Effects Of High Temperature Stress Research Articles

Changes in Photosynthetic Characteristics of Paeonia suffruticosa under High Temperature Stress

This study explored the changes in the photosynthetic characteristics of the Fengdan peony under high-temperature stress to provide a reference for understanding the tolerance of peony plants under heat stress. In this study, the effects of high-temperature stress (40 °C) on the photosynthetic characteristics of the Fengdan leaves were studied. At 25 °C, the net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) of the leaves decreased gradually with the increase in heat stress time, and intercellular CO2 concentration (Ci) decreased first and then increased. High-temperature stress reduced the light energy absorption (ABS/RC) and capture (TRO/RC), light energy for electron transport (ETO/RC), and heat dissipation (DIO/RC) per unit leaf area. The maximum photochemical efficiency (FV/FM), leaf photochemical performance index (PIabs), the probability that captured excitons can transfer electrons to other electron acceptors in the electron transport chain beyond QA (ψO), and the quantum yield for electron transport (φEo), decreased gradually. The results showed that high temperatures damaged the photosynthetic capacity of the peony leaves and destroyed the photosynthetic apparatus of leaves. This study provides a reference for understanding the photosynthetic characteristics and tolerance of peony plants under heat stress.

Effect of High Temperature Stress During the Reproductive Stage on Grain Yield and Nutritional Quality of Lentil (Lens culinaris Medikus).

High temperature during the reproductive stage limits the growth and development of lentil (Lens culinaris Medikus). The reproductive and seed filling periods are the most sensitive to heat stress, resulting in limited yield and nutritional quality. Climate change causes frequent incidents of heat stress for global food crop production. This study aimed to assess the impact of high temperature during the reproductive stage of lentil on grain yield, nutritional value, and cooking quality. Thirty-six lentil genotypes were evaluated under controlled conditions for their high temperature response. Genotypic variation was significant (p < 0.001) for all the traits under study. High temperature-induced conditions reduced protein, iron (Fe) and zinc (Zn) concentrations in lentils. Under heat stress conditions, mineral concentrations among lentil genotypes varied from 6.0 to 8.8 mg/100 g for Fe and from 4.9 to 6.6 mg/100 g for Zn. Protein ranged from 21.9 to 24.3 g/100 g. Cooking time was significantly reduced due to high temperature treatment; the range was 3–11 min, while under no stress conditions, cooking time variation was from 5 to 14 min. Phytic acid variation was 0.5–1.2 g/100 g under no stress conditions, while under heat stress conditions, phytic acid ranged from 0.4 to 1.4 g/100 g. All genotypes had highly significant bioavailable Fe and moderately bioavailable Zn under no stress conditions. Whereas under heat stress conditions, Fe and Zn bioavailability was reduced due to increased phytic acid levels. Our results will greatly benefit the development of biofortified lentil cultivars for global breeding programs to generate promising genotypes with low phytic acid and phytic acid/micronutrient ratio to combat micronutrient malnutrition.

Overexpression of &amp;lt;italic&amp;gt;ZmCIPKHT&amp;lt;/italic&amp;gt; enhances heat tolerance in plant

<p id="C3">The effects of high temperature stress on the normal growth and yield of plants is more and more serious. To adapt the changes of external environment, plants have evolved a series of molecular genetic mechanisms to respond to high temperature stress. The calcineurin B-like protein (CBL) interacting protein kinase (CIPK) is actively involved in response to high temperature stress depended on ABA signal transduction pathway in plants. Based on previous genome-wide association analysis, a candidate gene <italic>ZmCIPKHT</italic> related to maize high temperature tolerance was cloned in this study. Real-time quantitative PCR results showed that <italic>ZmCIPKHT</italic> gene was significantly induced by high temperature stress. Transient transformation of maize protoplasts revealed that ZmCIPKHT was localized in the nucleus. Overexpressing <italic>ZmCIPKHT</italic> plants of transgenic <italic>Arabidopsis thaliana</italic> had significantly higher survival rate and better growth status than wild type under high temperature stress. The yeast two-hybrid experiment confirmed that the interaction between ZmCIPKHT protein and ZmCBL4 protein in maize CBLs family. The relative expression levels of genes related to abscisic acid (ABA) pathway in transgenic <italic>Arabidopsis thaliana</italic> with <italic>ZmCIPKHT</italic> under high temperature stress were changed accordingly, indicating that the regulations of <italic>ZmCIPKHT</italic> genes under high temperature stress were in the ABA-dependent pathway. These results provide a new experimental basis for elucidating the molecular mechanism of maize CBL-CIPK signaling pathway dependent on ABA pathway to abiotic stress in plants.

