Low Night Temperature Research Articles

Factors Affecting Tolerance to Low Night Temperature Differ by Fruit Types in Tomato

Tolerance to low night temperature (LNT) can be a practical and economical target in tomato breeding programs for energy saving in greenhouses. This study was conducted to investigate the physiological and biochemical responses to LNT using four tomato accessions with cherry or large fruit types having LNT tolerance or sensitivity. The accessions were grown in two polyethylene film greenhouses with night temperature set-points of 10 and 15 °C for heating. LNT significantly reduced the plant height, and photosynthetic parameters were also lower in 10 than 15 °C among all accessions. Photosynthetic rate in 10 °C during the early growth period was reduced more in LNT-tolerant than -sensitive accessions. The numbers of flowers in 10 °C were significantly reduced in cherry but not in large fruit types. Fruit set in 10 °C significantly decreased in LNT-sensitive accessions of both fruit types, which was due to abnormal flower morphology. Proline accumulation patterns between 10 and 15 °C significantly differed between cherry and large fruit types as well as between LNT-tolerant and -sensitive accessions. Chlorophyll content at later growth stages in 10 °C was significantly higher in LNT-tolerant than -sensitive accessions in both fruit types. These results suggest that different tomato fruit types may have different mechanisms for LNT tolerance, possibly due to different proline accumulation patterns between cherry and large fruit types.

Elucidation of molecular and hormonal background of early growth cessation and endodormancy induction in two contrasting Populus hybrid cultivars

BackgroundOver the life cycle of perennial trees, the dormant state enables the avoidance of abiotic stress conditions. The growth cycle can be partitioned into induction, maintenance and release and is controlled by complex interactions between many endogenous and environmental factors. While phytohormones have long been linked with dormancy, there is increasing evidence of regulation by DAM and CBF genes. To reveal whether the expression kinetics of CBFs and their target PtDAM1 is related to growth cessation and endodormancy induction in Populus, two hybrid poplar cultivars were studied which had known differential responses to dormancy inducing conditions.ResultsGrowth cessation, dormancy status and expression of six PtCBFs and PtDAM1 were analyzed. The ‘Okanese’ hybrid cultivar ceased growth rapidly, was able to reach endodormancy, and exhibited a significant increase of several PtCBF transcripts in the buds on the 10th day. The ‘Walker’ cultivar had delayed growth cessation, was unable to enter endodormancy, and showed much lower CBF expression in buds. Expression of PtDAM1 peaked on the 10th day only in the buds of ‘Okanese’. In addition, PtDAM1 was not expressed in the leaves of either cultivar while leaf CBFs expression pattern was several fold higher in ‘Walker’, peaking at day 1. Leaf phytohormones in both cultivars followed similar profiles during growth cessation but differentiated based on cytokinins which were largely reduced, while the Ox-IAA and iP7G increased in ‘Okanese’ compared to ‘Walker’. Surprisingly, ABA concentration was reduced in leaves of both cultivars. However, the metabolic deactivation product of ABA, phaseic acid, exhibited an early peak on the first day in ‘Okanese’.ConclusionsOur results indicate that PtCBFs and PtDAM1 have differential kinetics and spatial localization which may be related to early growth cessation and endodormancy induction under the regime of low night temperature and short photoperiod in poplar. Unlike buds, PtCBFs and PtDAM1 expression levels in leaves were not associated with early growth cessation and dormancy induction under these conditions. Our study provides new evidence that the degradation of auxin and cytokinins in leaves may be an important regulatory point in a CBF-DAM induced endodormancy. Further investigation of other PtDAMs in bud tissue and a study of both growth-inhibiting and the degradation of growth-promoting phytohormones is warranted.

Exogenous DA-6 Improves the Low Night Temperature Tolerance of Tomato Through Regulating Cytokinin.

