Tropical Savanna Climate Research Articles

The current and future potential distribution of Gargaphia decoris: A biological control agent for Solanum mauritianum (Solanaceae)

The lace bug, Gargaphia decoris Drake (Hemiptera: Tingidae) is a biological control agent of the South American invasive tree Solanum mauritianum Scopoli (Solanaceae). Gargaphia decoris has been established with some success in New Zealand and South Africa. In this study, we used the climatic modelling software CLIMEX (Hearne Scientific Software Pty Ltd, Australia) to assess how current and future climatic conditions might influence the geographic distribution of the biocontrol agent in these countries and worldwide. CLIMEX parameters were based on experimental data and calibrated with distribution records from the insect’s native and non-native range. In its native range, our model predicts that G. decoris could expand its distribution into northern coastal regions of Brazil, with tropical dry summer or monsoon climate. It could also expand beyond its native range into other countries with temperate and subtropical climates, as well as several regions with tropical savanna, equatorial and monsoon climate in coastal regions. In New Zealand the greatest potential for further expansion is within the North Island, and in South Africa the expansion is limited to mostly coastal areas. In a future climate change scenario (A1B, CSIRO Mk3 2090), there is a predicted reduced distribution globally, especially for Asia, Africa, and the Americas. In Europe the climatic suitability for G. decoris will increase, with an expanded potential distribution. In South Africa the potential distribution is predicted to slightly reduce, while an expansion is predicted into the colder regions of New Zealand. These models provide a useful tool to inform future releases of G. decoris and to guide monitoring efforts within and beyond release areas.

Soil physico-chemical properties, biomass production, and root density in a green manure farming system from tropical ecosystem, North-eastern Brazil

Soil physico-chemical properties, biomass production, and root density are considered key factors indicating soil health in an agroecosystem. The soil physico-chemical changes and plant growth (e.g., shoot biomass production and root density) in a 6-year cultivation of plant species used as green manure in a sandy soil from Tropical ecosystem, North-eastern Brazil, were investigated between July and December 2019. We characterized soil physical and chemical properties, shoot biomass production, and root density under ten plant species used as green manure: Brachiaria decumbens Stapf. cv. Basilisk, Canavalia ensiformis (L.) DC, Crotalaria juncea L., Crotalaria ochroleuca G. Don, Crotalaria spectabilis Roth, Lablab purpureus (L.) Sweet, Mucuna pruriens (L.) DC, Neonotonia wightii (Wight & Arn.) J.A. Lackey, Pennisetum glaucum L., and Stilozobium aterrimum Piper and Tracy. The highest values of soil pH, exchangeable cations, CEC, and soil available water capacity were found on the plots where Poaceae plants were cultivated, whereas for H++Al3+, C.E.C., soil available water, and soil available water capacity were found on the plots where Fabaceae plants were cultivated. On the plots where C. ensiformis and N. wightii were cultivated, we found the highest shoot dry biomass and root density, respectively. The results highlight the importance to consider plant species from both Poaceae and Fabaceae family used as green manure as soil conditioner (by promoting soil fertility, nutrient cycling, and hydraulic properties into plant root zone), and thus creating a positive plant-soil feedback. Our findings suggest that (1) a consecutive green manure practice without any input of fertilizers after 6 years changed positively both soil physical and chemical properties, and improve plant growth (e.g., shoot dry biomass and root density) in tropical savanna climate conditions; and (2) by altering soil fertility, both Poaceae and Fabaceae plants used as green manure may create a sustainable cycle into the soil profile thus promoting soil health.

Estimation of daylight availability in Kolkata and approximation of indoor daylight levels for different daylighting methods

ABSTRACT This work estimated the daylight availability and luminous efficacy of solar illuminance and approximated indoor daylight levels for various indoor daylighting methods for Kolkata, a major city in eastern India having tropical savanna climate, by applying two computational methods: the Perez model and the IESNA recommended calculation procedure. It was found that hourly horizontal diffuse and global illuminance, horizontal sky and total daylight illuminance values remained mostly over 10 klx throughout the year, and global and diffuse luminous efficacies mostly remained around 95–120 and 110–150 lm/W, respectively. The linear correlation between solar irradiation and estimated illuminance was stronger for Perez model. Thus, the application of Perez model was considered the better choice to appraise the daylighting potential of Kolkata.

