International Journal of Environment and Climate Change

Aim: Several methods described previously for isolation and purification of soil DNA. Most of these protocols use combination of techniques or methods but the role and contribution of each individual method or component used is not clearly discussed. This study aims at analysing the effect of individual components used in extraction of DNA from soil and finally to optimize soil DNA isolation protocol and its validation by using 16SrDNA sequence analysis.

Methods and Results: The soil was washed with anionic buffers before lysis step to reduce humic substances and release microbial cells from soil matrix, then the cells were lysed using combination of SDS, heating and vortexing and finally humic substances were removed using chemical flocculation. Pre-lysis washing of soil with 100 mmol l-1 Na2EDTA proved good for releasing microbial cells from soil matrix. Heating the soil sample at 75°C yielded good quantity (15.73 µg g-1 soil) DNA followed by 2% SDS (10.28 µg g-1 soil) and vortexing at 1400 rpm (8.94 µg g-1 soil). Combination of heating, SDS and vortexing yielded 25 µg DNA per gram of soil. Different concentrations of chemical flocculants like AlNH4(SO₄)₂, FeCl₃, CaCl₂ and MgCl₂ were used to reduce humic substances. Flocculation with 100 mmol l-1 CaCl₂ removed 5.2 mg humic substances without significant loss of DNA. 16S rDNA sequence analysis of DNA extracted from soil reveals presence of all the common soil bacterial species indicating the protocol is unbiased.

Conclusion: Combination of chemical (SDS) and physical (heating and vortexing) methods yield good DNA whereas addition of enzyme (lysozyme) did not show significant effect on cell lysis. The digestion of isolated DNA with restriction enzyme and amplification of 16S rDNA using Taq DNA polymerase indicates the isolated DNA is pure enough for metagnomic analysis. 16Sr DNA sequencing of soil DNA indicates that this protocol can extract good quality and quantity DNA from range of bacteria present in soil varying in their cell wall composition. The optimised protocol is unbiased, very simple, does not need special equipments and many samples can be processed simultaneously.

Climate change is a scientific issue of global interest and Africa is one of the most vulnerable regions in the world strongly affected by its consequences in water resources for agriculture. Adaptation to climate change is one of the fundamental measures for human beings. Therefore, extensive researches on dew process have been carried out worldwide. Based on articles and relevant documents on the subject, this paper reviews the latest researches achievement in several domains of science, including measurements technics and dew possible contribution in plants water requirement satisfaction. A case study in Benin climate (West Africa) compares the probable amount of dew that can be harvested by maize canopy as water during the main stages of its growth cycle. Evaluation of dew amount and maize water requirements are done using the Penman-Monteith equation. The theoretical results show that dew can contribute for about 9 to 10% in the IZEE-W-SR-(ODE-TUWE) corn variety’s water requirements. So, future researches on dew can be performed in arid and semi-arid areas as alternative water for agriculture.

This study investigated the variability and trend of rainfall and extreme temperatures over three eastern and northeastern regions of Burundi during the period 1980-2015. Data used were collected from seven stations belonging to the geographical institute of Burundi. Annual and seasonal variability are assessed using standardized anomaly, coefficient of variance and precipitation concentration index. In addition, non parametric statistic tests Mann Kendall and Sen’s slope estimator are used to detect trends in rainfall, maximum and minimum temperatures. The results reveal a high monthly and inter-annual variability of rainfall whereas the temperature does not show high fluctuation at monthly scale. The northern region presents the lowest amount of rainfall for the first rainfall season (October-January) when drought is frequently observed. No significant rainfall trend detected over all regions at seasonal and annual scales whereas significant increasing trend was observed for both maximum and minimum temperatures over all regions. The spatial distribution of rainfall and extreme temperatures displays also a wide variation across the region depending on topography of the study area.

We examine variability and change components of precipitation and minimum and maximum daily temperatures, and the derived variables potential evapotranspiration (PET) and the Palmer Drought Severity Index (PDSI), over rangelands in the region 30-50N, 100- 125W. We focus on areas administered by the U.S. Bureau of Land Management (BLM) and Bureau of Indian Affairs (BIA), with a view toward understanding how future climate variations may affect ecosystems, and ultimately, grazing on these lands. Based on an analysis of the annual precipitation cycle we adopt a three-season partition for the year, classifying land areas by season of maximum precipitation; this yields a coherent subregional map. Masking with a combined BLM/BIA footprint, we find that in all subregions both tmin and tmax have increased in response to anthropogenic forcing, the rate being generally greater for tmax. Significant precipitation trends are not detected, whereas PET exhibits significant upward trends in all regions. While PET-normalized precipitation, as well as PDSI, do not exhibit significant trends individually (by variable and region), the fact that most trend downward nevertheless suggests a systematic drying. We conclude that temperature constitutes the principal detectable control on hydroclimatic changes in rangelands within the study area. Although ecosystem responses may be complex, future temperature increases are expected generally to reduce soil water availability. The unforced component of variability is
investigated with respect to several key climate indices on both interannual and decadal time scales.

A study was conducted to emphasize the importance of non-cultivated plants/weeds in North Bangalore, Karnataka from October 2014 to March 2015 in three locations. The pollinators were collected using sweep net method on cultivated and non-cultivated flowering plants. A total of 22 non-cultivated plant species and 11 cultivated plant species were observed on which 85 and 56 pollinator species were collected respectively belonging to the four families (Apidae, Halictidae, Megachilidae and Scoliidae) of Hymenoptera and two families (Syrphidae and Bombyliidae) of Diptera. It is found that association of pollinators were more towards non-cultivated plants than cultivated plants. Among cultivated flowering plants, Ocimum americanum was highly attractive followed by Field bean and Lavandula angustifolia. Among non-cultivated flowering plants, Alternanthera sessilis was highly attractive on which majority were Dipterans followed by Leucas aspera and Hyptis suaveolens indicating the importance of non-cultivated flowering plants/weeds in conservation of pollinators.

The study is aimed at finding the best distribution to match the steam flow and calculation of magnitude and frequency of flow. In the current study, we have used several statistical distributions to find the best fit distribution for stream flow and used flood frequency analysis techniques to find the magnitude and frequency of stream flow and non-exceedance probability of peak discharge. The study has been performed at Sikandarpur and Rosera gauging sites of BurhiGandak River. Historical (50 years) maximum annual peak discharge data of each station are used for statistical analysis for estimating maximum peak discharge in 5, 10, 25, 50, 100 year return period. In this study, Lognormal distribution, Galton distribution, Gamma distribution, Log Pearson Type III distribution, Gumbell distribution, Generalised extreme values distribution have been considered to describe the annual maximum stream flow. Flood frequency analysis methods were used for estimating the magnitude of the extreme flow events and their associated return periods. For both Sikandarpur and Rosera stations, Log Pearson type III distributions showed the lowest value of K–S and Chi-square test statistic. The annual probable peak discharge for 5, 10, 25, 50, and 100 years return period is calculated for each distribution. The most suitable distribution for both the stations is found to be the log-Pearson type III distribution.