Low night temperature (LNT) causes environmental stress and has a severe and negative impact on plant growth and productivity. Synthetic elicitors can regulate plant growth and induce defense mechanisms from this type of stress. Here, we evaluated the effect of the exogenous growth regulator diethyl aminoethyl hexanoate (DA-6) in tomato leaf response to LNT stress. Our results showed that exogenous DA-6 activates the expression of chlorophyll synthesis and photosystem-related genes, and results in higher photosynthetic activity and chlorophyll production. Furthermore, DA-6 can regulate the synthesis of endogenous cytokinin (CTK) and the expression of decomposition genes to stabilize chloroplast structure, reduce oxidative damage, and maintain the photochemical activity of tomato leaves under LNT stress. DA-6 maintains a high level of ABA content and induces the expression of CBF genes, indicating that DA-6 may participate in the cold response signaling pathway and induce the expression of downstream low temperature response genes and accumulation of compatible osmolytes. This study unravels a mode of action by which plant growth regulators can improve low temperature tolerance and provides important considerations for their application to alleviate the harmful effects of cold stress.

Технологічні параметри водорегулювання при вирощуванні високопродуктивних кормових культур на осушуваних землях гумідної зони України

Goal. To develop technological parameters of water regulation for growing highly productive fodder crops (paise, amaranth, and fodder beans) on drained lands of the humid zone of Ukraine. Methods. Analytical and experimental on production plots of reclamation systems, mathematical modeling, and processing of experimental data. Results. Technological parameters of water regulation (norms of groundwater level and moisture in the root layer of the soil) for growing highly productive fodder crops (paise, amaranth, and fodder beans) on peat and mineral soils are determined. Permissible terms are established in which the reclamation system should ensure the removal of excess water and timely reduction of the groundwater level to the recommended indicators. It is determined that modern climate changes in the Polissia region of Ukraine are manifested in uneven distribution of precipitation during the growing season, abnormal jumps in average daily air temperature, and low night temperatures (

Exogenous Calcium Alleviates Nocturnal Chilling-Induced Feedback Inhibition of Photosynthesis by Improving Sink Demand in Peanut (Arachis hypogaea).

Arachis hypogaea (peanut) is a globally important oilseed crop with high nutritional value. However, upon exposure to overnight chilling stress, it shows poor growth and seedling necrosis in many cultivation areas worldwide. Calcium (Ca2+) enhances chilling resistance in various plant species. We undertook a pot experiment to investigate the effects of exogenous Ca2+ and a calmodulin (CaM) inhibitor on growth and photosynthetic characteristics of peanut exposed to low night temperature (LNT) stress following warm sunny days. The LNT stress reduced growth, leaf extension, biomass accumulation, gas exchange rates, and photosynthetic electron transport rates. Following LNT stress, we observed larger starch grains and a concomitant increase in nonstructural carbohydrates and hydrogen peroxide (H2O2) concentrations. The LNT stress further induced photoinhibition and caused structural damage to the chloroplast grana. Exogenous Ca2+ enhanced plant growth following LNT stress, possibly by allowing continued export of carbohydrates from leaves. Foliar Ca2+ likely alleviated the nocturnal chilling-dependent feedback limitation on photosynthesis in the daytime by increasing sink demand. The foliar Ca2+ pretreatment protected the photosystems from photoinhibition by facilitating cyclic electron flow (CEF) and decreasing the proton gradient (ΔpH) across thylakoid membranes during LNT stress. Foliar application of a CaM inhibitor increased the negative impact of LNT stress on photosynthetic processes, confirming that Ca2+–CaM played an important role in alleviating photosynthetic inhibition due to the overnight chilling-dependent feedback.

Performance Analysis of Thermal Storage Assisted Cooling Tower with Night Cooling

As global warming and water scarcity issues continue to grow, it is essential to increase resources efficiency for air conditioners and power plants. In order to increase the efficiency, the systems need to be modified to take the advantages of the low night temperature and thermal storage tanks. In this study, the low night temperature and thermal storage tanks effects on the cooling tower is studied using TRNSYS. Using a chiller operating from 8:00 to 16:00 as a case study, hot water from the condenser is partially stored on daytime and cooled slowly during the night. The storage tank volume is optimized by considering two big tanks and five small tanks. The results show that night cooling reduces cooling water temperature by 5.8 °C or 21.8% while the cooling efficiency is increased by 36%. The thermal storage tanks enable to have the low continuous flow rate and help to reduce the fan power by 67.1%. On the storage side, compared to two tanks system, the tanks volume is reduced by 16.5% when 5 tanks are used. In theory this reduction can go up to 50% by increasing the number of tanks and reducing their individual size.