Recovery Characteristics of Cry1Ac Endotoxin Expression and Related Physiological Mechanisms in Bt Transgenic Cotton Squares after High-Temperature Stress Termination

High-temperature stress reduces the endotoxin expression of the insecticidal gene (Cry1Ac) in transgenic Bacillus thuringiensis (Bt) cotton and affects nitrogen metabolism. However, its effects on Cry1Ac endotoxin expression after high-temperature stress termination remain unclear. In order to investigate the effect of high-temperature stress on the expression of insecticidal proteins in Bt cotton squares, the conventional Sikang-1 cultivar and hybrid Sikang-3 cultivar were used as the experimental materials. The potted cotton plants in the squaring stage were moved to an artificial climatic chamber at 38 °C for 72 h and 96 h in 2017 and 2018, respectively, and plants were moved to the climate chamber where the control cotton plants were located (at 27 °C). Then, cotton squares were collected to measure the Bt protein concentration and nitrogen metabolism physiology at 0, 12, 24, 48, 72 and 96 h after high-temperature stress termination, respectively. The Cry1Ac endotoxin expression of the squares could be recovered to the corresponding control level and a longer recovery time was required as the high-temperature stress period increased. Therefore, the recovery degree of Cry1Ac endotoxin expression of cotton squares can be predicted according to the duration of high-temperature stress, which may provide a reference for the rational control of Helicoverpa armigera and related pests in cotton production.

Foliar application of a mixture of putrescine, melatonin, proline, and potassium fulvic acid alleviates high temperature stress of cucumber plants grown in the greenhouse

Putrescine (Put), melatonin (MT), proline (Pro), and potassium fulvic acid (MFA) are widely used as the plant growth regulators to enhance stress tolerance. However, the roles of their mixtures in response to stress are largely unknown. Here, we mixed Put with MT, Pro, and MFA (hereafter referred to as Put mixture) with different concentrations and foliar sprayed at different growth stages (seedling, flowering, and fruiting stage) of cucumber (<italic>Cucumis sativus</italic> L.) to investigate their roles on plant growth, fruit yield, and quality under high temperature stress. The foliar application of the Put mixture promoted cucumber growth, increased chlorophyll and Pro contents and net photosynthesis rate, and reduced the values of relative electrolyte leakage, H₂O₂ and malondialdehyde contents of cucumber leaves, indicating that treatment with Put mixture reduced the oxidative stress caused by high temperature. Furthermore, Put mixture-treated cucumber plants had lower fruit deformity rate and higher fruit yield compared with control. The contents of vitamin C and soluble solids of cucumber fruit significantly increased and the contents of tannin and organic acid decreased. The most profound effects were found in the plants treated with 8 mmol L⁻¹ Put, 50 µmol L⁻¹ MT, 1.5 mmol L⁻¹ Pro and 0.3 g L⁻¹ MFA every 7 d for three times at the seedling stage, indicating that cucumber seedlings treated with the mixture of Put, MT, Pro, and MFA significantly alleviated the negative effects of high temperature stress.

Effects of High-Temperature Stress during Plant Cultivation on Tomato (Solanum lycopersicum L.) Fruit Nutrient Content

Agriculture is among the sectors that will be impacted first and most by the adverse effects of climate change. Therefore, developing new high-temperature tolerant varieties is an essential economic measure in adaptation to near-future climate change. Likewise, there is a growing interest in increasing the antioxidant content of crops to improve food quality and produce crops with high-stress tolerance. Tomato is the most grown and consumed species in horticultural plants; however, it is vulnerable to 35°C and above high temperatures during cultivation. This study used twenty high-temperature tolerant, two susceptible genotypes, and two commercial tomato varieties in the open field. The experiment was applied under control and high-temperature stress conditions based on a randomized block design with 4 replications and 12 plants per repetition. The study investigated the fruit’s selected quality properties and antioxidant compounds, namely, total soluble solutes (Brix), titratable acidity, pH, electrical conductivity (EC), lycopene, β-carotene, and vitamin C, along with total phenols and total flavonoids under control and stress conditions. As a result, in general, total soluble solutes, titratable acidity, total phenol, and vitamin C contents under high-temperature conditions were determined to increase in tolerant tomato genotypes, while decreases were noted for pH, EC, total flavonoids, lycopene, and β-carotene. However, different specific responses on the basis of genotypes and useful information for breeding studies have been identified. These data on fruit nutrient content and antioxidants will be helpful when breeding tomato varieties to be grown in high-temperature conditions.

