Increase In Night Temperature Research Articles

CONSTRAINTS FACED BY FARMERS IN ADAPTING TO CLIMATE CHANGE

Some constraints faced by the farmers due to climate variability, be it the delay in seasonal rainfall; heavily or less occur rainfall, its unexpected arrival during the reproductive phase of the crops, or even the increase in night temperature, continue to strike the farmers financially, forcing them to rethink farming as a viable proposition. The present study involving a sample size of 240 farmers from Gujarat, India, employed the Garrett'smean scoreto determine the constraints to climate change. The findings revealed that among the Among the constraints in managing the adverse implications of climate change, lack of finance was found to be the most critical constraint faced by the farmers in the study area. With a Garrett mean score (GMS) of 57.10. The constraint was ranked two in the overall study area with a Garrett mean score of 55.76. High cost of adaptation is one constraint which is not perceived to be a serious issue across the study area as the perceptions of farmers with regards to its severity was found to be mixed. Only in the districts of Jamnagar and Junagadh, the constraint was ranked second in terms of severity with a Garrett mean score of 56.80 and 55.67, respectively.

Night Warming Has Mixed Effects on the Development of the Fall Armyworm, Spodoptera frugiperda (Lepidoptera, Noctuidae), in Southern China.

The Fall Armyworm, Spodoptera frugiperda (Lepidoptera, Noctuidae), is a serious migratory pest. After invading China in 2019, the species was established as a year-round breeding population in most of the southern provinces. The area of winter maize in this region has been increasing due to the huge demand of fresh maize consumption, which is potentially at risk from this invasive pest, although the growth and development of S. frugiperda in the region's changing climate is unclear, particularly with rising temperatures at night. Here, we used the highest daytime temperatures of 27 °C, 24 °C, 20 °C and decreased these by 2, 4 and 6 °C to reflect the range of nighttime temperatures indicative of winter conditions in a warming climate to evaluate the effect of increasing night temperatures on the growth and development of S. frugiperda. Results show that the survival of larvae and pupae significantly declined with daytime temperatures declining and the nighttime temperature range increasing. Significant developmental effects were observed across all daytime-nighttime temperature treatments, except for adults. Additionally, there were significant interaction effects for all stages, except the egg stage, and generation time. The development rate increased with the increasing daytime temperatures and nighttime temperatures, except for the intermediate treatments (Group II). The uniformity of pupation and emergence times were higher under high daytime temperatures and nighttime temperature treatments. Predictions of FAW development and warnings to local farmers need to be adjusted to take into account the more rapid development when nighttime temperatures increase in the warming climate. These results will support decision makers in developing long-term management strategies for FAW in southern China.

Increasing night temperature in a tunnel without heating system

Increasing night temperature in a tunnel without heating system

Warm-night temperature alters paternal allocation strategy in a North temperate-zone butterfly.

Warming temperatures are greatly impacting wild organisms across the globe. Some of the negative impacts of climate change can be mitigated behaviorally, for example, by changes in habitat and oviposition site choice. Temperatures are reportedly warming faster at night than during the day, yet studies assessing the impacts of increasing night temperature are rare. We used the Finnish Glanville fritillary butterfly (Melitaea cinxia) as study species and exposed adult butterflies of both sexes to warmer night conditions. Under a seminatural outdoor enclosure, we assessed whether females base their oviposition choices primarily on habitat site characteristics (open, suggestive of dry meadows, versus covered by a coarse canopy, suggestive of pastures) or on plant condition (dry vs. lush), and if their choice is altered by the thermal conditions experienced at night. As exposure to warmer environmental conditions is expected to increase resting metabolic rate and potentially reduce life expectancy, we further assessed the fitness implications of warm‐night temperatures. We found that females prefer open sites for oviposition and that females do not switch their oviposition strategy based on the thermal conditions they experienced at night prior to the reproductive event. Exposure to warm nights did not influence female lifespan, but the egg hatching success of their offspring was reduced. In addition, we found that males exposed to warm nights sired larger clutches with higher hatching rate. As warm‐night exposure reduced male lifespan, this may imply a switch in male resource allocation strategy toward increased offspring quality. The present work adds on to the complex implications of climate warming and highlights the importance of the often‐neglected role of males in shaping offspring performance.

