scholarly journals Physiological responses of garden roses to hot and humid conditions 

2019 ◽  
Vol 46 (No. 1) ◽  
pp. 26-33
Author(s):  
Lijuan Xie ◽  
Hua Zhang ◽  
Deying Li
Keyword(s):  
Superoxide Dismutase ◽  
Heat Stress ◽  
Relative Humidity ◽  
Heat Tolerance ◽  
Electrolyte Leakage ◽  
Physiological Responses ◽  
Net Photosynthesis ◽  
Marie Curie ◽  
Saturated Vapour ◽  
Net Photosynthesis Rate

Garden roses do not grow well under hot and humid conditions. The objective of this study was to investigate the physiological responses of ‘Marie Curie’ and ‘Lapjau’ to high temperatures and relative humidity. The study included temperatures of 25/18°C (day/night) and 35/28°C (day/night), and relative humidity of 70% and 100%. ‘Marie Curie’ was more tolerant to heat stress than ‘Lapjau’ based on relative electrolyte leakage (REL), malondialdehyde (MDA), and activities of superoxide dismutase (SOD). The heat tolerance of cultivars also was confirmed by the levels of chlorophyll content and the net photosynthesis rate. Both cultivars were more stressed under more water vapour deficit than saturated vapour at 35/28°C (day/night), while at 25/18°C (day/night) the cultivars were more stressed under saturated humidity condition than at 70% relative humidity. In conclusion, combined hot and saturated humidity does not necessarily result in increased stress over separated heat or humidity elevations to the garden roses. Rose growers can use this information in regions where hot and humid conditions concur.

scholarly journals Detrimental effects of heat stress on grain weight and quality in rice (Oryza sativa L.) are aggravated by decreased relative humidity

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11218
Author(s):  
Haoliang Yan ◽  
Chunhu Wang ◽  
Ke Liu ◽  
Xiaohai Tian
Keyword(s):  
Heat Stress ◽  
Relative Humidity ◽  
Heat Tolerance ◽  
Grain Filling ◽  
Grain Weight ◽  
Maximum Temperature ◽  
Daily Maximum Temperature ◽  
Filling Stage ◽  
Head Rice ◽  
Grain Filling Stage

There is concern over the impact of global warming on rice production due increased heat stress, coupled with decreased relative humidity (RH). It is unknown how rice yield and quality are affected by heat stress and decreased RH during the grain filling stage. We conducted experiments in controlled growth chambers on six rice cultivars, varying in heat tolerance using 12 combinative treatments of three factors: two RH levels (75% and 85%), three temperature levels (the daily maximum temperature at 33 °C, 35 °C, and 37 °C), and two durations (8 d and 15 d after anthesis). Results showed that RH75% with temperature treatments significantly reduced grain weight, which was higher than RH85%. The same trend was also observed for both head rice rate and chalkiness. R168 was the most heat-tolerant cultivar, but it still had some differences in grain weight, head rice rate, and chalkiness between the two RH regimes. The lower RH was most detrimental at 35 °C, and to a lesser extent at 33 °C, but had a negligible effect at 37 °C. Our results provide a better understanding of temperature and RH’s interaction effects on rice quality during the grain filling stage, suggesting that RH should be considered in heat tolerance screening and identification to facilitate rice breeding and genetic improvement.

scholarly journals SHORT DURATION HEAT PRECONDITIONING AND HEAT TOLERANCE IN ORNAMENTAL BEDDING PLANTS

HortScience ◽  
2005 ◽  
Vol 40 (3) ◽  
pp. 874d-874
Author(s):  
Seenivasan Natarajan ◽  
Jeff S. Kuehny ◽  
James E. Board
Keyword(s):  
Heat Stress ◽  
Stomatal Conductance ◽  
Plant Growth ◽  
Short Duration ◽  
Heat Tolerance ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
High Temperature Stress ◽  
Bedding Plants ◽  
Heat Tolerant

