scholarly journals Shade and Irrigation Effects on Growth, Flowering, Pod Yields and Cacao Tree Survival Following 5 Years of Continuous Dry Season Irrigation

2020 ◽  
pp. 54-64
Author(s):  
E. F. Charles ◽  
S. O. Agele ◽  
O. P. Aiyelari ◽  
I. B. Famuwagun ◽  
E. Faboade
Keyword(s):  
Scale Up ◽  
Dry Season ◽  
Canopy Development ◽  
Terminal Drought ◽  
Air Temperatures ◽  
Irrigation Interval ◽  
Tree Survival ◽  
Main Plot ◽  
Bean Yield ◽  
Irrigation Effects

The effects of plantain shade and dry season irrigation on the growth, field survival, flowering and pod production of cacao was investigated. Treatments were a 2 by 2 factorial combinations of shade regimes (Unshaded/open sun and shaded) and irrigation intervals (5-day and 10-day intervals) arranged in a split-plot design. There was an unirrigated but shaded control. The shade regimes constituted the main plot while irrigation intervals were the sub-plot treatments. The growth, dry season survival, flowering and pod/bean yield characters of cacao were enhanced in the unshaded (open sun) compared with the shaded plants. The open sun treatment combined with 5-day irrigation produced the largest canopy development, flowering and pod production compared with shading-irrigation combinations. The shade-irrigation ameliorated microclimate and enhanced growth and development, flowering and uniform fruiting/pod production and total bean yield and reduced dry season mortality (whole tree death, branch and twig dieback). For the non-irrigated but shaded cacao, about 30% dry season mortality (branch and twig dieback) were obtained. Air temperatures within the cacao field were highest for open sun cacao followed by moderate and dense shade respectively. Flowers were more profuse for unshaded (open sun) cocoa compared with the shaded while the yield and yield components of cacao for each harvest dates and total pod and bean yields were significantly different between the unshaded and shaded cacao regimes. Trees that were irrigated at 5-day intervals produced significantly (P < 0.05) higher LAI, branching, flowers and pods compared with those irrigated at 10-day intervals. The 5-day irrigation interval significantly increased percentage of trees bearing flowers and pods, and produced larger number, and heavier pods and beans compared with the 10-day interval. The drip irrigation strategy adopted ameliorated dry season terminal drought (hydrothermal stresses) in cacao. This is a veritable tool to scale up growth, survival, establishment and flower/pod production.

scholarly journals The Connection between Architectural Elements and Adaptive Thermal Comfort of Tropical Vernacular Houses in Mountain and Beach Locations

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7427
Author(s):  
Hermawan Hermawan ◽  
Jozef Švajlenka
Keyword(s):  
Thermal Comfort ◽  
Mixed Method ◽  
Rainy Season ◽  
Qualitative Methodology ◽  
Dry Season ◽  
Architectural Elements ◽  
Air Temperatures ◽  
Adaptive Thermal Comfort ◽  
Architectural Features ◽  
Study Results

Passive thermal comfort has been widely used to test the thermal performance of a building. The science of active thermal comfort is important to be connected with the science of architecture. The currently developing active thermal comfort is adaptive thermal comfort. Vernacular houses are believed to be able to create thermal comfort for the inhabitants. The present study seeks to analyze the connection between the architectural elements of vernacular houses and adaptive thermal comfort. A mixed method was applied. A quantitative approach was used in the measurement of variables of climate, while a qualitative methodology was employed in an interview on thermal sensations. The connection between architectural elements and adaptive thermal comfort was analyzed by considering the correlation among architectural features, the analysis results of thermal comfort, and the Olgyay and psychrometric diagrams. At the beginning of the rainy season, residents of exposed stone houses had the highest comfortable percentage of 31%. In the middle of the rainy season, the highest percentage of comfort was obtained by residents of exposed brick and wooden houses on the beach at 39%. The lowest comfortable percentage experienced by residents of exposed stone houses at the beginning of the dry season was 0%. The beginning of the dry season in mountainous areas has air temperatures that are too low, making residents uncomfortable. The study results demonstrate that adaptive thermal comfort is related to using a room for adaptation to create thermal comfort for the inhabitants.