Link performance evaluation of terrestrial FSO model for predictive deployment in Bhubaneswar smart city under various weather conditions of tropical climate

This paper proposes the link performance analysis of the terrestrial free-space optic (FSO) model, intended for deployment in Bhubaneswar smart city. The challenges of atmospheric adversity and its impact on the performance of FSO model have been analyzed from the real-time measured visibility data. A comparative study of different statistical models addressing the relation between measured visibility data and atmospheric attenuation has been carried out. The atmospheric losses such as haze, scintillation, rain, fog are considered for the link analysis due to the tropical savanna climate of the Bhubaneswar city. Thereafter the link margin is calculated for summer, rainy, winter season for the feasible establishment of FSO link. Comparison between two low absorption optical wavelengths such as 850 nm and 1550 nm has been considered for performance analysis. This is because of the commercial availability of optical components. Performance metrics such as received signal power, bit error rate (BER), signal to noise ratio (SNR), link margin has been used for the link performance analysis for a best fit FSO model for deployment in the city. Finally, the maximum achievable data rate is calculated for FSO link in all the three seasons for ensuring high-quality network reach.

Performance and economic viability of the PV system in different climatic zones of Nigeria

This study analyzed the effect of climatic variation on PV systems' performance and economic viability in four climatic zones of Nigeria (warm desert, warm semi-arid, tropical savanna, and monsoon climate). Performance ratio was found to be high in monsoon and tropical savanna climate due to the influence of cool-moist air from the ocean, low temperature, and increased cloud cover in the region. Meanwhile, the least performance ratio was noticed in the warm desert and warm semi-arid climate due to the dusty wind from the Sahara desert, relatively high temperature, and low precipitation in the region. In order to assess the cost-effectiveness and profitability of the solar project in Nigeria, the Levelized cost of electricity (LCOE), net present value (NPV), internal rate of return (IRR), and payback period (PP) were employed. The average LCOE across the climatic zones is 0.21 $/kWh, which is lower compared to the 0.25 $/kWh grid tariff. The average NPV and IRR are found to be $31,164 and 22%, respectively, making the project economically feasible. However, the payback period was found to be ranging from 3.7 to 5.2 years. Finally, the analysis has proven that solar PV technology is economically viable and profitable in Nigeria.

Canopy Structure and Photosynthetic Performance of Irrigated Cassava Genotypes Growing in Different Seasons in a Tropical Savanna Climate

Growth and photosynthesis performance of cassava during early vegetative growth are important determinants of final biomass. The objective of this work was to investigate canopy structure and photosynthesis performance of four cassava genotypes (Rayong 9, Rayong 11, Kasetsart 50, and CMR38-125-77) growing under irrigation at 3 and 6 months after planting (3MAP and 6MAP). Data for the 3MAP plants were collected from cassava planted on 30 June (Rainy PD), 10 November (Cool PD1), and 15 December (Cool PD2) 2015; and for the 6MAP from those planted on 20 April 2015 (Hot PD), Rainy PD, and Cool PD1. The plants growing in the rainy season had significantly higher leaf area index (LAI) than those growing in the cool and hot seasons. Consequently, they had lower percentage light penetration at the bottom of canopy, and therefore more light interception through the canopy, and hence a higher mean net photosynthesis rate (Pn) across the six canopy levels. At the 3MAP, which is the stage of maximum rate of leaf and stem growth, the Rainy PD and Cool PD2 plants of CMR38-125-77 showed the highest LAI and highest mean Pn. Similarly, the Cool PD1 plants of Kasetsart 50 showed the highest LAI and highest mean Pn. In contrast, at 6MAP during the stage of active starch accumulation in storage roots, the genotypes with the highest mean Pn were the ones having an intermediate (CMR38-125-77 for the Hot PD) or low LAI (Rayong 9 for the Rainy PD, and CMR38-125-77 for the Cool PD1). Data on variations in canopy structure and photosynthesis potentials of different cassava genotypes in response to seasonal variations may be useful for crop growth modeling and may be employed as a criterion for the selection of suitable genotypes for each growing season.

