Free Air Temperature Increase Research Articles

Experimental Warming Reduces the Grain Yield and Nitrogen Utilization Efficiency of Double-Cropping indica Rice in South China

The effect of climate warming on rice production in China is profound, yet there has been limited research on how it affects the grain yield, nitrogen (N) uptake, and N utilization efficiency (NUtE) of the double-cropping indica rice in South China. To address this gap, we conducted a free air temperature increase (FATI) experiment in Guangdong province during 2020 and 2021. Our findings revealed that warming led to a significant reduction in grain yield, with early rice (ER) and late rice (LR) experiencing average decreases of 5.2% and 6.3%, respectively, compared to control treatments. This decline was primarily attributed to the reduced grain weight of ER and the fewer spikelet numbers per panicle of LR under warming conditions. Although the dry matter translocation, harvest index, and N translocation efficiency of ER remained unchanged under warming conditions, these of LR decreased by an average of 58.1%, 8.8%, and 22.3%, respectively. Additionally, while warming did not affect the N uptake in ER at maturity, it significantly increased the N uptake in LR by an average of 11.0%. Therefore, under warming conditions, the NUtE of both ER and LR was markedly decreased by 6.9% and 15.5% over the two years. These results indicate that climate warming may have significant negative impacts on the grain yield and the NUtE of indica rice within double-rice cropping systems in South China. Understanding these dynamics is vital for maintaining the stability of rice yields in anticipation of future climate warming.

Different responses of enzyme activities to 6‐year warming after transplant of the 12 types of soils

AbstractBackgroundSoil enzymes regulate terrestrial nutrient cycles, and their activities are sensitive to environmental change. Facing climate warming, there are still contradictions over soil enzymes of different soil types in response to climate warming.AimsThe present study aims to reveal the impact of elevated temperature on soil properties. Specifically, we intended to explore the relationship between the activity of soil enzyme and soil property facing elevated temperature across soil types.MethodsA long‐term warming experiment was conducted to assess the possible responses of three enzymes (urease, phosphatase, and sucrase) to elevated temperature across 12 soil types. These soils were collected across China and transported to Nanjing in 2016. Free air temperature increase system with an infrared radiation heater was used to elevate the air temperature by 2°C in elevated treatment (eT). Wheat–soybean continuous rotation was cultivated in the long‐term experiment field since 2016. Enzyme activities, soil pH, soil organic carbon, available nitrogen (AN) and phosphorus (AP), and water content were measured after wheat harvest in 2021.ResultsWarming significantly increased the activities of urease and sucrase in most soil types but dramatically decreased phosphatase activity. The responses of the three enzyme activities to warming varied across soil types, which depended on soil properties. In contrast, soil pH was the major driver in regulating urease activity. Soil AN and water content were two key factors for driving phosphatase activity. However, no such relationship was found for sucrase activity. All these responses did not show obvious regional characteristics.ConclusionThese results suggested that soil enzyme was sensitive to air warming, which was associated with different soil properties. Thus, managing soil variables might be a potential strategy to maintain soil enzymatic activity in facing future climate warming.

Experimental warming under field conditions alters starch multi-structure and flour and starch functionality of late-season indica-japonica hybrid rice in southern China

IntroductionThe effects of climate warming on starch multi-structure and flour and starch functionality of late-season indica-japonica hybrid rice (IJHR) in double-rice cropping systems are still unclear to date.MethodsA 2 years field warming experiment was conducted by using free-air temperature increase facilities with an IJHR cultivar (Yongyou1538). The starch multi-structure and flour and starch functionality of IJHR were determined.ResultsExperimental warming (on average 2.1°C over the 2 years) reduced the amylose content and increased the amount of short amylopectin branch-chains (degree of polymerization 6–12), possibly due to decreased granule-bound starch synthase activity and increased starch-branch enzyme activity. Additionally, the protein content, starch granule diameter, relative crystallinity, and swelling power of IJHR were enhanced by experimental warming. The changes in rice components and starch multi-structure under warming conditions resulted in high peak viscosity, breakdown, pasting temperature, gelatinization temperatures and enthalpy and low setback of rice starch and high peak viscosity and pasting temperature and low setback of rice flour.ConclusionOur results indicated that climate warming might improve the pasting viscosities and enhance the thermal stability of late-season IJHR.