Warmer nights during early stages affect wheat development without grain yield penalty

This study analyses the impact of higher night temperature during the tillering phase on grain yield, focusing on crop development and tiller production dynamics in wheat (Triticum aestivum L.). Field experiments were carried out at the School of Agriculture, Buenos Aires, Argentina during the 2015 and 2016 growing seasons and combined: (1) two nitrogen availability levels (60 and 200 kg N ha–1) and (2) two night temperature conditions (control unheated and night temperature increase (NTI) during the tillering phase). The heating treatment increased night temperature ~2.3°C above the ambient night temperature. Across growing seasons, average minimum temperature during the tillering phase ranged from 8.5°C to 12.4°C. Warmer nights reduced time to anthesis (~4 days) due to a shortening in the duration of the tillering phase. NTI did not modify the maximum tiller number at plant level or per unit area. Higher N availabilities increased maximum tiller number ~30% compared with low N levels. Increased night temperature did not modify (P = 0.3418) grain yield in high and low N availabilities. Although development during the tillering phase was accelerated, the NTI during this stage would have a minor impact on both tillering and yield and its numerical components.

Can crop management reduce the negative effects of warm nights on wheat yield?

Abstract In wheat, warmer nights during the critical period reduce grain yield due to a diminished grain number per unit area, associated with lower spike number. Previous studies have evaluated the impact of increased night temperatures, but only under potential growing conditions. The aims of this study were to: (i) evaluate the impact of warmer nights during the critical period (i.e. from third detectable node to 10 days after anthesis) on grain yield and its numerical components, under contrasting nitrogen (N) and water levels and (ii) determine whether plant density could be useful as a management strategy to reduce yield losses caused by warmer nights. Two sets of experiments were conducted in Buenos Aires, the first in 2015 and 2016. In both years trials were carried out combining (i) two levels of nitrogen availability (60 and 200 kg N ha−1), (ii) two levels of water availability (rainfed and irrigated) and (iii) two conditions of night temperature (increased night temperature from third visible node to 10 days after anthesis and unheated crops during the whole crop cycle). The second experiment was performed in 2017 and combined: (i) three plant densities (ca. 100, ca. 150 and 300 plants m−2) and (ii) two-night temperature regimes (increased night temperature from third visible node to 10 days after anthesis and unheated crops during the whole crop cycle). Night temperatures were increased by heating systems, during the critical period average night temperatures ranged from 10.7 °C to 15.1 °C. Yield losses occurred when plants were exposed to warmer nights at high nitrogen levels (ca. 7% - i.e. 550 g m−2 - loss per °C of increase) but no effects were apparent under lower nitrogen availability. Warmer nights increased tiller mortality only under high nitrogen availability. No conclusions could be reached concerning water supply management or the convenience of this strategy to reduce the impact of warmer nights due to the lack of response of grain yield or grain number to modifications in water availability. Grain yield was significantly reduced by increases in night temperature only under higher nitrogen supply mostly due to a reduction in grain number per unit area, associated with reductions in spike dry weight; however, crops under high nitrogen levels yielded significantly more than those grown under low nitrogen, even when exposed to warmer nights. For all three densities, warmer nights reduced grain yield similarly (on average ca. 15 %).

Improved cyber-physical system captured post-flowering high night temperature impact on yield and quality of field grown wheat

Winter wheat (Triticum aestivum L.) is essential to maintain food security for a large proportion of the world’s population. With increased risk from abiotic stresses due to climate variability, it is imperative to understand and minimize the negative impact of these stressors, including high night temperature (HNT). Both globally and at regional scales, a differential rate of increase in day and night temperature is observed, wherein night temperatures are increasing at a higher pace and the trend is projected to continue into the future. Previous studies using controlled environment facilities and small field-based removable chambers have shown that post-anthesis HNT stress can induce a significant reduction in wheat grain yield. A prototype was previously developed by utilizing field-based tents allowing for simultaneous phenotyping of popular winter wheat varieties from US Midwest and advanced breeding lines. Hence, the objectives of the study were to (i) design and build a new field-based infrastructure and test and validate the uniformity of HNT stress application on a scaled-up version of the prototype (ii) improve and develop a more sophisticated cyber-physical system to sense and impose post-anthesis HNT stress uniformly through physiological maturity within the scaled-up tents; and (iii) determine the impact of HNT stress during grain filling on the agronomic and grain quality parameters including starch and protein concentration. The system imposed a consistent post-anthesis HNT stress of + 3.8 °C until maturity and maintained uniform distribution of stress which was confirmed by (i) 0.23 °C temperature differential between an array of sensors within the tents and (ii) statistically similar performance of a common check replicated multiple times in each tent. On average, a reduction in grain-filling duration by 3.33 days, kernel weight by 1.25% per °C, grain number by 2.36% per °C and yield by 3.58% per °C increase in night temperature was documented. HNT stress induced a significant reduction in starch concentration indicating disturbed carbon balance. The pilot field-based facility integrated with a robust cyber-physical system provides a timely breakthrough for evaluating HNT stress impact on large diversity panels to enhance HNT stress tolerance across field crops. The flexibility of the cyber-physical system and movement capabilities of the field-based infrastructure allows this methodology to be adaptable to different crops.