Spatial and temporal distributions of stable isotopes in precipitation over Thailand

AbstractSpatial and temporal variations of the isotopic composition of precipitation over Thailand were investigated. The local meteoric water line for Thailand deviates slightly from the global meteoric water line, with lower slopes (7.62 ± 0.07, 7.59 ± 0.08) and intercepts (6.42 ± 0.39, 6.22 ± 0.42) using ordinary and precipitation weighted methods. Differences in spatial and temporal δ18O distributions between the tropical monsoon and tropical savanna climate zones were found due to differing moisture source contributions and seasonal precipitation patterns. The temporal data reveals that the northeast monsoon rains originate from isotopically‐enriched local moisture with isotope values of −9.36 to −0.09‰ (mean − 3.73 ± 0.42‰), whereas the southwest monsoon clouds had a more significant rainout effect from Rayleigh distillation, with isotope values of −9.56 to −1.78‰ (mean − 5.40 ± 0.38‰). The precipitation amount at each site was negatively correlated with δ18O (−0.24 to −3.20‰ per 100 mm, R2 = 0.1–0.9). Furthermore, δ18O was negatively correlated with geography (latitude, altitude) for the southwest monsoon periods, as expected based on other observed correlations. However, an inverse correlation was seen in the northeast monsoon due to differing moisture transportation as part of the continental effect. The correlation coefficient (R) was higher in the southwest monsoon (−0.84 for latitude effect, −0.64 for altitude effect) than the northeast monsoon (0.67 for latitude effect, 0.35 for altitude effect). The spatial pattern of isotopic composition reflects the southwest monsoon more clearly than the northeast monsoon, but the two monsoons also have a cancelling impact on orographic patterns. An agreement of the δ18O and deuterium excess (d‐excess) was a negative correlation and found to reflect precipitation sources and re‐evaporation processes. The d‐excess was slightly higher for the northeast monsoon, bringing moisture from the Pacific Ocean and travelling across the continent before reaching the observed stations. By contrast, the d‐excess was relatively lower for the Indian Ocean's moisture in the southwest monsoon.

Ranking PCMs for building façade applications using multi-criteria decision-making tools combined with energy simulations

The use of phase change materials (PCMs) in building envelopes has a potential to improve the energy performance of buildings. Even though Multi-Criteria Decision-Making (MCDM) tools have been widely applied to rank PCMs for various applications, the following issues still need more elaboration: a) How to account for the climate-related factors in the ranking of PCMs? b) How can the environmental footprint and chemical properties of various PCMs be considered in the ranking of PCMs? Therefore, this study presents a methodology for ranking phase change materials based on the AHP–TOPSIS and Fuzzy AHP–Modified Fuzzy TOPSIS methods combined with building energy simulations. Thermophysical (thermal conductivity, latent heat of fusion, phase change temperature, specific heat, density, cycling stability, supercooling), economic (initial cost), chemical (toxicity, flammability, corrosiveness), and environmental (recyclability, embodied energy) criteria were considered. The application of the methodology was demonstrated for eight cities of the tropical savanna climate zone. A comparative analysis was conducted, and the rankings obtained utilizing AHP–TOPSIS and Fuzzy AHP–Modified Fuzzy TOPSIS methods were found to be concordant. A sensitivity analysis indicated that the ranking developed by the proposed methodology has considerable robustness to alteration of weightings of criteria.

Vector-borne pathogens in dogs from Guatemala, Central America.

