Search

Introduction: Crops are vulnerable to precipitation and heat extremes during late spring through summer. Methods: We analyzed for a north-central U.S. region short-term drought and agricultural heat stress during April-May-June-July. We used the 4-km Parameter Elevation Regression on Independent Slopes Model (PRISM) for observations, aggregated to a 25-km grid, and two 25-km Regional Climate Model version 4 (RegCM4) simulns used either GFDL- or MPI-GCM boundary conditions. We chose 1981-2000 as our contemporary time period, and 2041-2060 as our scenario time period, which used the Representative Concentration Pathway 8.5 emissions scenario. We used object-oriented analysis to identify events of interest in observations and simulations by identifying objects in a space-time domain that meet specified criteria, such as exceeding a heat-stress temperature threshold. The event diagnosis allowed analysis of compound events, occurring when temperature and drought objects overlap. Results: Identified objects yielded events that can undermine agricultural productivity and which are thus relevant to decision makers, making them building blocks for possible climate storylines. The observations and simulations showed similar spatial distributions of event frequencies across the analysis region. However, the simulations attained this distribution by having fewer events that tend to cover larger areas compared to observed events, suggesting that the effective resolution of the simulations was coarser than their 25-km grids. Short-term drought frequency increased and heat-stress frequency decreased in transitioning to the scenario climate. When compounding occurred heat-stress events generally preceded the short-term drought events. The overlapping, compound events tended to be more extreme compared to non-overlapping events of either type. Discussion: The information yielded projected changes in these agriculturally motivated events. One prominent conditional behavior emerging from the work was that a heat-stress event should be a warning to watch for potential drought, as both could compound each other to more intense levels. [ABSTRACT FROM AUTHOR]

Background: Cotton is a strategically important fibre crop for global textile industry. It profoundly impacts several countries' industrial and agricultural sectors. Sustainable cotton production is continuously threatened by the unpredictable changes in climate, specifically high temperatures. Breeding heat-tolerant, high-yielding cotton cultivars with wide adaptability to be grown in the regions with rising temperatures is one of the primary objectives of modern cotton breeding programmes. Therefore, the main objective of the current study is to figure out the effective breeding approach to imparting heat tolerance as well as the judicious utilization of commercially significant and stress-tolerant attributes in cotton breeding. Initially, the two most notable heat-susceptible (FH-115 and NIAB Kiran) and tolerant (IUB-13 and GH-Mubarak) cotton cultivars were spotted to develop filial and backcross populations to accomplish the preceding study objectives. The heat tolerant cultivars were screened on the basis of various morphological (seed cotton yield per plant, ginning turnout percentage), physiological (pollen viability, cell membrane thermostability) and biochemical (peroxidase activity, proline content, hydrogen peroxide content) parameters. Results: The results clearly exhibited that heat stress consequently had a detrimental impact on every studied plant trait, as revealed by the ability of crossing and their backcross populations to tolerate high temperatures. However, when considering overall yield, biochemical, and physiological traits, the IUB-13 × FH-115 cross went over particularly well at both normal and high temperature conditions. Moreover, overall seed cotton yield per plant exhibited a positive correlation with both pollen viability and antioxidant levels (POD activity and proline content). Conclusions: Selection from segregation population and criteria involving pollen viability and antioxidant levels concluded to be an effective strategy for the screening of heat-tolerant cotton germplasms. Therefore, understanding acquired from this study can assist breeders identifying traits that should be prioritized in order to develop climate resilient cotton cultivars. [ABSTRACT FROM AUTHOR]

Objective: Heat stress is a significant factor leading to decreased crop yield. Exceeding the plant's temperature tolerance threshold in ecosystems often results in significant cellular damage and potentially cellular death. Signaling elicitors may mitigate elevated temperatures' detrimental impact and enhance plant defense mechanisms. Materials and Methods: The present study investigates the influence of varying temperatures (25, 30, 35, 40, and 45°C) and pre-harvest salicylic acid (SA) application (0, 0.5, 1.5, 2.5, 5, and 10 mM) on the morpho-physiological and biochemical attributes of maize. A factorial-based experiment was set up following a completely randomized design and conducted in a growth room. Results: The findings demonstrated that a 2.5 mM SA treatment at 35°C produced the largest plant leaf area and total chlorophyll content. The temperature and SA application interplay on carotenoid content were maximum at 5 mM. SA treatment under hightemperature conditions effectively elevated proline content, chl a, chl b, chl total, and malondialdehyde compared to untreated plants. The peak stomatal conductance was also observed with a 2.5 mM SA treatment at 30°C. The maximal catalase and peroxidase activities were recorded at 35°C. Furthermore, 2.5 mM SA at 25°C resulted in the highest levels of soluble proteins and RWC. SA (2.5 mM) applied at 30°C was more efficient at decreasing H2O2 production. The highest proline content was observed with 2.5 mM SA at 45°C. Conclusion: SA(2.5 mM) treatment can have optimal effects on maize plant growth parameters under high-temperature conditions, potentially mitigating the damaging effects of heat stress. [ABSTRACT FROM AUTHOR]

Heat and drought are prominent abiotic stressors that limit crop productivity and yield, particularly concerning climate change; therefore, understanding the molecular mechanisms underlying plant stress responses is crucial for stress-tolerant crop production. This study conducted a transcriptomic analysis to elucidate how garlic (Allium sativum L.) responds to drought and heat stress conditions. Transcriptome libraries were generated to identify differentially expressed genes (DEGs) induced by drought and heat stresses. Functional classification and clustering analysis of DEGs revealed stress-specific gene expression patterns. Notably, cell wall-related genes were implicated in the drought response, whereas heat stress was associated with heat stress transcription factors and heat shock proteins. Our results provide essential information for future studies on stress tolerances in garlic. [ABSTRACT FROM AUTHOR]

It is predicted that the average world temperature will rise by 1.5 °C in the next few decades, which may adversely affect vegetable productivity and global food security. The present study aimed to identify lettuce genotype(s) that are tolerant of heat stress so that they may be good candidates for future breeding programs to develop heatstress-tolerant lettuce cultivars. While using a complete randomized design with three replicates, we evaluated the performance of eight lettuce genotypes using a hydroponic system under non-stress (controlled) and heat stress (high temperature) environmental treatments. The effects of environmental treatments on the morphophysiological and agronomic characteristics of the genotypes were assessed. Ten traits were recorded after harvest, i.e., the number of leaves, plant height, root length, yield, fresh root weight, plant weight, leaf area, leaf width, leaf length, and chlorophyll contents. In general, lettuce genotypes cultivated under heat stress exhibited decreased performance in most traits compared to the non-stress treatment group. The yield of SAL092, SAL093, SAL094, SAL095, SAL096, SAL097, and SAL099 decreased by 65.8%, 66.4%, 65%, 28.2%, 40.6%, 76.3%, and 73.1%, respectively, under heat stress. In contrast, SAL098 grown under non-stress conditions showed higher yield, leaf count, root length, plant weight, and plant height by 0.1%, 15.2%, 0.9%, 4%, and 27%, respectively, compared to non-stress conditions. In addition, during heat stress, every trait exhibited a positive correlation with yield, except leaf width, suggesting that productive attributes are crucial for enhancing yield under high-temperature conditions. SAL095 and SAL098 exhibited effective adaptive mechanisms and may be regarded as potential heat-tolerant genotypes for future breeding programs and developing heat-tolerant cultivars and high yields. [ABSTRACT FROM AUTHOR]

