Natural Resources Depletion in Hill Areas of Bangladesh:A Review

Hilly or mountainous terrain occupies around 12% of the area of Bangladesh.Natural resources associated with Bangladesh's hill are forest resources,biodiversity,minerals,and agricultural crops.Natural resources have been exploited in the recent four decades due to excessive clearing of hill forest cover,resulting in loss of species richness, impacts related to increased water flow variability, increased hill slope erosion and flooding intensity, and a gradual decrease in the extent of hill area in Bangladesh.This review explores the major causes and effects of depletion of natural resources by linking drivers,pressures and the related impacts.A review has been conducted to structure the effects on the hilly areas and describe the responses to minimize them in the associated DPSIR framework.Population growth has been identified as a major driver contributing to high deforestation rates.This may negatively effect agricultural productivity and increase the frequency of serious flooding.Slash and burn cultivation also impacts the regeneration of evergreen forests,which may accelerate soil erosion. Due to this and other factors,local people are facing a deficits of natural resources(food,fodder,fuel wood and water),which exacerbates the effects of poverty. Future research should try to facilitate decision making for sustainable utilization of natural resources management in the hilly areas of Bangladesh. Additional conservation measures should be developed to increase the resilience of ecosystems at national and regional levels.

Leaf thermal tolerance and sensitivity of temperate tree species are correlated with leaf physiological and functional drought resistance traits

Climate change is causing more frequent and severe climatic events,such as extreme heat and co-occurring drought,potentially accelerating tree mortality.Which tree species will cope better with those extreme events is still being researched.This study focuses on heat as a physiological stress factor and interspecifi c variation of thermal tolerance and sensitivity traits in 15 temperate coniferous and broad-leaved tree species.We investigate(1)whether thermal tolerance and sensitivity traits correlate with a droughtrelated physiological trait,particularly the leaf turgor loss point(πtlp,wilting point),and(2)how thermal tolerance and sensitivity traits co-vary within diff erent tree-functional types classifi ed by morphological and physiological traits of the leaf,i.e.,leaf mass per area(LMA)and percentage loss of area(PLA).The study was carried out in the Traunstein Forest Dynamics Plot of the ForestGEO network in Germany.The temperature response of the maximum quantum yield of photosystem II(F_(v)/F_(m))on leaf discs was determined,from which various physiological leaf traits were estimated,one of which is the breaking point temperature(T_(5)),the temperature at which F_(v)/F_(m)declines by 5%.Additionally,the temperature of 50%(T_(50))and 95%(T_(95))decline in F_(v)/F_(m)was evaluated.The decline width between T_(50)and T 5(DW T_(50)−T_(5))was taken as an indicator of the species’thermal sensitivity.The breaking point temperature ranged from 35.4±3.0 to 47.9±3.9℃among the investigated tree species and T 50 ranged between 46.1±0.4 and 53.6±0.7℃.A large interspecifi c variation of thermal tolerance and sensitivity was found.European ash(Fraxinus excelsior L.)was the most heat-sensitive species,while Wild cherry(Prunus avium L.)was the least heat-sensitive species.Species with a more negativeπtlp tended to have a higher breaking point temperature than species with a less negativeπtlp.A lower thermal sensitivity characterized species with a higher LMA,and high PLA was found in species with low thermal sensitivity.Accordingly,species with thicker and tougher leaves have lower thermal sensitivity which coincides with a lower wilting point.We conclude that species that develop drought-adapted foliage can cope better with heat stress.Further,they might be able to maintain transpirational cooling during combined heat and drought stress,which could lessen their mortality risk during climatic extremes.

