جستجوی مقالات مرتبط با کلیدواژه « Growth promotion » در نشریات گروه « گیاهپزشکی »

Modern agriculture in the 21st century must provide food security for this growing population, which means producing more food and fiber with less labor. Therefore, agriculture in this century requires smart investment based on more efficient and environmentally friendly production methods. Common wheat root rot caused by B. sorokiniana is one of the most important pathogens of wheat, which causes economic losses every year. In this research, from 180 Bacillus isolates from the samples collected from the wheat fields of Hamadan province, wastes of edible mushrooms, palm wastes and wood wastes, 9 isolates were able to produce γ-PGA with different production rates. 2 isolates were able to produce γ-PGA independently of glutamic acid. Bacillus velezensis UTB97 with a production rate of 40 g/L γ-PGA was selected as the superior producer isolate. UTB97 could prevent 65% growth of pathogenic fungi in laboratory conditions by dual culture method. Greenhouse result showed that the treatment of UTB97 and UTB97 + γ-PGA was able to control Common wheat root rot disease by 59 and 73%, respectively, compared to the control treatment, and also the treatment of UTB97 + γ-PGA was able to increase the growth index of wheat. (stem length and root dry weight), in the presence and absence of the pathogenic fungus.

Wheat is one of the most important agricultural products in Iran, that plays an important role in ensuring food security. Crown and root rot disease by F. pseudograminearum is one of the most important pathogens that cause economic damages every year. In this study, 80 isolates of Bacillus were isolated from wheat rhizosphere. In dual-culture test, UTB 3, UTB 11, UTB 22, UTB 4 and UTB 7 isolates with 60, 55, 37.5, 22.5 and 20% maximum ability, respectively. In effect test of volatile metabolites on inhibination the growth of F. pseudograminearum, UTB 3, UTB 7 and UTB 11 with 54, 52 and 49% showed the highest percentage of inhibition of fungal growth. These isolates were also capable of nitrogen fixation, production of siderophore and extracellular enzymes involved in biological control (protease, lipase and chitinase), but none of the isolates were able to produce phosphatase enzyme. Greenhouse studies by treating wheat seeds with selected isolates showed that UTB 3 was able to control crown and root rot of wheat by 80.33% compared to the control treatment. Also, this isolate could increase the growth indices of wheat (stem length and root dry weight) in the presence and absence of pathogenic fungi. Therefore, this isolate is introduced as the selected isolate to control crown and root rot disease and increase wheat growth indices.

Chickpea (Cicer arietinum L.) is the third most important legume crop in the world. Ascochyta blight caused by Ascochyta rabiei (Pass.) Lab. is one of the most important threats for producing chickpea in most of the growing areas. The pathogen invades all aerial parts of the plant and causes severe yield and quality losses. The present study aims to evaluate the effect of some defense inducing volatile compounds in inhibiting A. rabiei, as well as the effect of these compounds on some chickpea growth traits at the presence of the pathogen.

First, six volatile compounds including methyl salicylate, 2,3-butanediol, methyl-jasmonate, acetoin, indole and 3-pentanol were prepared in sterile distilled water (100 μM) containing 0.2% Tween 20, and were used for laboratory and greenhouse studies. The in vitro antifungal activity of volatile compounds was tested on chickpea seed meal dextrose agar (CDA) medium. Then, a five-millimeter agar disk containing the mycelium of the pathogen was placed on the surface of CDA medium in 9 cm diameter Petri dishes. The Petri dishes were inverted and 100 μl of the emulsion of each volatile compound was placed inside the lid. The Petri dishes were sealed and kept at the same inverted position to avoid the dropping of volatile compounds over the culture medium. A greenhouse experiment with nine treatments (including six volatile compounds, chlorothalonil fungicide, healthy and diseased controls) was conducted in a completely randomized design. In addition, the emulsions of volatile compounds were sprayed on the leaf surfaces 12 days after sowing chickpea seeds (variety Bivanij). After 48 hours, the conidial suspension of the pathogen in water (2 x 104 conidia/mL) was sprayed to the surface of chickpea seedlings. Disease severity and plant growth indices including shoot fresh weight, shoot dry weight, root fresh weight and root dry weight were measured two weeks after inoculation. Statistical analyses were performed by SAS software (version 9.3). The means were compared by Duncan's test at a statistical probability level of 5%.

All volatile compounds inhibited the mycelial growth of A. rabiei on CDA with the highest (64.91%) and lowest (4.67%) inhibition obtained by 3-pentanol and methyl jasmonate, respectively. In the greenhouse test, all volatile compounds, except methyl jasmonate, reduced the incidence of blight symptoms compared to the diseased control. The highest disease reduction was obtained by chlorothalonil (86.04%) and methyl salicylate (55.81%). At the presence of the pathogen, all volatile compounds increased root fresh weight, root dry weight and shoot fresh weight, and increased shoot dry weight with the exception of 3-pentanol and methyl jasmonate. Compared to the diseased control, the effect of indole on root fresh and dry weight and shoot dry weight, as well as the effect of methyl salicylate on shoot fresh weight was more than other compounds. Methyl jasmonate had the least improving effect on growth traits compared to other volatile compounds.

The volatile compounds used in this study inhibited A. rabiei in both in vitro and greenhouse tests. They also improved chickpea growth parameters at the presence of the pathogen. The use of volatile compounds could be considered as a new and promising strategy for the integrated management of Ascochyta blight.