scholarly journals Effects of Incorporating Biochar into the Soil Using Power Tiller and Ox-Plough

2017 ◽  
Vol 6 (4) ◽  
pp. 93
Author(s):  
Masauso Ndhlovu ◽  
Nicholas Kiggundu ◽  
Joshua Wanyama ◽  
Noble Banadda
Keyword(s):  
Water Retention ◽  
Scale Up ◽  
Growth And Yield ◽  
Soil Water Retention ◽  
Negative Effects ◽  
Application Rates ◽  
Significant Difference ◽  
Main Plot ◽  
Power Tiller ◽  
Plot Design

Existing knowledge about biochar is derived from trials where biochar incorporation into the soil is done by hands, a practice too tedious to scale-up to commercial levels. To enhance scalability, biochar incorporation needs to be integrated into conventional mechanised tillage systems. This study aimed at assessing the effects of incorporating biochar by power tiller and ox-plough on soil water retention, maize growth and yield. A 2 x 3 factorial experiment was conducted in a split-plot design with biochar incorporating method as a main plot factor and biochar level as subplot factor, on ferralsols of central Uganda. Incorporation methods were by power tiller and ox-plough with hand mixing in planting basins as a control, while levels of biochar were 0 and 10 t ha-1 application rates. Data was analysed using two-way ANOVAs in Minitab for significant differences among incorporation methods. Results showed that incorporating biochar by power tiller significantly increased water retention effect of biochar by 27.5% (p < 0.05), while no significant effect was observed (p ≥ 0.05) when incorporated by ox-plough, compared to hand mixing. No significant difference on growth and yield was observed (p ≥ 0.05) as a result of incorporating biochar by power tiller and ox-plough instead of hands in planting basins. These findings suggest that biochar incorporation can be scaled-up, to commercial levels, through the use of power tiller and ox-plough, without negative effects on biochar performance. It is recommended that promotion of biochar technology encompasses the use of power tillers and ox-ploughs to enhance scalability. 

Agronomic studies on soybean (Glycine max (L.) Merrill) in the dry season of the tropics. III. Effect of artificial photoperiod extension on phenology, growth and seed yield

1991 ◽  
Vol 42 (7) ◽  
pp. 1109 ◽  
Author(s):  
JD Mayers ◽  
RJ Lawn ◽  
DE Byth
Keyword(s):  
Seed Yield ◽  
Dry Season ◽  
Yield Potential ◽  
Wet Season ◽  
Canopy Development ◽  
North West ◽  
Precocious Flowering ◽  
Natural Photoperiod ◽  
Artificial Photoperiod ◽  
Delayed Flowering

Soybean cultivars developed for the tropical wet season performed poorly when grown in the dry season in north-west Australia. The proposition that breeding for later flowering time might enhance yields was tested by using artificial photoperiod extension (14 h day-1 for 28 days post-emergence) to delay flowering of field plots of agronomically improved genotypes. Canopy development and interception of photosynthetically active radiation (PAR), dry matter (DM) accumulation, seed yield and seed composition were examined, and compared with that from plants grown under natural photoperiods. Photoperiod extension delayed flowering an average 24 days, and maturity by an average 14.5 days, the effect being greater in the earlier-flowering genotypes. Differences among genotypes and photoperiod treatments in above-ground DM at the beginning and end of flowering were almost entirely due to the consequences of differences in phenology for cumulative PAR interception. DM at maturity was a simple linear function of crop duration (r2 = 0.95**), while seed yield exhibited an optimum-type response with DM ( R2 = 0.79**). The net consequence was that photoperiod extension increased DM production by an average 2.23 t ha-1 and seed yield by an average 0.65 t ha-1. The analyses suggested that a crop duration of c. 143-146 days would be needed to maximize seed yield under the agronomic conditions of the study, whereas the longest duration among the agronomically improved genotypes under natural photoperiod conditions was 136 days. It was concluded that breeding to constrain precocious flowering under short day conditions would be a viable strategy to improve the yield potential of soybean in the dry season.