Integration of non-target metabolomics and sensory analysis unravels vegetable plant metabolite signatures associated with sensory quality: A case study using dill (Anethum graveolens)

Using dill (Anethum graveolens L.) as a model herb, we reveal novel associations between metabolite profile and sensory quality, by integrating non-target metabolomics with sensory data. Low night temperatures and exposure to UV-enriched light was used to modulate plant metabolism, thereby improving sensory quality. Plant age is a crucial factor associated with accumulation of dill ether and α-phellandrene, volatile compounds associated with dill flavour. However, sensory analysis showed that neither of these compounds has any strong association with dill taste. Rather, amino acids alanine, phenylalanine, glutamic acid, valine, and leucine increased in samples exposed to eustress and were positively associated with dill and sour taste. Increases in amino acids and organic acids changed the taste from lemon/grass to a more bitter/pungent dill-related taste. Our procedure reveals a novel approach to establish links between effects of eustressors on sensory quality and may be applicable to a broad range of crops.

Carabus Population Response to Drought in Lowland Oak Hornbeam Forest

Forest management practices and droughts affect the assemblages of carabid species, and these are the most important factors in terms of influencing short- and long-term population changes. During 2017 and 2018, the occurrences and seasonal dynamics of five carabid species (Carabus coriaceus, C. ulrichii, C. violaceus, C. nemoralis and C. scheidleri) in four oak hornbeam forest stands were evaluated using the method of pitfall trapping. The climate water balance values were cumulatively calculated here as cumulative water balance in monthly steps. The cumulative water balance was used to identify the onset and duration of drought. The number of Carabus species individuals was more than three times higher in 2018 than in 2017. Spring activity was influenced by temperature. The extremely warm April in 2018 accelerated spring population dynamics; however, low night temperatures in April in 2017 slowed the spring activity of nocturnal species. Drought negatively influenced population abundance, and the effect of a drought is likely to be expressed with a two-year delay. In our investigation, a drought in 2015 started in May and lasted eight months; however, the drought was not recorded in 2016, and 2016 was evaluated as a humid year. The meteorological conditions in the year influenced seasonal activity patterns and the timings of peaks of abundance for both spring breeding and autumn breeding Carabus species.

Low temperatures in dark period affect biomass productivity of a cyanobacterium Arthrospira platensis

Heating cost during the night is a problem in outdoor cultivation of a cyanobacterium Arthrospira platensis. Low night temperature causes decreased biomass productivity during daytime and biomass loss during night, but there are few studies to fully investigate these impacts at the same time. To evaluate the effect of dark-period temperature (10–35 °C) on the net productivity (g-DW L−1 d−1) of Arthrospira platensis, semi-continuous cultivations were conducted in 1-L cylindrical glass photobioreactors with an LD cycle of 12-hour light and 12-hour dark under a light-period temperature of 35 °C and dark-period temperatures between 10 and 35 °C. By monitoring at 12-hour intervals, daytime productivity (g-DW L−1 d−1) and night biomass loss (%biomass) were investigated to understand net productivity. There was no significant difference in the net productivity and daytime productivity at high dark-period temperatures (25, 30 and 35 °C). On the other hand, at lower dark-period temperatures (10 and 15 °C), the net productivity and daytime productivity were at most 30% lower than that recorded at higher temperatures (25 and 30 °C). The dark-period temperatures were negatively correlated with carbon to nitrogen (C:N) ratio and positively correlated with dark-respiration rates, which suggested low protein synthesis at low dark-period temperature leading to the low net productivity at 10 and 15 °C. The tolerance of Arthrospira platensis to low dark-period temperature (25 °C) indicates possible cost reduction to control temperature during dark period. This study clarified that the low night temperature reduced net productivity of microalgae and cyanobacteria, and night temperature should be managed in outdoor cultivation based on the permissible dark-period temperature range.