Effect of High-Temperature Stress on Plant Physiological Traits and Mycorrhizal Symbiosis in Maize Plants.

Increasing high temperature (HT) has a deleterious effect on plant growth. Earlier works reported the protective role of arbuscular mycorrhizal fungi (AMF) under stress conditions, particularly influencing the physiological parameters. However, the protective role of AMF under high-temperature stress examining physiological parameters with characteristic phospholipid fatty acids (PLFA) of soil microbial communities including AMF has not been studied. This work aims to study how high-temperature stress affects photosynthetic and below-ground traits in maize plants with and without AMF. Photosynthetic parameters like quantum yield of photosystem (PS) II, PSI, electron transport, and fractions of open reaction centers decreased in HT exposed plants, but recovered in AMF + HT plants. AMF + HT plants had significantly higher AM-signature 16:1ω5cis neutral lipid fatty acid (NLFA), spore density in soil, and root colonization with lower lipid peroxidation than non-mycorrhizal HT plants. As a result, enriched plants had more active living biomass, which improved photosynthetic efficiency when exposed to heat. This study provides an understanding of how AM-mediated plants can tolerate high temperatures while maintaining the stability of their photosynthetic apparatus. This is the first study to combine above- and below-ground traits, which could lead to a new understanding of plant and rhizosphere stress.

Effects of High Temperature Stress on Leaf Chlorophyll Fluorescence Characteristics of Kiwifruit

Kiwifruit is a vine with poor resistance to high temperature. The original habitat is mostly semi shade environment under mountain forest, with humid air, mild temperature change and weak light. The main problem in production is that the temperature of tree is often too high when the tree is introduced from the original forest environment in mountainous areas to cultivated under the direct sunlight in farmland. The leaves, fruits and trunks often get damaged.With the background of climate warming, in Shaanxi, the main kiwifruit producing area, extreme high temperature weather with daily maximum temperature over 40 ℃ often occurs. The high temperature damage of kiwifruit is particularly prominent, such as leaf wilting, shedding, fruit sunburn, fruit drop, and even tree death.In order to explore the effects of high temperature stress on photosynthetic apparatus of kiwifruit leaves and establish a heat injury identification index based on chlorophyll fluorescence response, the variation characteristics of the FO(minimal recorded fluorescence intensity), Fm(maximal recorded fluorescence intensity), Fa(maximal photochemistry efficiency), ΔWK(relative variable fluorescence difference at 300 μs), Tr(trapped energy flux per area at t=0), Et(electron transport flux per area at t=0), Dd(dissipated energy flux per area at t=0), Rm (density of QA-reducing PSⅡ reaction centers) in kiwifruit leaves under 30 ℃, 33 ℃, 36 ℃, 39 ℃, 42 ℃, 45 ℃, 48 ℃, 50 ℃, 52 ℃, 54 ℃ condition are studied by using the technique of fast chlorophyll fluorescence induction dynamics analysis(JIP-test). The results show that Tr, Rm and ΔWK are all affected by temperature stress in the range of 30-54 ℃, which belongs to PSⅡ sensitive site parameters, in which Tr, Rm show a linear downward trend with the increase of stress temperature, while ΔWK shows an exponential upward trend with the increase of stress temperature. FO, Fm, Fa, Dd, Et show stable or less variable under lower temperature stress, and intensified under higher temperature stress, which belongs to the secondary sensitive site parameters of PSⅡ. Most chlorophyll fluorescence parameters have two mutation critical points at 39 ℃ and 45 ℃. The results show that kiwifruit leaves have mild temperature stress at 30 ℃ ≤ T < 39 ℃, moderate temperature stress at 39 ℃ ≤ T < 45 ℃, and severe temperature stress at T ≥ 45 ℃.