One of the greatest impediments to production of marketable ornamental herbaceous plants in southern U.S. is high temperature stress. Exposure of plants to sub-lethal temperature (heat preconditioning) before sustained heat stress helps some plants to tolerate subsequent heat stress a phenomenon often referred as acquired thermotolerance. The objective of this research was to examine various morphological, physiological and anatomical responses of `Vista red' (heat tolerant) and `Sizzler red'(heat sensitive) cultivars of Salvia splendens to heat preconditioning (HC) and subsequent heat stress treatments (challenging temperatures, CT). Cultivars of Salvia were subjected to short duration HC of 35 °C for 3 hours every third day until 5 weeks after germination and subsequent exposure to two CT treatments 30/23 °C and 35/28 °C (D/N) cycles in growth chambers for the next five weeks. Plant growth, marketable quality, stomatal conductance and net photosynthesis declined for Sizzler Red without HC treatment. Compared with nonpreconditioned plants, heat preconditioned Sizzler Red had 38.28% higher root dry weight, 95% greater leaf thickness, 50% higher marketable quality at 35/28 °C heat stress condition. Heat preconditioning helped both Vista Red and Sizzler to survive in both the heat stress treatments. Vista Red had greater heat tolerant traits than Sizzler Red, these traits exacerbated with heat preconditioning treatment. The results demonstrated that heat preconditioning enhanced heat tolerance in cultivars of Salvia, which could be related to maintenance of dense plant growth with shorter internodes, thicker stems, greater stomatal conductance, extensive root growth that compensated the transpirational water loss and overall cooling of plants.

Phenotyping from lab to field – tomato lines screened for heat stress using Fv/Fm maintain high fruit yield during thermal stress in the field

2019 ◽  
Vol 46 (1) ◽  
pp. 44 ◽  
Author(s):  
Damodar Poudyal ◽  
Eva Rosenqvist ◽  
Carl-Otto Ottosen
Keyword(s):  
Heat Stress ◽  
Heat Tolerance ◽  
Pollen Viability ◽  
Crop Improvement ◽  
Field Performance ◽  
Net Photosynthesis ◽  
Plant Size ◽  
Fruit Yield ◽  
Heat Sensitivity ◽  
Solanum Lycopersicum L

This study aimed to phenotype young tomato (Solanum lycopersicum L.) plants for heat tolerance by measuring Fv/Fm after short-term heat treatments in climate chambers and selected sensitive (low Fv/Fm) and tolerant (high Fv/Fm) cultivars to investigate their in-field performance. Twenty-eight genotypes were phenotyped at 40:28°C for 2 days in climate chambers. A second screening (four high Fv/Fm and four low Fv/Fm genotypes) was conducted for 4 days at 38:28°C, followed by 5 days’ recovery (26:20°C). The tolerant genotypes maintained high net photosynthesis (PN) and increased stomatal conductance (gs) at 38°C, allowing better leaf cooling. Sensitive genotypes had lower Fv/Fm and PN at 38°C, and gs increased less than in the tolerant group, reducing leaf cooling. Under controlled conditions, all eight genotypes had the same plant size and pollen viability, but after heat stress, plant size and pollen viability reduced dramatically in the sensitive group. Two tolerant and two sensitive genotypes were grown in the field during a heat wave (38:26°C). Tolerant genotypes accumulated more biomass, had a lower heat injury index and higher fruit yield. To our knowledge, this is the first time screening for heat tolerance by Fv/Fm in climate chambers was verified by a field trial under natural heat stress. The differences after heat stress in controlled environments were comparable to those in yield between tolerant and sensitive groups under heat stress in the field. The results suggest that Fv/Fm is effective for early detection of heat tolerance, and screening seedlings for heat sensitivity can speed crop improvement.