Effects of Warming and Fertilization on Soil Organic Carbon and Its Labile Components in Rice-wheat Rotation

Farmland is the important soil carbon pool of terrestrial ecosystems and organic nutrient pool for crop growth. To clarify the impact of climate warming on the soil carbon pool, this study analyzed the effects of warming and fertilization on soil organic carbon and its labile components under rice-wheat rotation using a free-air temperature increase system. The variation in soil carbon pool management index (CPMI) was also evaluated. The results showed that the combined effects of warming and fertilization on soil organic carbon content and labile organic carbon components were insignificant. Warming increased the soil organic carbon (SOC) content, and the differences between warming and the ambient control in total organic carbon (TOC) and recalcitrant organic carbon (ROC) reached a statistically significant level. Compared with those under the ambient control, the contents of TOC, ROC, and labile organic carbon (LOC) subjected to warming increased by 7.72%, 7.42%, and 10.11%, respectively. The increased microbial biomass carbon (MBC) content (20.4%) and decreased particulate organic carbon (POC) content (36.51%) may have been the main reason for the variation in SOC. Warming showed no significant effect on soil dissolved organic carbon (DOC) content, whereas it markedly reduced its soluble microbial by-product components (41.89%). The results also showed that fertilization had no significant effect on soil TOC, ROC, and LOC, but it notably reduced the contents of DOC and POC and increased the MBC content. Compared with those under the control without fertilization, the contents of DOC and POC subjected to fertilization decreased by 35.44% and 28.33%, respectively, and the MBC content increased by 33.38%. Additionally, fertilization tended to increase the anthropogenic humus component (5.13%) and soluble microbial by-product component (29.41%) in dissolved organic matter and reduce the terrestrial humus component (13.33%). Warming and fertilization both tended to improve soil CPMI. Affected by SOC and LOC, the increase in soil carbon pool index and soil lability index were the main reason for the increase in soil CPMI under warming and fertilization, respectively. Overall, the results revealed that climate warming can affect the soil carbon pool by changing soil labile carbon components, which are not affected by fertilization.

Fertilization and Global Warming Impact on Paddy CH4 Emissions.

This study aimed to assess the influence of experimental warming and fertilization on rice yield and paddy methane emissions. A free-air temperature increase system was used for the experimental warming treatment (ET), while the control treatment used ambient temperature (AC). Each treatment contained two fertilization strategies, (i) normal fertilization with N, P and K fertilizers (CN) and (ii) without N fertilizer input (CK). The yield was remarkably dictated by fertilization (p < 0.01), but not warming. Its value with CN treatment increased by 76.24% compared to CK. Also, the interactive effect of warming and fertilization on CH4 emissions was insignificant. The seasonal emissions from warming increased by 36.93% compared to AC, while the values under CN treatment increased by 79.92% compared to CK. Accordingly, the ET-CN treatment obtained the highest CH4 emissions (178.08 kg ha-1), notably higher than the other treatments. Also, the results showed that soil fertility is the main driver affecting CH4 emissions rather than soil microorganisms. Fertilization aggravates the increasing effect of warming on paddy methane emissions. It is a daunting task to optimize fertilization to ensure yield and reduce methane emissions amid global warming.