Exogenous Sucrose Protects Potato Seedlings Against Heat Stress by Enhancing the Antioxidant Defense System

To analyze the ability of exogenous sucrose application to moderate adverse effect of high-temperature stress on potato seedlings. Potato (Solanum tuberosum L.) seedlings were pretreated with 100-mM sucrose solution for 24 h and then exposed to a heat stress treatment at 42 °C. Our results showed that exogenous sucrose enhanced the thermotolerance of potato seedlings and alleviated morphological injuries caused by heat stress. Sucrose pretreatment was found to efficiently inhibit heat stress-induced increases in electrolyte leakage in potato leaves and to reduce the accumulation of reactive oxygen species (ROS) such as superoxide radicals (O2•-) and hydrogen peroxide (H2O2) under heat stress. Sucrose treatment alone was found to significantly enhance peroxidase activity (POD), ascorbate peroxidase (APX), and endogenous sucrose content. Additionally, sucrose pretreatment was also found to help maintain higher activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), APX, and POD, and to increase the accumulation of endogenous sucrose and proline in leaves when potato seedlings were exposed to heat stress for 6 and 8 h. Our results show that sucrose can alleviate the detrimental effects of heat stress on potato seedlings by enhancing the antioxidant enzyme system and increasing sucrose and proline accumulation. Therefore, exogenous sucrose treatment may be a useful experimental tool to enable potato plants to tolerate heat that might otherwise cause plants to accumulate lethal levels of ROS.

Differing thermal sensitivities in a host–parasitoid interaction: High, fluctuating developmental temperatures produce dead wasps and giant caterpillars

Abstract Insect parasitoids, and the arthropod hosts they consume during development, are important ecological players in almost all environments across the globe. As ectothermic organisms, both parasitoid and host are strongly impacted by environmental temperature. If thermal tolerances differ between host insect and parasitoid, then the outcome of their interaction will be determined by the ambient temperature. As mean temperatures continue to rise and extreme temperatures become more frequent, we must determine the effect of high temperature stress on host–parasitoid systems to predict how they will fare in the face of climate change. The majority of studies conducted on host–parasitoid systems focus on either performance under constant temperature or a fixed metric of thermal tolerance (CTmax) for individual organisms. However, performance at constant temperatures is not predictive of performance under ecologically relevant, fluctuating temperatures and measurements of thermal thresholds provide little information regarding the effects of temperature throughout development. We address this by testing the effects of increasing mean temperature in both constant and fluctuating (±10°C) environments throughout development on the performance of the parasitoid wasp Cotesia congregata and its lepidopteran larval host, Manduca sexta. The growth of M. sexta was influenced by mean temperature, diurnal fluctuations and parasitization status. Caterpillar growth rate increased with increasing mean temperature, but decreased in response to diurnal fluctuations and parasitization by C. congregata wasps. Wasp survival decreased with increasing mean temperature and with diurnal fluctuations. The effect of diurnal fluctuations was stronger at higher mean temperatures. Diurnal fluctuations at our highest mean temperature treatment (30 ± 10°C) resulted in complete wasp mortality, and parasitized hosts displayed abnormal physiology, wherein they failed to exhibit wasp emergence, did not enter the prepupal stage, continued to feed and grew up to twofold larger than a normal, unparasitized caterpillar. Our results indicate hosts and parasitoids in this system have different thermal tolerances during development; the parasitoid wasp suffered complete mortality at a temperature regime that is mildly stressful for the unparasitized caterpillar host species. Our findings suggest C. congregata will suffer more severely under increasing temperatures than M. sexta, with cascading trophic and ecological effects. A free Plain Language Summary can be found within the Supporting Information of this article.

Nitric Oxide Enhances Photosynthetic Nitrogen and Sulfur-Use Efficiency and Activity of Ascorbate-Glutathione Cycle to Reduce High Temperature Stress-Induced Oxidative Stress in Rice (Oryza sativa L.) Plants.