Phytochemicals, polyphenols content, in vitro antioxidant and antibacterial activities of Albizia coriaria Welw ex. Oliver flowers

Albizia coriaria Welw ex.Oliver(hereafter A.coriaria)is a revered medicinal tree whose organs are used by indigenous African societies for managing various ailments.Herein,we assessed the secondary metabolites,total polyphenolics,free radical scavenging and antimicrobial activities of A.coriaria flowers.The dry powdered sample was extracted serially with ethyl acetate,ethanol and distilled water.Results of classical phytochemical screening showed that saponins,phenols,alkaloids,flavonoids,tannins and terpenes were the dominant phytochemicals.The highest total polyphenolic content(10.37±0.02 mg QE/g DW and 72.09±0.09 mg GAE/g DW)and free radical scavenging potential(IC50=24.23±0.04 mg/mL)were for the ethyl acetate extract.It also had a higher bacteriostatic activity than the ethanolic extract against Pseudomonas aeruginosa,Salmonella typhi,Escherichia coli and Staphylococcus aureus with diameters of inhibition ranging from 7.00±0.00 to 22.00±1.73 mm.The aqueous extract showed no appreciable antibacterial effect on the tested microorganisms.This is the first report which support the use of floral extracts of this species in the management of ailments in African traditional medicine.

Pharmacognostic and phytochemical studies as an invaluable approach for correct identification of medicinal plants:The case of Artemisia vulgaris L.substituted for Artemisia annua L.in Western Uganda

Background:Different parts of Artemisia vulgaris L.(A.vulgaris)are ethno-medicinally used as an emmenagogue and for the treatment of ailments such as malaria fever,ulcers,and cancer.However,anecdotal evidence shows that the plant is often substituted for Artemisia annua L.(A.annua)by herbalists in Western Uganda due to similarities in their morphology.Misidentification of medicinal plants and mislabelling of herbal products have been incriminated in toxicity and adverse health outcomes in traditional medicine practise.Because safety continues to be a major issue with the use of herbal remedies,it becomes imperative therefore that medicinal plants should be correctly identified.Methods:This study focused on investigating the macroscopic,microscopic,physicochemical characteristics and phytochemical composition of A.vulgaris leaves compared to A.annua to ease its correct identification.Results:The results showed that there are some colour differences between the leaves of the two species,with a close arrangement of microscopic features but different leaf constants.The leaves of the two Artemisia species had similar tastes,but their shapes and colours(greenish-yellow for A.annua and dark green for A.vulgaris)can be used by the local community to distinguish between them.The artemisinin content was higher in A.vulgaris leaves(1.72%)than in A.annua(1.43%),but the reverse was observed for the total flavonoid content.Conclusion:This observation could justify the change in the use of A.vulgaris by the indigenous community in western Uganda.Further studies should consider the pharmacognostic comparison of A.annua with other species in the genus Artemisia and the use of molecular techniques such as DNA barcoding.

Identifying genetic susceptibility to Aspergillus fumigatus infection using collaborative cross mice and RNA-Seq approach

Background:Aspergillus fumigatus(Af)is one of the most ubiquitous fungi and its infection potency is suggested to be strongly controlled by the host genetic back-ground.The aim of this study was to search for candidate genes associated with host susceptibility to Aspergillus fumigatus(Af)using an RNAseq approach in CC lines and hepatic gene expression.Methods:We studied 31 male mice from 25 CC lines at 8 weeks old;the mice were infected with Af.Liver tissues were extracted from these mice 5 days post-infection,and next-generation RNA-sequencing(RNAseq)was performed.The GENE-E analysis platform was used to generate a clustered heat map matrix.Results:Significant variation in body weight changes between CC lines was ob-served.Hepatic gene expression revealed 12 top prioritized candidate genes differ-entially expressed in resistant versus susceptible mice based on body weight changes.Interestingly,three candidate genes are located within genomic intervals of the previ-ously mapped quantitative trait loci(QTL),including Gm16270 and Stox1 on chromo-some 10 and Gm11033 on chromosome 8.Conclusions:Our findings emphasize the CC mouse model's power in fine mapping the genetic components underlying susceptibility towards Af.As a next step,eQTL analysis will be performed for our RNA-Seq data.Suggested candidate genes from our study will be further assessed with a human cohort with aspergillosis.