Chloroplast is one of the most sensitive organelles to heat stress in plants. In chloroplasts, various proteases affect photosynthesis by degrading proteins under stress conditions. Tomato Lutescent2 (SlL2), a chloroplast zinc metalloprotease, was previously reported to alter chloroplast development and delay fruit ripening. However, its enzyme activity and roles in plant response to abiotic stress are still unclear. Here, we confirmed that the SlL2 protein which localized on thylakoid membrane was an ATP-independent hydrolase, and SlL2 gene responded to heat stress. Phenotype analysis showed that SlL2 plays a negative role in the heat-response mechanism. Under heat stress, the transgenic plants overexpressing SlL2 (OE) grew worse than the wild type (WT), as reflected by their decreased membrane stability, osmotic-regulating substance, and antioxidative enzyme activities, as well as increased reactive oxygen species (ROS) accumulation. By contrast, l2 mutant line showed the opposite phenotype and corresponding physiological indices under heat stress. In addition, overexpression of SlL2 decreased the photosynthetic activities, especially photosystem II. Moreover, SlL2 was found to interact with chloroplast-located chaperone protein SlCDJ1, decreasing its content under heat stress. These results indicate that SlL2 reduces the thermotolerance of tomato by reducing the content of SlCDJ1. [ABSTRACT FROM AUTHOR]

In temperate climates, most fruit trees need cold weather, low temperatures in winter, and a certain amount of heat during the growing season until harvest. One of the most apparent effects of climate change is the elevated temperature in all seasons of the year. In our study, the changes in thermal conditions have been calculated in Hungary's most significant growing region of apples using the Chill Unit for winters and the Growing Degree Days for summers. The meteorological data were obtained from the gridded dataset of the Hungarian Meteorological Service on a 10 km × 10 km grid, so the whole studied area is well-covered over the last 50 years. The results show that the trees are more exposed to early budding than a few decades ago. Furthermore, the accumulated heat amount in summers has increased drastically, which may increase the heat stress and lead to higher yield losses. [ABSTRACT FROM AUTHOR]

To clarify the characteristics of photoinhibition and the primary defense mechanisms of ephemeral plant leaves against photodestruction under high temperature stress, inhibitors and the technology to determine chlorophyll fluorescence were used to explore the protective effects of D1 protein turnover and the lutein cycle in the high temperature stress of the leaves of three ephemeral plants. The results showed that the maximum light conversion efficiency (Fv/Fm) of the ephemeral plant leaves decreased, and the initial fluorescence (Fo) increased under 35°C ± 1°C heat stress for 1-4 h or on sunny days in the summer. Both Fv/Fm and Fo could be recovered after 8 h of darkness or afternoon weakening of the external temperature. Streptomycin sulfate (SM) or dithiothreitol (DTT) accelerated the decrease of Fv/Fm and the photochemical quenching coefficient (qP) in the leaves of three ephemeral plants at high temperature, and the decrease was greater in the SM than in the DTT treatment. When the high temperature stress was prolonged, the Y(II) values of light energy distribution parameters of PSII decreased, and the Y(NPQ) and Y(NO) values increased gradually in all the treatment groups of the three ephemeral plants. The results showed that the leaves of the three ephemeral plants had their own highly advanced mechanisms to protect against photodamage, which inhibited the turnover of D1 protein and xanthophyll cycle. This can damage the PSII reaction center in the leaves of the three ephemeral plants under high temperature. The protective effect of D1 protein turnover on heat stress in Erodium oxyrrhynchum and Senecio subdentatus was greater than that of the lutein cycle, while the protective effect of lutein cycle was greater than that of D1 protein turnover in Heliotropium acutiflorum subjected to heat damage. [ABSTRACT FROM AUTHOR]

As global temperature rise, the threat of heat stress to rapeseed production is becoming more obvious. Exploring the response characteristics of two important biological pathways, oil accumulation and photosynthesis, to heat stress during B. napus seed filling is helpful in the genetic improvement of heat-tolerant rapeseed. The effects of heat stress on seed oil accumulation and chlorophyll fluorescence characteristics of 29 B. napus germplasms with different oil content and environmental sensitivity, including 6 rapeseed varieties which exhibited environmentsensitive/insensitive and with high, medium or low oil content, were tested by whole plant heat stress or the in vitro silique culture system. Both assay exhibited similar trend on oil content of the rapeseed germplasms. The heat effect on the chlorophyll fluorescence kinetic parameters Fv/Fm, ETR and Y(II) were also consistent. Heat stress significantly decreased oil content, although there was abundant genetic variation on heat tolerance among the genotypes. Correlation analysis showed that the decrease rate of Fv/Fm of silique heat-stressed B. napus developing seed was positive correlative to the decrease rate of mature seed oil content of the whole plant heat-stressed rapeseed (R = 0.9214, P-value < 0.01). Overall, the results indicated that heat stress inhibited oil accumulation and photosynthesis in B. napus developing seed. The decrease rate of chlorophyll fluorescence parameter Fv/Fm of heat-stressed developing seed could be used as the index of heat tolerant rapeseed identification. Further, two heat insensitive rapeseed varieties with high oil content were identified. [ABSTRACT FROM AUTHOR]

Fifty-two potato (Solanum tuberosum L.) genotypes were evaluated in early crop season (75 days) at experimental field of ICAR-Central Potato Research Institute, Regional Station, Modipuram, Meerut, Uttar Pradesh, during 2020 and 2021. Significant differences were recorded among for tuber yield and tuber attributes like plant vigour (1-5 scale), foliage maturity (1-5 scale), tuber colour, tuber shape, eye depth and flash colour. The pooled results of 2020 and 2021 crop seasons indicated that eight genotypes namely Kufri Mohan (260 g), Kufri Lima (256 g), CP4149 (252g), Kufri Garima (241g), Kufri Bahar (239 g), CP3273 (236 g), Kufri Neelkanth (221 g), CP4143 (212 g), CP1326 (208 g) and Kufri Arun (207 g), were found high-yielding in term of total tuber yield/plant. The highest marketable tuber yield/plant was recorded in Kufri Lima (234g), CP4149 (230 g), Kufri Mohan (225 g), CP3273 (213 g), Kufri Bahar (211 g), Kufri Garima (208 g), CP4143 (190 g), Kufri Neelkanth (182 g), Atlantic (178 g) and Kufri Arun (177 g). The genotypes, CP1931, CP3319, CP3322, CP3450, CP3470, CP3499, CP4149, CP4238, Kufri Garima, Kufri Lima, Kufri Surya and Lady Rossetta, were found highly tolerant with 0% hopper burn incidence. Most of the genotypes were highly tolerant with 0% mite damage incidence except CP3495, CP3341and CP3472 (20%) and Kufri Sindhuri and Kufri Pukhraj (40%). On an overall basis CP4149, Kufri Mohan, Kufri Garima and Kufri Lima were found promising for high plant stand, plant vigour, marketable/total tuber yield, marketable/total tuber number and nil/low incidence of hopper and mite burn. [ABSTRACT FROM AUTHOR]

