نشریه پژوهش های کاربردی در گیاه پزشکی
سال سیزدهم شماره 3 (پاییز 1403)

The pathogen, Pythium aphanidermatum is one of the causal agents of sugar beet root rot in Iran. In order to evaluate the reaction of cultivars to the pathogen, at first, the screening method of evaluation was optimized. Then, a number of 24 cultivars that are commonly cultivated in Iran were evaluated against the pathogen. Three different evaluation methods in the greenhouse including grass leaf suspension, oospore suspension, and grass leaf suspension using through making wounds on the roots were compared with each other. A number of 12 cultivars were inoculated with these three inoculation methods. The results showed that positive and significant correlation of the three methods with each other. Then, 24 commercial sugar beet cultivars were evaluated with grass leaf suspension method under the greenhouse conditions. Based on the results of the evaluation of the 24 commercial cultivars of sugar beet and the comparison of the disease index of Pythium root rot based on Duncan's multi-range test, Ivano, Boomrang, Flores and Tous had the lowest rot index among the cultivars with the average index of 2.58, 2.65, 2.72 and 2.75 respectively and were introduced as resistant cultivars to the disease. Cultivars Jolgeh, Rasool, Shirin and Jam were categorized as susceptible.

Saffron (Crocus sativus) is a high-value perennial plant cultivated widely in Iran as a spice and medicinal plant. Several pathogens including viruses can infect saffron and decrease its quality and quantity. Precise and reliable detection is a critical aspect of disease management in viral diseases because of the lack of commercially available chemicals against plant viruses. Nowadays, high throughput sequencing (HTS) has been considered as a routine technology for detection of known and novel viruses in commercial plants. In this study, using HTS data, saffron latent virus (SaLV) and prunus virus T (PrVT) were identified in transcriptomic data of stigma of saffron and near complete genome of these viruses were obtained. The near complete genome of SaLV isolate had 98.3% nucleotide sequence identity with the only available isolate in GenBank. The complete genome of saffron isolate of PrVT shared 42.9 (potato virus T isolate Peru) – 76.9 % (olive virus T isolate GR168) nucleotide sequence identity with those of tepoviruses available in GenBank. In a phylogenetic tree, the PrVT isolate clustered with two Greece OlVT isolates along with an isolate of PrVT. To the best of our knowledge, this is the first report of PrVT infection in saffron worldwide.

Over the past two decades, biological control of wheat septoria tritici blotch (STB) caused by Zymoseptoria tritici has been evaluated as a reliable and safe alternative or complement to chemical control. The genus Trichoderma includes several biocontrol agents (BCAs) widely used worldwide against plant diseases. Besides direct control of plant pathogens, Trichoderma spp as BCAs provide numerous other beneficial features for their plant hosts. The current study aimed to assess the potential biocontrol ability of several antagonistic Trichoderma isolates with endophytic potential on STB reduction in wheat cultivar Tirgan under greenhouse conditions. The antagonists were used as a seed-coated treatment at the sowing time and sprayed on the plants 72 h before Z. tritici IPO323 inoculation. STB severity was calculated 21 days after the pathogen inoculation. The biocontrol isolates significantly (α = 0.01) reduced the disease severity on cv. Tirgan. T. harzianum AS12-2 provided the highest average percentage of STB inhibition in both application methods. Application of T. harzianum AS12-2 led to a reduction in the percentage of leaf area covered by lesions (PLACL) and the percentage of leaf area covered by pycnidia (PLACP) by 80.12% and 77.71%, respectively. Trichoderma biocontrol isolates could be considered safe and reliable alternatives/complements for sustainable agriculture in integrated management programs of wheat STB.

The diversity of weed communities and their differences in response to herbicides have made mixed herbicides application inevitable. In this research, the efficacy of transplanted rice herbicides in controlling weeds in rice direct seeded rice was investigated. Comparison of the efficiency of premixed herbicide pretilachlor + pyribenzoxim (solito, EC 32%, 480 g ai ha-1) in a pot experiment with the common herbicides bispyribac-sodium (two formulations SC40%, SC10%), pyribenzoxim and bentazone + MCPA showed that the premixed herbicide provided similar control of barnyardgrass and bulrush as did common herbicides. Field experiment treatments included bentazone + MCPA + pendimethalin, bentazone + MCPA + thiobencarb, bispyribac-sodium + pendimethalin, bispyribac-sodium + thiobencarb, pretilachlor + bensulfuron-methyl and doses of 0, 50, 100, 150 and 200% of pretilachlor + pyribenzoxim mixed with thiobencarb. The results showed that pretilachlor + pyribenzoxim did not show any phytotoxicity symptoms on rice up to twice the recommended dose. Application of the recommended dose of pretilachlor + pyribenzoxim + thiobencarb provided 90% and 70% control of barnyardgrass (Echinochloa crus-galli) and bulrush (Bolboschoenus planiculmis) respectively. The lowest and highest yield of paddy was 517 and 5495 kg/ha, respectively, which was recorded in the weedy and bispyribac-sodium + thiobencarb treatments. The yield of paddy at the recommended and twice the recommended dose of pretilachlor + pyribenzoxim was statistically the same 4761 and 4827 kg/ha, respectively. Overall, the results of this research indicated that the application of pretilachlor + pyribenzoxim (480 g ai ha-1) after soil-applied thiobencarb (2750 g ai ha-1) provided very good control on the important weeds of rice in direct cultivation on wet bed and can be introduced as a suitable alternative to common herbicides.

To investigate the effect of black rust disease (Puccinia graminis f. sp. tritici) on wheat yield and its components and to identify genetic resources resistant to this disease, 24 wheat genotypes were evaluated in 2020-2021 at the East Azarbaijan Research Center for Agriculture and Natural Resources. The evaluation was conducted under both infected and non-infected conditions with the native race TKTTF of the black rust, using a randomized complete block design with three replications. Talcum powder was used for inoculation, and after sprinkling distilled water and saltrol oil on the plants, inoculation was done using a mechanical sprinkler. The test results indicated a significant difference between the genotypes in terms of plant height, spike length, spike diameter, spike weight, number of seeds per spike, hundred seed weight, seed yield, biomass and harvest index was observed at the probability level of 1%. Additionally, the results demonstrate that pathogen infection causes a decrease in stem diameter, number of seeds per spike, hundred seed weight, seed yield, biomass and harvest index. Based on the studied traits, the Zareh and Heyran cultivars, as well as the C-98-14, C-98-13, C-98-12 and CD-94-5 lines, were identified as resistant genotypes. The genotypes were classified into four groups under infection and non-infection conditions and into three groups under medium infection conditions, based on cluster analysis and detection function analysis. The research results indicate that black rust infection has a negative impact on both the yield and its components. Additionally, the diversity between genotypes can be utilized to enhance wheat genotypes.