Effect of climate warming on the grain quality of early rice in a double-cropped rice field: A 3-year measurement

IntroductionThe threat of climate warming to global rice production has been widely addressed, but little is known about its influence on the quality of rice grains.MethodsA free-air temperature increase (FATI) facility with two widely-planted high-quality cultivars was used to explore the impact of warming on the grain quality of early rice in subtropical China over 3 consecutive years.ResultsCompared with the control, FATI increased diurnal canopy temperature by 1.5°, and thus, rice growth duration was shortened by 4.0 d under warming. We found that warming significantly reduced both the milled rice and head rice rates relative to the control, thereby leading to a decrease in the milled rice and head rice yield by 3.9 and 8.3%, respectively. The chalky grain rate and chalkiness were increased by 19.1 and 22.2% under warming compared with the control, respectively. The content of protein, essential amino acids, and non-essential amino acids were increased by 4.1, 5.4, and 4.9% under warming, respectively. Warming reduced the amylose content and setback by 2.0 and 47.5% but increasing peak viscosity, trough viscosity, breakdown, and final viscosity by 9.5, 13.6, 5.7, and 6.0%, respectively.ConclusionOur results suggest that the deteriorated milling and appearance quality induced by warming may be an upcoming challenge for high-quality early rice production in the future.

Effect of warming on rice yield and methane emissions in a Chinese tropical double-rice cropping system

Global warming often affects crop yield and greenhouse gas emissions from cropland. However, the effects of warming on rice yield and methane (CH4) emissions from rice paddies in the tropical double-rice cropping systems are still unknown. Therefore, we conducted a field experiment to investigate the effect of warming on rice growth and CH4 emissions in a Chinese tropical double-rice cropping system, using the free air temperature increase facility. The results showed that warming did not affect the rice plant biomass, but significantly reduced the early rice yield by 5.0% and late rice yield by 6.5%. Warming trended to increase CH4 emissions, especially in the flooded stage of early rice seasons. Warming significantly stimulated the abundance of methanogens and methanotrophs, and CH4 production and oxidation potential by 93.3%, 84.3%, 29.3% and 66%, respectively. Warming non-significantly increased the soil dissolved organic carbon concentrations, but significantly reduced the soil NH4+ concentrations. Warming significantly increased yield-scaled CH4 emissions by 7–41%. Our findings suggest that warming may reduce rice yield but increase CH4 emissions from the Chinese tropical double-rice cropping systems and underline the need for agricultural practices of higher rice yield and lower CH4 emissions.

Effects of warming and fertilization on paddy N2O emissions and ammonia volatilization

Several studies have proved the influence of warming to N2O emissions and NH3 volatilization in paddies. However, it is not clear whether the performance is affected by fertilization. Here, we performed a field trial to evaluate the impacts of warming and fertilization on N2O emissions and NH3 volatilization from paddies. A free air temperature increase system was used for the experimental warming treatment (ET), while the control treatment used ambient temperature (AC). Both ET and AC treatments were combined with nitrogen (N) fertilizer (CF) or without fertilizer input (CK). The results showed insignificant interaction effects of warming and fertilization on seasonal cumulative N2O emissions and NH3 volatilization. Compared with AC, seasonal cumulative N2O emissions and ammonia volatilization in the ET treatment increased by 118.44% and 38.41%, respectively. Moreover, fertilization surprisingly stimulated seasonal cumulative N2O emissions and ammonia volatilization; values were 15.91 and 2.35 times higher than those in the CK treatment. These results imply that fertilization could intensify the increasing effect of warming on N2O emissions and ammonia volatilization. The variable importance for the projection (VIP) analysis revealed that soil N transformation (the rates of N mineralization, nitrification, and denitrification) was the key to affecting reactive N loss rather than soil fertility. Additionally, the ammonia volatilization rate increased with ambient temperature and NH4+-N solution concentration in the microsystem. Importantly, there was a "surge" inflection point of the ammonia volatilization rate under both high ambient temperature (30 °C) and NH4+-N concentration (15 mg/L) conditions. Our findings indicate that warming did promote N2O emissions and ammonia volatilization in paddies by accelerating soil N transformation, which might be aggravated by fertilization. Furthermore, the "surge" effect of high ambient temperature and NH4+-N concentration on ammonia volatilization deserves further attention.

