scholarly journals Immature growth performance of three important rubber tree (Hevae brasiliensis) clones in a drought-prone area

2020 ◽  
pp. 469-474
Author(s):  
Sophea Nhean ◽  
Supat Isarangkool Na Ayutthaya ◽  
Rachanee Rathanawong ◽  
Frederic C. Do
Keyword(s):  
Rubber Tree ◽  
Genetic Material ◽  
Dry Season ◽  
Wet Season ◽  
Monthly Basis ◽  
Common Strategy ◽  
Prone Area ◽  
The Difference ◽  
Dehydration Avoidance ◽  
Drought Prone Area

Adaptation of rubber tree clones to water-limited areas and maintenance of trunk radial growth are important keys for performance of genetic material. The rubber farmers need to shorten the interim phases to produce latex, which is considered “immature” phase, i.e. the time without income. The objective of this study was to compare the performance of three important rubber tree clones: GT1, the elder clone as control, which is still widely used in Cambodia and West Africa; RRIM600, the “all-round” clone, the most planted clone in Thailand, the first world producer; and RRIT251, the expanding clone, recommended by the Rubber Authority of Thailand, all in the field condition. The investigation was conducted in a drought-prone area of Northeast Thailand, where the dry season lasts 5 to 6 months. The cumulated growth and the annual growth were analyzed 4.5 years after planting. The trunk girth and height were measured monthly. Main climatic variables were hourly recorded. The year was separated in three periods: the leaves-shed season from January to April, the wet season from May to September, and the dry season with canopy maintenance from October to December. The results showed significant clonal effect on both trunk girth and height; however, with relatively low differences. The trunk girth of clone RRIT251 was about 29 cm and 10% higher than GT1. The difference was not significant in RRIM600. The annual girth increment was mainly located in wet season (63%) without clonal effect. The clonal difference was occurred in the dry season, where RRIT251 was better performed particularly in the leave-shed period preceding wet season. On a monthly basis, the relative trunk girth increment rate was highly negatively related to the vapor pressure deficit. We hypothesized that rubber clones shared a common strategy of dehydration avoidance, while RRIT251 expressed a little less degree of avoidance.

scholarly journals Investigation of Heavy Metals Level in selected Boreholes around the Vicinity of some Cemeteries in Benin City, Nigeria

2021 ◽  
Vol 25 (5) ◽  
pp. 841-845
Author(s):  
C.A.E. Ibhadode ◽  
I.R. Ilaboya
Keyword(s):  
Heavy Metals ◽  
Pollution Index ◽  
Mean Value ◽  
Dry Season ◽  
Wet Season ◽  
Monthly Basis ◽  
Benin City ◽  
Standard Procedures ◽  
The Mean ◽  
Mean Concentration

Groundwater pollution by heavy metals such as lead, copper, nickel and iron is one of the major environmental issues of concern which has developed into a widely studied area. In this study, attempt was made to investigate the level of heavy metals in selected boreholes around the vicinity of cemeteries in Benin City. Seventy-two (72) samples of groundwater were taken from boreholes in 9 stations around the three cemeteries in Benin City on monthly basis. The samples were analysed for 7 heavy metals, in accordance with standard procedures. The heavy metals include; Zinc, Lead Iron, Copper, Cadmium, Nickel and Mercury. From the results of the study, a variation in the mean concentration of zinc was observed. The mean concentration of zinc in site 1 was 0.450mg/l, for site 2, it was 0.140mg/l and for site 3, it was 1.0533mg/l. For iron, mean concentration was 0.072mg/l in site 1. For site 2, mean concentration of iron was 2.140mg/l and for site 3, mean concentration of iron was 0.560mg/l. It was further revealed based on the results that mean value of heavy metals in groundwater around cemeteries in Benin City were generally lower during dry season compared to wet season. In addition, result of computed pollution index (Pi) revealed that the heavy metal with the highest potential to pollute groundwater is Cadmium, with Pi of 0.5333 and 0.400 representing dry season and wet season respectively.

