Imbalance between the accumulation and removal of nitric oxide and its derivatives is a challenge faced by all plants at the cellular level, and is especially important under stress conditions. Exposure of plants to various biotic and abiotic stresses causes rapid changes in cellular redox tone potentiated by the rise in reactive nitrogen species that serve as signaling molecules in mediating defensive responses. To understand mechanisms mediated by these signaling molecules, we performed a large-scale analysis of the Arabidopsis transcriptome induced by nitrosative stress. We generated an average of 84 and 91 million reads from three replicates each of control and 1 mM S-nitrosocysteine (CysNO)-infiltrated Arabidopsis leaf samples, respectively. After alignment, more than 95% of all reads successfully mapped to the reference and 32,535 genes and 55,682 transcripts were obtained. CysNO infiltration caused differential expression of 6436 genes (3448 up-regulated and 2988 down-regulated) and 6214 transcripts (3335 up-regulated and 2879 down-regulated) 6 h post-infiltration. These differentially expressed genes were found to be involved in key physiological processes, including plant defense against various biotic and abiotic stresses, hormone signaling, and other developmental processes. After quantile normalization of the FPKM values followed by student's T-test (P < 0.05) we identified 1165 DEGs (463 up-regulated and 702 down-regulated) with at least 2-folds change in expression after CysNO treatment. Expression patterns of selected genes involved in various biological pathways were verified using quantitative real-time PCR. This study provides comprehensive information about plant responses to nitrosative stress at transcript level and would prove helpful in understanding and incorporating mechanisms associated with nitrosative stress responses in plants.

Screenhouse experiments were conducted to test the efficacy of cowdung and urine separately and in combination in the control of root-knot nematode of tomato. Equal quantities of cowdung, urine and their mixture were separately made up to one litre with autoclaved soil. Two weeks old seedlings of tomato raised in autoclaved soil were transplanted into soil manure mixture and inoculated with 1,000 second stage larvae of Meloidogyne incognita race I. Treatments were completely randomized and effects assessed based on plant height, dry weight, extent of galling and the nematode multiplication factor. Results obtained showed that cowdung, urine, and their mixture produced significantly higher result than the untreated control. Similarly, the mixture of urine and cowdung, produced significantly higher results than the separate treatments.

Salinity is one of the major abiotic factors that limit rice production worldwide. Previous trends show that salt concentration in rivers is increasing consistently, posing potentially adverse threats in the near future. Thus, crops currently being cultivated, particularly in small-scale farming systems, are under high threat from salinity. In this study, we investigated the mitigating effect of nitric oxide (NO) on salt stress in rice based on the assessment of changes in the transcript levels of different genes and the phenotypic response of rice genotypes. We observed that exogenously applied NO increased the expression levels of OsHIPP38, OsGR1, and OsP5CS2 in the susceptible genotype of rice, whereas in the tolerant genotype, the effect of NO was mainly in counteracting the salt-induced gene expression that diverts cellular energy for defense. Moreover, seedlings that were pretreated with NO showed high biomass production under salt stress conditions, indicating the positive role of NO against salt-induced leaf chlorosis and early senescence. The effect of NO-mediated enhancement was more pronounced in the salt tolerant genotype. Therefore, the use of NO with the integration of tolerant genes or genotypes will enhance salt tolerance levels in rice.

ABSTRACT

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Ascochyta blight disease is a major problem in faba bean (Vicia faba L) production that causes 90% to 100% yield loss. A field experiment was conducted to evaluate the efficacy of three fungicides with three spray frequency levels against Ascochyta blight disease of faba bean varieties. For the assessment of disease management, a total of 21 treatments were used, which comprised three fungicides, three spray frequencies, two varieties, and control. The field experiment was arranged in a randomized complete block design with factorial combinations of variety, fungicide, and spray frequency levels in three replications. An analysis of variance was performed for disease, yield, and yield related and plant growth parameter data, using the Statistical Analysis System (SAS, 2003) version 9.1.3 software. The economic data obtained from the field experiment was analyzed using the partial budget analysis method. The results showed that area under disease progress curve, percent severity index, disease progress rate, and percent disease incidence had strong mean significant differences ( p < 0.01 ) between treated and untreated plots. Application of fungicide significantly increased plant height, stem girth, pod per plant, grain yield, and harvesting index ( p < 0.01 ) over untreated plots. Greater total return (195,938 Ethiopian birr ha−1), net return (101,761.3 Ethiopian birr ha−1), and net benefit (34,768.17 Ethiopian birr ha−1) were obtained by EH00102-4-1 variety, in two times Mancolaxyl treatment. The linear regression analysis result (R2) indicated that the variation in average grain yield of EH00102-4-1 and local susceptible varieties, due to the mean area under the disease progress curve, was 64.50% and 68.64%, respectively. Therefore, the use of EH00102-4-1 variety, with two times Mancolaxyl spray frequency application, at early growth stage and the onset of the disease is suggested as an agronomic management option, in Northwestern Ethiopia.

No abstract

Lake Tana is the largest freshwater body in Ethiopia. Currently, the lake has been facing alarming environmental degradation and loss of biodiversity due to the invasion of water hyacinth. Although the weed is invasive, it can be converted into various benefits. Hence, this study was conducted in North Eastern Lake Tana, Sheha Gomengie Kebele. The main objective is compost preparation in terms of its drying periods, analyses, and user perception. Physicochemical and nutrient analyses were performed according to the standard procedures. Acid digestion was used for heavy metal analyses. From the result, the pH measurements ranged from 7.619 ± 0.195 to 7.719 ± 0.261, and the moisture content ranged from 38.712 ± 0.680 to 49.60 ± 9.06%. The mean electrical conductivity (EC) values of all treatments of matured compost ranged from 2.780 ± 0.542 to 3.51 ± 0.971 ds/m. The TN values of the matured compost ranged from 0.420 ± 0.379 to 0.754 ± 0.194 on a dry weight basis. The overall mean values of the C:N ratio for all the treatments were 11.60 which is within an acceptable range. A high amount of available P concentrations was observed in all compost treatments which ranged from 2.740 ± 0.190 to 2.940 ± 1.410 g/kg. Moreover, the concentrations of heavy metals in all treatments were below the permissible limit of different agencies and there was also no significant difference in the mean values of analysis of variance at (P < 0.05). Therefore, the prepared compost can be recommended for better agricultural purposes. Considering users’ understanding of compost preparation as an opportunity, converting WH into compost is promising in terms of its rich supply and the possibility of preparing in the dry season where labor is abundant. Therefore, it can be one way of sustainably reducing WH adverse effects on the Lakeshore.