It is necessary to identify the appropriate traits that influence yield in a given environment as part of a breeding programme. The objective of this study was to identify the morphological traits that contribute to maize grain weight (GWt) under abiotic stress conditions. Three drought-tolerant maize varieties were grown under no-stress (NHWS), heat-stress (HS), and combined heat- and water-stress (CHWS) conditions. Data from 19 morphological traits were analysed. The correlation results revealed that eight traits consistently produced a significant positive relationship with GWt under the three growth conditions. The path coefficient analysis revealed that in the NHWS, HS, and CHWS conditions, five traits consistently had a positive direct effect on the GWt. Given the magnitude of the positive direct effects, increasing dry biomass yield, harvest index, and grain number in the NHWS; grain number, harvest index, and ear width in the HS; and harvest index, days till silk appearance, leaf chlorophyll content, and grain number in the CHWS will increase GWt. Under various abiotic stress conditions, maize phenotypic expression varied. Therefore, the identified traits that contributed positively to GWt under various stress conditions should be considered when developing a maize improvement programme in a stress-prone environment. [ABSTRACT FROM AUTHOR]

Because high temperatures impair rice production, it is desirable to elucidate the regulatory mechanisms involved in rice response to heat stress. The objectives of this study were to identify candidate genes and characterize their response patterns during rice adaptation to high temperatures at the seedling stage. Ten heat-associated quantitative-trait loci were identified in a genome-wide association study. Comparison of transcript abundances in heat-sensitive and heat-tolerant rice pools under heat stress revealed approximately 400 differentially expressed genes. The expression of genes from heatsensitive accessions changed more than those from heat-tolerant accessions under heat stress. Alternative splicing (AS) events responded to heat stress in rice. The types of AS variants significant different between the heat-sensitive and heat-tolerant accessions. Expression patterns differing between the heat-sensitive and heat-tolerant accessions were identified for genes known to be involved in heat stress. We identified eleven genes associated with rice heat stress response. These genes could be pyramided to breed heat-tolerant rice accessions. [ABSTRACT FROM AUTHOR]

Research on the morphophysiological behavior of forest seeds during germination with respect to climate change is scarce. To date, there have been no studies on the biochemical or morphological aspects of Ormosia spp. In this study, we subjected Ormosia coarctata seeds to various temperature conditions to investigate temperature-dependent impacts on morphology, reactive oxygen species (ROS) generation, antioxidant systems, and storage systems. Analyses were performed on seeds exposed to 25, 35, and 40 °C for 48, 96, and 144 h. The morphology was evaluated by radiation using a Faxitron MX-20 device. ROS production (superoxide anion and hydrogen peroxide), malonaldehyde (MDA), carbonylated proteins, antioxidant enzyme activity (superoxide dismutase [SOD], ascorbate peroxidase [APX], catalase [CAT], and peroxidase [POX]), β-carotene, lycopene, glucose, and reserve enzyme activity (α- and β-amylase, lipase, and protease) were analyzed by spectrophotometry. Heat stress (40 °C) decreased germination by 76.2% and 78.1% (compared to 25 and 35 °C, respectively), caused damage to the external morphology of the seed, increased the content of ROS, MDA, and carbonylated proteins, and reduced APX, CAT, and POX activity. Furthermore, heat stress decreased glucose content and α-amylase activity. These results suggest that an increase of 5 °C in temperature negatively affects germination, promotes oxidative stress, and induces deterioration in O. coarctata seeds. [ABSTRACT FROM AUTHOR]

Wheat production is seriously influenced by extreme hot weather, which has attracted increasing attention. It is important to compare wheat responses to heat at seedling and reproductive stages, to explore the potential relationship between the performances at different growing stages and the possibility of early selection to accelerate heat tolerance breeding. In this study, forty wheat genotypes were screened under heat stress at both seedling and adult stages. It was found that root lengths at seedling stage were severely reduced by heat stress with significant variations among wheat genotypes. Heat-tolerant genotypes at seedling stage showed less root length decrease than susceptible ones. Wheat genotypes tolerant at seedling stage showed higher yield at adult stage after heat treatment. The performances of wheat genotypes screened under heat stress at seedling and adult stages were ranked by seedling damage index and adult damage index. A significant positive relationship was found between heat tolerance at seedling stage and at adult stage (r = 0.6930), suggesting a similar tolerant/susceptible mechanism at different plant growth stages and the possibility of early selection at seedling stage for breeding heat tolerance. Extremely tolerant and susceptible genotypes with consistent performances at seedling and adult stages were genetically compared and associated SNP markers and linked candidate genes were identified. [ABSTRACT FROM AUTHOR]

The rapeseed mustard is one of the most important sources of edible oil in India and contributes 28.6% in total oilseed production. The mustard growing areas in India are experiencing the vast diversity in the agro climatic conditions. Here, we studied forty-nine advanced breeding lines of Brassica juncea L. for two consecutive years (2016-18) to examine the variations in the remobilization of assimilates from flowering to maturity stage and their contribution to seed filling under stressed environment. Further, we investigated the impact of high temperature on dry matter accumulation and partitioning from source to sink in Brassica germplasm. The synchronization between the seed filling stage and the onset of heat spell is critical event that determines the overall yield. Imbalances caused due to miss-matching of above events created hindrance in source-sink translocation, thus resulted in yield losses. Amount of remobilized dry matter, remobilization efficiency and remobilization percentage increased significantly, while the dry matter accumulation, total carbohydrates content and seed yield per plant declined in the late sown genotypes during both crop seasons. Reduced accumulation of photo assimilates under stress and higher sink demand resulted in more number of shriveled seeds leading to yield depression. The higher remobilization efficiency in late sown genotypes was strongly associated with dry matter at flowering that consequently tended to affect the final seed weight. This study will provide insights for better understanding of source-sink relationships in Indian mustard under heat stress and the differential remobilization efficiencies in the advanced breeding lines. [ABSTRACT FROM AUTHOR]

Climate change is happening at a breakneck speed around the world. Due to continuous alterations, the climate has created various abiotic stress situations in which heat stress is among the most crucial that negatively impact the growth, development, and metabolism of crops. When stress is too intense, the signaling process leading to cell apoptosis is also triggered. The plant reaction to high temperature (HT) depends on the degree, time duration for exposure, and plant type. Heat stress affects plant development by causing a variety of biochemical, morphological, physiological, and molecular modifications. The ability of plants to sense the HT signals, create and forward them, to begin necessary biochemical or physiological modifications to tolerate the stress is critical for their capability during HT stress. Furthermore, the responses of plants to heat stress (HS) are complicated, with unknown physiological features as well as molecular or gene pathways. A noteworthy feature of plants is that they show numeric transgenic, epigenetic approaches against heat stress. This review describes and discusses the numerous ways to improve plant thermotolerance and different molecular and physiological responses, modifications, and tolerance to HT at the cellular level. [ABSTRACT FROM AUTHOR]