scholarly journals Tropospheric ozone over Equatorial Africa: regional aspects from the MOZAIC data

2005 ◽  
Vol 5 (2) ◽  
pp. 311-335 ◽  
Author(s):  
B. Sauvage ◽  
V. Thouret ◽  
J.-P. Cammas ◽  
F. Gheusi ◽  
G. Athier ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Central Africa ◽  
Lower Troposphere ◽  
Dry Season ◽  
Vertical Profiles ◽  
Gulf Of Guinea ◽  
Wet Season ◽  
Monthly Basis ◽  
Regional Flow ◽  
Equatorial Africa

Abstract. We analyze ozone observations recorded over Equatorial Africa between April 1997 and March 2003 by the MOZAIC programme, providing the first ozone climatology deriving from continental in-situ data over this region. Three-dimensional streamlines strongly suggests connections between the characteristics of the ozone monthly mean vertical profiles, the most persistent circulation patterns in the troposphere over Equatorial Africa (on a monthly basis) such as the Harmattan, the African Easterly Jet, the Trades and the regions of ozone precursors emissions by biomass burning. During the biomass burning season in each hemisphere, the lower troposphere exhibits layers of enhanced ozone (i.e. 70 ppbv over the coast of Gulf of Guinea in December-February and 85 ppbv over Congo in June-August). The characteristics of the ozone monthly mean vertical profiles are clearly connected to the regional flow regime determined by seasonal dynamic forcing. The mean ozone profile over the coast of Gulf of Guinea in the burning season is characterized by systematically high ozone below 650hPa ; these are due to the transport by the Harmattan and the AEJ of the pollutants originating from upwind fires. The confinement of high ozone to the lower troposphere is due to the high stability of the Harmattan and the blocking Saharan anticyclone which prevents efficient vertical mixing. In contrast, ozone enhancements observed over Central Africa during the local dry season (June-August) are not only found in the lower troposphere but throughout the troposphere. Moreover, this study highlights a connection between the regions of the coast of Gulf of Guinea and regions of Congo to the south that appears on a semi annual basis. Vertical profiles in wet-season regions exhibit ozone enhancements in the lower troposphere due to biomass burning products transport from fires situated in the opposite dry-season hemisphere.

Comparative Researches on the Provenances of Suspended Sediments in Different Reaches of Dongtiaoxi and Xitiaoxi Watershed

2014 ◽  
Vol 937 ◽  
pp. 597-603
Author(s):  
Zhao Peng Lu ◽  
Xu Yin Yuan ◽  
Huan Wang ◽  
Hai Long Chen ◽  
Wen Wen Xu
Keyword(s):  
Taihu Lake ◽  
Arable Land ◽  
Suspended Sediments ◽  
Urban Land ◽  
Dry Season ◽  
Wet Season ◽  
Geochemical Model ◽  
Geochemical Parameters ◽  
Main Discharge ◽  
The Difference

Dongtiaoxi and Xitiaoxi river are the two main discharge rivers of Taihu Lake. It is important to research the provenances of suspended sediments (SS) and the difference of the provenances. This paper establishes the geochemical model to quantify the proportions of SS sources with geochemical parameters, and then analyzes the contribution differences of the sources to SS in the basins and its reasons. The results show that the contribution of woodland is highest in the upper reaches of both Dongtiaoxi and Xitiaoxi basin, but the contribution of arable land has more differences. Arable land becomes a major contributor to the midstream of Dongtiaoxi and Xitiaoxi basin, while the contributions of woodland and urban land are larger in Dongtiaoxi basin. The SS contribution of urban land is highest in the downstream of Dongtiaoxi and Xitiaoxi basin, while the contribution of arable land is larger in Dongtiaoxi basin. During wet season and dry season, the differences of the sources contribution variations in Dongtiaoxi basin are not obvious, while that in Xitiaoxi basin are significantly obvious, that is the SS contributions of woodland and urban land in wet season are significantly higher than in dry season, while the contributions of arable land and bank sediment are on the contrary.