The effects of nitric oxide (NO) as 100 µM sodium nitroprusside (SNP, NO donor) on photosynthetic-nitrogen use efficiency (NUE), photosynthetic-sulfur use efficiency (SUE), photosynthesis, growth and agronomic traits of rice (Oryza sativa L.) cultivars, Taipie-309 (high photosynthetic-N and SUE) and Rasi (low photosynthetic-N and SUE) were investigated under high temperature stress (40 °C for 6 h). Plants exposed to high temperature stress caused significant reduction in photosynthetic activity, use efficiency of N and S, and increment in H2O2 and thiobarbituric acid reactive substance (TBARS) content. The drastic effects of high temperature stress were more pronounced in cultivar Rasi than Taipie-309. However, foliar spray of SNP decreased the high temperature induced H2O2 and TBARS content and increased accumulation of proline and activity of ascorbate–glutathione cycle that collectively improved tolerance to high temperature stress more effectively in Taipie-309. Exogenously applied SNP alleviated the high temperature induced decrease in photosynthesis through maintaining higher photosynthetic-NUE and photosynthetic-SUE, activity of ribulose 1,5 bisphosphate carboxylase/oxygenase (Rubisco), and synthesis of reduced glutathione (GSH). The use of 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxy-3-oxide (cPTIO, NO scavenger) substantiated the study that in the absence of NO oxidative stress increased, while NO increased photosynthetic-NUE and photosynthetic-SUE, net photosynthesis and plant dry mass. Taken together, the present investigation reveals that NO increased heat stress tolerance and minimized high temperature stress adversaries more effectively in cultivar Taipie-309 than Rasi by enhancing photosynthetic-NUE and SUE and strengthening the antioxidant defense system.

Grain-filling of superior spikelets and inferior spikelets for japonica rice under low-amplitude warming regime in lower reaches of Yangtze River Basin

AbstractGrain-filling, as the final growth stage of rice, is sensitive to environmental temperature change. Previous studies mainly concerned about the effects of high temperature stress during grain-filling on rice growth, and most experiments were carried out with pot for cultivating rice and greenhouse for warming. This research investigated the response of rice grain-filling of superior spikelets (SS) and inferior spikelets (IS) of two japonica cultivars to elevated temperature during grain-filling stage under open-field warming conditions in lower reaches of Yangtze River Basin using free-air temperature enhancement facility. Results indicated that rice yield was not significantly changed by warming less than 4°C. SS and IS showed different responses to elevated temperature during the grain-filling stage, whereas there were similar trends between two cultivars and years. For SS, although elevated temperature enhanced its filling rate during the early grain-filling period, and caused a shorter grain-filling period and a lighter grain weight; for IS, elevated temperature improved its grain weight by enhancing its filling rate during middle and late grain-filling period due to the increased number of days with suitable temperature. For both SS and IS, key starch biosynthesis enzymes and indole-3-acetic acid content exhibited generally a similar dynamics trend with grain-filling rates, and these sink strength parameters presented higher levels under elevated temperature relative to natural temperature for IS during middle and late grain-filling period. Consequently, warming less than 4°C presented different influences on SS and IS; the improvement of IS filling under warming regime was associated with the intensification of grain sink strength.

Effect of fungicide pretreatment on lipid peroxidation, antioxidant enzyme systems and proline accumulation in tomato (Lycopersiconesculentum Mill.) leaves under high temperature stress

The aim of the present study was to determine the effect of high temperature stress (HT) and to evaluate the protective role of fungicide pretreatment against HT stress in tomato leaves. The oxidative stress was triggered under HT stress through an increase in the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2). Also, it caused a decline in photosynthetic pigments and enhanced the proline in tomato. However, the activities of catalase (CAT; EC 1.11.1.6), peroxidase (POX; EC 1.11.1.7), and glutathione S-transferase (GST; EC.2.5.1.18), as well as ascorbate-glutathione cycle enzymes (APX, EC 1.11.1.11, DHAR, EC 1.8.5.1, MDHAR EC 1.6.5.4, GR; EC 1.6.4.2) were found to be increased after heat treatment. In addition, the transcript level of LeCAT1, LeAPX1, LeAPX6, LecGR, LeDHAR genes was up-regulated under HT stress. Foliar pretreatment of fungicide improved the physiological process that decrease H2O2 and MDA content, enhance pigment content, increase proline accumulation and CAT, POX, and GST activity, as well as LeCAT1 and LeGST2 transcript levels compared to nonpretreated leaves under control temperature. When tomato leaves exposed to high temperature stress, fungicide pretreatment accelerated the antioxidant enzyme system by enhancing activities and gene expression levels of CAT, POX, GST, and ascorbate-glutathione enzyme, resulting in the decrement of MDA and H2O2 contents. Further, the protective effect of fungicide pretreatment improved the efficiency of the photosynthetic pigment under HT stress. Consequently, the study was to indicate the evidence for the ability of potential use of fungicide as a protective agent against HT stress in tomato.

Physiological and molecular responses to thermal stress in red cusk-eel (Genypterus chilensis) juveniles reveals atrophy and oxidative damage in skeletal muscle.

