tr6 T. harzianum سبب القاي مقاومت نسبت به گياه‌خواري سفيدبالك، كاهش ترجيح ميزباني و تخم‌گذاري شد و كاربرد آن ميتواند يك گزينه اميدواركننده در برنامه مديريت تلفيقي اين آفت در گلخانه باشد.
چكيده لاتين :
Background and Objectives
The greenhouse whiteflies, Trialeurodes vaporariorum (Westwood), are one of the major pests of vegetable and ornamental crops in greenhouses in the world. They damage crops through direct feeding, inserting their stylet into leaf veins, and extracting nourishment from the phloem sap. As a by-product of feeding, honeydew is excreted, which is an indirect but yet another substantial source of damage. The third most harmful characteristic is the ability of adults to transmit various plant viruses. Induced resistance is a non-chemical control method that has no negative impact on the environment and human health and can be a desirable approach in plant protection and pest control. Trichoderma spp. has spread in many ecosystems and its various species such as Trichoderma harzianum Rifai have been successful as non-pathogenic symbionts in controlling plant pathogens via different mechanisms. Some of these mechanisms include enzymatic degradation, secretion of antibiotics, and increasing root absorption capacity. Recent findings suggest that T. harzianum is also a potent inducer of Induced Systemic Resistance (ISR) and can stimulate the immune system in plants against plant diseases and pests. In this study, the efficacy of T. harzianum Tr6 was investigated on host preference and egg production of T. vaporariorum.
Material and Methods To evaluate the effect of T. harzianum Tr6, four tests were carried out: 1) Total phenol assay using Folin–Ciocalteu reagent, 2) The effect of time on induced resistance, 3) Free choice, and 4) Non choice. These tests were conducted on tomato plants (Falat cultivar) at 25±2°C, relative humidity of 60-70%, and a photoperiod of 8 h/16 h (day/night). Also, these experiments were performed on one-day-old adults in plots with four or six leaves in shelves equipped with organza mesh. ResultsAccording to the phenol assay, the highest amount of total plant phenol was observed three and four days after inoculation by Tr6 strain respectively 0.3503±0.001 and 0.3323±0.001mg/g. Therefore, for the next three tests, plants that were inoculated after three days were used as treated samples, and plants watered with distilled water were used as control ones. In these experiments, the lowest number of adults on the back of the leaves after 24 hours was observed two and four days upon inoculation respectively 2.2± 0.86 and 2.0± 0.63. On the other hand, plants inoculated by Tr6 displayed a significant decrease in adults on the back of the leaves (3.4± 0.66), egg-laying (7.4± 1.51), and honeydew droplets (1± 0.28) compared to control plants.Conclusion
The most important factor in controlling the whitefly population is reducing the reproduction rate. Induced resistance can repel insects from plants and limit their nutrition, and thus, reduce their reproduction. This study implied that the inoculation of tomato by T. harzianum Tr6 strain could induce resistance to whitefly and reduce host preference and egg production, as well as honeydew secretion. Therefore, this strain can be a promising option in preventing the outbreak of this multi-generational pest.