Effects of exogenous application of abscisic acid on membrane stability, osmotic adjustment, photosynthesis and hormonal status of two lucerne (Medicago sativa L.) genotypes under high temperature stress and drought stress

2014 ◽  
Vol 65 (3) ◽  
pp. 274 ◽  
Author(s):  
Yuan An ◽  
Peng Zhou ◽  
Jinfeng Liang
Keyword(s):  
Heat Stress ◽  
Photosynthetic Rate ◽  
Electrolyte Leakage ◽  
Physiological Responses ◽  
Proline Content ◽  
Water Conditions ◽  
Medicago Sativa L ◽  
Heat Tolerant ◽  
Soil Water Conditions ◽  
Aba Content

This study was designed to examine effects of high temperature, drought and exogenous abscisic acid (ABA) on membrane stability, osmotic adjustment, photosynthesis and the hormone status of two lucerne (alfalfa, Medicago sativa L.) genotypes contrasting in heat tolerance: Ameristand 801S (AS801) (heat-tolerant), and Aohan (heat-sensitive), The results showed that AS801 had lower electrolyte leakage, but higher chlorophyll content, net photosynthetic rate, stomatal conductance, proline content, ABA content and zeatin riboside (ZR) content than Aohan during 72 h of heat stress under well-watered conditions. Under drought conditions, however, only proline content and ZR content in roots, electrolyte leakage in leaves and roots, net photosynthetic rate, and ABA content were significantly different between the two genotypes. A foliar application of ABA to heat-stressed plants significantly decreased electrolyte leakage and stomatal conductance, and increased recovery in growth and leaf water potential in the two genotypes under both watering conditions. The other physiological responses measured differed under drought or well-watered conditions, and appeared to be genotype-specific. These results suggest that the physiological responses of heat-sensitive and heat-tolerant lucerne to heat stress under different soil-water conditions varied. The heat-induced changes in proline accumulation in roots, electrolyte leakage in leaves and roots, and photosynthetic rate could serve as early instant stress indicators for evaluating the tolerance of lucerne genotypes to heat stress under different soil water conditions.

scholarly journals Mikroklimat, Termoregulasi dan Produktivitas Sapi Perah Friesians Holstein pada Ketinggian Tempat Berbeda

2019 ◽  
Vol 6 (1) ◽  
pp. 70
Author(s):  
Elmy Mariana ◽  
Cece Sumantri ◽  
Dewi Apri Astuti ◽  
Anneke Anggraeni ◽  
Asep Gunawan
Keyword(s):  
Heat Stress ◽  
Heat Tolerance ◽  
Environmental Temperature ◽  
Physiological Responses ◽  
Mild Stress ◽  
Altitude Effect ◽  
Temperature Humidity Index ◽  
Humidity Index ◽  
Kg Medium ◽  
Different Altitudes

ABSTRAKTujuan penelitian ini adalah untuk mengetahui pengaruh ketinggian tempat terhadap kondisi mikroklimat,termoregulasi dan produktivitas sapi Friesian-Holstein (FH). Penelitian dilakukan pada tiga lokasi dengan ketinggian berbeda, yaituPodok Ranggon (97mdpl), Ciawi (576mdpl), dan Lembang (1241mdpl). Sebanyak 63 sapi FH dalam kondisi laktasi normal digunakan dalam penelitian ini.  Aspek lingkungan meliputi suhu udara, kelembaban relatif dan Temperature-Humidity Index di dicatat setiap 2 jam dari pukul 08.00 sampai 16.00 WIB. Parameter termoregulasi yang diamati terdiri atas suhu kulit (Ts),suhu rektal (Tr), suhu tubuh (Tb), denyut jantung (Hr),laju pernapasan (Rr), dan Heat Tolerance Coeficient (HTC).Berdasarkan nilai Ta, Rr dan THI, dataran rendah memberikan dampak cekaman panas sedang, dataran sedangdan tinggi memberikan dampak cekaman panas ringan pada sapi perah. Hasil menunjukkan bahwa sapi dataran rendah memiliki Nilai HTC, Tr, Ts dan Tb tertinggi (P<0,05) dan Hr yang terendah (P<0,05). Produksi susu di ketiga lokasi penelitian berbeda nyata (P<0,05), dengan produksi susu tertinggi di dataran tinggi (13,1±3,52 kg),dataran sedang (11,3±4,73 kg) dan dataran rendah (7,0±3,36 kg). Secara umum sapi FH di dataran rendah, sedang dan tinggi tercekam panas akibat kondisi lingkungan yang berada pada kondisi di luar zona nyamanselama musim kemarau, akan tetapi mampu beradaptasi terhadap kondisi tersebut. Kata kunci: ketinggian tempat, produktivitas, sapi perah, cekaman panas, termoregulasiABSTRACTThe purpose of this research was to determine altitude effect on microclimate, thermoregulation and productivity of Friesian Holstein. Research was conducted in different altitudes, i.e.: Pondok Ranggon (97m asl), Ciawi (576m asl), and Lembang (1241 m asl). A total of 63 FH cows in normal lactation were used in this study. Microclimate aspects observation includes environmental temperature (Ta), relative humidity (RH) and Temperature-Humidity Index (THI) were recorded every 2 hours from 08.00 to 16.00. The physiological responses measurements consisted of skin temperature (Ts), rectal temperature (Tr), body temperature (Tb), heart rate (Hr), respiratory rate (Rr) and Heat Tolerance Coeficient (HTC). Lowland environmental provide moderate heat stress, while the medium and highland impacts with mild stress. The results showed that lowland cows have highest HTC, Tr, Ts and Tb (P<0.05) and lowest Hr (P<0.05). Milk production in the different altitude was significantly different (P<0.05), with the highest milk yields in the highlands (13.1±3.52 kg), medium (11.3±4.73 kg) and lowland (7.0±3.36 kg). In general, HF dairy cows in low-, medium- and highland are exposed to climatic stress during dry season conditions, although they have the ability to adapt physiologically and cope with environmental stress.  Keyworlds: altitude, dairy cattle, heat stress, productivity, physiological responses