Impact of high night temperature stress on different growth stages of wheat

Increasing temperature especially the High night temperature (HNT) is a major constriction for sustaining global food production under changing climate scenario. Recent climate change has resulted into events of abrupt night temperature rise either throughout the crop period or at specific growth stage. Historical temperature observations and model projections have predicted a more pronounced increase in night temperature [minimum temperature (Tmin.)] compared to that of day temperatures [maximum temperature (Tmax.)]. Hence, the present study was carried out to identify the most critical growth stage affected by HNT and their effects on physiological, growth and yield traits of wheat. A unique field-based movable temperature controlling system was designed to enhance the night temperature by 5 °C than ambient temperature. The three critical phenological stages of wheat i.e. at GS 15 (before tillering initiation), GS 45 (booting) and GS 75 (grain filling) of Zadok’s scale were separately subjected to HNT treatment. The results reveals that GS 75 (grain filling) was the most sensitive stage affected by HNT, which has recorded remarkable reduction in grain yield (GY), Harvest Index (HI), Thousand grain weight (TGW) and grain weight per spike (GWPS) compared to control treatment. Pearson correlation analysis showed that breeders can choose lines with higher TGW, GWPS and grain number per spike (GNPS) for obtaining better GY under HNT conditions and vegetative/booting stage HNT in field condition may not attribute for any significant yield loss.

Coupling high‐resolution monitoring and modelling to verify restoration‐based temperature improvements

AbstractRivers are dynamic, complex integrators of their environment, which makes verification of the beneficial outcomes of restoration challenging. Thermal regime is central to habitat suitability and is often a focus in planning and evaluating the impact of restoration and climate resilience. Among these concerns, high summer stream temperature has frequently been identified as a limiting factor for salmon, steelhead, and trout. Our objective was to demonstrate the utility of combining high resolution thermal observation and modelling to evaluate restoration designed to mitigate stream thermal processes. This was demonstrated on the Middle Fork of the John Day River which is a critically impacted salmonid fishery in northeast Oregon, USA. We employed distributed temperature sensing and energy‐balance modelling to define the thermal regime. Restoration was predicted to result in a 0.7°C reduction of peak daily stream temperatures while increasing night temperatures by 0.9°C. This combined modelling and monitoring approach suggests that the 2012 restoration offered relief for native fish species stressed by excessive stream temperatures. This powerful combination of technology can be used in many projects to make optimal use of restoration investments to achieve durable and quantifiable improvements in habitat.

Pericarp growth dynamics associate with final grain weight in wheat under contrasting plant densities and increased night temperature.

The pericarp weight comprises <17 % of wheat grain weight at harvest. The pericarp supports the hydration and nutrition of both the embryo and endosperm during early grain filling. However, studies of the pericarp and its association with final grain weight have been scarce. This research studied the growth dynamics of wheat pericarp from anthesis onwards and its relationship to final grain weight under contrasting plant densities and night warming. Two spring wheat cultivars contrasting in kernel weight (Bacanora and Kambara) were sown in field conditions during seasons 2012-13 and 2014-15. Both genotypes were grown under contrasting plant density (control, 370 plants m-2; and low plant density, 44 plants m-2) and night temperatures, i.e. at ambient and increased (>6 °C) temperature for short periods before and after anthesis. From anthesis onward, grains were harvested every 3 or 4 d. Grain samples were measured and the pericarp was removed with a scalpel. Whole grain and pericarp fresh and dry weight were weighed with a precision balance. At harvest, 20 grains from ten spikes were weighed and grain dimensions were measured. Fresh weight, dry matter and water content of pericarp dynamics showed a maximum between 110 and 235 °Cd. Maximum dry matter of the pericarp ranged between 4.3 and 5.7 mg, while water content achieved values of up to 12.5 mg. Maximum values and their timings were affected by the genotype, environmental condition and grain position. Final grain weight was closely associated with maximum dry matter and water content of the pericarp. Maximum pericarp weight is a determinant of grain weight and size in wheat, which is earlier than other traits considered as key determinants of grain weight during grain filling. Better growing conditions increased maximum pericarp weight, while higher temperature negatively affected this trait.