scholarly journals Contrasting patterns of litterfall seasonality and seasonal changes in litter decomposability in a tropical rainforest region

2014 ◽  
Vol 11 (6) ◽  
pp. 7901-7929
Author(s):  
S. A. Parsons ◽  
V. Valdez-Ramirez ◽  
R. A. Congdon ◽  
S. E. Williams
Keyword(s):  
Seasonal Changes ◽  
Biogeochemical Cycles ◽  
Dry Season ◽  
Tropical Region ◽  
Soil N ◽  
Wet Season ◽  
Evergreen Forests ◽  
P Limitation ◽  
Global Trend ◽  
The Difference

Abstract. The seasonality of litter inputs in forests has important implications for understanding ecosystem processes and biogeochemical cycles. We quantified the drivers of seasonality in litterfall and leaf decomposability, using plots throughout the Australian wet tropical region. Litter fell mostly in the summer (wet, warm) months in the region, but other peaks occurred throughout the year. Litterfall seasonality was modelled well with the level of deciduousness of the site (plots with more deciduous species had lower seasonality than evergreen plots), temperature (higher seasonality in the uplands), disturbance (lower seasonality with more early secondary species) and soil fertility (higher seasonality with higher N : P/P limitation) (SL total litterfall model 1 = deciduousness + soil N : P + early secondary sp: r2 = 0.63, n = 30 plots; model 2 = temperature + early secondary sp. + soil N : P: r2 = 0.54, n = 30; SL leaf = temperature + early secondary sp. + rainfall seasonality: r2 = 0.39, n = 30). Leaf litter decomposability was lower in the dry season than in the wet season, driven by higher phenolic concentrations in the dry, with the difference exacerbated particularly by lower dry season moisture. Our results are contrary to the global trend for tropical rainforests; in that seasonality of litterfall inputs were generally higher in wetter, cooler, evergreen forests, compared to generally drier, warmer, semi-deciduous sites that had more uniform monthly inputs. We consider this due to more diverse litter shedding patterns in semi-deciduous and raingreen rainforest sites, and an important consideration for ecosystem modellers. Seasonal changes in litter quality are likely to have impacts on decomposition and biogeochemical cycles in these forests due to the litter that falls in the dry being more recalcitrant to decay.

scholarly journals PHOTOSYNTHETIC ACTIVITY AND EARLY GROWTH OF FOUR CACAO GENOTYPES AS INFLUENCED BY DIFFERENT SHADE REGIMES UNDER WEST AFRICAN DRY AND WET SEASON CONDITIONS

2012 ◽  
Vol 49 (1) ◽  
pp. 31-42 ◽  
Author(s):  
K. ACHEAMPONG ◽  
P. HADLEY ◽  
A. J. DAYMOND
Keyword(s):  
Leaf Area ◽  
Photosynthetic Activity ◽  
Vapour Pressure Deficit ◽  
Dry Season ◽  
West African ◽  
Limiting Factor ◽  
Genotypic Differences ◽  
Wet Season ◽  
Photosynthetic Rates ◽  
The Difference

SUMMARYThe physiological performance of four cacao clones was examined under three artificial shade regimes over the course of a year in Ghana. Plants under light shade had significantly higher photosynthetic rates in the rainy seasons whereas in the dry season there was a trend of higher photosynthetic rates under heavy shade. The results imply that during the wet seasons light was the main limiting factor to photosynthesis whereas in the dry season vapour pressure deficit was the major factor limiting photosynthesis through stomatal regulation. Leaf area was generally lower under heavier shade but the difference between shade treatments varied between clones. Such differences in leaf area allocation appeared to underlie genotypic differences in final biomass production in response to shade. The results suggest that shade for young cacao should be provided based on the current ambient environment and genotype.