Resin infiltration of deproteinised natural occlusal subsurface lesions improves initial quality of fissure sealing

The aim of this ex vivo study was to evaluate the infiltration capability and rate of microleakage of a low-viscous resin infiltrant combined with a flowable composite resin(RI/CR) when used with deproteinised and etched occlusal subsurface lesions(International Caries Detection and Assessment System code 2). This combined treatment procedure was compared with the exclusive use of flowable composite resin(CR) for fissure sealing. Twenty premolars and 20 molars revealing non-cavitated occlusal carious lesions were randomly divided into two groups and were meticulously cleaned and deproteinised using Na OCl(2%). After etching with HCl(15%), 10 premolar and 10 molar lesions were infiltrated(Icon/DMG; rhodamine B isothiocyanate(RITC)-labelled) followed by fissure sealing(G-?nial Flo/GC; experimental group, RI/CR). In the control group(CR), the carious fissures were only sealed. Specimens were cut perpendicular to the occlusal surface and through the area of the highest demineralisation(DIAGNOdent pen, Ka Vo). Using confocal laser-scanning microscopy, the specimens were assessed with regard to the percentage of caries infiltration, marginal adaption and internal integrity. Within the CR group, the carious lesions were not infiltrated. Both premolar(57.9% ± 23.1%) and molar lesions(35.3% ± 22.1%) of the RI/CR group were uniformly infiltrated to a substantial extent, albeit with significant differences(P = 0.034). Moreover, microleakage(n = 1) and the occurrence of voids(n = 2) were reduced in the RI/CR group compared with the CR group(5 and 17 specimens,respectively). The RI/CR approach increases the initial quality of fissure sealing and is recommended for the clinical control of occlusal caries.

Species Richness, Diversity and Density of Understory Vegetation along Disturbance Gradients in the Himalayan Conifer Forest

We investigated whether species richness, diversity and density of understory herbaceous plants differed along logging(gap) and grazing(primarily by cattle) disturbance gradients, and sought to identify drivers of richness, diversity and density of understory vegetation of logged sites. A factorial experiment was conducted in the mixed conifer forest of Gidakom in Western Bhutan. Levels of the logging treatment included small(0.15 – 0.24 ha), medium(0.25 – 0.35 ha) and large(0.36 – 1.31 ha) gaps. The grazing treatment included grazed(primarily by cattle) and ungrazed(where herbivores were excluded by a fence) plots nested within each gap. Data were collected from 12 gaps(4 replicates at each level of logging) using the point intercept method. Shannon Weaver Diversity and Margalef's indices were used to estimate species diversity and describe species richness, respectively. Soil samples were analyzed for pH and nutrients. The interaction effect of logging and grazing was significant(p≤0.001) only on species diversity. Relative to ungrazed areas, species diversity was significantly higher(0.01≤p≤0.05) in medium grazed gaps. Under grazed conditions, soil P was negatively correlated with gap size and species diversity. While species diversity was positivelycorrelated(0.01≤p≤0.05) with soil N in grazed plots species richness was positively correlated(0.001≤p≤0.01) with soil N in ungrazed plots. Relative density of Yushania microphylla and Carex nubigena were higher under ungrazed conditions. Our study suggests that the combined effect of cattle grazing and logging results in higher species diversity of understory vegetation in medium and grazed gaps in mixed conifer forests of Bhutan,whereas increase or decrease in relative density of major species is determined primarily by the independent effects of grazing and logging. From management perspective, forest managers must refrain from creating large gaps to avoid loss of nutrients(mainly P and N), which may eventually affect tree regeneration. Managers intending to maintain understory vegetation diversity must consider the combined effects of grazing and logging, ensuring low to moderate grazing pressure.

Balancing development and conservation needs of stakeholders in the Tusheti Protected Landscape

Public governance and civil society play an important role in the preservation of the environmental and cultural values of the specific region of Tusheti. This area is an interesting study object also due to its unique governing model and different management issues including the historical background of the region and the current growth of tourism. In the region, where there is a significant number of initiatives supported by donors, a management plan for the protected landscape was prepared and put into practice and selected measures were implemented. Our evaluation of the activities was focused on relevance, efficiency, effectiveness,impacts and sustainability of outcomes. On the basis of the formulated conclusions, a few recommendations related to process and system nature, implementation and replicability of approaches are suggested. The results show an increase in tourism in the region,which leads to an improvement in the quality of life of the local population. On the other hand, it represents a threat to natural and cultural values, historical identity and uniqueness. The Management Plan is an excellent platform for stakeholder cooperation and implementation of specific measures to protect this exceptional territory.

