Adaptation of soybean (Glycine max (L.) Merrill) to the dry season of the tropics. I. Genotypic and environmental effects on phenology

1991 ◽  
Vol 42 (3) ◽  
pp. 497 ◽  
Author(s):  
JD Mayers ◽  
RJ Lawn ◽  
DE Byth
Keyword(s):  
Environmental Effects ◽  
Linear Models ◽  
Dry Season ◽  
Maximum Temperature ◽  
Warm Temperature ◽  
Long Day ◽  
Sowing Dates ◽  
Glycine Max L ◽  
The Tropics ◽  
Flowering Development

Eight soybean genotpes were sown at weekly intervals in three tropical dry season environments to examine genotypic and environmental effects on phenology. A series of simple linear models was used to test the relationships, for individual genotypes, between rate of development for the vegetative (Rf) and reproductive (Rr) phases and photoperiod and temperature. For each genotype, most (> 85%) of the variation across sites, years and sowing dates in Rf and more than half the variation in Rr could be accounted for by variation in photoperiod and/or temperature. Rf was generally negatively associted with mean maximum temperature and mean photoperiod, and positively with mean minimum temperature. Rr was generally positively associated with either mean, or mean maximum, temperature and negatively with mean photoperiod. It was concluded that variations in photothermal regime across sites, years and sowing dates within the tropical dry season are sufficiently large to induce instability in time to flowering of most present soybean cultivars. Most genotypes are also poorly adapted to the relatively long day-warm temperature conditions experienced by dry season crops during podfilling, presumably because they have been developed as summer crops. Breeding soybeans for the dry season will therefore need to place strong emphasis on photothermal effects during post-flowering as well as pre-flowering development.

Adaptation of soybean (Glycine max (L.) Merrill) to the dry season of the tropics. II. Effects of genotype and environment on biomass and seed yield

1991 ◽  
Vol 42 (3) ◽  
pp. 517 ◽  
Author(s):  
JD Mayers ◽  
RJ Lawn ◽  
DE Byth
Keyword(s):  
Seed Yield ◽  
Environmental Effects ◽  
Vegetative Growth ◽  
Dry Season ◽  
Genotypic Differences ◽  
Sowing Dates ◽  
Soybean Genotypes ◽  
Main Basis ◽  
Delayed Flowering ◽  
The Relationship

Eight soybean genotypes were sown at weekly intervals in three tropical dry season environments to examine genotypic and environmental effects on growth and seed yield per plant. In general, dry matter (DM) at maturity increased exponentially with crop duration and so was greater with later maturing genotypes and sowing dates where photothermal conditions slowed development. Across environments, thermal time provided a better description of DM accumulation than did crop duration, indicating direct effects of temperature on growth rates. Among genotypes, the relationship between seed yield and DM production was strongly linear, implying that under the wide spacings of the study, DM production was the main basis of genotypic differences in seed yield. Among environmental means, the relationship was both weaker and curvilinear, suggesting that environmental effects on vegetative growth were not necessarily reflected in seed yield. Further, where photothermal regime delayed flowering and maturity, vegetative growth was often excessive, and harvest index (HI) smaller. HI was also smaller where flowering coincided with cool night temperatures (< c. 14�C) and podset was reduced. Overall, HI was negatively correlated with crop duration. Responses are discussed in terms of the implications for soybean improvement for the tropical dry season.

scholarly journals Projected Changes in Climate Extremes Using CMIP6 Simulations Over SREX Regions

2021 ◽  
Vol 5 (3) ◽  
pp. 481-497
Author(s):  
Mansour Almazroui ◽  
Fahad Saeed ◽  
Sajjad Saeed ◽  
Muhammad Ismail ◽  
Muhammad Azhar Ehsan ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Extreme Events ◽  
First Century ◽  
Maximum Temperature ◽  
Annual Maximum ◽  
Temperature And Precipitation ◽  
Projected Change ◽  
Twenty First Century ◽  
Projected Changes ◽  
The Tropics