Comparison of Wastewater Treatment Technologies in the ED-WAVE Tool to Technologies of Similar Cases in Malawi: Case of Blantyre and Soche WWTW

2010 ◽  
Vol 4 (1) ◽  
pp. 57-64
Author(s):  
Victor Chipofya ◽  
Andrzej Kraslawski ◽  
Yury Avramenko
Keyword(s):  
Wastewater Treatment ◽  
Removal Efficiency ◽  
Biological Treatment ◽  
Dry Season ◽  
Wet Season ◽  
Trickling Filters ◽  
Treatment Technologies ◽  
The Difference ◽  
Study Manager

This paper compares the wastewater treatment technologies at Blantyre and Soche wastewater treatment works (WWTW) in Malawi with technologies of a similar case according to the ED-WAVE tool to determine if existing cases in the tool can be invoked and appropriately modified to arrive at a particular design alternative. The ED-WAVE tool is a shareware PC based package for imparting training on wastewater treatment technologies. The system consists of four modules viz. Reference Library, Process Builder, Case Study Manager, and Treatment Adviser. The paper also compares the reduction in the levels of BOD5, COD, and TSS at the three respective treatment works. The study established that there is a similarity in the sequencing of treatment units of Municipal Case 6 in the ED-WAVE tool and the sequencing of treatment units at Blantyre and Soche WWTW, respectively. All the three plants incorporate screening, grit removal, aerobic biological treatment, and sedimentation. Soche and Blantyre WWTW use hand-raked inclined bar screens and constant velocity grit channels, where longitudinal flow velocity is hydraulically controlled. Rotary mechanically-raked bar screens and mechanically stirred grit chambers are used in the ED-WAVE tool. In addition, Municipal Case 6 uses oxidation ditches for aerobic biological treatment while Blantyre and Soche WWTW use trickling filters. BOD5 removal efficiency at Soche WWTW at 95% and 96% for dry season and wet season, respectively, is comparable to the removal efficiency at Municipal Case 6 (95%). The dry season BOD5 removal efficiency at Blantyre WWTW at 87% is slightly lower than the removal efficiency at Municipal Case 6. TSS removal efficiency at Soche WWTW is at 80% in the wet season and 35% in the dry season. TSS removal efficiency at Blantyre WWTW is only 3% in the wet season, while there is an increase of 11% in the wet season. TSS removal efficiency at Municipal Case 6 is 96%. Inspite of the difference in the BOD5 and TSS removal efficiencies at Municipal Case 6 as compared to Blantyre and Soche WWTW, there is a close match in technologies at Blantyre and Soche WWTW, and Municipal Case 6 in Greece as invoked by the Case Study Manager in the ED- WAVE tool. What is evident from this study is the need to appropriately modify the case arrived at through the Case Study Manager in order to come up with a design appropriate to the local situation in terms of operation and maintenance.

scholarly journals Heavy Metal Contamination of Irrigation Water, Soil, and Vegetables and the Difference between Dry and Wet Seasons Near a Multi-Industry Zone in Bangladesh

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 583 ◽  
Author(s):  
Minhaz Ahmed ◽  
Masaru Matsumoto ◽  
Akinori Ozaki ◽  
Nguyen Thinh ◽  
Kiyoshi Kurosawa
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Irrigation Water ◽  
Heavy Metal Contamination ◽  
Analysis Data ◽  
Dry Season ◽  
Wet Season ◽  
Metal Concentrations ◽  
Heavy Metal Concentrations ◽  
The Difference