Repeated thermal conditioning during the neonatal period affects behavioral and physiological responses to acute heat stress in chicks

2020 ◽  
Vol 94 ◽  
pp. 102759
Author(s):  
Yoshimitsu Ouchi ◽  
Hiroshi Tanizawa ◽  
Jun-ichi Shiraishi ◽  
John F. Cockrem ◽  
Vishwajit S. Chowdhury ◽  
...  
Keyword(s):  
Heat Stress ◽  
Neonatal Period ◽  
Physiological Responses ◽  
Acute Heat Stress

scholarly journals The Effect Of Outside Corridor’s Orientation to Interior Thermal Condition at Lawang Sewu Semarang.

2018 ◽  
Vol 73 ◽  
pp. 01011
Author(s):  
Benediktus Yosef Arya Wastunimpuna ◽  
Wahyu Setia Budi ◽  
Erni Setyowati
Keyword(s):  
Heat Stress ◽  
Relative Humidity ◽  
Thermal Condition ◽  
Natural Ventilation ◽  
Thermal Conditions ◽  
Standard Theory ◽  
Hot Wire ◽  
Air Movement ◽  
Dutch Colonial

The outside corridor of Dutch Colonial Building in Indonesia was made to make the temperature of the room more comfortable. Lawang Sewu Building in Semarang is one example of a building that has an outside corridor along the building and until now still use natural ventilation. This study focuses on finding out whether there is a difference on the thermal conditions of each room’s orientation, so after that we know the effect of orientation of the outdoor corridor to the temperature of the interior. In this study the experiment based on measurement using Heat Stress WBGT Meter for Wet Bulb Temperature, Dry Bulb Temperature, Relative Humidity, and KW0600653 Hot Wire Anemometer for the air movement. The data will be analysed using thermal standard theory to find out which point has the most comfortable thermal conditions.. At the end of this study will be found the effect of corridor’s orientation to thermal condition of the interior in Lawang Sewu Semarang.

scholarly journals Exploring Morpho-Physiological Variation for Heat Stress Tolerance in Tomato

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 347
Author(s):  
Samikshya Bhattarai ◽  
Joshua Harvey ◽  
Desire Djidonou ◽  
Daniel Leskovar
Keyword(s):  
Heat Stress ◽  
Chlorophyll Fluorescence ◽  
Open Field ◽  
Electrolyte Leakage ◽  
Leaf Gas Exchange ◽  
Total Yield ◽  
Stress Conditions ◽  
Heat Injury ◽  
Injury Index ◽  
Heat Tolerant