The red cusk-eel (Genypterus chilensis) is a native species with strong potential to support Chilean aquaculture diversification. Environmental stressors, such as temperature, may generate important effects in fish physiology with negative impact. However, no information exists on the effects of thermal stress in Genypterus species or how this stressor affects the skeletal muscle. The present study evaluated for the first time the effect of high temperature stress in red cusk-eel juveniles to determine changes in plasmatic markers of stress (cortisol, glucose and lactate dehydrogenase (LDH)), the transcriptional effect in skeletal muscle genes related to (i) heat shock protein response (hsp60 and hsp70), (ii) muscle atrophy and growth (foxo1, foxo3, fbxo32, murf-1, myod1 and ddit4), and (iii) oxidative stress (cat, sod1 and gpx1), and evaluate the DNA damage (AP sites) and peroxidative damage (lipid peroxidation (HNE proteins)) in this tissue. Thermal stress generates a significant increase in plasmatic levels of cortisol, glucose and LDH activity and induced heat shock protein transcripts in muscle. We also observed an upregulation of atrophy-related genes (foxo1, foxo3 and fbxo32) and a significant modulation of growth-related genes (myod1 and ddit4). Thermal stress induced oxidative stress in skeletal muscle, as represented by the upregulation of antioxidant genes (cat and sod1) and a significant increase in DNA damage and lipid peroxidation. The present study provides the first physiological and molecular information of the effects of thermal stress on skeletal muscle in a Genypterus species, which should be considered in a climate change scenario.

Using of Nano - Selenium in Reducing the Negative Effects of High Temperature Stress on Chrysanthemum morifolium Ramat.

Under climate change, the escalating in temperature is considered a serious challenge threaten the agricultural production. This production includes food, feed and all other human needs. These higher temperatures represent heat stress, which cause physiological and biochemical damages in cultivated plants. Nano-selenium (nano-Se) has distinguished features enhancing the cultivated plants under stress. These features include the high bioactivity of nano-Se, which ameliorate the growth of different cultivated plants under different abiotic and biotic stresses such as salinity, drought, waterlogging and heat stress. This study was carried out to investigate the ameliorative role of nano-Se on two sensitive chrysanthemum cultivars under high temperature stress (i.e., 39.5, 40.6 and 41.6℃). The growth of these cultivars, plant antioxidant system and floral attributes were investigated under graded nano-Se doses (i.e., 50, 100, 150 and 200 mg nano-Se L-1) during two successive growth seasons. The foliar application of nano-Se improved heat tolerance in chrysanthemum by enhancing the activities of antioxidant enzymes including catalase and peroxidase (up to 150 mg nano-Se L-1) and decreasing polyphenol oxidase and electrolyte leakage up to 200 mg nano-Se L-1. The nano-Se-treated cut chrysanthemum flowers under heat stress indicated the positive effects of nan-Se on improving of flower quality and the economic value. These results may confirm the definite roles of nano-Se in management the heat stress-induced adverse effects on not only cut chrysanthemum flowers but also other crops under climate change.

Effect of high temperature stress during ripening on the accumulation of key storage compounds among Japanese highly palatable rice cultivars

High temperature stress during ripening increases the frequency of chalky grains, resulting in a lower market value for rice (Oryza sativa L.). Changes in starch properties and the accumulation pattern of storage proteins are proposed to be related to the occurrence of chalky grains. This study investigated changes in the accumulation of key storage compounds in the grains of Japanese highly palatable rice cultivars, subjected to high temperature stress when grown in a growth chamber and the field. The 13 kDa prolamin content was significantly reduced in a highly heat-sensitive cultivar, Tsukushiroman, whereas the 13 kDa prolamin content was not affected in a heat-tolerant cultivar, Genkitsukushi, even in a high temperature chamber condition (31/26 °C day/night), when compared with the control chamber condition (26/21 °C day/night) for both genotypes. In addition, grains grown in field conditions revealed that severely chalky grains had less 13 kDa prolamin than perfect grains in all five genotypes. Changes in amylose content and the distribution of amylopectin chain lengths did not explain the difference in grain appearance both for chamber and field experiments. These results strongly suggest that physiological processes linked with the synthesis of 13 kDa prolamin are associated with grain appearance in Japanese highly palatable under high temperature stress.

