Field screening of rice (Oryza sativa L.) genotypes for resistance to bacterial leaf blight (Xanthomonas oryzae pv. oryzae) disease

Rice is the most important crop in Nepal followed by maize and wheat in terms of area (1.4 million ha), production (5.15 million) and productivity (3.5 mt/ha). Bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv. oryzae is considered to be the most widespread and destructive disease of rice in both irrigated and rainfed environments in Nepal. Use of host plant resistance is the most feasible and economical way to combat this disease. However, breakdown of resistance of a variety often occurs after few years of release due to genetic adaptation of the pathogen. Regular screening of the genotypes is utmost for developing the resistant genotypes. Considering the point, this investigation effort has been made to screen the rice genotypes against BLB under natural field condition at Khajura, Banke during 2018 and 2019. In the study, plants were assessed by measuring disease severity (percentage of leaf diseased) and area under the disease progress curve (AUDPC). Differences in resistance among the rice genotypes were observed in both of the tested year. Among the screened 150 rice genotypes during 2018, 6 genotypes scored resistant (R), 81 moderately resistant (MR), 59 moderately susceptible (MS) and 4 susceptible (S) to BLB. Whereas, in 2019, among the tested 315 rice genotypes, none of the genotypes were resistant, 183 MR, 131 MS and 1 S to BLB disease. This showed that the tested genotypes were composed of different genetic background. &nbsp

Technical efficiency of potato production in mid western terai region of Nepal

A study was done in 2018 to estimate the technical efficiency of potato production in mid western terai region of Nepal.30 households each from Dang, Banke and Bardiya districts were interviewed. Maximum likelihood estimate of the parameter showed the mean technical efficiency of 0.79 which indicated a high scope of increasing the production with the improvement of production technology. The coefficient for the parameter seed, Urea, DAP, MOP and labour were positive contributing for the production of potato. The parameter Compost, pesticides, herbicides and hour of tractor use were negative. The use of these input could be improved for increasing the production of potato. The farm specific variables Education, contact with the extension agent and farm size showed negative coefficient which causes less inefficiency of the farmers in production of potato while the coefficient for Age was estimated to be positive

Performance of black gram varieties to mungbean yellow mosaic disease at different sowing dates under spring and summer condition in western terai of Nepal

A field experiment was conducted at Grain Legumes Research Program (GLRP), Khajura, Banke, Nepal during spring and summer season 2019 to elucidate the effect of date of sowing and blackgram varieties on mungbean yellow mosaic disease severity and yield. The experiment was conducted in 2 factorial randomized complete block design with 3 replications. Factor A comprised date of sowing (S1= 5th April 2019, S2= 20th April 2019, S3= 5th May 2019, S4= 20th May 2019, S5= 25th July 2019, S6= 10th August 2019, S7= 25th August 2019 and S8= 10th September 2019) and factor B (Variety): V1= Khajura Mas 1 and V2= Rampur Mas. Disease severity was scored in 1-6 scale. Results revealed that mean values for days to disease appearance, disease score and grain yield in spring season sowing was 26 days, 3.72 and 635 kg/ha, whereas for summer season sowing was 14 days, 5.04 and 185 kg/ha.  Among the date of sowing, April 5th sown crop recorded minimum mean disease score (3.1) with highest yield (719 kg/ha). Whereas, September 10th sown crop recorded maximum mean disease score (5.1) with lowest yield (174 kg/ha). Black gram varieties showed significant response to mean disease score and yield at early sowing condition but when the sowing date was delayed, there was no significant response of varieties to mean disease score and yield. The contribution of regression (R2 =0.791) and (R2 = 0.655) for spring season and summer season indicate that 79% and 65% of the blackgram yield would be affected by disease for the respective season. Therefore, it is better to sow blackgram in early season to escape mungbean yellow mosaic disease and minimize yield loss

Screening of local, improved and hybrid rice genotypes against leaf blast disease (Pyricularia oryzae) at Banke district, Nepal