The Drought of Amazonia in 2005

2008 ◽  
Vol 21 (3) ◽  
pp. 495-516 ◽  
Author(s):  
José A. Marengo ◽  
Carlos A. Nobre ◽  
Javier Tomasella ◽  
Marcos D. Oyama ◽  
Gilvan Sampaio de Oliveira ◽  
...  
Keyword(s):  
Forest Fires ◽  
El Niño ◽  
El Nino ◽  
Dry Season ◽  
Trade Wind ◽  
Amazon River ◽  
Air Temperatures ◽  
Tropical North Atlantic ◽  
Southern Amazonia ◽  
Southwestern Amazonia

Abstract In 2005, large sections of southwestern Amazonia experienced one of the most intense droughts of the last hundred years. The drought severely affected human population along the main channel of the Amazon River and its western and southwestern tributaries, the Solimões (also known as the Amazon River in the other Amazon countries) and the Madeira Rivers, respectively. The river levels fell to historic low levels and navigation along these rivers had to be suspended. The drought did not affect central or eastern Amazonia, a pattern different from the El Niño–related droughts in 1926, 1983, and 1998. The choice of rainfall data used influenced the detection of the drought. While most datasets (station or gridded data) showed negative departures from mean rainfall, one dataset exhibited above-normal rainfall in western Amazonia. The causes of the drought were not related to El Niño but to (i) the anomalously warm tropical North Atlantic, (ii) the reduced intensity in northeast trade wind moisture transport into southern Amazonia during the peak summertime season, and (iii) the weakened upward motion over this section of Amazonia, resulting in reduced convective development and rainfall. The drought conditions were intensified during the dry season into September 2005 when humidity was lower than normal and air temperatures were 3°–5°C warmer than normal. Because of the extended dry season in the region, forest fires affected part of southwestern Amazonia. Rains returned in October 2005 and generated flooding after February 2006.

scholarly journals Calibration of Methods to Estimate Solar Irradiance in Northeastern Pará

2020 ◽  
Vol 35 (2) ◽  
pp. 345-355
Author(s):  
João Vitor de Nóvoa Pinto ◽  
Hildo Giuseppe Garcia Caldas Nunes ◽  
Daniely Florencia Silva de Souza ◽  
Deborah Luciany Pires Costa ◽  
Paulo Jorge de Oliveira Ponte de Souza
Keyword(s):  
Solar Radiation ◽  
Performance Index ◽  
Solar Irradiance ◽  
Sunshine Duration ◽  
Dry Season ◽  
Daily Maximum ◽  
Wet Season ◽  
Average Performance ◽  
Daily Minimum ◽  
Air Temperatures

Abstract Two models aimed to estimate solar irradiance were calibrated in six locations in Northeastern Pará (Belém, Cametá, Conceição do Araguaia, Marabá, Soure, and Tucuruí). The first one is the equation of Angström-Prescott (AP), which requires observations of sunshine duration hours. The second model is a modified version of Hargreaves' radiation formula (MH), which requires observations of daily maximum and daily minimum air temperatures. Both models were calibrated to estimate daily and monthly solar radiation. The calibration of both equations for each season (i.e., dry season and wet season) in each location was also tested. AP has an average performance about 74% higher than MH for daily estimates (excluding Soure) and 83% higher than MH for monthly estimates (excluding Soure and Tucuruí). The use of seasonally calibrated equations slightly improves the performance of AP, measured by the performance index, by 0.68% and improves the performance of MH in most locations, when estimating daily solar radiation. The performance of both models is much higher when estimating monthly solar radiation than daily solar radiation, with an increase of the performance index of 10.95% for AP.

scholarly journals Microclimatic Warming Leads to a Decrease in Species and Growth Form Diversity: Insights From a Tropical Alpine Grassland