Effects of high temperature stress during anthesis and grain filling periods on photosynthesis, lipids and grain yield in wheat

BackgroundShort episodes of high temperature (HT) stress during reproductive stages of development cause significant yield losses in wheat (Triticum aestivum L.). Two independent experiments were conducted to quantify the effects of HT during anthesis and grain filling periods on photosynthesis, leaf lipidome, and yield traits in wheat. In experiment I, wheat genotype Seri82 was exposed to optimum temperature (OT; 22/14 °C; day/night) or HT (32/22 °C) for 14 d during anthesis stage. In experiment II, the plants were exposed to OT or HT for 14 d during the grain filling stage. During the HT stress, chlorophyll index, thylakoid membrane damage, stomatal conductance, photosynthetic rate and leaf lipid composition were measured. At maturity, grain yield and its components were quantified.ResultsHT stress during anthesis or grain filling stage decreased photosynthetic rate (17 and 25%, respectively) and grain yield plant− 1 (29 and 44%, respectively), and increased thylakoid membrane damage (61 and 68%, respectively) compared to their respective control (OT). HT stress during anthesis or grain filling stage increased the molar percentage of less unsaturated lipid species [36:5- monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG)]. However, at grain filling stage, HT stress decreased the molar percentage of more unsaturated lipid species (36:6- MGDG and DGDG). There was a significant positive relationship between photosynthetic rate and grain yield plant− 1, and a negative relationship between thylakoid membrane damage and photosynthetic rate.ConclusionsThe study suggests that maintaining thylakoid membrane stability, and seed-set per cent and individual grain weight under HT stress can improve the photosynthetic rate and grain yield, respectively.

Amelioration of high temperature stress by exogenously applied salicylic acid: Genotype‐specific response of physiological traits

AbstractIn arid and semi‐arid regions of the world, high temperature stress adversely affects growth and development of cool‐season grasses during late spring and summer. Salicylic acid (SA) is one of the endogenous plant growth regulators that plays an important role in the regulation of plant growth and development in response to high temperature stress. The aim of the present study was to assess the effectiveness of SA in alleviating the negative effects of high temperature during the summer in different tall fescue (Festuca arundinacea Schreb.) genotypes under field conditions. Twenty genotypes of tall fescue (selected from a broad native and exotic germplasm) were assessed at field condition for morphological and physiological characteristics during 2016 and 2017 under normal irrigation in the presence of two SA concentrations (0 and 1 mM). High temperature during the summer led to induction of incomplete summer dormancy and depression in summer forage yield. Application of SA decreased the adverse effects of high temperature stress by elevation of photosynthetic pigments, proline accumulation, and increasing nonenzyme and enzymatic antioxidant activities, and could therefore be used to enhance forage yield and heat tolerance in tall fescue genotypes. The genotypes exhibited obvious differences in their response to SA application under the semiarid climate conditions of central Iran. Among the studied genotypes, 3L and 1E were recognized as heat tolerant and stable genotypes that would be preferable for regions with high temperature.

Dampak Suhu Tinggi terhadap Pertumbuhan dan Hasil Tanaman Padi

Global warming becomes a pressure in food production sustainability because it affected crop growth and development. The purpose of this study was to obtain information on the effect of high-temperature stress on the growth and development phase of rice and to evaluate the genotype for tolerance to high-temperature stress. Two environment conditions were used in the field and greenhouse of IPB Cikabayan experimental field, IPB University from August 2016 until February 2017. The study used varieties of IPB 4S, IPB 6R, Mekongga, and Situ Patenggang. High-temperature treatment was done by transferring the rice plants to the greenhouse at 50 days after transplanting. Observations were made on the generative phase in two different environmental conditions. The results showed that the total tillers number, filled grain number per panicle, unfilled grain number per panicle, total grain number per panicle, grain filling rate, percentage of filled grain and filled grain weight per plant had different responses among rice genotypes due to high-temperature stress. High-temperature decreased pollen fertility in all genotypes, which classified IPB 4S as a sensitive genotype and Mekongga as a tolerant genotype. This information could be useful for development and improving rice variety to anticipate high-temperature stress.&#x0D; Keywords: Climate change, fertility, pollen, stress tolerance index

Effect of high temperature stress on seed filling and nutritional quality of rice (&lt;em&gt;Oryza sativa&lt;/em&gt; L.)

Effect of high temperature stress on seed filling and nutritional quality of rice (&lt;em&gt;Oryza sativa&lt;/em&gt; L.)