Rice (Oryza sativa) is the major cereal crop of Nepal which is being faced by the devastating rice blast disease caused by Pyricularia oryzae Cavara. An experiment was conducted to screen rice genotypes against leaf blast disease under disease conducive upland nursery at Regional Agricultural Research Station (RARS), Khajura, Banke, Nepal during July to November, 2016. A total of 101 rice genotypes (comprising of local, improved and hybrid) including resistant and susceptible check were screened in a randomized complete block design with two replications. Disease scoring was done beginning from the 20th days of sowing by using the disease rating scale 0-9. Amongst the tested 101 rice genotypes, 28 genotypes were found resistant, 15 genotypes were moderately resistant, 16 genotypes were moderately susceptible, 39 genotypes were susceptible and 3 genotypes were highly susceptible to leaf blast. The information revealed from this study could be helpful for rice leaf blast disease management and utilizing these resistant and moderately resistant genotypes for further resistance breeding program

RESPONSE OF LOCAL POTATO CULTIVARS TO LATE BLIGHT DISEASE (Phytophthora infestans (Mont.) de Bary) UNDER FIELD CONDITIONS

Developing host resistance is an economic and long-term approach to disease management; however, resistance reactions that differ depending on the genotypes. Potato late blight is the devastating disease caused due to Phytophthora infestans (Mont.) de Bary.  In order to identify late blight resistance in potato genotypes, seven local potato cultivars (Bardiya Rato Local, Bardiya Seto Local, Cardinal, Deukhuri Rato Local, Deukhuri Seto Local, Kailali Local and Khumal Ujjowal) were evaluated in randomized complete block design (RCBD) with three replications during October 2018 to January 2019 on naturally infested soils in Deukhuri, Dang, Nepal. Results showed that significantly the highest disease incidence (99.17%), and the highest disease severity (88%) were found on Cardinal followed by Deukhuri Rato Local (64%), and Deukhuri Seto Local (60%). Potato cultivar namely Khumal Ujjowal was moderately resistant, whereas Deukhuri Rato local and Deukhuri Seto Local were susceptible to late blight disease. Significantly the highest yield (12.67 t ha-1) was produced by Khumal Ujjowal followed by Bardiya Rato Local (10.78 t ha-1) and Bardiya Seto Local (9.40 t ha-1). The disease incidence and Area under disease progressive curve (AUDPC) value was negatively co-related with the tuber yield. The potato cultivar Khumal Ujjowal followed by Bardiya Rato Local were found moderately resistant to late blight disease in Deukhuri conditions. This study suggests that potato cultivar Bardiya Rato Local can be grown for higher tuber production in Dang and similar topographic regions.DOI: 10.37637/ab.v3i1.46

Evaluation of common bean (Phaseolous vulgaris L.) genotypes against anthracnose (Colletotrichum lindemuthianum Sacc. and Magn.)

Saabunud / Received 21.10.2021 ; Aktsepteeritud / Accepted 27.12.2021 ; Avaldatud veebis / Published online 27.12.2021 ; Vastutav autor / Corresponding author: Sujata K.C. [email protected] genotypes of common bean were evaluated against anthracnose under natural epiphytotic conditions. This study was carried out in a randomized complete block design with three replications at the research field of Agriculture Research Station (ARS), Vijaynagar, Jumla, Nepal from June to September 2018. The area under the disease progress curve (AUDPC) and disease severity were calculated. In laboratory conditions, artificial inoculation was carried out on detached leaves of twelve genotypes using a pure culture suspension of Colletotrichum lindemuthianum (1.2× 106 conidia ml–1) in a completely randomized design with three replications. The results showed that bean genotypes varied significantly for disease severity both in the field and laboratory conditions. In the field, bean genotypes showed resistance to highly susceptible reactions. Their AUDPC value ranged from 120.55 to 502.31. The lowest mean AUDPC value was recorded in KBL-1 (120.55) followed by KBL-3 (123.79) and KBL-2 (124.44). Similarly, the lowest severity value was recorded with KBL-1 (0.51), KBL-2 (0.52) and KBL-3 (0.53). Detached leaf assay in laboratory experiment showed that the lowest mean AUDPC was found in KBL-2 (16.67) and KBL-3 (16.67). Therefore, KBL-2 and KBL-3 could be utilized as resistant varieties to anthracnose disease under Jumla and similar field conditions