Vector-borne pathogens (VBPs) of dogs have been extensively studied worldwide, though scientific information for some countries, as is the case for Guatemala, is almost nonexistent. From 2012 to 2015, 975 dogs residing in different departments of Guatemala were sampled and screened using a rapid ELISA for detecting antigen of Dirofilaria immitis and antibodies against Anaplasma spp., Ehrlichia spp. and Borrelia burgdorferi. Out of 975 samples analyzed, 46.4% (n=452) scored positive for at least one pathogen, with D. immitis being the most prevalent (29.7%), followed by Ehrlichia spp. (11.5%) and Anaplasma spp. (5.1%). None of the dogs were positive to B. burgdorferi. Co-infections were observed in 18.1% (n=176) of dogs, with the simultaneous detection of D. immitis and Ehrlichia spp. being most common. The frequency of VBPs was higher in the department of Santa Rosa (southeast coast of Guatemala), which has a tropical savanna climate. In this region, 59.7% of the dogs surveyed were infected with D. immitis. Our results suggest that the prevalence of VBPs in dogs in Guatemala may be affected by the climate, with dogs living in the southeast coast being at higher risk, as compared to other regions studied. Increased awareness regarding the risk of VBPs in dogs in Guatemala is advocated and the adoption of preventive strategies should be encouraged.

Colletotrichum species causing cassava (Manihot esculenta Crantz) anthracnose in different eco-zones within the Recôncavo Region of Bahia, Brazil.

A survey to investigate the occurrence of cassava anthracnose disease (CAD) and distribution of Colletotrichum spp. in cassava plantations in different eco-zones of the Reconcavo Region in Bahia, Brazil, investigated during the rainy season of 2014. A total of 50 cassava fields distributed among 18 municipalities were visited and intensity of anthracnose evaluated. The highest disease incidence (DI) (83.3%) was in samples collected in São Félix, and the lowest (34.4%), in Varzedo. Municipalities that presented the highest values for DI were located within the ‘Af’ Köppen–Geiger eco-zone, also presenting the highest values for the estimated McKinney disease index. Based on previous studies of multilocus phylogeny, seven different species of Colletotrichum were identified (Colletotrichum fructicola, Colletotrichum tropicale, Colletotrichum gloeosporioides s.s, Colletotrichum theobromicola, Colletotrichum siamense, Colletotrichum brevisporum and Colletotrichum plurivorum) and a new approach based on ERIC-PCR was used aiming to group the 82 isolates according to these findings. The highest percentage of genetic variance (> 78%) was among isolates within fields. Based on the survey and genetic analysis, C. fructicola is probably the main causal agent of cassava anthracnose in the Recôncavo Region, since this species was present with highest incidence in all eco-zones, 47.61, 42.86 and 57.14% for Af (tropical rainforest climate), As (tropical dry savanna climate) and Aw (tropical wet savanna climate), respectively. This study is the first report of C. fructicola lineages as the most likely pathogen causing anthracnose disease of cassava in Brazil, and these findings may be used to guide the selection of resistant varieties.

Drivers for the cracking of multilayer polyamide‐based backsheets in field photovoltaic modules: In‐depth degradation mapping analysis

AbstractThere is a lack of understanding on the root cause of cracking of photovoltaic (PV) backsheets due to the challenge of multilayer characterization and the complicated failure modes at the submodule level. In this work, the in‐depth degradation mapping of field‐exposed polyamide‐based (PA‐based) PV module backsheets was studied, with the major focus on the identification of underlying drivers for the through cracking (in between the solar cells). PV modules were retrieved from five different locations, comprising a variety of climates, including humid subtropical, hot‐summer Mediterranean, tropical savanna climate, and hot arid. A suite of microscale cross‐sectional characterizations, including chemical changes, fluorescence intensity, and modulus as a function of distance from the air surface of the backsheet, was performed. Results showed more advanced signs of degradation of the inner layer than the outer layer in the cracking region. Increases in the modulus were identified as the major indicator for the cracking. Moreover, a rudimentary test by immersion in acetic acid, which forms during photodegradation of the ethylene‐vinyl acetate copolymer (EVA) encapsulant, showed the first‐time direct evidence that acetic acid can largely accelerate the chemical degradation and facilitate the cracking of PA inner layer. This study suggests that the field cracking of PA‐based backsheet can be attributed to the combined effects of chemical degradation and physical reorganization (chemi‐crystallization) under cyclic thermomechanical stresses. Therefore, it is important to consider effects of local microclimates and interlayer infection to understand the heterogeneous nature of backsheet failures.