Heavy metal (Cr, Cu, Zn, As, Cd, and Pb) contamination in irrigation water, soil, and vegetables was investigated in farmland adjacent to a multi-industry zone in Bangladesh in dry and wet seasons. In the zone, many factories release wastewater into nearby irrigation canals, and vegetables cultivated with this water could be a major food chain route for human exposure. In the irrigation water and vegetables, heavy metal concentrations exceeded permissible levels in the two seasons, but this was not the case in soil. Zn had the highest concentration, and Cd had the lowest concentration in irrigation water, soil, and vegetables. All heavy metal concentrations were found to be lower in the wet than in the dry season, which is due to the dilution of water by rainfall, lower absorption of heavy metals from the diluted irrigation water, and heavy metal absorption from low concentrated irrigation water and/or soil. The cluster analysis data of irrigation water, soil, and vegetables revealed that the heavy metals in vegetables were considered to be absorbed from irrigation water in the wet season and from soil in the dry season. In the dry season, the high heavy metal concentrations in vegetables might be caused by a high bioconcentration factor (mostly > 20%).

scholarly journals Seasonal evolution of faecal egg output by gastrointestinal worms in goats on communal farms in eastern Namibia

2003 ◽  
Vol 70 (4) ◽  
Author(s):  
F.F. Kumba ◽  
H. Katjivena ◽  
G. Kauta ◽  
E. Lutaaya
Keyword(s):  
Parasitic Infection ◽  
Small Ruminants ◽  
Dry Season ◽  
Least Square ◽  
Wet Season ◽  
Monthly Basis ◽  
Faecal Samples ◽  
Hot Dry Season ◽  
Food Shortages ◽  
Worm Problem

As a more detailed continuation of a previous study, faecal samples for worm egg counts were collected per rectum from ten marked adult animals in selected flocks of goats, in each of six villages evenly spread out in the communal farming district of Okakarara in eastern Namibia. The study was conducted on a monthly basis from August 1999 to July 2000. Average faecal worm egg counts (FECs) were highest during the warm-wet season, much lower during the cold-dry months and moderate during the hot-dry season. Least square means of FECs were 2 140, 430 and 653 per gram of faeces for the three seasons, respectively. Seasonal variation in egg counts was significant (P < 0.0001). Gastrointestinal strongyles, and to a lesser extent Strongyloides species, were the predominant parasite groups identified in goats. Kidding rates peaked in the cold-dry season and mortality rates in the hot-dry season. Results of this study suggest that gastrointestinal parasitism may be a problem that accentuates the effect of poor nutrition on small ruminants during the season of food shortages in the east of Namibia and that the use of FECs per se to assess the severity of gastrointestinal parasitic infection in goats followed by chemoprophylactic strategic and / or tactical treatment, may not be the best approach to addressing the worm problem under resource-poor conditions. The use of the FAMACHA(c) system that identifies severely affected animals for treatment is technically a better option for communal farmers.

scholarly journals Contrasting patterns of litterfall seasonality and seasonal changes in litter decomposability in a tropical rainforest region

2014 ◽  
Vol 11 (18) ◽  
pp. 5047-5056 ◽  
Author(s):  
S. A. Parsons ◽  
V. Valdez-Ramirez ◽  
R. A. Congdon ◽  
S. E. Williams
Keyword(s):  
Seasonal Changes ◽  
Biogeochemical Cycles ◽  
Dry Season ◽  
Tropical Region ◽  
Soil N ◽  
Wet Season ◽  
Evergreen Forests ◽  
P Limitation ◽  
Global Trend ◽  
The Difference