2021 ◽  
Vol 9 ◽  
Author(s):  
Sisimac A. Duchicela ◽  
Francisco Cuesta ◽  
Carolina Tovar ◽  
Priscilla Muriel ◽  
Ricardo Jaramillo ◽  
...  
Keyword(s):  
Plant Community ◽  
Growth Form ◽  
Dry Season ◽  
Rate Of Change ◽  
Community Diversity ◽  
Alpine Regions ◽  
Air Temperatures ◽  
Thermal Amplitude ◽  
Soil Temperatures ◽  
Tropical Alpine

Due to warming, changes in microclimatic temperatures have shifted plant community structure and dynamics in tundra and alpine regions. The directionality and magnitude of these changes are less known for tropical alpine ecosystems. To understand the likely trajectory of these shifts in the Andes, we conducted a warming experiment in the northern Andes—using open-top chambers (OTC). In this study, we ask (1) how do OTCs affect air and soil temperatures in microclimates of tropical alpine regions, year-round and during the dry season? (2) What are the effects of 7 years of warming on (a) the aboveground biomass (AGB) and (b) the plant taxonomic and growth form diversity? We installed five monitoring blocks in 2012 at ca. 4,200 m asl with 20 OTCs and 50 control plots randomly distributed within each block. We measured AGB, plant community diversity, and growth form diversity between 2014 and 2019. After 7 years of warming, we found significant increases in mean monthly (+0.24°C), daily (+0.16°C), and night air temperatures (+0.33°C) inside the OTCs, and the OTCs intensified microclimatic conditions during the dry season. Additionally, OTCs attenuated extreme temperatures—particularly in the soil—and the number of freezing events. AGB significantly increased in OTCs, and by 2019, it was 27% higher in OTCs than in control. These changes were driven mainly by a progressive increment of tussock grasses such as Calamagrostis intermedia, typical of lower elevations. The increase of tussocks led to a significant decrease in species diversity and evenness inside OTCs, but not in species richness after accounting by sampling time. Furthermore, cushions and herbs decreased inside OTCs. Our results show that experimental warming using OTCs in equatorial regions leads to decreased daily thermal amplitude and night temperatures rather than the level of increase in mean temperatures observed in temperate regions. The increase of tussocks and decrease in diversity of species and growth forms due to prolonged modifications in microclimatic temperature might be a step toward shrub-dominated ecosystems. Further research on this topic would help understand shifts in growth form dominance and the direction and rate of change of the system.

Growth Strategies of Eucalyptus camaldulensis Dehnh. At Three Sites in Northern Australia

1994 ◽  
Vol 21 (5) ◽  
pp. 653 ◽  
Author(s):  
A Gibson ◽  
EP Bachelard ◽  
KT Hubick
Keyword(s):  
Gas Exchange ◽  
Shoot Growth ◽  
Eucalyptus Camaldulensis ◽  
Dry Season ◽  
Growth Strategies ◽  
Wet Season ◽  
Wind Speeds ◽  
The North ◽  
Air Temperatures ◽  
Semi Arid

The morphology and physiology of trees of Eucalyptus camaldulensis growing in the field at two monsoonal and one semi-arid location were compared. In the wet season, shoot growth at the monsoonal locations was similar and larger than that at the semi-arid location. In the dry season, new shoot growth at the more humid monsoonal location (Petford) was similar to growth in the wet season while at the less humid (Katherine) and the semi-arid (Tennant Creek) locations, shoot growth was foreshortened and the leaves had larger dry weights per unit area. In the summer wet season, leaves on both the north and south sides of the trees were maintained at or below (by up to 5�C) air temperatures throughout the day except for north facing leaves at Petford which were consistently above (by up to 3�C) air temperatures. Midday gas exchange in the dry season at both monsoonal localities was restricted to trees at the water's edge, whereas most trees, including those at drier sites, at the semi-arid location exhibited significant rates of gas exchange. The results, which are discussed in relation to environmental variables (vapour pressure deficits, wind speeds) to which the trees are exposed, and to previous results obtained in the glasshouse, indicate that the differences in shoot growth and physiology are adaptations to the environment in which the trees have evolved.