Impact of environmental variables on the degradation of photovoltaic components and perspectives for the reliability assessment methodology

Backsheet cracking has been a major issue observed in the field; however, standardized qualification tests, such as IEC61215, are inadequate to reliably identify such failures of PV modules due to the lack of the critical weathering factors applied sequentially or in combination, such as those found in the service environments. To address this problem, we investigated the effects of various environmental variables on the degradation and failure behaviors of the polyamide-based backsheet in PV modules retrieved from five different locations, encompassing a variety of climates, including humid subtropical, hot-summer Mediterranean, tropical savanna climate and hot arid. The correlations between the degradation indicators and the weathering variables were further demonstrated by principle components analysis (PCA). We found strong relationships between: carbonyl formation and reflected solar radiation; hydroxyl formation and module temperature; yellowness and NO2 concentration, while no simple correlation could be found between a specific weathering factor and cracking. By introducing additional stress factors to the aged polyamide-based backsheet films with the novel “fragmentation test”, we successfully reproduced the field cracking behaviour. This study has demonstrated that different degradation modes of PV components respond differently to the environmental stresses encountered in service. Thereby, any accelerated laboratory test based on a single set condition or lacking key environmental variables would be inadequate to assess the long-term performance of PV modules and components. A new reliability-based methodology is proposed to quantitatively link laboratory testing with field results for the service life prediction of PV materials.

Influence of potassium on yield and quality of cabbage and cauliflower on alfisols under seasonally dry tropical savanna climate

Influence of potassium on yield and quality of cabbage and cauliflower on alfisols under seasonally dry tropical savanna climate

Etiology and distribution of foliar fungal diseases of citrus in Panama

The etiology and distribution of foliar fungal diseases of citrus in Panama were studied in this work. In total, 85 orchards spanning six provinces were surveyed from 2011 to 2013. Symptoms observed ranged from yellow-brown spots on the abaxial surface of the leaves, brown lesions on petals, twig dieback as well as raised pustules on leaves and fruit. Representative fungal isolates obtained from symptomatic plant tissues were identified based on morphological characteristics, sequences of the ITS, EF1-α and TUB2 loci, and pathogenicity tests. Citrus greasy spot, caused by Zasmidium citri-griseum (=Mycosphaerella citri), was identified as the most prevalent fungal disease of citrus in Panama, confirmed in 68.2% of the orchards. Postbloom fruit drop (PFD) and Key lime anthracnose, caused by Colletotrichum acutatum sensulato, and melanose, caused by Diaporthe citri, were identified for the first time in Panama. Citrus scab, caused by Elsinoe fawcettii, was also detected. Greasy spot was found mainly in areas with a tropical monsoon climate (Am) and to a lesser extent in tropical savanna (Aw) and tropical rainforest (Af) climates. Melanose, PFD and citrus scab were detected only in areas with Am and Af climates. Information about the etiology and geographic distribution of fungal diseases in Panama will help to design effective strategies for disease management.

Performance evaluation of phase change materials suitable for cities representing the whole tropical savanna climate region

