A pot experiment was conducted to assess the effect of drought stress on growth and secondary compound accumulation of Ocimum species, in a semi-controlled greenhouse during the year 2020. The experiment was performed as a factorial that was based on a randomized complete design with three species of basil namely O. basilicum ‘Genovese’, O. x africanum, and O. americanum, and three levels of water supply (70, 50, and 30% soil water capacity-SWC) that were replicated twice. The results revealed that severe drought conditions (30% SWC) significantly lowered the relative water content and, as a consequence, plants were shorter, narrower in the canopy, and produced smaller leaves which, in turn, resulted in a 50% fresh and dry herb yield loss. Furthermore, severe drought stress negatively affected the essential oil content (except O. x africanum where no change was seen), essential oil yield, and the antioxidant capacity. However, slight enhancements of glandular hair density were observed in the drought treatment than in the control. Regardless of the soil water capacity variation, the major compound of the essential oil and total polyphenol content remained unchanged. Besides drought, morphological and chemical variations were also detected among the Ocimum species. Sweet basil cultivar Genovese produced the maximum biomass (344.7 g/plant) whereas O. x africanum accumulated higher essential oil (2.79%). The major compounds that were identified were linalool in O. basilicum; 1, 8-cineole, and camphor in O. x africanum; and O. americanum had more neral and geranial. In conclusion, a higher water supply is recommended for higher biomass and essential oil yield production in the tested basil species.

Surface incoming shortwave (solar) radiation data are an important component of many scientific analyses, but direct measurements are not commonly available. Estimates can be obtained from gridded meteorological analysis or reanalysis systems, such as the Global Data Assimilation Systems (GDAS) and Modern Era Retrospective Reanalysis System (MERRA-2), or calculated using empirical models dependent on meteorological variables such as air temperature. The purpose of this analysis was to compare multiple methods for estimating daily shortwave radiation in a tropical highland environment in Ethiopia. Direct solar radiation outputs of GDAS and MERRA-2, topographically corrected outputs of the two analysis systems, and empirically estimated solar radiation values calculated with the systems’ air temperature data were compared to see which produced the most reliable radiation values. GDAS appeared to underestimate the seasonal variability, resulting in low correlation (R 2 ) with in situ data and large mean bias error (MBE). In comparison, MERRA-2 did not underestimate variability, but produced larger bias than the empirical model estimates. There was an improvement in correlation and reduction in MBE when using the GDAS air temperature predictions in the empirical model, but the opposite was true for MERRA-2. The empirical model using station air temperature data ( stationT ) produced the highest correlation across all four stations, with best performance at the lower elevation sites. The direct shortwave radiation outputs of MERRA-2 produced comparable correlation values, with larger R 2 at stations at higher elevation. Topography possibly influenced these results, as MERRA-2 performed comparably to stationT at the stations in moderate terrain, but not in steeper terrain. This work can serve as a starting point for analyses in other tropical highland regions, where continuous in situ solar radiation data are rarely available.

Summary Introduction: Irrigation plays an important role in the cultivation of medicinal plants. There is a lack of information on intraspecific variability of reactions to the effect of drought. Objective: The aim of the current study was to test the effect of irrigation on four sweet basil (Ocimum basilicum L.) cultivars (‘Genovese’, ‘Kasia’, ‘Keskenylevelű’, ‘Wala’). Methods: In an open field experiment irrigated and non-irrigated treatments were set. Plants were harvested in full flowering stage. Before the harvest, the stomatal conductance and chlorophyll content were measured. The production-related parameters were recorded. In the plant material the glandular hair density, essential oil content and composition (GC-MS) and volatile composition (SPME-GC-MS) were identified. Results: Stomatal conductance of the irrigated plants was 2.5–4.5 times higher than in the non-irrigated ones. The chlorophyll content showed only slight changes. The irrigation had a positive effect on the production. The leaf to stem ratio was not modified by the watering. Irrigation negatively influenced the glandular hair density and the EO content, however it increased the EO yield by 40–129%, depending on the cultivar. Significant compositional changes were registered only in the EO of cultivar ‘Kasia’ for linalool, 1,8-cineole and tau-cadinole ratios. Conclusion: Irrigation increases the biomass and EO yield of basil while the composition of the EO is mostly unchanged. Only slight differences were observed among the cultivars.

Summary Introduction: Drought stress is known to change biochemical activities resulting in altered plant growth and development. Objective: Due to the shortage of research evidence in a certain taxa of basil, it is imperative to examine the relationship between drought stress and morphological changes as well as essential oil accumulation. Methods: An open field experiment was conducted in 2020 to determine the effects of drought stress on the morphological and biochemical responses of selected Ocimum species. Five basil species, namely O. basilicum ‘Genovese’, O. basilicum ‘Ohre’, O. × africanum, O. americanum, O. selloi, and O. sanctum ‘Krishna’ were grown under irrigated (control) and non-irrigated (drought stress treatment) plots with two block replications. Results: The result showed that irrigation had a positive effect on production. Consequently, fresh and dry biomass yields were higher on irrigated plots by 39% and 33%, respectively. No significant changes were detected between the treatments in essential oils (EO) yield and EO composition of major compounds. However, a slight increase in camphor (O. × africanum), nerol (O. americanum), and trans-β-caryophyllene (O. sanctum ‘Krishna’) ratios were observed under irrigation treatments. On the other hand, drought stress increased EO content, polyphenol content, and antioxidant capacity. Furthermore, drought stress had a positive effect on the ratios of 1,8-cineole (O. × africanum), and eugenol (O. sanctum ‘Krishna’). There is only a slight increase in EO content under drought stress, which is not comparable to the significant yield reduction recorded. Morphological and biochemical variations were also detected among basil species. Accordingly, higher biomass (616.33 g/plant) and EO yield (3.72 ml/100 g) among the species were obtained from O. basilicum ‘Genovese’ and O. × africanum, respectively. Conclusion: Irrigation is imperative for maximizing biomass and EO yield of tested basil species.

Sweet potato is grown for its nature of versatility and adaptability and is a secure food crop in southern parts of Ethiopia. Therefore, this research has been conducted to determine the magnitude of GEI for yield and yield-related traits and to evaluate the adaptability and stability of eight orange-fleshed sweet potato varieties across locations in North West Ethiopia. The experiment was conducted from 2018 to 2019 under rainfed conditions in four districts of East Gojjam Zone (Baso liben, Gozamin, Gonchasiso enesie, and Enbsie Sar mider) using eight OFSP varieties (Kulfo, Kabode, Vitea, Naspot 13, Naspot 12, Nekawango, RW-11, and Mayai). Data were collected on yield and yield-related traits. Genstat statistical software was used to deploy both combined analysis of variance and meta-analysis of the collected data. The combined ANOVA revealed that environment, varieties, and their interaction affect the tested varieties significantly across locations. Debremedhanite was the high-yielding environment (35.9 t/ha), and Kulfo was the best-performing variety (30.67 t/ha) over different environments. Based on the AMMI result, the environment contributes at large (48.49%) to the total variation of variety performance followed by variety (27.18%) and their interaction (24.23%). The testing locations fall in two mega environments that implies that variety recommendation needs to be specific for each mega environment. Hence, Kulfo and Naspot 12 are recommended for Debremedhanit, Arasma, and Degesech based on yield potential and stability of the varieties, and Naspot 13 is recommended for Yelamgej, Eneba, and Getesemani testing locations. This result is useful for breeders and nutritionists who are working on breeding of sweet potatoes and nutrition.