AbstractThis paper presents projected changes in extreme temperature and precipitation events by using Coupled Model Intercomparison Project phase 6 (CMIP6) data for mid-century (2036–2065) and end-century (2070–2099) periods with respect to the reference period (1985–2014). Four indices namely, Annual maximum of maximum temperature (TXx), Extreme heat wave days frequency (HWFI), Annual maximum consecutive 5-day precipitation (RX5day), and Consecutive Dry Days (CDD) were investigated under four socioeconomic scenarios (SSP1-2.6; SSP2-4.5; SSP3-7.0; SSP5-8.5) over the entire globe and its 26 Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) regions. The projections show an increase in intensity and frequency of hot temperature and precipitation extremes over land. The intensity of the hottest days (as measured by TXx) is projected to increase more in extratropical regions than in the tropics, while the frequency of extremely hot days (as measured by HWFI) is projected to increase more in the tropics. Drought frequency (as measured by CDD) is projected to increase more over Brazil, the Mediterranean, South Africa, and Australia. Meanwhile, the Asian monsoon regions (i.e., South Asia, East Asia, and Southeast Asia) become more prone to extreme flash flooding events later in the twenty-first century as shown by the higher RX5day index projections. The projected changes in extremes reveal large spatial variability within each SREX region. The spatial variability of the studied extreme events increases with increasing greenhouse gas concentration (GHG) and is higher at the end of the twenty-first century. The projected change in the extremes and the pattern of their spatial variability is minimum under the low-emission scenario SSP1-2.6. Our results indicate that an increased concentration of GHG leads to substantial increases in the extremes and their intensities. Hence, limiting CO2 emissions could substantially limit the risks associated with increases in extreme events in the twenty-first century.

Rising ecosystem water demand exacerbates the lengthening of tropical dry seasons

2021 ◽  
Author(s):  
Hao Xu ◽  
Xu Lian ◽  
Ingrid Slette ◽  
Hui Yang ◽  
Yuan Zhang ◽  
...  
Keyword(s):  
Water Demand ◽  
Potential Evapotranspiration ◽  
Central Africa ◽  
Dry Season ◽  
Land Area ◽  
Key Factor ◽  
Dry Seasons ◽  
The Tropics ◽  
Factor Governing

Abstract The timing and length of the dry season is a key factor governing ecosystem productivity and the carbon cycle of the tropics. Mounting evidence has suggested a lengthening of the dry season with ongoing climate change. However, this conclusion is largely based on changes in precipitation (P) compared to its long-term average (P ̅) and lacks consideration of the simultaneous changes in ecosystem water demand (measured by potential evapotranspiration, Ep, or actual evapotranspiration, E). Using several long-term (1979-2018) observational datasets, we compared changes in tropical dry season length (DSL) and timing (dry season arrival, DSA, and dry season end, DSE) among three common metrics used to define the dry season: P < P ̅, P < Ep, and P < E. We found that all three definitions show that dry seasons have lengthened in much of the tropics since 1979. Among the three definitions, P < E estimates the largest fraction (49.0%) of tropical land area likely experiencing longer dry seasons, followed by P < Ep (41.4%) and P < P ̅ (34.4%). The largest differences in multi-year mean DSL (> 120 days) among the three definitions occurred in the most arid and the most humid regions of the tropics. All definitions and datasets consistently showed longer dry seasons in southern Amazon (due to delayed DSE) and central Africa (due to both earlier DSA and delayed DSE). However, definitions that account for changing water demand estimated longer DSL extension over those two regions. These results indicate that warming-enhanced evapotranspiration exacerbates dry season lengthening and ecosystem water deficit. Thus, it is necessity to account for the evolving water demand of tropical ecosystems when characterizing changes in seasonal dry periods and ecosystem water deficits in an increasingly warmer and drier climate.

scholarly journals Dry season bean production at different sowing dates under the South Minas Gerais conditions, Brazil

2015 ◽  
Vol 10 (28) ◽  
pp. 2705-2710 ◽  
Author(s):  
Fortes Gris Cristiane ◽  
Henrique Evaristo Carlos ◽  
Eduardo de Oliveira Aparecido Lucas ◽  
Henrique Silva Nadaleti Denis
Keyword(s):  
Minas Gerais ◽  
Dry Season ◽  
The South ◽  
Sowing Dates

scholarly journals The Response of Soybean (glycine max (l.) Meer.) Varieties from the Tropical Region to Five Watering Regimes under a Controlled Environment

2018 ◽  
Vol 1 (2) ◽  
Keyword(s):  
Glycine Max ◽  
Drought Stress ◽  
Stomatal Conductance ◽  
Water Supply ◽  
Dry Season ◽  
Plant Response ◽  
Tropical Region ◽  
Transpiration Efficiency ◽  
Wide Range ◽  
Glycine Max L