Effects of Simulated Diurnal Asymmetrical Warming on the Growth Characteristics and Grain Yield of Winter Highland Barley in Tibet

There has been an obvious diurnal asymmetrical warming effect as a result of the overall climate warming in the Tibetan Plateau. To reduce the uncertainty caused by the diurnal asymmetrical warming effect on future food security predictions in the Tibetan Plateau, this study used winter highland barley (var. Dongqing No. 1) for the experimental materials, and the FATI (Free Air Temperature Increase) field open heating system to carry out a simulated diurnal asymmetrical warming experiment (AW: All-day warming, DW: Daytime warming, NW: Nighttime warming, CK: Control) for two growing seasons (2018–2019 and 2019–2020) at the Lhasa Agroecosystem Research Station. The growth characteristics and yield of Tibetan winter highland barley were investigated in this study. Compared to the control, all the AW, DW and NW treatments had significant effects on the phenological period of winter highland barley, with the advancement of the phenological phase and shortening of the whole growth period. The degree of influence was AW>NW>DW, and all the AW, DW and NW treatments shortened the interval from sowing to heading of winter highland barley and increased the interval from heading to maturity. The effect on the phenological phase was the most obvious for AW and reached a statistically significant level (P<0.05). During the generative growth phase, the biomass above-ground and plant height of winter highland barley had an increasing tendency under the different warming conditions. In the late growth period, the biomass above-ground and plant height of the NW treatment were significantly higher than those of the other treatments. In addition, the warming caused a decrease in the dry matter distribution proportions of leaves and stems at the mature stage, and an increase in the distribution ratios of roots and spikes; and the AW, NW and DW treatments increased grain yields by 16.4%, 24.6% and 9.5%, respectively, on average in the two years. The increasing effect on grain yields of the NW treatment reached a significant level compared with the control in 2019–2020 (t=–2.541, P=0.026). In terms of yield composition, the effective spike number and 1000-grain weight tended to increase. The grain number per spike tended to increase, except for the AW treatment, while panicle length and seed setting rate tended to decrease, except for the NW treatment. Therefore, the effects of different simulated diurnal asymmetrical warming treatments on the growth characteristics and yield of winter highland barley were variable in the Tibetan Plateau.

Warming increase the N2O emissions from wheat fields but reduce the wheat yield in a rice-wheat rotation system

Global warming often affects the greenhouse gas (GHG) emissions, yet the effect of simulated warming on GHG emissions from wheat fields, the major source of nitrous oxide (N2O) emissions, is still unclear. Therefore, using a free-air temperature increase system, we conducted a two-year field experiment to explore the effects of simulated warming on N2O and methane (CH4) emissions as well as wheat yields in a rice-wheat rotation system. Our results showed that compared with the ambient control, warming increased the cumulative seasonal emissions of N2O by 34.21 % (P < 0.05), but did not affect the seasonal CH4 emissions in the two years. Soil C/N ratio, pH, nirK gene and (nirK+nirS)/nosZ ratio were the main causes affecting N2O emissions. Warming reduced the wheat yield by 19.42 % mainly due to the reduction of panicles and shorter vegetative growth (P < 0.05). Greenhouse gas intensity of warming treatment was 10.42 % higher than that of the ambient control. Our findings indicate that warming may reduce the wheat yield but increase N2O emissions in China’s wheat-rice rotation system and emphasize the need for agronomic practices of high wheat yields and low GHG emissions in the climate change world.

Effects of free-air temperature increase on grain yield and greenhouse gas emissions in a double rice cropping system