Pea pollen viability and seed set response at high night temperatures

Field pea (Pisum sativum L.), a major pulse crop in western Canada, is sensitive to elevated temperature and possibly to high night temperature. Our objective was to examine if increasing night temperature while maintaining a constant daytime temperature affected pollen viability and seed set in two pea cultivars (CDC Golden and CDC Sage). Cultivars were exposed to 27/18, 27/22, 27/26 °C (day/night temperatures) for 7 d during flowering stage. Results indicated that increased night temperatures had no significant effect on pollen viability, the number of reproductive nodes and flowers, percentage of flower abortion, seed number per pod, and seed yield per plant.

Breeding Wheat for Resilience to Increasing Nighttime Temperatures

Increases in global mean temperature since 1960 are largely attributed to the rise in minimum nighttime temperatures thereby decreasing diurnal temperature variation. Increased night temperatures are known to affect crop development. A multi-year study investigating the effects of increased night temperatures on soft red winter wheat (Triticum aestivum L.) varieties was conducted during the 2015-2016 growing seasons at the University of Kentucky Spindletop Research Farm in Lexington, KY. Thirty-six cultivars and breeding lines were chosen based on their genotypes at photoperiod and vernalization loci. This material was planted in a randomized complete block experiment with two replications and two environments, control and passively warmed. To create a passively warmed environment, thermal covers were mounted to frames in plots and connected to a datalogger programmed to cover plants from dusk to dawn based on coordinate location. Night temperature increases ranged from 0.27–0.75 °C above ambient temperature. Grain yield, averaged across genotypes, was significantly reduced in the passively warmed environment by 224 kg ha−1 (p ≤ 0.05) or 6.44%; however, yield response to environment varied among genotypes with several genotypes displaying an increased yield in the warmed environment. Yield reductions may reflect reduced nitrogen utilization (9.4%; p ≤ 0.001) under increased night temperatures.

Warm nights in the Argentine Pampas: Modelling its impact on wheat and barley shows yield reductions

Efforts to anticipate how climate change and variability will affect future crop production can benefit from understanding the impacts of current and historic changes. This study aimed to quantify and compare the impact of increased night temperature on potential yield and phenology of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) crops modelled using APSIM with historical climate series (1961–2014) in sites representative of the Argentinean Pampas. For each site, the sowing date was adjusted to avoid frost and heat events at flowering, based on historical probability. The critical period was the more sensitive crop phase (shortened by 0.6d decade−1) for the observed asymmetric warming; regional minimum temperature trend of ca. 0.14 and 0.16°Cdecade−1 in wheat and barley, respectively. Wheat and barley yields declined across the region between ca. 2% and 9% per °C increase in the minimum temperature during the critical period, linked to lower cumulative radiation capture as a result of a shorter crop phase and lower incident radiation due to displacement towards winter. Regional variability in the simulated yield response to the observed night warming was mainly explained by differences the response of incident solar radiation during the critical period to the minimum temperature increase.

Increased Night Temperature Negatively Affects Grain Yield, Biomass and Grain Number in Chilean Quinoa.

Quinoa high nutritive value increases interest worldwide, especially as a crop that could potentially feature in different cropping systems, however, climate change, particularly rising temperatures, challenges this and other crop species. Currently, only limited knowledge exists regarding the grain yield and other key traits response to higher temperatures of this crop, especially to increased night temperatures. In this context, the main objective of this study was to evaluate the effect of increased night temperature on quinoa yield, grain number, individual grain weight and processes involved in crop growth under the environmental conditions (control treatment) and night thermal increase at two phases: flowering (T1) and grain filling (T2) in southern Chile. A commercial genotype, Regalona, and a quinoa accession (Cod. BO5, N°191, grain bank from Semillas Baer, hereby referred to as Accession) were used, due to their adaptability to Southern Chilean conditions and contrasting grain yield potential, grain weight and size of plants. Temperature was increased ≈4°C above the ambient from 8 pm until 9 am the next morning. Control treatments reached a high grain yield (600 and 397 g m-2, i.e., Regalona and Accession). Temperature increase reduced grain yield by 31% under T1 treatment and 12% when under T2 in Regalona and 23 and 26% in Accession, respectively. Aboveground biomass was negatively affected by the thermal treatments and a positive linear association was found between grain yield and aboveground biomass across treatments. By contrast, the harvest index was unaffected either by genotype, or by thermal treatments. Grain number was significantly affected between treatments and this key trait was linearly associated with grain yield. On the other hand, grain weight showed a narrow range of variation across treatments. Additionally, leaf area index was not affected, but significant differences were found in SPAD values at the end of T1 treatment, compared to control. Little change was found in the harvest index, individual grain weight, grain protein content or water soluble carbohydrates in response to the increased night temperature in this crop.