Screening of sesame genotypes against powdery mildew disease caused by Erysiphe cichorecearum

Powdery mildew disease of sesame occurs on epidemic scale in areas of high rainfall and humidity coupled with low night temperature causing considerable yield losses. Use of host plant resistance is the practical approach to manage this disease, but proper resistance sources with combining ability for the trait are unknown. Hence, an experiment was conducted to determine resistance in sesame genotypes against powdery mildew disease. Among the twenty four genotypes screened, none was found resistant while, nine genotypes exhibited moderately resistant to tolerant reaction and 15 genotypes exhibited susceptible reaction. Apparent rate of infection value varied and at times they did not remain consistent for given genotype and also did not show a particular trend which is attributed to genetic character of the genotype. The AUDPC values differed considerably for different genotypes. The values of AUDPC and apparent rate of infection of susceptible varieties were high as compared to moderately susceptible varieties. Genotype ‘JLS-302-11’ and ‘JLT-7’ having minimum AUDPC and apparent rate of infection value showed lowest intensity of powdery mildew while, genotype ‘JLT-408’ having maximum AUDPC and apparent rate of infection value showed highest intensity of powdery mildew.

Visible evidence of climate change and its impact on fruit production in Nepal

In recent years, Nepal is experiencing visible impact of climate change in agriculture. This review paper describes the recent climate change pattern and phenomenon with its impact on fruit production in Nepal. Various researches suggest that change in temperature has played vital to reduce the level of soil organic carbon, and soil micronutrients. With exposure to extreme temperatures, insects may produce heat shock proteins, cryoprotectants and osmolyte compounds within their bodies to survive, so these insects can exist in such environment. Most of the researches resulted that higher temperature induces early flowering under the subtropics may result in low fruit-set because of abnormalities arising from prevailing low night temperatures. Similarly, insufficient chilling greatly influences flower initiation and fruit coloration along with deterioration in fruit texture and taste. Besides the effect of high and low temperature, papers also claimed that decline in rainfall from November to April adversely affects the winter and spring crops that ultimately reduces food production. Hence, organization related to fruit research, education and development in Nepal have to run effective program to bring new genetic sources that can resist the adverse effect of climate and may bring some positive vibe to tackle the climate change.

Cyclic electron flow protects photosystem I donor side under low night temperature in tomato

Cyclic electron flow (CEF) around photosystem I (PSI) is an important photoprotective mechanism, mediated mainly by PGR5/PGRL1 proteins and the chloroplast NAD(P)H dehydrogenase (NDH) complex. Here, chemical inhibition of PGR5/PGRL1- or NDH-dependent CEF was performed to determine their roles in preventing photoinhibition in tomato leaves under low night temperature (LNT) stress. Experimental treatments were with either antimycin A (A) or rotenone (R) to inhibit PGR5/PGRL1- or NDH-dependent CEF, respectively. The results showed that net photosynthetic rate (Pn), antioxidant enzyme activity, maximal photochemistry efficiency (Fv/Fm), effective photochemical quantum yield of PSII [Y(II)], non-photochemical quenching (NPQ), coefficient of photochemical fluorescence quenching (qP), and effective photochemical quantum yield of PSI [Y(I)] decreased more under LNT following A treatment than following R treatment. In A-treated plants, analysis of the normalized relative variable fluorescence at the K step (Vk) and the relative variable fluorescence at the J step (VJ) showed that both the donor and acceptor sides of PSII were severely damaged under LNT. Moreover, the donor side limitation of PSI [Y(ND)] increased whereas the acceptor side limitation of PSI [Y(NA)] decreased and the expression of genes encoding photosystem core subunits was significantly reduced. A treatment also resulted in increased ROS content and inhibition of SOD and APX activities under LNT. These data suggest that PGR5/PGRL1-dependent CEF plays a more important role than NDH-dependent CEF regarding resistance to LNT stress in tomato.