The responses of grain yield and greenhouse gas (GHG) emissions to climate warming in rice paddies are serious concerns for both global food security and climate change mitigation. However, the impact of free-air temperature increase (FATI) on grain yield and methane (CH 4 ) and nitrous oxide (N 2 O) emissions remains unclear for one of the most globally significant rice production practices: the double rice cropping system. Here, we conducted a two-year field experiment to examine the effect of FATI by infrared heaters on grain yield and CH 4 and N 2 O emissions in a double rice field in subtropical China. FATI increased rice canopy temperature by 2.0 °C and soil temperature by 1.2 °C on average but had no effect on either early or late rice yield production. FATI did not affect CH 4 emissions, but significantly increased N 2 O emissions in both the early and late rice seasons. Averaged across two years, N 2 O emissions increased by 0.3 kg ha −1 and 0.7 kg ha −1 in the warmed plots for the early and late rice seasons, respectively. Consequently, FATI enhanced the global warming potential (GWP) and GHG intensity (i.e., yield scaled GWP) in the double rice cropping system. In addition, warming increased the abundance of ammonia-oxidising bacteria, ammonia-oxidising archaea, and a nitrite reductase gene ( nirS ), but decreased that of a nitrous oxide reductase gene ( nosZ ). Our results indicate that warming by FATI does not affect grain yield and CH 4 emissions but stimulates N 2 O emissions in the double rice cropping system and therefore promotes a potential positive feedback with future climate warming. • Free-air temperature increase (FATI) with infrared heater was performed in a double rice field. • Moderate warming by FATI had no significant effect on rice yield. • Moderate warming by FATI did not significantly affect CH 4 emissions. • Moderate warming by FATI stimulated N 2 O emissions.

Unexpected Parabolic Temperature Dependency of CH4 Emissions from Rice Paddies.

Global warming is expected to affect methane (CH4) emissions from rice paddies, one of the largest human-induced sources of this potent greenhouse gas. However, the large variability in warming impacts on CH4 emissions makes it difficult to extrapolate the experimental results over large regions. Here, we show, through meta-analysis and multi-site warming experiments using the free air temperature increase facility, that warming stimulates CH4 emissions most strongly at background air temperatures during the flooded stage of ∼26 °C, with smaller responses of CH4 emissions to warming at lower and higher temperatures. This pattern can be explained by divergent warming responses of plant growth, methanogens, and methanotrophs. The effects of warming on rice biomass decreased with the background air temperature. Warming increased the abundance of methanogens more strongly at the medium air temperature site than the low and high air temperature sites. In contrast, the effects of warming on the abundance of methanotrophs were similar across the three temperature sites. We estimate that 1 °C warming will increase CH4 emissions from paddies in China by 12.6%─substantially higher than the estimates obtained from leading ecosystem models. Our findings challenge model assumptions and suggest that the estimates of future paddy CH4 emissions need to consider both plant and microbial responses to warming.

Climate warming-induced drought constrains vegetation productivity by weakening the temporal stability of the plant community in an arid grassland ecosystem

An investigation of the influences of climatic warming on ecosystem function and stability is crucial to project the impact of global climate change on terrestrial ecosystems. However, few studies have applied multiple warming treatments in arid ecosystems, which play a critical role in the global carbon cycle and are among the ecosystems most sensitive to future climatic change. To explore the effects of climatic warming on plant community function and stability, moderate warming and acute warming treatments were conducted in desert grassland, Inner Mongolia, China, using free-air temperature increase facilities. Aboveground net primary production (ANPP) of plant community significantly decreased with climatic warming, particularly in warmer years with drier conditions. The decrease in ANPP was mainly caused by decreased soil moisture induced by climatic warming. Climatic warming reduced the temporal stability of the plant community by weakening plant species asynchrony and shifting key functional groups, such as perennial vs annual grass and C3 vs C4 species. Our findings indicate that climatic warming could hamper plant community productivity via decreased soil moisture and constrain plant community functioning by weakening community stability. This result highlights that shifts in plant community composition and consequent functional changes can play a key role in predicting the responses of arid ecosystems to climatic change.

Effects of free air temperature increase on nitrogen utilization of rice in northeastern China