In some rice dominated tropical regions, such as in Indonesia, soybeans are an increasingly important dry season crop which are often exposed to periods of drought stress. The morphological and physiological responses, which could lead to some tolerance to water stress, may vary between varieties. By better understanding the plant response to drought stress and finding if these responses vary between varieties better dry season production could be achieved. An experiment was conducted to compare the response of four varieties of soybean (glycine max (l.) Meer.) to five watering regimes, with the objective of determining the response of common soybean varieies across a wide range of water supply. Plant response to water supply was measured using gas exchange measurement with the rate of photo synthesis decreasing progressively from well watered to dry conditions across the four varieties. A correlation of stomatal conductance and transpiration rate has a close relationship with photosynthetic rate, where stomatal conductance of Burangrang variety has higher value than other varieties. Varieties Burangrang and Argomulyo stomatal conductances are higher value than those of Anjasmoro and Grobogan varieties. In a deficit of water condition, the Argomulyo varieties have a higher value of transpiration efficiency and significantly different than the other three varieties. The transpiration efficiency significantly declined for treatments watered once every two or three weeks. The transpiration efficiency values of Agromulyo and Burangrang varieties were significantly higher than another varieties.

scholarly journals The relation between the crude fibre content of food and the milk production.

1955 ◽  
Vol 3 (1) ◽  
pp. 35-39
Author(s):  
P. Schoorl
Keyword(s):  
The Netherlands ◽  
Milk Production ◽  
Feeding Practices ◽  
Dry Season ◽  
Fibre Content ◽  
Crude Fibre ◽  
The Tropics ◽  
Crude Fibre Content

The Friesian cow in Indonesia gives about 1, 500 1. milk in about 240 days compared with 3, 800 1. in 300 days in the Netherlands. The author believes that the main reason for the low production in the tropics is not climate, but faulty feeding practices. A cow fed a typical Indonesian ration of reedy grass and fibrous concentrates gave 1, 003 1. milk in the first no days of her first lactation, but increased to 1, 870 1. in the first 102 days of her second lactation when given a diet containing much less crude fibre, in spite of the fact that the former lactation was in the wet and the latter in the dry season. G.F.S. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Temporal changes in arthropod activity in tropical anthropogenic forests

2018 ◽  
Vol 108 (6) ◽  
pp. 792-799 ◽  
Author(s):  
G.-J. Brandon-Mong ◽  
J.E. Littlefair ◽  
K.-W. Sing ◽  
Y.-P. Lee ◽  
H.-M. Gan ◽  
...  
Keyword(s):  
Land Use ◽  
Global Warming ◽  
Biodiversity Loss ◽  
Well Being ◽  
Peninsular Malaysia ◽  
Feedback Mechanism ◽  
Maximum Temperature ◽  
Arthropod Communities ◽  
Reserve Forest ◽  
The Tropics

AbstractArthropod communities in the tropics are increasingly impacted by rapid changes in land use. Because species showing distinct seasonal patterns of activity are thought to be at higher risk of climate-related extirpation, global warming is generally considered a lower threat to arthropod biodiversity in the tropics than in temperate regions. To examine changes associated with land use and weather variables in tropical arthropod communities, we deployed Malaise traps at three major anthropogenic forests (secondary reserve forest, oil palm forest, and urban ornamental forest (UOF)) in Peninsular Malaysia and collected arthropods continuously for 12 months. We used metabarcoding protocols to characterize the diversity within weekly samples. We found that changes in the composition of arthropod communities were significantly associated with maximum temperature in all the three forests, but shifts were reversed in the UOF compared with the other forests. This suggests arthropods in forests in Peninsular Malaysia face a double threat: community shifts and biodiversity loss due to exploitation and disturbance of forests which consequently put species at further risk related to global warming. We highlight the positive feedback mechanism of land use and temperature, which pose threats to the arthropod communities and further implicates ecosystem functioning and human well-being. Consequently, conservation and mitigation plans are urgently needed.

The Atmospheric Component of Biogeochemical Cycles in the Amazon Basin

2001 ◽  
Author(s):  
Paulo Artaxo
Keyword(s):  
Land Use ◽  
Tropical Forests ◽  
Amazon Basin ◽  
Aerosol Particles ◽  
Trace Gases ◽  
Biogeochemical Cycles ◽  
Dry Season ◽  
Earth System ◽  
The Earth ◽  
The Tropics