The response of rice (Oryza sativa L.) to elevated night temperature with application of Pyraclostobin

Rice productivity is having a problem related with climate change phenomenon, mainly the global warming. The rising of temperature in some country threat the rice production. The increasing of temperature is a major limiting factor that affects yield through the growth and development of rice plant. This study was aimed to examine the response of rice ( Oryza sativa L.) to elevated night temperature with the application of Pyraclostobin. A glasshouse experiment that was conducted from March to August 2015 at Brawijaya University Research Station of Jatikerto – Malang, used nested plot design with three replications and two treatments. The first treatments were the night temperature level (normal temperature, increased 2 o C, and increased 4 o C). The second treatments were the concentration of Pyraclostrobin (0 ppm, 400 ppm and 800 ppm). Results of the study showed that the increase of temperature at night for about 2 o C and 4 o C, as well as application of Pyraclostrobin , affected growth and yield of rice. Application of Pyraclostrobin by concentrations of 400 ppm and 800 ppm effectively reduced yield loss by increasing night temperature of 2 o C, which resulted in 20.20% and 24.93%, respectively, in comparison with the control; while the increase of night temperature by 4 o C have resulted 26.86% and 33.33% in comparison with the control. Pyraclostrobin was effective in maintaining percentage of the filled spikelets by the increase of temperature at night for about 2 o C and 4 o C.

Increased Night Temperatures During Cotton's Early Reproductive Stage Affect Leaf Physiology and Flower Bud Carbohydrate Content Decreasing Flower Bud Retention

AbstractHigher than optimum temperatures during cotton's (Gossypium hirsutum L.) growing season is a common occurrence in cotton‐growing areas around the world with negative consequences on productivity. According to climate projections, night temperatures are expected to increase more than day temperatures. The objective of this study was to monitor and record the effects of higher than optimum night temperatures during cotton's early reproductive stage on physiological (photosynthesis, respiration and membrane damage) and biochemical (leaf adenosine triphosphate (ATP) levels, as well as glutathione reductase (GR) content and soluble carbohydrate concentrations of the leaf subtending the flower buds. Number, dry weight, carbohydrate concentrations and GR levels of flower buds were also measured at the end of the experiment. Growth chamber experiments were conducted using cotton cultivar ST 5288 B2RF and treatments consisted of normal day/night temperatures (32/24 °C) and high night temperatures (32/30 °C) for 7 days at squaring (approximately 4 weeks after planting). The results indicated that high night temperatures had an immediate effect on leaf respiration rates and membrane damage by significantly increasing them compared to the control and a similar pattern was observed on leaf photosynthesis and ATP levels that were markedly decreased. Leaf GR levels were also substantially increased under conditions of high night temperatures, in contrast to flower bud GR content which remained unaffected. High night temperatures had a significant effect on leaf carbohydrate concentrations resulting in significant decreases in hexose, sucrose and starch levels. Nevertheless, flower bud sucrose content was substantially increased under conditions of high night temperatures, while hexose content was decreased and starch concentrations remained unaffected. A detrimental effect of elevated night temperatures on the number of flower buds per plant and on the dry weight of flower buds was observed, and it was concluded that high night temperatures had a negative effect on cotton flower bud production due to disruptions on flower bud carbohydrate metabolism as a result of the insufficient GR response.

Grain yield and quality responses of tropical hybrid rice to high night-time temperature

High temperature has a pronounced effect on grain yield and quality in rice. Climate change has increased night temperature more than day temperature in many parts of the world. How rice responds to high night-time temperature (HNT) is largely unknown. This study presents the first effort to assess the response of tropical hybrid rice to HNT. Six commercial tropical hybrid rice cultivars together with a tolerant (N22-aus) and a susceptible (Gharib-indica) genotype were evaluated under control temperature (23°C) and HNT (29°C) starting from panicle initiation until maturity under field conditions at the International Rice Research Institute during the dry (DS) and wet (WS) seasons of 2013. Overall, HNT significantly decreased grain yield of Gharib and all tested hybrids across both seasons, with less average reduction in the DS (13.4%) than in the WS (18.6%). Among the yield components, spikelets m−2 most significantly contributed to yield variation under control and/or HNT during both DS and WS followed by grain weight, while the contribution of seed-set was low and season-specific. Grain quality in most hybrids was also strongly affected by HNT, with decreased head rice yield, increased chalkiness and reduced grain width. Given this vulnerability to HNT, there is an urgent need to explore options for improving the adaptation of rice hybrids to increasingly warmer nights.