Phase change materials can be applied into building framework to reduce energy and fossil fuel consumption as well as to make the building sector more sustainable. In this research, it is hypothesized that a group of PCMs in the narrow range can be used for the whole tropical savanna climate according to Koppen-Geiger climate classification. Eight representative cities (Bamako, Bangalore, Bangkok, Brasilia, Dar es Salaam, Kolkata, Maputo and Surabaya) from seven different countries (Mali, Thailand, Brazil, Tanzania, India, Mozambique and Indonesia) were chosen in accordance with their demographical and economical state. Numerical simulations were performed in DesignBuilder software to carry out detailed investigation about thermal behavior and energy performance of a residential building integrated with eleven different PCMs (PCM21-PCM31). In addition, the impact of PCM thickness, its location in the wall (external, middle, and internal) and different surface area were assessed. Results of thermal performance during a summer day revealed that temperature fluctuations in PCM integrated building dropped by up to 2.76 °C even when the HVAC system was switched off. From energy analysis, the hypothesis of this research was confirmed, and the narrow range of PCMs (PCM25-PCM29) were found to be optimum for this climate zone. Considerable energy savings and energy consumption reduction up to 68.63% was obtained. Furthermore, for constant volume, the thinner PCM layer with greater surface area exhibited superior performance in terms of energy savings. Hence, the incorporation of PCM in buildings located in a tropical savanna climate is feasible.

Growth rates and yields of cassava at different planting dates in a tropical savanna climate

ABSTRACT: Details on growth and yield for cassava planted on different dates are useful for determining suitable genotypes for particular growing seasons. Our aim was to study growth and yield of cassava planted on different dates. Four cassava genotypes (Kasetsart 50, Rayong 9, Rayong 11 and CMR38-125-77) were evaluated using a randomized complete block design (RCBD) with four replications in six growing periods (20 Apr, 25 May, 30 June, 5 Oct, 10 Nov and 15 Dec 2015-2016) at Khon Kaen, Thailand. Soil properties were determined prior to planting, and crop traits and weather data were recorded. The six planting dates had a statistically significant effect on all crop traits. Low temperatures and solar radiation related to low biomass accumulation rates and short periods of linear phases for total crop and storage root dry weights with the 30 June planting date. CMR38-125-77 is likely to be a good genotype with respect to total crop and storage root dry weights at final harvest for almost all growing dates, except for the 20 Apr. Leaf area index (LAI) at 120, 240 and 300 days after planting (DAP), specific leaf area (SLA) at 120 DAP, storage root growth rate (SRGR) during 300-360 DAP and leaf growth rate (LGR) during 60-120 and 300-360 DAP were the components for the physiological determinants of total crop and storage root dry weight. The relationship between these physiological traits and storage root could be useful for cassava breeding.

Towards developing a building typology for Sudan

Sudan suffers from hard summers with temperatures approaching 42 0C in the South and 48 0C in the North. In spite of that, the technical solutions in buildings for protection against solar radiation and natural ventilation are generally beyond reach. There isn’t sufficient information provided on the characteristics of the building stock, building physics and energy use of buildings in Sudan. The main objective of this research paper is to collect the data from the population and housing census, scientific research papers and different reports, and to use these in preparing a building typology table. The climate in Sudan is divided into three zones: warm desert climate, warm semi-arid climate, and tropical savanna climate zone. The building varies according to the climate zones, geographical feature, and urbanization levels. Building materials range from natural ones like straw, wood, and mud to moderns one like bricks and concrete. Building typology varies from structures to provide temporary shelter to the permanent single or multi-family houses. The main result of this research paper is to identify a building typology in Sudan with reference buildings. This is the first paper that introduced the typology table of Sudan.

Short - term effects of temperature on hospital admissions for acute myocardial infarction: A comparison between two neighboring climate zones in Vietnam