Türk Mısır (Zea mays L.) Hibridlerinin Üşüme Stresine Karşı Toleranslarında Genetik Varyasyonlar

Maize (Zea mays L.) is a tropical crop and chilling temperatures (below 15 ºC) cause growth retardation and yield losses. The development of chilling-tolerant maize varieties is a main goal of plant breeders in order to produce maize under cool climates. Hybrids are more vigorous then their parents, including being more tolerant to diverse stresses. However, stress screening is an obstacle. This study aims to evaluate chilling stress tolerance of Turkish maize hybrids and determine suitable indicators for selection of the most tolerant hybrid. Nine hybrids were subjected to low night temperature following germination until the third leaf was fully enlarged. Hybrids were evaluated at morphological, cellular and physiological levels by comparison with control seedlings. The data were analyzed by kinematic analysis and statistical tools. The findings showed that all indicators significantly differed among the hybrids. Indicators such as leaf elongation rate (LER), mature cell length (MCL) and cell production (CP) increase our understanding of stress tolerance by making connections between phenotype and cellular functions. Fresh and dry weight of shoot (SFW and SDW) were observed to be useful indicators to uncover relatedness between growth and the physiological stress response of seedlings. In conclusion, this study defines beneficial indicators for breeding studies at early seedling screening of maize hybrids which are displayed genetic variation for chilling stress tolerance.

A Review of Blast Disease of Rice in Nepal

Blast disease is caused by Magnaporthe grisea (syn. Pyricularia oryzae) firstly reported in 1637 from China. In Nepal it was firstly reported from Thimi, Bhaktapur in 1964. Symptoms of this disease appear in all stages from seedling in nursery to heading in main field, however, the most devastating stages are seedling stage, tillering stage and panicle initiation stage. Typical symptoms of blast appear on leaves, node, neck, collar, panicles, rachis and even the glumes are also affected. Globally, blast of rice is responsible for 10-30% of yield losses every year. In susceptible varieties the disease causes 10-20% yield reduction but in severe condition it went upto 80% in Nepal. Cloudy weather, high relative humidity (93-99%), low night temperature between 15-20°C, longer duration of dew are the most favorable condition for the outbreak of blast fungus. The most usual approaches for the management of rice blast disease are management in fertilizers and irrigations, plantation of resistant varieties and application of fungicides. Higher dose of nitrogen increase susceptibility so, it should be applied in split doses. Use of resistant cultivars such as Khumal-1, Khumal-2, Khumal-3, Radha-12, Chandannath-1, Chandannath-3, Sabitri and Palung-2 for the management of rice blast is sustainable and ecofriendly approach. Seed treatment with Trichoderma viridae at 4 g/kg or Pseudomonas fluorescens at 10 g/kg help to inhibit growth of blast fungus. Use of chemical named Kasugamycin used to control blast fungus is most commonly used and popular among Nepalese farmers.

Influence of 4-CPA Growth Regulator for Enhancing Yield of Tomato During Low Night Temperature Stress

Influence of 4-CPA Growth Regulator for Enhancing Yield of Tomato During Low Night Temperature Stress

Selection of sowing date and biofertilization as alternatives to improve the yield and profitability of the F68 rice variety

Multiple factors influence rice yield. Developing management practices that increase crop yield and an efficient use of resources are challenging to modern agriculture. Consequently, the aim of this study was to evaluate biological nitrogen fixation and bacterial phosphorous solubilization (biofertilization) practices with the selection of the sowing date. Three sowing dates (May, July and August) were evaluated when interacting with two mineral nutrition treatments using a randomized complete block design in a split-plot arrangement. Leaf carbon balance, leaf area index, interception and radiation use efficiency, harvest index, dry matter accumulation, nutritional status, and yield were quantified. Results showed that the maximum yield was obtained in the sowing date of August. Additionally, yield increased by 18.92% with the biofertilization treatment, reaching 35.18% of profitability compared to the local production practice. High yields were related to a higher carbon balance during flowering, which was 11.56% and 54.04% higher in August than in July and May, respectively, due to a lower night temperature. In addition, a high efficient use of radiation, which in August was 17.56% and 41.23% higher than in July and May, respectively, contributed to obtain higher yields and this behavior is related to the selection of the sowing date. Likewise, a rapid development of the leaf area index and an optimum foliar nitrogen concentration (>3%) were observed. This allowed for greater efficient use of radiation and is attributed to the activity of nitrogen-fixing and phosphate solubilizing bacteria that also act as plant growth promoters.