Limited impact of irrigation on the phenology of Brachychiton megaphyllus: a deciduous shrub that flowers while leafless during the tropical dry season

2015 ◽  
Vol 31 (5) ◽  
pp. 459-467 ◽  
Author(s):  
Patricia J. Bate ◽  
Donald C. Franklin
Keyword(s):  
Soil Moisture ◽  
Reproductive Activity ◽  
Dry Season ◽  
Reproductive Phenology ◽  
Wet Season ◽  
Canopy Development ◽  
Seasonally Dry ◽  
Dry Tropics ◽  
Tap Root ◽  
Leaf Flush

Abstract:A suite of woody plants inhabiting the seasonally dry tropics flower while leafless during the dry season, raising intriguing questions about the role of moisture limitation in shaping their phenology. Brachychiton megaphyllus is one such species, a shrub of open forests and savannas in northern Australia. We documented leaf and reproductive phenology of 14 shrubs, and irrigated a further 15, to determine if soil moisture affected leafiness and reproductive activity. Brachychiton megaphyllus showed first flower buds shortly after the cessation of wet-season rains, and budded and flowered throughout the dry season. In some plants, leaf flush occurred prior to the first rains. Rates of fruit set and maturity were very low. Irrigation did not significantly influence leaf shoot or subsequent canopy development. Contrary to expectation, irrigation decreased the production of buds and flowers though it had no impact on the production of fruit, a response for which we suggest a number of hypotheses. Phenological responses to irrigation may have been limited because B. megaphyllus responds primarily to cues other than soil moisture and is buffered against seasonal drought by a large tap root. This suggests mechanisms by which flowering while leafless may occur in a range of species.

Influence of planting date and herbicide program on Amaranthus palmeri control in dry bean

2021 ◽  
pp. 1-23
Author(s):  
Clint W. Beiermann ◽  
Cody F. Creech ◽  
Stevan Z. Knezevic ◽  
Amit J. Jhala ◽  
Robert Harveson ◽  
...  
Keyword(s):  
Weed Control ◽  
Field Experiments ◽  
Acetolactate Synthase ◽  
Planting Date ◽  
Palmer Amaranth ◽  
Dry Bean ◽  
Control Programs ◽  
Main Plot ◽  
Bean Yield ◽  
Density And Biomass

Abstract Late-emerging summer annual weeds are difficult to control in dry bean production fields. Dry bean is a poor competitor with weeds, due to its slow rate of growth and delayed canopy formation. Palmer amaranth is particularly difficult to control due to season-long emergence and resistance to acetolactate synthase (ALS)-inhibiting herbicides. Dry bean growers rely on PPI and preemergence residual herbicides for the foundation of their weed control programs; however, postemergence herbicides are often needed for season-long weed control. The objective of this experiment was to evaluate effect of planting date and herbicide program on late-season weed control in dry bean in western Nebraska. Field experiments were conducted in 2017 and 2018 near Scottsbluff, Nebraska. The experiment was arranged in a split-plot design, with planting date and herbicide program as main-plot and sub-plot factor, respectively. Delayed planting was represented by a delay of 15 days after standard planting time. The treatments EPTC + ethalfluralin, EPTC + ethalfluralin fb imazamox + bentazon, and pendimethalin + dimethenamid-P fb imazamox + bentazon, resulted in the lowest Palmer amaranth density three weeks after treatment (WAT) and the highest dry bean yield. The imazamox + bentazon treatment provided poor Palmer amaranth control and did not consistently result in Palmer amaranth density and biomass reduction, compared to the non-treated control. In 2018, the delayed planting treatment had reduced Palmer amaranth biomass with the pendimethalin + dimethenamid-P treatment, as compared to standard planting. Delaying planting did not reduce dry bean yield and had limited benefit in improving weed control in dry bean.

NON-UNIFORMITY CONVENTIONAL SPRINKLER IRRIGATION EFFECTS ON BEAN YIELD

2000 ◽  
pp. 853-865 ◽  
Author(s):  
R. Rezende ◽  
A.C.A. Gonçalves ◽  
J.A. Frizzone ◽  
M.V. Folegatti ◽  
J.A. Muniz
Keyword(s):  
Sprinkler Irrigation ◽  
Bean Yield ◽  
Irrigation Effects
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