Tropical forests, with their high biological activity, have the potential to emit large amounts of trace gases and aerosol particles to the atmosphere. The accelerated development and land clearing that is occurring in large areas of the Amazon basin suggest that anthropogenic effects on natural biogeochemical cycles are already occurring (Gash et al. 1996). The atmosphere plays a key role in this process. The tropics are the part of the globe with the most rapidly growing population, the most dramatic industrial expansion and the most rapid and pervasive change in land use and land cover. Also the tropics contain the largest standing stocks of terrestrial vegetation and have the highest rates of photosynthesis and respiration. It is likely that changes in tropical land use will have a profound impact on the global atmosphere (Andreae 1998, Andreae and Crutzen 1997). A significant fraction of nutrients are transported or dislocated through the atmosphere in the form of trace gases, aerosol particles, and rainwater (Keller et al. 1991). Also the global effects of carbon dioxide, methane, nitrous oxide, and other trace gases have in the forest ecosystems a key partner. The large emissions of isoprene, terpenes, and many other volatile organic compounds could impact carbon cycling and the production of secondary aerosol particles over the Amazon region. Vegetation is a natural source of many types of aerosol particles that play an important role in the radiation budget over large areas (Artaxo et al. 1998). There are 5 major reservoirs in the Earth system: atmosphere, biosphere (vegetation, animals), soils, hydrosphere (oceans, lakes, rivers, groundwater), and the lithosphere (Earth crust). Elemental cycles of carbon, oxygen, nitrogen, sulfur, phosphorus, and other elements interact with the different reservoirs of the Earth system. The carbon cycle has important aspects in tropical forests due to the large amount of carbon stored in the tropical forests and the high rate of tropical deforestation (Jacob 1999). In Amazonia there are two very different atmospheric conditions: the wet season (mostly from November to June) and the dry season (July-October) (see Marengo and Nobre, this volume). Biomass burning emissions dominate completely the atmospheric concentrations over large areas of the Amazon basin during the dry season (Artaxo et al. 1988).

scholarly journals Multiple Factors Influence Seasonal and Interannual Litterfall Production in a Tropical Dry Forest in Mexico

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1241
Author(s):  
Hernán Morffi-Mestre ◽  
Gregorio Ángeles-Pérez ◽  
Jennifer S. Powers ◽  
José Luis Andrade ◽  
Astrid Helena Huechacona Ruiz ◽  
...  
Keyword(s):  
Linear Models ◽  
Tropical Dry Forest ◽  
Basal Area ◽  
Dry Forest ◽  
Maximum Temperature ◽  
Dry Forests ◽  
Evergreen Species ◽  
Flat Terrain ◽  
Litterfall Production ◽  
Successional Age

Litterfall production plays a fundamental role in the dynamics and function of tropical forest ecosystems, as it supplies 70–80% of nutrients entering the soil. This process varies annually and seasonally, depending on multiple environmental factors. However, few studies spanning several years have addressed the combined effect of climate variables, successional age, topography, and vegetation structure in tropical dry forests. In this study, we evaluated monthly, seasonal, and annual litterfall production over a five-year period in semideciduous dry forests of different successional ages growing on contrasting topographic conditions (sloping or flat terrain) in Yucatan, Mexico. Its relationship with climate and vegetation structural variables were also analyzed using multiple linear regression and generalized linear models. Litterfall was measured monthly in 12 litterfall traps of 0.5 m2 in three sampling clusters (sets of four 400 m2 sampling plots) established in forests of five successional age classes, 3–5, 10–17, 18–25, 60–79, and >80 years (in the latter two classes either on slopping or on flat terrain), for a total of 15 sampling clusters and 180 litterfall traps. Litterfall production varied between years (negatively correlated with precipitation), seasons (positively correlated with wind speed and maximum temperature), and months (negatively correlated with relative humidity) and was higher in flat than in sloping sites. Litterfall production also increased with successional age until 18–25 years after abandonment, when it attained values similar to those of mature forests. It was positively correlated with the aboveground biomass of deciduous species but negatively correlated with the basal area of evergreen species. Our results show a rapid recovery of litterfall production with successional age of these forests, which may increase with climate changes such as less precipitation, higher temperatures, and higher incidence of hurricanes.

scholarly journals Forests as ‘sponges’ and ‘pumps’: Assessing the impact of deforestation on dry-season flows across the tropics

2019 ◽  
Vol 574 ◽  
pp. 946-963 ◽  
Author(s):  
Jorge L. Peña-Arancibia ◽  
L. Adrian Bruijnzeel ◽  
Mark Mulligan ◽  
Albert I.J.M. van Dijk
Keyword(s):  
Dry Season ◽  
The Tropics ◽  
The Impact
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