Evaluation of different chemical fungicides against rice blast in field conditions

Evaluation of different fungicides against rice blast was carried out in research plot of the Agronomy farm of IAAS, Prithu Technical College, Lamahi Municpality, Dang district of the Lumbini Province, inner terai region of Nepal during June to November, 2017. The objective of the experiment was to evaluate the efficiency of different chemical fungicides against rice blast. The experiment was conducted in Randomized Complete Block Design with the use of susceptible variety ‘Mansuli’. Different fungicides like Hexaconazole 5% SC (Udaan), Propiconazole 25% EC (Tilt), Captan 70% + Hexaconazole 5% WP, Validamycin 3% L, Tricyclazole 75% WP (TRIP) and Biomycin (Kasugamycin 3% S.L.) were applied five times at weekly interval with the doses of 2mL/L of H2O, 1.5mL/L of H2O, 2g/L of H2O, 2mL/L of H2O, 2g/L of H2O and 2mL/L of H2O respectively. From the result, it was concluded that all the fungicides were effective in controlling leaf blast but Tricyclazole 75% WP (TRIP) was more effective among other fungicides and untreated control plots with least leaf blast severity (27.85%), least incidence (35.5%), least mean AUDPC (64.64%) and highest grain yield (3.93 t ha-1) followed by Biomycin. It is thus concluded that fungicide Tricyclazole 75% WP should be sprayed five times at weekly interval for the management of leaf blast in rice

Genetic variability, heritability and genetic advance in Lentil (Lens culinaris Medik.)

The present study was carried out to study the variation, broad-sense heritability, and genetic advance, correlation among traits for growth, yield, and its attributing traits in lentil genotypes. Sixty lentil genotypes were evaluated in augmented design in 2020 at Khajura, Banke. The results indicated that the genotypes were significantly different for days to flowering, days to maturity, 500 seed weight and grain yield kg/ha. The phenotypic coefficient of variation (PCV) was greater than the genotypic coefficient of variance (GCV) for all traits. The 500 seed weight showed the highest PCV (22%) and GCV (21%) whereas days to maturity showed the lowest PCV (5.5%) and GCV (3.2%). The highest value (90%) of heritability (broad sense) was in and lowest (3%) in pods per plant. Genetic Advance Mean 40% was the highest for seed weight but lowest at 1.2% in pods per plant. Grain yield showed a positive and significant correlation in genotypic level with days to maturity (r = 0.7**), plant height (r = 1.66*), pods per plant (r = 1.15**) and seed weight (r = 0.56*). Path analysis found that the seed weight had the most impact on grain yield followed by pod per plant. Thus, selection for yield in lentils through these characteristics would be effective in the varietal developmental program. &nbsp

Meeting report: The first soil viral workshop 2022.

Soil viral ecology is a growing research field; however, the state of knowledge still lags behind that of aquatic systems. Therefore, to facilitate progress, the first Soil Viral Workshop was held to encourage international scientific discussion and collaboration, suggest guidelines for future research, and establish soil viral research as a concrete research area. The workshop took place at Søminestationen, Denmark, between 15 and 17th of June 2022. The meeting was primarily held in person, but the sessions were also streamed online. The workshop was attended by 23 researchers from ten different countries and from a wide range of subfields and career stages. Eleven talks were presented, followed by discussions revolving around three major topics: viral genomics, virus-host interactions, and viruses in the soil food web. The main take-home messages and suggestions from the discussions are summarized in this report