Simulation of increasing night temperature on vegetative and generative of paddy (Oryza sativa L.)

The rate of respiration increases with increasing temperature. It causes a problem to occur with photosynthesis result (photosynthate) generated during photosynthesis as a source of energy for metabolism of plants. The objective of this study was to evaluate of growth and the production result by affected an increasing night temperature on paddy. The simulation was performed in growth chamber with increased night temperature by 20 C (T1) and 40 C (T2) higher than normal night temperature (T0). Growth phase of rice plant treated an increase in night temperature among others on the vegetative phases continues on the generative phase (VG), was treated only on the vegetative phase (V) and treated only on the generative phase (G). The number of tillers, leaf area, number of leaf, the total dry weight of rice plant on the T2 had values that were lower than at T0 and T1. The decreased values in the parameter number of tillers, leaf area, number of leaf, and total dry weight at the end of the observation were observed on T2V and T2 VG. The T2 had longer panicle than T1 and T0, but the number of panicle, weight of seedper plant, harvest index (HI), the number of productive tillers, flowering time, harvesting time , nitrogen content in the leaves, the and percentage of open stomata values were lower than T1 and T0. T1G, T1VG, T2VG and T2G showed lower percentage of full grain than at T0. T1 and T2 treatments on VG and V resulted in the delay of flowering time. T1 and T2 on the VG phase resulted in the delay of harvesting time.

Differential response of rice plants to high night temperatures imposed at varying developmental phases

Increasing night temperatures can reduce growth and yield of rice plants, but limited information is available on the comparative effects of high night temperature (HNT) treatment at different growth stages on growth and physiological responses of rice. We conducted a study in controlled-environment chambers to determine the growth and physiological responses and spikelet differentiation of rice cultivars to HNT treatment at different growth stages. Plants were exposed to two temperatures: 30/21°C (low) and 30/25°C (high) day/night temperatures. At the end of the vegetative period, plants grown in the low (LNT) and high (HNT) night temperatures were further subdivided and plants were exposed to different temperature treatments in the reproductive growth period. Photosynthesis, night respiration rates, and plant growth parameters were measured at various stages. High night temperature had no significant effects on the growth of rice cultivars during the vegetative phase. Maximum photosynthesis at the vegetative phase was not significantly affected, but plant dark respiration increased (within the 14–20% range). Genotypic variation in dark respiration was observed at later growth stages. Rice plants that received HNT at the early reproductive stage had the lowest number of spikelets per panicle, presenting a 35.9% of degenerated spikelets, significantly higher than those observed in other treatment times. This study shows that the response of rice cultivars to HNT varies with time of treatment and that the occurrence of HNT during the reproductive period provided supportive evidence on how HNT might reduce yield by increasing plant’s dark respiration rate and spikelet degeneration (which consequently reduced sink size), thus, decreasing biomass production.

Increase in night temperature in rice enhances respiration rate without significant impact on biomass accumulation

Night temperature (NT) increases faster than day temperature with global warming and this may have strong implications for crop yield. One of the assumptions is the increase in night respiration and thus the increase in carbon losses over time. Some rice cultivars (indica, aus and japonica types) were grown in the field in the Philippines and in heated greenhouses in Montpellier, France, to quantify the response of respiration to increased NT and its implication at crop level. Increased NT by 3.8 and 5.4°C over the whole crop cycle in two greenhouse experiments and by 1.9°C in the field from 33 days after transplanting up to maturity using a free-air-controlled enhancement increased night respiration rate significantly. Overall, the cost in CH2O of night respiration over crop duration was 17 to 20% (field) and 8 to 18% (greenhouse) of the potential shoot dry matter (including that lost by respiration). Additional respiratory burden due to increased NT was only 1 to 7% of the potential shoot dry matter at maturity, and was not associated with significant loss in additional dry matter. The absence of any dry matter reduction with increased NT within indica cultivars questions the assumptions of recent papers.