Abstract. The seasonality of litter inputs in forests has important implications for understanding ecosystem processes and biogeochemical cycles. We quantified the drivers of seasonality in litterfall and leaf decomposability using plots throughout the Australian wet tropical region. Litter fell mostly in the summer (wet, warm) months in the region, but other peaks occurred throughout the year. Litterfall seasonality was modelled well with the level of deciduousness of the site (plots with more deciduous species had lower seasonality than evergreen plots), temperature (higher seasonality in the uplands), disturbance (lower seasonality with more early secondary species) and soil fertility (higher seasonality with higher N : P/P limitation) (SL total litterfall model 1 = deciduousness + soil N : P + early secondary sp.: r2 = 0.63, n = 30; model 2 = temperature + early secondary sp. + soil N : P: r2 = 0.54, n = 30; SL leaf = temperature + early secondary sp. + rainfall seasonality: r2 = 0.39, n = 30). Leaf litter decomposability was lower in the dry season than in the wet season, driven by higher phenolic concentrations in the dry, with the difference exacerbated particularly by lower dry season moisture. Our results are contrary to the global trend for tropical rainforests; in that seasonality of litterfall input was generally higher in wetter, cooler, evergreen forests, compared to generally drier, warmer, semi-deciduous sites that had more uniform monthly inputs. We consider this due to more diverse litter shedding patterns in semi-deciduous and raingreen rainforest sites, and an important consideration for ecosystem modellers. Seasonal changes in litter quality are likely to have impacts on decomposition and biogeochemical cycles in these forests due to the litter that falls in the dry season being more recalcitrant to decay.

scholarly journals Water use strategies of a young <i>Eucalyptus urophylla</i> forest in response to seasonal change of climatic factors in South China

2015 ◽  
Vol 12 (13) ◽  
pp. 10469-10510 ◽  
Author(s):  
Z. Z. Zhang ◽  
P. Zhao ◽  
R. Oren ◽  
H. R. McCarthy ◽  
J. F. Niu ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Use ◽  
South China ◽  
Dry Season ◽  
Boundary Line ◽  
Eucalyptus Urophylla ◽  
Wet Season ◽  
Large Trees ◽  
Nocturnal Transpiration ◽  
The Difference

Abstract. To depict the wet (April with a soil water content, SWC, of 37 %) and dry (October with a SWC of 24.8 %) seasonal changes in the water use and physiological response of a Eucalyptus urophylla plantation in subtropical South China characterized by monsoon climate, the whole-year (June 2012 to May 2013) transpiration of E. urophylla was monitored using the TDP method. Daily transpiration (ET) in October averaged 5.7 ± 2.9 kg d−1 and was 58.0 % higher than that in April (3.6 ± 2.3 kg d−1). The difference is consistent with that of the radiation and evaporative demand of the two months, while the nocturnal transpiration (ET-NOC) in the wet season (0.18 ± 0.021 kg d−1) was almost twice that in the dry season (0.11 ± 0.01 kg d−1). Trees displayed a higher stomatal conductance (GS) (53.4–144.5 mmol m−2 s−1) in the wet season and a lower GS (45.7–89.5 mmol m−2 s−1) in the dry season. The leaf-soil water potentials (ΨL) of the two months (April and October) were −0.62 ± 0.66 and −1.22 ± 0.10 MPa, respectively. A boundary line analysis demonstrated that the slight improvement in the GS by SWC in wet season was offset by a significant decrease in D, and the slope of GS sensitivity to D (dGS/dlnD) in response to GSref (references GS at D = 1 kPa) was affected by the variance of radiation instead of SWC. Specific hydraulic conductivity (ks) of trees of different sizes decreased by 45.3–65.6 % from the wet to the dry season. Combining the decreased maximum reference GS at D = 1 kPa (GSref-max) by 22.4 % with the constant max GS (GSmax) when ΨL < −1.2 MPa, we shed some light on the mechanism underlying the high water-use efficiency (WUE) of this Eucalyptus specie. With a slight change in GSref-max and high sensitivity of ks to decreasing ΨL, large trees used water more efficiently than small ones did. In addition, the −m in the dry season (0.53 ± 0.007) was lower than that in the wet season (0.58 ± 0.01) due to the difference in the ratio of GS to the boundary layer conductance (gb) in the two months. The negative relationship between −m (except when light is limited) and Q proved to be a plastic response to environmental changes for E. urophylla but did not change with decreased ks as expected.

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