Relationship between vegetation types, soil and topography in southern forests of Iran

For sustainable forest management, understanding the ecological factors that determine vegetation composition are important. Here, the relation between the vegetation composition and environmental factors(elevation, aspect, slope, CaCO3, K, P, C, N, C/N, bulk density,soil porosity, saturation moisture content, EC, pH, sand, silt and clay) was investigated in the Khonj forests, Fars Province, Iran. Characteristic land units, each 200 m2, were chosen for sampling to analyze species composition, soil characteristics and topographic factors. The floristic data were classified using a two-way indicator species analysis(TWINSPAN). Means were then compared using an ANOVA and Duncan multiple range test to detect any variations between groups. Also, the Kaiser–Meyer–Olkin index and Bartlett test were used to measure sampling adequacy. The four vegetation groups identified comprised the species Achillea wilhelmsii, Tanacetum parthenium,Convolvulus spinosus, Capparis spinosa. A detrended canonical correspondence analysis(DCCA) ordination diagram clearly illustrated the relationship between vegetation and environmental factors. According to the results,group 1 with A. wilhelmsii as the indicator species has a positive relation with slope and elevation. T. parthenium was the indicator species of group 2, that appears in areas with high silt and low bulk density and sand. The results showed that group 3 with Convolvulus spinosus as the indicator species was distributed in soils with high bulk density, low silt and pH as well. Group 4 with C. spinosa as the indicator species occurs in sandy soils and low slopes.Using DCCA, we determined the relationship between species and environmental factors more accurately. Results of this study can be used to restore vegetation or maintain species composition in ecological sensitive areas.

Performance of Hydra Probe and MPS-1 Soil Water Sensors in Topsoil Tested in Lab and Field

Soil water sensors are commonly used to monitor water content and matric potential in order to study hydrological processes such as evaporation. Finding a proper sensor is sometimes difficult, especially for measurements in topsoil, where changes of temperature and soil water dynamics occur generally with greater intensity compared to deeper soil layers. We assessed the perfor-mance of Hydra Probe water content sensors and MPS-1 matric potential sensors in topsoil in the laboratory and in the field. A common soil-specific calibration function was determined for the Hydra Probes. Measurement accuracy and sensor-to-sensor variation were within the manufacturer specification of ±0.03 m3·m-3. Hydra Probes can operate from dry to saturated conditions. Sensor-specific calibrations from a previous study were used to reduce sensor-to-sensor variation of MPS-1. Measurement accuracy can be expressed by a mean relative error of 10%. According to the manufacturer, the application range of matric potential readings is from -10 kPa to -500 kPa. MPS-1 delivered also values beyond this range, but they were not reliable. Sensor electronics of the MPS-1 were sensitive to ambient temperature changes. Beyond instrument effects, field measurements showed substantial temperature-driven fluctuations of soil water content and matric potential, which complicated data interpretation.

Ecology,growth and management of black locust(Robinia pseudoacacia L.),a non-native species integrated into European forests

Black locust(Robinia pseudoacacia L.),a species native to the eastern North America,was introduced to Europe probably in 1601 and currently extends over2.3×10~6 ha.It has become naturalized in all sub-Mediterranean and temperate regions rivaling Populus spp.as the second most planted broadleaved tree species worldwide after Eucalyptus spp.This wide-spreading planting is because black locust is an important multipurpose species,producing wood,fodder,and a source of honey as well as bio-oil and biomass.It is also important for carbon sequestration,soil stabilization and re-vegetation of landfills,mining areas and wastelands,in biotherapy and landscaping.In Europe,black locust is drought tolerant so grows in areas with annual precipitation as low as 500-550 mm.It tolerates dry,nutrient poor soils but grows best on deep,nutrient-rich,well-drained soils.It is a fast-growing tree and the height,diameter and volume growth peak before the age of 20.It mostly regenerates vegetatively by root suckers under a simple coppice system,which is considered the most cost-effective management system.It also regenerates,but less frequently,by stool sprouts.Its early silviculture in production forests includes release cutting to promote root suckers rather than stool shoots,and cleaning-respacing to remove low-quality stems,reduce the number of shoots per stool,and adjust spacing between root suckers.In addition,early,moderate and frequent thinning as well as limited pruning are carried out focusing on crop trees.The species is regarded as invasive in several European countries and its range here is expected to expand under predicted climate changes.