Background: Clematis species are attractive ornamental plants with a variety of flower colors and patterns. Heat stress is one of the main factors restricting the growth, development, and ornamental value of Clematis. Clematis lanuginosa and Clematis crassifolia are large-flowered and evergreen Clematis species, respectively, that show different tolerance to heat stress. We compared and analyzed the transcriptome of C. lanuginose and C. crassifolia under heat stress to determine the regulatory mechanism(s) of resistance. Results: A total of 1720 and 6178 differentially expressed genes were identified from C. lanuginose and C. crassifolia, respectively. The photosynthesis and oxidation–reduction processes of C. crassifolia were more sensitive than C. lanuginose under heat stress. Glycine/serine/threonine metabolism, glyoxylic metabolism, and thiamine metabolism were important pathways in response to heat stress in C. lanuginose, and flavonoid biosynthesis, phenylalanine metabolism, and arginine/proline metabolism were the key pathways in C. crassifolia. Six sHSPs (c176964_g1, c200771_g1, c204924_g1, c199407_g2, c201522_g2, c192936_g1), POD1 (c200317_g1), POD3 (c210145_g2), DREB2 (c182557_g1), and HSFA2 (c206233_g2) may be key genes in the response to heat stress in C. lanuginose and C. crassifolia. Conclusions: We compared important metabolic pathways and differentially expressed genes in response to heat stress between C. lanuginose and C. crassifolia. The results increase our understanding of the response mechanism and candidate genes of Clematis under heat stress. These data may contribute to the development of new Clematis varieties with greater heat tolerance. [ABSTRACT FROM AUTHOR]

Urban heat islands (UHI) and rapid urbanisation create new health risks for residents of urban territories. The authors consider lawns as an eco-stabilising factor of the urban environment and an element of ensuring the environmental safety of the capital. The purpose of this study was to determine the qualitative state of lawns to the factors of the urban ecosystem and their thermoregulatory function. To determine the impact of anthropogenic factors on research objects, the study assessed the amount of emissions into the atmospheric air from stationary and mobile sources, satellite maps of the intensity of nitrogen dioxide emissions (NO2) and sulphur dioxide (SO2) in the city’s air basin, heat distribution, and normalised difference moisture index (NDMI). To assess the condition and quality of lawns, the methods of assessing the grasslands of A. A. Laptev (1983) and an unmanned aerial vehicle (UAV) were used. It was established that the results of the evaluation of lawn coenoses using the method of O.O. Laptev and UAV are correlated (r=0.87). Lawn areas that were rated as in “satisfactory condition” are characterised by a higher temperature on the heat map and lower NDMI values. Indicators of lawn cover that were rated as in “good condition” correlate with surface temperature and NDMI. The difference in surface temperatures over the area of the experimental sites reaches 5°C and depends on the objects surrounding the perimeter. It was established that lawn areas adjust the thermal mode of the urban system in the warm period of the year, and reduce the temperature of the asphalt surface by about 0.5°C, and together with flower and woody plants – by about 0.9°C. The study results improve the understanding of the physiological effects of heat stress on lawn areas, which allows developing practical strategies for managing urban green spaces with limited water resources and anthropogenic loads. [ABSTRACT FROM AUTHOR]

Khuzestan province has good potential for oilseed crops production, such as soybeans. At present, however, there are no suitable soybean cultivars in the country that can tolerate the hot conditions of this province well. Therefore, Gelareh Kalhor Agriculture Company, in coordination with the Ministry of Agriculture Jihad, has imported four soybean cultivars (BRS391, BRS232, BRS511, and BRS284) from Brazil. This study aimed to compare the yield of imported soybean cultivars tolerant to heat stress with common cultivars in the country (Rahmat, Caspian, and SK-93) in Dezful climate conditions. The experiment was performed in 2021 in a randomized complete block design with three replications. Results of the analysis of variance showed that soybean cultivars had significant effects on the number of branches per plant, pod production per plant, seeds per pod, 1000-seed weight, and seed yield. But, there was no statistically significant difference among the cultivars studied for seed oil and protein contents. The results showed that imported soybean cultivars were able to produce about 25% more pods per plant, 21% more seeds per pod, and 8% higher seed weight, and in total, 20% higher seed yield than common cultivars. Conversely, the potential for branching in common soybean cultivars in the country was about 33% higher than that of the imported cultivars from Brazil. Among the cultivars imported, BRS232 and BRS284 with seed yields of 2793 and 2697 kg ha-1, respectively, showed higher production potential than the other two cultivars. [ABSTRACT FROM AUTHOR]

Pepper (Capsicum annuum L.) is one of the most economically important crops worldwide. Heat stress (HS) can significantly reduce pepper yield and quality. However, changes at a molecular level in response to HS and the subsequent recovery are poorly understood. In this study, 17-03 and H1023 were identified as heat-tolerant and heat-sensitive varieties, respectively. Their leaves’ transcript abundance was quantified using RNA sequencing to elucidate the effect of HS and subsequent recovery on gene expression. A total of 11,633 differentially expressed genes (DEGs) were identified, and the differential expression of 14 randomly selected DEGs was validated using reverse-transcription polymerase chain reaction. Functional enrichment analysis revealed that the most enriched pathways were metabolic processes under stress and photosynthesis and light harvesting during HS and after recovery from HS. The most significantly enriched pathways of 17-03 and H1023 were the same under HS, but differed during recovery. Furthermore, we identified 38 heat shock factors (Hsps), 17 HS transcription factors (Hsfs) and 38 NAC (NAM, ATAF1/2, and CUC2), and 35 WRKY proteins that were responsive to HS or recovery. These findings facilitate a better understanding of the molecular mechanisms underlying HS and recovery in different pepper genotypes. [ABSTRACT FROM AUTHOR]

Global warming is predicted to be increased in the upcoming years, resulting in frequent heatwaves or hot days worldwide, which can seriously affect crop growth and productivity. The responses of heat stress to several photophysiological and biochemical traits in three tomato cultivars were investigated in a pot experiment, and the heat tolerance capability of these cultivars was evaluated based on the investigated traits. The experiment was followed by a factorial completely randomized design, and the factors were (i) tomato cultivars (BARI Hybrid Tomato-5, BARI Tomato-14, and BARI Tomato-15) and (ii) heat stress (control and heat). The plants of three tomato cultivars were exposed to short-term heat stress (four days at 38/25 ◦C day/night temperature) at the flowering stage. The measured traits such as dry mass, leaf greenness (SPAD), maximum photochemical efficiency of photosystem II (Fv/Fm), photosynthetic rate (A), stomatal conductance (gs), transpiration rate (E), leaf chlorophyll, and carotenoid content were significantly declined, while the catalase and ascorbate peroxidase activities were increased by heat stress in all three tomato cultivars except BARI Tomato-15, which showed unaltered gs, E, and carotenoids. The percent reduction (over control) in SPAD, Fv/Fm, A, total chlorophyll, and total carotenoids was significantly lower (11, 06, 25, 34, and 19%, respectively), whereas the percent increase in catalase and ascorbate peroxidase activities was substantially higher (70 and 72%, respectively) in BARI Tomato-15 than in other cultivars. Based on the measured physiological and biochemical traits, the cultivar BARI Tomato-15 showed better heat tolerance than the other cultivars. [ABSTRACT FROM AUTHOR]

