Morpho-physiological and molecular evaluation of drought tolerance in cassava (Manihot esculenta Crantz)

Open Access Article; Published online: 28 Jun 2020Understanding drought tolerance mechanisms of cassava is a pre-requisite to improve the performance of the crop in water-scarce regions. Several hypotheses have been formulated to suggest how cassava can withstand a prolonged period of drought. We performed field trials under drought conditions with a selection of 37 cassava genotypes to identify phenotypic and molecular patterns associated with drought tolerance. Plant morphologies varied significantly between cassava genotypes under drought conditions in Kenya, which indicates a strong genetic basis for phenotypic differences. Drought stress reduced yield by 59%, the number of edible storage roots by 43% and leaf retention by 50% on average. Over three years and in two experimental field sites, the most drought tolerant genotype bulked 7.1 (±2.1) t/ha yield while the most drought susceptible genotype yielded 3.3 (±1.4) t/ha under drought conditions. The significant positive correlation of yield under irrigated and non-irrigated conditions suggests that selection of genotypes with high yield performance under well-watered or control conditions should be prioritized to identify genotypes with superior performance under drought stress. The positive correlation between yield and leaf retention provided further evidence that leaf longevity positively contributes to yield in water-deficit conditions. Yield differences could be attributed in part to variation in stomatal conductance (gs) because selected drought tolerant genotypes maintained higher gs and delayed stomatal closure as compared to drought susceptible genotypes. Further analysis revealed that genetic or molecular differences for gs between drought tolerant and susceptible genotypes could be detected at early stages of water deficit. These differences likely involve both abscisic acid (ABA)-dependent and ABA-independent molecular pathways

PREPARATION AND DISSEMINATION OF THE AVERAGED MAPS AND FIELDS OF SELECTED SATELLITE PARAMETERS FOR THE BLACK SEA WITHIN THE SeaDataNet PROJECT

Statistical sea surface temperature (SST) and chlorophyll a (Chl.a) maps and fields (monthly, seasonal and annual) have been prepared for the Black Sea region in the framework of the SeaDataNet project. Daily MODIS/Aqua (SST and Chl.a) and SeaWiFS (Chl.a) level 2 (L2) datasets were utilised to produce 1 km resolution final products, which are disseminated through the Internet. Data processing was done with the SeaDAS (SeaWiFS Data Analysis System) software package. Standard algorithms were used for calculation of Chl. a and SST. Only 'clean' pixels (i.e. pixels without any SeaDAS flag) were taken for averaging. Data interpolating empirical orthogonal functions (DINEOF) method was tested to reconstruct missing SST data, however, it did not work properly in conditions of insufficient data, producing some unrealistic results so it was not applied to the final products. In total, about 500 averaged maps and fields were prepared for period of September 1997 to December 2004 (Chl. a from SeaWiFS) and for period July, 2002, December 2007 (Chl. a and SST from MODIS)

Morpho-physiological and molecular evaluation of drought tolerance in cassava (Manihot esculenta Crantz)

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Habitat use and preliminary demographic evaluation of the critically endangered Mediterranean monk seal (Monachus monachus) in the Cilician Basin (Eastern Mediterranean)

Over the last few decades a dramatic decline in the number of Mediterranean monk seals (Monachus monachus) limited scientific studies on the biology.. behaviour, and ecology of the species. This lack of information impaired the effectiveness of conservation strategies. Thus, any further information gathered on the monk seal has utmost value in the work to halt and reverse the plight of the species. A hitherto unknown Cilician Basin colony of the Mediterranean monk seal has been investigated during a 6-year period between 1995 and 2001. Results of direct in-cave surveys and land based seal-watch observations enabled the evaluation of habitat use and preliminary demographic information. A total of 39 caves were discovered among which only three were used for breeding. Scarcity of the breeding caves emphasised the importance of breeding habitat in the survival of the colony. Common features of the breeding caves are found as an entrance with a protective barrier against strong waves; a chamber with a wide beach; and a well-sheltered shallow pool. Supplementary data obtained from infrared monitors installed in three actively used caves were used to assess the number of individuals. Throughout the study period, 25 individuals were identified and 11 newborn pups were found. Evaluation of the results Suggests the presence of sub-regions inhabited by an individually identified sub-group of monk seals. Recommendations for conservation guided by this information is a Marine Protected Area consisting of two zones; a restricted core zone prohibiting any human activity securing breeding habitat and a restricted fishery zone securing sustainability of the food source

Electronic, optical, and spectroscopic analysis of TBADN organic semiconductor: Experiment and theory

In this study, the electronic, optical and spectroscopic properties of 2-tert-Butyl-9,10-di(naphth-2-yl) anthracene (TBADN) semiconductor in different solvents were investigated by experimentally and computationally. Obtained theoretical and experimental UV–VIS spectra of the TBADN were found to be quite in good agreement and can be controlled with various solvents. Refractive index values of the TBADN semiconductor in different solvents were experimentally measured and calculated theoretically. Finally, the FTIR spectra of the TBADN organic semiconductor in different solvents were investigated by theoretical and experimental methods. It was found that the band gap is sensitive to the concentration of the solute. © 2017 Elsevier B.V

Ab initio studies of the Rg–NO + (X 1 Σ + ) van der Waals complexes (Rg = He, Ne, Ar, Kr, and Xe)

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