Seed production,seed dispersal and seedling establishment of two afromontane tree species in and around a church forest：implications for forest restoration

Background：Seed production,seed dispersal and seedling establishment are relevant life phases of plants.Understanding these processes and their patterns is essential to recognize vegetation dynamics and to apply it to forest restoration.Methods：For Olea europaea and Schefflera abyssinica,fecundity was estimated using randomized branch sampling.Seed dispersal and seedling establishment were monitored using spatially explicit seed traps and plots.Dispersal functions were calibrated applying inverse modeling.Results：O.europaea produced more seeds and had longer dispersal distances compared to S.abyssinica.Correlations between observed and predicted number of recruits were statistically significant.Seedlings of the two species showed different niche requirements.Conclusions：The studied species were recruitment-limited due to low dispersal activity or lack of suitable microsites.Restoration relying on natural regeneration should overcome these limitations by increasing disperser visitation and reducing biotic and abiotic stresses.

A Combination of Wheat Bran and Vegetable Oils as Feedstuff in Laying Hens’Diet:Impact on Egg Quality Parameters

Wheat bran (WB) is an important side product of the milling industry and plays an increasing role in animal feeding. Despite its nutritional value, its application is limited as a result of its pronounced fiber content. Taking into account the potential use of WB supplementation in feed for laying hens thereby replacing human edible foodstuffs, the influence of different WB levels (0 g·kg-1, 75 g·kg-1, and 150 g·kg-1) combined with sunflower or rapeseed oil on egg quality was studied. Among the egg-related quality parameters investigated, eggshell cleanliness, shell rigidity, egg weight, haugh units, yolk and albumen mass, color, pH value, dry matter, crude protein, crude ash, fatty acid spectrum, cholesterol and α-tocopherol of the yolk were monitored. No negative effect of WB supplementation was observed in terms of egg weight, shell weight, albumen weight, yolk weight, haugh unit, shell thickness and eggshell breaking strength. However, certain parameters (i.e. α-tocopherol content, Σn-3 PUFA) were enhanced by feeding 75 g·kg-1 and 150 g·kg-1 WB. The use of WB (75 g·kg-1 and 150 g·kg-1) had no negative effect on egg quality and can, therefore, be recommended for laying hen diets up to 150 g·kg-1. Additionally, the application of rapeseed oil high in Σn-3 PUFA resulted in yolks exhibiting a low Σn-6 PUFA/Σn-3 PUFA ratio.

Change of Species and Habitat Diversity in the Pannonian Region of Eastern Lower Austria over 170 Years:Using Herbarium Records as a Witness

By dint of historical herbarium specimens, we show how changes in species and habitat diversity can be reviewed and correlated with historical events. Our work is based on a digital database of specimens of the BOKU herbarium (WHB), which can be assigned to the Pannonian region of eastern Lower Austria. The complete dataset (n = 6655 specimens) was analyzed with the aid of statistical methods allowing computational elimination of collectors' effects (i.e. unbalanced collecting interests of collectors over time;multiple regression analysis, general linear model), from the first herbarium specimens (dating back to 1830) to the present. As a result, a significant decrease in the proportion of species of some habitats (above all water bodies and closely associated habitats, humid and wet meadows, fens and fen meadows, and nutrient poor grassland) was detected. For water-influenced habitats, this decrease correlates with the time of Danube regulation. Moreover, an increase in the proportion of species of ruderal sites was asserted during the observation period. The analysis procedure developed can be used for evaluation of major digitized herbaria in order to trace historical changes in species and habitat diversity.