High temperatures due to global warming can cause harmful effects on the productivity of lettuce, a cool-season crop. To identify lettuce heat shock protein (HSP) genes that could be involved in early responses to heat stress in plants, we compared RNA transcriptomes between lettuce plants with and without heat treatment of 37 °C for 1 h. Using transcriptome sequencing analyses, a total of 7986 differentially expressed genes (DEGs) were identified including the top five, LsHSP70A, LsHSP70B, LsHSP17.3A, LsHSP17.9A and LsHSP17.9B, which were the most highly differentially expressed genes. In order to investigate the temporal expression patterns of 24 lettuce HSP genes with a fold-change greater than 100 under heat stress, the expression levels of the genes were measured by qRT-PCR at 0, 1, 4, 8, 14, and 24 h time points after heat treatment. The 24 LsHSP genes were classified into three groups based on the phylogenetic analysis and/or major domains available in each protein, and we provided a potential link between the phylogenetic relationships and expression patterns of the LsHSP genes. Our results showed putative early heat-responsive lettuce HSP genes that could be possible candidates as breeding guides for the development of heat-tolerant lettuce cultivars. [ABSTRACT FROM AUTHOR]

A major agronomic challenge for chickpea (Cicer arietinum L.) production is temperatures above 35 °C, which causes reduced fertility and seed development. This study was aimed at assessing the phenotypic variation of chickpea genotypes under variable heat stress conditions. Chickpea genotypes were grown in heat‐stressed locations in both Ethiopia and India to assess phenotypic variation for heat tolerance. In addition, genomic relationships among the genotypes were assessed using genome‐wide single nucleotide polymorphism (SNP) markers. A total of 121 genotypes were assessed at three field sites in Ethiopia, under heat stress and nonstress conditions, and 57 genotypes were assessed under high‐heat‐stress conditions at the International Crops Research Institute for the Semiarid Tropics (ICRISAT) in Hyderabad, India. Data for five phenological and seven agromorphological traits were recorded. The results showed that the chickpea genotypes were severely affected by excessive heat at Hyderabad as compared with those planted under non‐heat‐stress conditions in Debre Zeit, Ethiopia. At extremely high temperatures, chickpea plants exhibited reduced floral initiation, arrested seed and pod development, shortened life cycles, and reduced plant height, seed size, grain yield, and yield‐related traits. Across stressed and nonstressed environments, there were highly significant differences among the genotypes for most of the traits (ANOVA, P ≤.001). Under heat‐stressed environments, DZ‐Cr‐0034 was found to be a highly tolerant, whereas DZ‐Cr‐0026 was found to be a highly sensitive genotype. Genetic relationships among the genotypes were determined using 5,722 SNPs, revealing a single group of Ethiopian genotypes with small number of cultivars showing introgression from Middle Eastern germplasm. This study clearly demonstrated that there is genetic variability in chickpea for heat tolerance that can be harnessed to meet expected shifts towards warmer climatic conditions. Core Ideas: Heat‐tolerant chickpea genotypes were screened under three heat‐stressed environments.Chickpea genotypes were evaluated under non‐heat‐stress environment for comparison.Genetic variability of genotypes for phenological and agromorphological traits were determined.The correlations among traits and genotypes were demonstrated.The genomic relations among the genotypes were assessed using SNPs. [ABSTRACT FROM AUTHOR]

Under high temperature stress, a large number of proteins in plant cells will be denatured and inactivated. Meanwhile Hsfs and Hsps will be quickly induced to remove denatured proteins, so as to avoid programmed cell death, thus enhancing the thermotolerance of plants. Here, a comprehensive identification and analysis of the Hsf and Hsp gene families in eggplant under heat stress was performed. A total of 24 Hsf-like genes and 117 Hsp-like genes were identified from the eggplant genome using the interolog from Arabidopsis. The gene structure and motif composition of Hsf and Hsp genes were relatively conserved in each subfamily in eggplant. RNA-seq data and qRTPCR analysis showed that the expressions of most eggplant Hsf and Hsp genes were increased upon exposure to heat stress, especially in thermotolerant line. The comprehensive analysis indicated that different sets of SmHsps genes were involved downstream of particular SmHsfs genes. These results provided a basis for revealing the roles of SmHsps and SmHsp for thermotolerance in eggplant, which may potentially be useful for understanding the thermotolerance mechanism involving SmHsps and SmHsp in eggplant. [ABSTRACT FROM AUTHOR]

Drought and heat stress affect global wheat production and food security. Since these climate hazards are expected to increase in frequency and intensity due to anthropogenic climate change, there is a growing need for effective planning and adaptive actions at all timescales relevant to the stakeholders and users in this sector. This work aims at assessing the forecast quality in predicting the evolution of drought and heat stress by using user-relevant agro-climatic indices such as Standardized Precipitation Evapotranspiration Index (SPEI) and Heat Magnitude Day Index (HMDI) on a multi-annual timescale, as this time horizon coincides with the long-term strategic planning of stakeholders in the wheat sector. We present the probabilistic skill and reliability of initialized decadal forecast to predict these indices for the months preceding the wheat harvest on a global spatial scale. The results reveal the usefulness of the study in a climate services context while showing that decadal climate forecasts are skillful and reliable over several wheat harvesting regions. [ABSTRACT FROM AUTHOR]

In-planta mechanisms of biochar (BC)-mediated improved growth were evaluated by examining oxidative stress, metabolic, and hormonal changes of Arabidopsis wild-type plants under basal or acute heat stress (–HS/ + HS) conditions with or without BC (+ BC/–BC). The oxidative stress was evaluated by using Arabidopsis expressing redox-sensitive green fluorescent protein in the plastids (pla-roGFP2). Fresh biomass and inflorescence height were greater in + BC(‒HS) plants than in the –BC(‒HS) plants, despite similar leaf nutrient levels, photosystem II (PSII) maximal efficiencies and similar oxidative poise. Endogenous levels of jasmonic and abscisic acids were higher in the + BC(‒HS) treatment, suggesting their role in growth improvement. HS in ‒BC plants caused reductions in inflorescence height and PSII maximum quantum yield, as well as significant oxidative stress symptoms manifested by increased lipid peroxidation, greater chloroplast redox poise (oxidized form of roGFP), increased expression of DNAJ heat shock proteins and Zn-finger genes, and reduced expression of glutathione-S-transferase gene in addition to higher abscisic acid and salicylic acid levels. Oxidative stress symptoms were significantly reduced by BC. Results suggest that growth improvements by BC occurring under basal and HS conditions are induced by acclimation mechanisms to 'microstresses' associated with basal growth and to oxidative stress of HS, respectively. [ABSTRACT FROM AUTHOR]