BackgroundVietnam is one of the countries most affected by climate change, but few studies have focused on the population health effects of climate variation. Extreme heatwaves and cold spells might exacerbate underlying chronic conditions and precipitate hospitalization or early death. This study examined the short-term effects of ambient temperature extremes on hospital admissions (HAs) due to acute myocardial infarction (AMI) between different climate zones in the Central Coast region of Vietnam. MethodsInformation from medical records of all 3328 cases of AMI HAs (with hospital records cross-checked by clinicians) was collected from three hospitals in the South-Central Coast region (tropical savanna climate) and North-Central Coast region (tropical monsoon climate) for the period 2008–2015. Meteorological data were obtained from the National Hydro-Meteorological and Environment Network Centre. We used distributed lag non-linear models to assess the association between daily average temperature and AMI HAs, accounting for long-term trend and other meteorological variables. ResultsWe found a negative and significant association between AMI HAs and temperature in the North-Central Coast region while conversely there was a positive and significant association in the South-Central Coast region. In the North-Central Coast region, the risk of AMI HAs increased by 11% (Relative risk (RR): 1.11, 95% CI: 0.91–1.35, p > 0.05) at moderately low temperatures (10th percentile of temperature range – 18.5 °C) and increased by 25% (RR: 1.25, 95% CI: 1.02–1.55, p < 0.05) at extremely low temperatures (5th percentile of temperature range – 16.8 °C). In the South-Central Coast region, the risk of AMI HAs increased by 18% (RR: 1.18, 95% CI: 0.95–1.47, p > 0.05) and 36% (RR: 1.36, 95% CI: 1.06–1.73, p < 0.05) at moderately high temperatures (90th percentile of temperature range −29.5 °C) and extreme high temperatures (95th percentile of temperature range – 29.9 °C), respectively. ConclusionsRisk of AMI is associated with extremely high and extremely low temperature in Vietnam and the risk varies in relation to the local regional climate. Public health preparedness and multi-level interventions should attempt to reduce people's exposure in periods of disadvantageous temperatures.

Seasonal Variation in Diurnal Photosynthesis and Chlorophyll Fluorescence of Four Genotypes of Cassava (Manihot esculenta Crantz) under Irrigation Conditions in a Tropical Savanna Climate

Photosynthesis performance during early vegetative growth is an important physiological trait determining yield of cassava, but limited information is currently available for the tropical savanna climate of Asia. Diurnal photosynthesis and chlorophyll fluorescence of the three-month-old plants of four commercial cassava genotypes (Rayong 9, RY9; Rayong 11, RY11; Kasetsart 50, KU50 and CMR38-125-77) grown under irrigation, were investigated in three seasons i.e., rainy, cool and hot. The mean daily net photosynthetic rate (Pn) across genotypes in the rainy season (11.75 µmolCO2/m2/s) was significantly lower than that in the cool season (14.60 µmolCO2/m2/s). Daily mean Pn in the hot season was 14.32 µmolCO2/m2/s. In the rainy season, maximum photochemical quantum yield of PSII (Fv/Fm) and effective quantum yield of PSII photochemistry (ΦPSII) were significantly higher than the other seasons, while electron transfer rate (ETR) and non-photochemical quenching (NPQ) were significantly lower. Genotypic variation was observed during the hot season in which RY11 had the highest and CMR38-125-77 the lowest mean daily Pn. The prominent mechanism to avoid damages from stress during afternoon in the hot season was to reduce leaf temperature by enhancing transpiration for RY11; to close stomata early for RY9, and to increase NPQ for CMR38-125-77.

Estimation of electricity generation potential by solar radiation on Sardar Sarovar dam

Abstract The western region of the subcontinent of India experiences a tropical savanna climate. During summers, the temperature elevates to scorching 48oC, which causes intensification in the evaporation rate of the surface of the water bodies of that region. One such water body is the Sardar Sarovar dam’s reservoir. This gravity dam is one of the world’s largest dams and one of the pre-eminent renewable energy sources in the country. Even though Sardar Sarovar Dam generates surplus electricity around the year, in summer, the value takes a dip. This is when the Global Horizontal Solar Irradiance (GHI) is at peak. This benefactor has been utilised by the installation of solar panels on the still water area. A method was developed to exploit this solar radiation and to depress the evaporation rate of the reservoir to increase the output by the dam. A standard model was prepared for installation of offshore solar panels at the target site. The measured value of the GHI at three nearby locations was acquired from National Institute of Wind Energy’s database. This data was interpolated at the target area to estimate monthly GHI and calculate the solar angles and the solar farm parameters. These parameters were used for sensitivity analysis to determine the variation in electricity potential by implementing different types of solar panels. The maximum value of power that can be generated by the farm was estimated to be 173.6 MW. This is 0.59% of the total power generated by the state and 2.77% of the power generated by the renewable sources in the state.