Suitability of Hermetia illucens larvae meal and fat in broiler diets:effects on animal performance,apparent ileal digestibility,gut histology,and microbial metabolites

Background:The possibility of partially replacing soybean meal(SBM)with Hermetia illucens(HI)defatted larvae meal in broiler nutrition has frequently been suggested.For sustainability reasons,however,the larvae fat produced during defatting should also be used and could be particularly beneficial regarding gut health due to its fatty acid composition.To evaluate the suitability of HI larvae as protein and fat source,a 2×3 factorial arrangement with two types of protein,i.e.SBM(S)or SBM and 15%of its crude protein replaced by HI larvae meal(L),and three levels of fat sources,namely 0(0 L),50%(50 L)or 100%HI larvae fat(100 L)at the expense of soybean oil was applied.Results:In the starter phase,an interaction showed higher body weight(BW),average daily gain(ADG)and improved feed conversion ratio(FCR)if 50%or 100%HI larvae fat was fed with HI larvae meal.Moreover,BW,ADG and FCR improved when feeding HI larvae meal as protein source.Additionally,we observed an increased average daily feed intake in the grower,finisher,and overall phase in the L groups and an improved FCR in 0 L compared to 50 L groups during the overall period.Regarding apparent ileal digestibility,HI larvae meal feeding increased dry matter,organic matter,and fat digestibility.Feeding HI larvae meal as protein source decreased the concentrations of agmatine,spermidine,spermine and ammonia in the caecal digesta,whereas fat source affected agmatine with higher concentrations in 50 L compared to 0 L in the colonic digesta.In contrast,caecal ethanolamine concentrations increased in HI larvae meal groups compared to SBM.Caecal butyric acid concentrations decreased with HI larvae meal feeding.An interaction was found for the jejunal villus area,being higher in L+100 L compared to S+100 L.Furthermore,L groups had greater villus width.Conclusions:A partial replacement of SBM with HI larvae meal and soybean oil with HI larvae fat in broiler diets without impairing animal performance or gut health seems possible.Feeding HI larvae meal affected broiler performance positively in the starter phase and improved apparent ileal digestibility.

Regeneration and Tree Species Diversity of Sitakund Botanical Garden and Eco-Park,Chittagong,Bangladesh

Anthropogenic disturbances influence plant regeneration and species diversity, which impact the conservation status of protected areas. A study was conducted in the Sitakund Botanical Garden and Eco-park(SBGE), Chittagong,Bangladesh to analyze the natural regeneration and tree species diversity in disturbed and less disturbed zones. Stratified and systematic random sampling was used to select 50 sample plots from each of the two zones. A total number of 109 plant species from 43 families were recorded in the study; of which 93 species were of natural origin while the rest were planted. From the species with natural origin 66 were tree species, 9 were shrub species and 18 were climbers. Species richness, density of regeneration and disturbance index in the height classes(0- 0.5 m)and(dbh > 6 cm) indicated significant differences between the zones. The study analyzed how disturbances affect species diversity in the area. It was found that species richness and basal area are negatively related with disturbances. Moreover,density(N/ha) of trees was more likely to decrease with increasing tree height that reflects the huge demand of local people to harvest large trees as part of their income generating activities. The study findings have implications for future management decisions of the SGBE. To restore these ecosystems, management should focus on both biodiversity conservation and providing benefits to local people without hampering forest ecosystems.

Habitat requirements of Boreal Owl(Aegolius funereus)and Pygmy Owl(Glaucidium passerinum)in rear edge montane populations on the Balkan Peninsula

Rear-edge populations of montane species are known to be vulnerable to environmental change,which could affect them by habitat reduction and isolation.Habitat requirements of two cold-adapted boreo-alpine owl species—Boreal Owl(Aegolius funereus)and Pygmy Owl(Glaucidium passerinum)—have been studied in refugial montane populations in the western Rhodopes,South Bulgaria.Data on owl presence and forest stand attributes recorded in situ have been used to identify significant predictors for owl occurrence.The results revealed Boreal Owl’s preference for comparatively dense forests(high canopy closure values),big trees(diameter at breast height≥50 cm)and large amount of fallen dead wood in penultimate stage of decay.For Pygmy Owl the only significant explanatory variable was the total amount of fallen dead wood.Results suggest preference of both owl species for forests with structural elements typical of old-growth forests(i.e.,veteran trees,deadwood),the Pygmy Owl being less prone to inhabit managed forests.Being at the rear edge of their Palearctic breeding range in Europe both Boreal and Pygmy Owls are of high conservation value on the Balkan Peninsula.Hence,additional efforts are needed for their conservation in the light of climate change and resulting alteration of forest structural parameters.Current findings can be used for adjusting forest management practices in order to ensure both,sustainable profit from timber and continuous species survival.