Pepper is a thermophilic crop, shallow-rooted plant that is often severely affected by abiotic stresses such as heat, salt, and drought. The growth and development of pepper is seriously affected by adverse stresses, resulting in decreases in the yield and quality of pepper crops. Small heat shock proteins (s HSPs) play a crucial role in protecting plant cells against various stresses. A previous study in our laboratory showed that the expression level of CaHSP18.1a was highly induced by heat stress, but the function and mechanism of CaHSP18.1a responding to abiotic stresses is not clear. In this study, we first analyzed the expression of CaHSP18.1a in the thermo-sensitive B6 line and thermo-tolerant R9 line and demonstrated that the transcription of CaHSP18.1a was strongly induced by heat stress, salt, and drought stress in both R9 and B6, and that the response is more intense and earlier in the R9 line. In the R9 line, the silencing of CaHSP18.1a decreased resistance to heat, drought, and salt stresses. The silencing of CaHSP18.1a resulted in significant increases in relative electrolyte leakage (REL) and malonaldehyde (MDA) contents, while total chlorophyll content decreased under heat, salt, and drought stresses. Overexpression analyses of CaHSP18.1a in transgenic Arabidopsis further confirmed that CaHSP18.1a functions positively in resistance to heat, drought, and salt stresses. The transgenic Arabidopsis had higher chlorophyll content and activities of superoxide dismutase, catalase, and ascorbate peroxidase than the wild type (WT). However, the relative conductivity and MDA content were decreased in transgenic Arabidopsis compared to the wild type (WT). We further showed that the CaHSP18.1a protein is localized to the cell membrane. These results indicate CaHSP18.1a may act as a positive regulator of responses to abiotic stresses. [ABSTRACT FROM AUTHOR]

Tomatoes are usually consumed daily in the human diet. High temperatures reduce the number of tomato yields per year. Heat stress has been considered one of the most prominent causes of alterations in morphological and molecular characteristics in crops that decrease normal growth, production, and yield in diverse plants, including tomatoes (Solanum lycopersicum L.). In this study, we evaluated six tomato lines, namely G1, G2, G3, G4, G5, and G6, at morphological, molecular, and cytological levels under heat stress. The average results of two seasons (2018 and 2019) clarified that the G6, G1, and G2 lines recorded the highest flowering values, as well as some fruit and vegetative growth traits. Furthermore, G6 and G2 had the maximum number of fruits/plant, whereas G2 and G1 produced the highest yield/plant under high temperatures. The number of chromosomes in all lines was 2n = 24, except for G5, in which the number was 2n = 26, whereas chromosome sizes were small, ranging from 323.08 to 464.48 µm. The G1 cultivar was a symmetrical cultivar (primitive), having the highest total form percentage (TF%) and symmetry index (Syi) values and the minimum karyotype asymmetry index (ASK) value, whereas G4 was asymmetrical (advanced). Molecular marker analysis demonstrated that intersimple sequence repeat (ISSR) primers 49A, HB-14, 49A, 49B, and 89B presented the highest values for polymorphism percentage P%, marker index (MI), effective multiplex ratio (EMR), and polymorphism information content (PIC), respectively. In contrast, OP-A3, OP-B3, SCoT 2, and SCoT 12 primers showed the highest PIC, EMR, MI, P%, and resolving power (Rp) values across the studied random amplified polymorphic DNA (RAPD) and start codon-targeted (SCoT) primers. Moreover, ISSR revealed the highest number of unique specific markers (6), followed by RAPD (4) and SCoT (3) markers. Cluster analysis of combined cytological data and data relating to molecular marker attributes separated the G1, G2, and G3 lines into one group, whereas the other lines were clustered in another group. On the whole, the application of combined analysis using morphological, cytological, and molecular genetics techniques could be considered to provide suitable parameters for studying the evolution of the genetic divergence between the studied tomato lines [ABSTRACT FROM AUTHOR]

Spot blotch and terminal heat are two of the most important stresses for wheat in South Asia. A study was initiated to explore the use of spelt (Triticum spelta) to improve tolerance to these stresses in spring wheat (T. aestivum). We assessed 185 recombinant inbred lines (RILs) from the cross T. spelta (H + 26) × T. aestivum (cv. HUW234), under the individual stresses and their combination. H + 26 showed better tolerance to the single stresses and also their combination; grain yield in RILs was reduced by 21.9%, 27.7% and 39.0% under spot blotch, terminal heat and their combined effect, respectively. However, phenological and plant architectural traits were not affected by spot blotch itself. Multivariate analysis demonstrated a strong negative correlation between spikelet sterility and grain yield under spot blotch, terminal heat and their combination. However, four recombinant lines demonstrated high performance under both stresses and also under their combined stress. The four lines were significantly superior in grain yield and showed significantly lower AUDPC than the better parent. This study demonstrates the potential of spelt wheat in enhancing tolerance to spot blotch and terminal heat stresses. It also provides comprehensive evidence about the expression of yield and phenological traits under these stresses. [ABSTRACT FROM AUTHOR]

Improving the heat tolerance of cotton is a major concern for breeding programs. To address this need, a fast and effect way of quantifying thermotolerant phenotypes is required. Triphenyl tetrazolium chloride (TTC) based enzyme viability testing following high-temperature stress can be used as a vegetative heat tolerance phenotype. This is because when live cells encounter a TTC solution, TTC undergoes a chemical reduction producing a visible, insoluble red product called triphenyl formazan, that can be quantified spectrophotometrically. However, existing TTC based cell viability assays cannot easily be deployed at the scale required in a crop improvement program. In this study, a heat stress assay (HSA) based on the use of TTC enzyme viability testing has been refined and improved for efficiency, reliability, and ease of use through four experiments. Sampling factors that may influence assay results, such as leaf age, plant water status, and short-term cold storage, were also investigated. Experiments conducted in this study have successfully downscaled the assay and identified an optimal sampling regime, enabling measurement of large segregating populations for application in breeding programs. The improved HSA methodology is important as it is proposed that long-term improvements in cotton thermotolerance can be achieved through the concurrent selection of superior phenotypes based on the HSA and yield performance in hot environments. Additionally, a new way of interpreting both heat tolerance and heat resistance was developed, differentiating genotypes that perform well at the time of a heat stress event and those that maintain a similar performance level to a non-stressed control. [ABSTRACT FROM AUTHOR]

Long noncoding RNAs (lncRNAs) are widely present in different species and play critical roles in response to abiotic stresses. However, the functions of lncRNAs in Chinese cabbage under heat stress remain unknown. Here, we first conducted a global comparative analysis of 247,242 lncRNAs among 37 species. The results indicated that lncRNAs were poorly conserved among different species, and only 960 lncRNAs were homologous to 524 miRNA precursors. We then carried out lncRNA sequencing for a genome-wide analysis of lncRNAs and their target genes in Chinese cabbage at different stages of heat treatment. In total, 18,253 lncRNAs were identified, of which 1229 differentially expressed (DE) lncRNAs were characterized as being heat-responsive. The ceRNA network revealed that 38 lncRNAs, 16 miRNAs, and 167 mRNAs were involved in the heat response in Chinese cabbage. Combined analysis of the cis- and trans-regulated genes indicated that the targets of DE lncRNAs were significantly enriched in the "protein processing in endoplasmic reticulum" and "plant hormone signal transduction" pathways. Furthermore, the majority of HSP and PYL genes involved in these two pathways exhibited similar expression patterns and responded to heat stress rapidly. Based on the networks of DE lncRNA-mRNAs, 29 and 22 lncRNAs were found to interact with HSP and PYL genes, respectively. Finally, the expression of several critical lncRNAs and their targets was verified by qRT-PCR. Overall, we conducted a comparative analysis of lncRNAs among 37 species and performed a comprehensive analysis of lncRNAs in Chinese cabbage. Our findings expand the knowledge of lncRNAs involved in the heat stress response in Chinese cabbage, and the identified lncRNAs provide an abundance of resources for future comparative and functional studies. [ABSTRACT FROM AUTHOR]