Carbon Dioxide Exchange of Woody Plants in Urban Ecosystems

The study of all factors that contribute to the carbon balance in the biosphere is of paramount importance due to the current increase in carbon dioxide content in the atmosphere. This article presents data on the carbon dioxide exchange for the needles of common spruce (Picea abies L.) and Douglas fir (Pseudotsuga menziesii L.) in an urban environment (based on the example of Moscow). It is established that the warm spell in autumn 2018 contributed to the prolongation of the period of carbon dioxide uptake by coniferous trees. Our analysis into the effect of environmental factors on the needle photosynthetic activity has revealed that the intensity of photosynthesis depends only on the level of illumination. The midday increase in air temperature failed to affect the photosynthesis intensity, which is probably explained by the adaptation of the plants to low night and morning air temperatures. A regression analysis has shown that the dependence of CO2 assimilation on illumination represented a logarithmic curve (with the approximation validity coefficient (R2) of 0.8). The effect of environmental conditions on conifer photosynthesis in autumn has proven to be species-specific. Common spruce was the most resistant to environmental factors: its photosynthetic activity was 1.4 times higher than that of Douglas fir. Calculations revealed that the level of CO2 assimilation was 3.6 and 2.7 times higher than the light respiration level for common spruce and Douglas fir, respectively, which indicates a positive carbon dioxide exchange and an important role of coniferous trees in regulating the carbon balance of an urban ecosystem.

Effects of sun exposure and vegetation cover on Woodpecker nest orientation in subtropical forests of South America

Variations in the orientation behavior of Woodpecker nests can be due to environmental factors such as latitude as well as local climate conditions. In this study, the orientations of dot-fronted Woodpecker nesting cavities (Veniliornis frontalis, Picidae) were examined at a subtropical site in Northwestern Argentina. It was evaluated whether solar radiation influences the mean orientation of cavities well covered by vegetation and cavities with less or non-external vegetal protection. Results obtained in this work provide that both covered and uncovered nests orient in a defined way towards the North and the Northwest, respectively, finding mean differences between both types of vegetation cover. These results indicate that, being exposed to the North (protected cavities) they get more solar radiation during the day to reduce the humidity of cavities’ microhabitat, due to the intense rainfall; and Northwest (unprotected cavities); to increase the temperature within the cavity due to the low night temperatures and humid climate. This study highlights the importance of studying the vegetation over the nests (protection) together with the local climatic conditions, given that they are important determinants for bird nest orientation.

Low night temperatures during the early growth phase enhance flowering in primocane shoots of red raspberries (Rubus idaeus L.)

Low night temperatures during the early growth phase enhance flowering in primocane shoots of red raspberries (Rubus idaeus L.)

Drought and heat waves associated with climate change affect performance of the potato aphid Macrosiphum euphorbiae

The combined effect of drought and heat waves on insect-plant interactions is complex and not fully understood. Insects may indirectly benefit from water-deficit stress through increased plant nitrogen levels. Heat stress may have a direct negative effect, yet insect performance may be improved when day-time heat is followed by cooler night temperatures. We show that moderate water-deficit stress (25–30% pot capacity) and high day-night temperatures (30/20 °C) affected Macrosiphum euphorbiae on potato (Solanum tuberosum) differently than their interactions. Water stress lowered stomatal conductance, and both water and heat stress reduced leaf area. The effect of water stress on nymphal and adult survival depended on temperature. Water stress added to reduced nymphal survival at high but not current (25/15 °C) day-night temperatures. Adult survival at high temperatures was reduced only when combined with water stress. Water stress and high temperatures independently but not interactively reduced the number of daily offspring. Moderate water stress when combined with high temperatures had a negative bottom-up effect on aphid survival even though lower night temperatures aided in the recovery from direct heat stress. Our study illustrates the importance of combining multiple stressors to better understand their impact on insect-plant interactions in the context of climate change.