Spatial Variability of Selected Soil Attributes under Agricultural Land Use System in a Mountainous Watershed, Ethiopia

In the Ethiopian Highlands, research projects were often measuring soil attributes of spatially structured point data but soil variability at a watershed scale is not clearly defined. This study was conducted to assess the correlation among selected soil attributes and to illustrate the spatial pattern and dependence of neighboring observations. The 53.7 km2?study watershed was divided into a 500 m by 500 m square grid using arcgis and at the center of each grid soil samples from 0 to 25 cm depth were collected within 184 locations. The descriptive statistics revealed available phosphorous (AP) had the largest coefficient of variation (CV = 104) while pH was the least variable. There was a positive link between elevation and SOC whereas bulk density (ρd) and pH indicated an inverse relationship with elevation and SOC. The value for nugget/sill of ρd, pH and elevation are less than 0.25, and depicts that it has strong spatial autocorrelation. The value for nugget/?sill of SOC, and TN found between 0.25 and 0.75, and indicate that they have moderate spatial?autocorrelation. With regard to AP, the value for nugget/sill is more than 0.75, which displays a weak?spatial autocorrelation. Semivariograms of ρd, pH and elevation were best fitted to Gaussian model whereas SOC, TN and AP were best fitted to exponential function. Generally, the study verified that soil measurements taken at the given scale through regular sampling interval were adequate to capture the spatial dependence of numerous initial soil assessments in the study watershed.

Micro-Tuber Production in Diploid and Tetraploid Potato after Gamma Irradiation of in Vitro Cuttings for Mutation Induction

Micro-tubers are important propagules in potato breeding and potato production, and they are also dormant and easily transported and therefore good targets for mutation induction in potato mutation breeding. A prerequisite for mutation breeding is to determine optimal mutation treatments. Therefore, radio-sensitivity tests of a tetraploid and a diploid potato to gamma irradiation were undertaken. Effects of different gamma sources on radio-activity were also studied. In vitro potato cuttings were gamma irradiated using a wide dose range (0, 3, 6, 9, 12, 15 and 20 Gy). The irradiated cuttings were then cultured to induce micro-tubers directly in vitro. Micro-tuber morphotypes were assessed after irradiation of cuttings using three gamma sources with emission activities of 1.8, 7.07 and 139 Gy/min. The diploid species (Solanum verrucosum) was more radio-sensitive than the tetraploid cultivar Desirée (Solanum tuberosum). Gamma dose rates had significant influences on subsequent micro-tuber production at various mutant generations. Effects included reductions in the number, size and weight of micro-tubers produced. Gamma dose was more lethal for the diploid potato genotype and micro-tubers produced were small compared to those produced by the tetraploid genotype after irradiation. Different treatments are recommended for diploid and tetraploid potato irradiation in producing large mutant micro-tuber populations. The mutant micro-tuber populations may then be screened for interesting mutations/trait for both genetics and plant breeding purposes.

Bertalanffy-Pütter Models for the Growth of Tropical Trees and Stands

The Bertalanffy-Pütter (BP) five-parameter growth model provides a versatile framework for the modeling of growth. Using data from a growth experiment in literature about the average size-at-age of 24 species of tropical trees over ten years in the same area, we identified their best-fit BP-model parameters. While different species had different best-fit exponent-pairs, there was a model with a good fit to 21 (87.5%) of the data (“Good fit” means a normalized root-mean-squared-error NRMSE below 2.5%. This threshold was the 95% quantile of the lognormal distribution that was fitted to the NRMSE values for the best-fit models for the data). In view of the sigmoidal character of this model despite the early stand we discuss whether the setting of the growth experiment may have impeded growth.