WRKY transcription factors (TFs) are of great importance in plant responses to different abiotic stresses. However, research on their roles in the regulation of thermotolerance remains limited. Here, we investigated the function of LlWRKY39 in the thermotolerance of lily (Lilium longiflorum 'white heaven'). According to multiple alignment analyses, LlWRKY39 is in the WRKY IId subclass and contains a potential calmodulin (CaM)-binding domain. Further analysis has shown that LlCaM3 interacts with LlWRKY39 by binding to its CaM-binding domain, and this interaction depends on Ca2+. LlWRKY39 was induced by heat stress (HS), and the LlWRKY39-GFP fusion protein was detected in the nucleus. The thermotolerance of lily and Arabidopsis was increased with the ectopic overexpression of LlWRKY39. The expression of heat-related genes AtHSFA1, AtHSFA2, AtMBF1c, AtGolS1, AtDREB2A, AtWRKY39, and AtHSP101 was significantly elevated in transgenic Arabidopsis lines, which might have promoted an increase in thermotolerance. Then, the promoter of LlMBF1c was isolated from lily, and LlWRKY39 was found to bind to the conserved W-box element in its promoter to activate its activity, suggesting that LlWRKY39 is an upstream regulator of LlMBF1c. In addition, a dual-luciferase reporter assay showed that via protein interaction, LlCaM3 negatively affected LlWRKY39 in the transcriptional activation of LlMBF1c, which might be an important feedback regulation pathway to balance the LlWRKY39-mediated heat stress response (HSR). Collectively, these results imply that LlWRKY39 might participate in the HSR as an important regulator through Ca2+-CaM and multiprotein bridging factor pathways. [ABSTRACT FROM AUTHOR]

Temperature is a key factor influencing plant growth and productivity, however sudden increases in temperature can cause severe consequences in terms of crop performance. We evaluated the influence of elementary sulfur application on the physiology and growth of two tomato genotypes ("Ahmar" and "Roma") grown in two growth chambers (at 25 and 45 °C). Plants were sprayed with 2, 4, 6, and 8 ppm Sulfur 45 days after sowing (untreated plants were kept as control). Plants of the "Roma" cultivar receiving 6 ppm Sulfur exhibited maximal shoot and root biomass values followed by those receiving 4 ppm under both temperature conditions. Maximal CO2 index, photosynthetic rate, transpiration rate, and greenness index values (188.1 μmol mol-1, 36.3 μmol CO2 m-2 s-1 1.8 μmol H2O m-2 s-1 and 95 SPAD, respectively) were observed in plants of "Roma" cultivar grown at 25 °C, indicating positive influences of sulfur on tomato physiology. Similarly, sulfur maximized proline, nitrogen, phosphorus, and potassium contents in leaves of both genotypes at both temperatures. The differences between control and sulfur-treated plants grown under heat stress indicate a possible role of sulfur in mitigating heat stress. Overall, our results suggest that 6 ppm of sulfur is the best dose to alleviate tomato heat stress and enhance the morphological, physiological, and biochemical attributes of tomato plants. [ABSTRACT FROM AUTHOR]

Hydroponic systems are known to provide a platform for uniform growth conditions until the reproductive stage. However, many plant species, including sunflower, show poor growth and survivability under conventional hydroponic systems due to poor nutrient availability, hypoxia and algal contamination. Thus, we tested various hydroponic systems to select a hydroponic system suitable for screening of sunflower germplasm. Sunflower accessions showed better growth and leaf gas exchange in newly-designed over conventional hydroponic systems. Selected hydroponic systems were further engaged in sunflower accession screening under heat and osmotic stress in a two-pan system (210 cm × 60 cm). Heat stress treatment was applied by growing sunflower germplasm at 42 °C and osmotic stress by adding polyethylene glycol 8000 which decreased the osmotic potential to − 0.6 MPa. There was significant variability among the sunflower accessions for their ability to survive under stress. Accessions such as C-2721 (43%), C-291 (46%) and D-14 (43%) had lower cell membrane injury percentage under osmotic stress and high seedling survivability (60‒80%) under heat stress when compared with susceptible accessions. Moreover, resistant accessions exhibited greater cuticular waxes and root length but lower transpiration losses. The newly designed hydroponic platform proved reliable for the selection of resistant sunflower accessions. Selected parental lines were validated by assessing their hybrids under field trials across two seasons under water and temperature stress during the reproductive phase (autumn). Hybrid H3 obtained by crossing drought and heat resistant parents had the highest seed yield and water use efficiency. [ABSTRACT FROM AUTHOR]

Global warming is unusually increasing the earth temperature over the past century at an average rate of 0.07°C per decade since 1880. The increased temperature exhibit greater impact on grain yield, approximately 5.18 million tons of rice yields due to heat wave. Heat shock factors (HSF) has major role in regulating heat shock proteins which in turn responsible for survival of plants in heat stress by refolding proteins, maintaining functional confirmation, aiding in host defence mechanism. The aim of this research was to analyse phenological, biochemical changes and key genes highly expressed during heat stress at flowering stage in rice. Expression analysis of nine HSF genes had given a differential expression under heat stress as compared to controlled traits. This study suggested OsHSP26.7 as most responsive gene under heat stress and rice line 159, RRF-127, GP-145-103 and Annada with heat tolerant adaptive mechanisms and better performance under high temperatures and was found to be in correlation with the estimated biochemical traits. This can be taken as a base for heat tolerance response of the crop, which may be useful for further validation studies of the candidate genes for heat tolerance in the rice as well as other crop plants. [ABSTRACT FROM AUTHOR]

Understanding the changes in peanut (Arachis hypogaea L.) anther lipidome under heat stress (HT) will aid in understanding the mechanisms of heat tolerance. We profiled the anther lipidome of seven genotypes exposed to ambient temperature (AT) or HT during flowering. Under AT and HT, the lipidome was dominated by phosphatidylcholine (PC), phosphatidylethanolamine (PE), and triacylglycerol (TAG) species (> 50% of total lipids). Of 89 lipid analytes specified by total acyl carbons:total carbon–carbon double bonds, 36:6, 36:5, and 34:3 PC and 34:3 PE (all contain 18:3 fatty acid and decreased under HT) were the most important lipids that differentiated HT from AT. Heat stress caused decreases in unsaturation indices of membrane lipids, primarily due to decreases in highly-unsaturated lipid species that contained 18:3 fatty acids. In parallel, the expression of Fatty Acid Desaturase 3-2 (FAD3-2; converts 18:2 fatty acids to 18:3) decreased under HT for the heat-tolerant genotype SPT 06-07 but not for the susceptible genotype Bailey. Our results suggested that decreasing lipid unsaturation levels by lowering 18:3 fatty-acid amount through reducing FAD3 expression is likely an acclimation mechanism to heat stress in peanut. Thus, genotypes that are more efficient in doing so will be relatively more tolerant to HT. [ABSTRACT FROM AUTHOR]