Texas tomato production is vulnerable to extreme heat in the spring-summer cropping period, which is exacerbated by the lack of superior genetic materials that can perform well in such environments. There is a dire need for selecting superior varieties that can adapt to warm environments and exhibit high yield stability under heat stress conditions. This research aimed at identifying heat-tolerant varieties under heat-stress conditions in controlled and open-field environments and was carried out in three stages. For the first experiment, 43 varieties were screened based on yield responses in natural open-field environment. From those, 18 varieties were chosen and exposed to control (greenhouse: 26/20 °C) and constant heat-stress (growth-chamber: 34/24 °C) conditions for three months. Measurements were done for chlorophyll fluorescence, chlorophyll content (SPAD), plant height, stem diameter and heat injury index (HII). The last experiment was conducted in an open field with a pool of varieties selected from the first and second experiments. Leaf gas exchange, leaf temperature, chlorophyll fluorescence, SPAD value, electrolyte leakage, heat injury index and yield were assessed. From the combined studies, we concluded that heat-tolerant genotypes selected by using chlorophyll fluorescence and HII in controlled heat-stress conditions also exhibited heat-tolerance in open-field environments. Electrolyte leakage and HII best distinguished tomato varieties in open-field environments as plants with low electrolyte leakage and HII had higher total yield. 'Heat Master,' 'New Girl,' 'HM-1823,' 'Rally,' 'Valley Girl,' 'Celebrity,' and 'Tribeca' were identified as high heat-tolerant varieties. Through trait correlation analysis we provide a better understanding of which traits could be useful for screening and breeding other heat-tolerant tomato varieties.

scholarly journals Genotype-by-environment interaction in Holstein heifer fertility traits using single-step genomic reaction norm models

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Rui Shi ◽  
Luiz Fernando Brito ◽  
Aoxing Liu ◽  
Hanpeng Luo ◽  
Ziwei Chen ◽  
...  
Keyword(s):  
Heat Stress ◽  
Dairy Cattle ◽  
Candidate Genes ◽  
Heat Tolerance ◽  
Reaction Norm ◽  
Single Step ◽  
Conception Rate ◽  
Critical Periods ◽  
Genotype By Environment ◽  
Fertility Traits

Abstract Background The effect of heat stress on livestock production is a worldwide issue. Animal performance is influenced by exposure to harsh environmental conditions potentially causing genotype-by-environment interactions (G × E), especially in highproducing animals. In this context, the main objectives of this study were to (1) detect the time periods in which heifer fertility traits are more sensitive to the exposure to high environmental temperature and/or humidity, (2) investigate G × E due to heat stress in heifer fertility traits, and, (3) identify genomic regions associated with heifer fertility and heat tolerance in Holstein cattle. Results Phenotypic records for three heifer fertility traits (i.e., age at first calving, interval from first to last service, and conception rate at the first service) were collected, from 2005 to 2018, for 56,998 Holstein heifers raised in 15 herds in the Beijing area (China). By integrating environmental data, including hourly air temperature and relative humidity, the critical periods in which the heifers are more sensitive to heat stress were located in more than 30 days before the first service for age at first calving and interval from first to last service, or 10 days before and less than 60 days after the first service for conception rate. Using reaction norm models, significant G × E was detected for all three traits regarding both environmental gradients, proportion of days exceeding heat threshold, and minimum temperature-humidity index. Through single-step genome-wide association studies, PLAG1, AMHR2, SP1, KRT8, KRT18, MLH1, and EOMES were suggested as candidate genes for heifer fertility. The genes HCRTR1, AGRP, PC, and GUCY1B1 are strong candidates for association with heat tolerance. Conclusions The critical periods in which the reproductive performance of heifers is more sensitive to heat stress are trait-dependent. Thus, detailed analysis should be conducted to determine this particular period for other fertility traits. The considerable magnitude of G × E and sire re-ranking indicates the necessity to consider G × E in dairy cattle breeding schemes. This will enable selection of more heat-tolerant animals with high reproductive efficiency under harsh climatic conditions. Lastly, the candidate genes identified to be linked with response to heat stress provide a better understanding of the underlying biological mechanisms of heat tolerance in dairy cattle.

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