Cowpea is one of the vital grain legumes used for human and animal nutrition. Due to its rich protein content, cowpea supplies the protein requirement, especially in the African continent. Although cowpea is morphologically similar to common bean, it is a more tolerant species to heat and drought conditions. So, cowpea production has various advantages in semi-arid regions. The aim of this study was to determine some agronomic traits of used cowpea genotypes and evaluate their correlations with yield components. Plant height (PH), stem diameter (SD), leaf surface temperature (LST), total chlorophyll content (TCC), number of pods per plant (NP), number of seeds per plant (NS) and seed yield (SY) changed between 54.6-91.3 cm, 3.1-7.6 mm, 27.9-31.7 °C, 39-56.1%, 25.7-49.1, 307.5-684 and 646-2381 kg ha-, respectively. It is noteworthy that Karagöz produced the maximum SY compared to the other varieties. Besides, it was determined that SY has positive significant correlation with NS (r=0.98**), NP (r=0.96**), TCC (r=0.93**), SD (r=0.91**) and PH (r=0.86**). [ABSTRACT FROM AUTHOR]

Years with high fruit production, known as mast years, are the usual reproduction strategy of European beech. Harsh weather conditions such as frost during flowering can lead to pollination failure in spring. It has been assumed that mast is controlled by flowering, and that after successful pollination, high amounts of fruits and seeds would be produced. However, the extremely hot and dry European summer of 2018 showed that despite successful pollination, beechnuts did not develop or were only abundant in a few forest stands. An in-depth analysis of three forest sites of European beech from the Swiss Long-Term Forest Ecosystem Research Programme over the last 15–19 years revealed for the first time that extreme summer heat and drought can act as an "environmental veto", leading to early fruit abortion. Within the forest stands in years with fruit abortion, summer mean temperatures were 1.5 °C higher and precipitation sums were 45% lower than the long-term average. Extreme summer heat and drought, together with frost during flowering, are therefore disrupting events of the assumed biennial fruiting cycle in European beech. [ABSTRACT FROM AUTHOR]

A plantation of small-leaved lime (Tilia cordata Mill.) containing two types of planting stock - large-sized transplants (LST) and standard-sized transplants (SST) - was planted on a site with strong weed competition. The aim was to compare the growth, survival and health of those types of planting stock under a weeded and non-weeded regime in a dry and warm climate. Recorded variables were: overall mortality, stem height, root-collar diameter and chlorophyll content. Increments in height and root collar diameter were calculated. Precipitation, soil and air temperatures were continuously monitored by an automatic climate station. Soil analysis revealed equal conditions for the treatments. Simple analysis of costs was calculated. The results showed that LST exhibited greater height increment than SST in the first 5 years after afforestation under strong weed competition. Non-weeded (under the regime of no weeding) SST also showed increased mortality. Weeding regime positively influenced the height increment of SST but did not influence the height increment of LST. Chlorophyll content was significantly higher in the leaves of LST than in SST in the first growing period. Economic analysis showed that the number of trees was the most important variable, while weeding was less important. LST can be recommended for reforestation of weed-infested sites, even if they have relatively low annual precipitation. [ABSTRACT FROM AUTHOR]

Corn grain yield is extremely responsive to the weather conditions during the growing season. Drought stress, as a result of high temperatures and limited naturally occurring precipitation, often limits grain yield in the Mid-South. Drought stresses often occur during the transition fromthe vegetative to the reproductive growth stage, which is most impactful to yield because of the high water demand. Our hypothesis was that short-season corn hybrids of <110 d (~2700 growing degree units) could avoid heat and drought by flowering earlier when these heat and drought stresses are less likely. Our objective was to evaluate short-season hybrids inMid-South environments along with standard full-season hybrids for grain yield. The study was conducted in Brooksville and Starkville, MS, in 2015 and Starkville and Verona, MS, in 2016. Earlier maturing hybrids tasseled 3-7 d before standard full-season hybrids, providing very little benefit from a drought avoidance perspective. Choosing full-season hybrids increases yield potential in high-yielding environments in Mississippi in which growing degree units are not limiting as in northern geographies. Short-season hybrids did not aid in the avoidance of heat and drought and limited overall grain yield. Across all locations, there was a 0.8 bu ac-1 increase in corn grain yield for every day increase in relative maturity from 92 to 120 d. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Slovenica is the property of Biotechnical Faculty of the University of Ljubljana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The increasing occurrence of heatwaves has intensified temperature stress on terrestrial vegetation. Here, we investigate how two contrasting isoprene-emitting tropical species, Ficus benjamina and Pachira aquatica , cope with heat stress and assess the role of internal plant carbon sources for isoprene biosynthesis in relation to thermotolerance. To our knowledge, this is the first study to report isoprene emissions from P. aquatica. We exposed plants to two levels of heat stress and determined the temperature response curves for isoprene and photosynthesis. To assess the use of internal C sources in isoprene biosynthesis, plants were fed with 13C position-labelled pyruvate. F. benjamina was more heat tolerant with higher constitutive isoprene emissions and stronger acclimation to higher temperatures than P. aquatica , which showed higher induced isoprene emissions at elevated temperatures. Under heat stress, both isoprene emissions and the proportion of cytosolic pyruvate allocated into isoprene synthesis increased. This represents a mechanism that P. aquatica , and to a lesser extent F. benjamina , has adopted as an immediate response to sudden increase in heat stress. However, in the long run under prolonged heat, the species with constitutive emissions (F. benjamina) was better adapted, indicating that plants that invest more carbon into protective emissions of biogenic volatile organic compounds tend to suffer less from heat stress. [ABSTRACT FROM AUTHOR]

A field experiment was carried to reduce the damage of heat stress and moisture stress, by increasing the reflection rate in infrared radiation by dispersing the reflective material on the plants, in addition to treatment ofcommercial anti-transpiration which represented a reduction factor of moisture stress damage. This was considered as a double objective in drought resistance. The experimental treatments were divided according to the Randomized Complete Block Design (RCBD) with three replicates. The main irrigation treatments represented the control treatment water reclamation ratio 100, 75 and 50% of the irrigation water for the comparison treatment. Stress tolerances treatment were represented by the secondary plots, which wasspraying with distilled water, black sand, red sand, anti-transpiration and aluminum foil. The obtained results of the experiment showed that the stress increasing has reduced all growth indicators at each increase in the level of moisture stress and decreased the seed yield in irrigation by 50% treatment by 68.56% compared to the comparison treatment. The treatment of aluminum foil has exceeded the other treatments in most of thestudied growthindicators, such as plant height, weight of the stem, weight of leaves, weight of 1000 seeds and seed yield, in proportions of 8.90, 26.13, 54.18, 35.12 and 55.46% respectively. Additionally, a significanteffect was detected in the interaction between irrigation treatments and stress tolerancetreatments on some growth, yield and components characteristicsexcept for disc diameter. [ABSTRACT FROM AUTHOR]