<p id="C3">Northeastern China is one of the regions where are experiencing the most significant global warming trend. Revealing the effects of anticipated warming on nitrogen absorption and utilization of rice in northeastern China can provide reference for regional sustainable production of rice and optimal management of nitrogen fertilizer. In this study, the field and pot experiments were setup based on free air temperature increase (FATI) system in Harbin, Heilongjiang province during 2019 to 2020, combined with ¹⁵N isotope tracer technique, to investigate the effects of anticipated warming (+1.5℃) on rice yield, nitrogen utilization, and the fate of fertilizer nitrogen. The results showed that warming treatment (W) promoted rice above-ground dry-matter accumulation. The mean grain yields in field and pot experiments during 2019 and 2020 under warming treatment were higher by 10.4% and 10.8% than those under control (CK), respectively. Compared with CK, the mean total nitrogen uptake of two years under W treatment significantly increased by 21.3%, however, the nitrogen utilization efficiency of rice grains showed a decreased trend. Under W treatment, the nitrogen absorbed from fertilizer decreased significantly, while the nitrogen absorbed by rice from soil increased by 31.1%, resulting in the reduction of 12.5% in fertilizer nitrogen recovery rate and the increase of 14.2% in fertilizer nitrogen loss rate. Overall, warming tended to increase rice grain yield, but decreased the proportion of fertilizer nitrogen uptake by plant, which leading to the decrease in nitrogen use efficiency and the significant increase in nitrogen loss rate. Under the background of climate warming, it was suggested to reasonably increase the transplanting density of rice to make full use of the positive effect of global warming on rice yield, as well as appropriately reduce the amount of nitrogen fertilizer application and optimize the management of nitrogen fertilizer operation to improve the nitrogen use efficiency of rice.

Open Field Simulating Nocturnal Warming on Summer Maize Performance in the North China Plain

Climate changes show asymmetrical warming, and warming is typically greater at night than during the day. To understand how nocturnal warming (NW) affects the performance of maize (Zea mays L.), an open-field experiment with a free air temperature increase (FATI) facility was conducted for three seasons during 2014 to 2016 at Luancheng eco-agro-experimental station on the North China Plain (NCP). Three nocturnal warming scenarios were set up: the entire growing period (T1, from V4 to maturity), only the vegetative stages (T2, from V4 to a week presilking) and the reproductive stages (T3, from a week presilking to R6). The treatment without NW was the control. Maize lodged seriously in 2015 due to heavy rainfall combined with strong winds, and the experiment failed. The results from 2014 and 2016 were analyzed in this study. During the experimental duration, the average nocturnal temperature was increased by approximately 3.6 and 3.3 °C at 150 cm height and 2.0 and 1.7 °C at the soil surface during the vegetative stages. The corresponding increases were 2.1 and 2.5 °C and 0.7 and 1.2 °C at the soil surface during the reproductive stages in 2014 and 2016, respectively, as compared with that of the CK treatment. NW during the whole growth period significantly decreased maize yield for the two seasons. Treatment T2 had a smaller impact on maize yield than T1 and T3. The silking stage was delayed by 2 days in 2014 and 2016 under T1. As a result, presilking duration and VT-R1 interval were prolonged by 1–2 days; and the postsilking duration were shortened by 1–3 days under T1. The soil moisture in the warmed plots was slightly lower than that in the control plots in the 2014 and during the stages before the earlier grain-filling stages in 2016, but NW decreased soil water content greatly at the later grain-filling stages in 2016, which caused the fast green leaf senescence and exacerbated the negative effects of NW on maize yield. NW for the whole growth duration (T1) significantly decreased seed weight and harvest index. NW increased leaf nighttime respiration rate in both seasons. No significant effects of NW on ear leaf net photosynthesis, leaf area, and specific leaf weight at early grain-filling stage were observed, irrespective of the warming stage and season. The results suggested that reproductive stages were more sensitive to NW compared to vegetative stages under the growing conditions of NCP. The negative effects of NW were worsened in dry seasons. The reduction in maize yield with nocturnal warming was driven by the reduction in the aboveground carbon allocation from shoot to grain during postanthesis stage.

A hot-blast warming facility for simulating global warming in low-stature crop systems and its application case to assess elevated temperature effects on rice in Central China

BackgroundTo study the impact of climate warming on crops, it is crucial to have a warming equipment suitable for their field environment. A facility is needed that can provide suitable combinations of different temperatures at reasonable cost for large plots.ResultsHere, an additional field warming facility option named the hot-blast warming facility (HBWF), which comprised heaters, blowers, wind breaks, and a control board was developed. An application case based on HBWF was carried out to assess elevated temperature effects on rice in Central China during 2015 and 2016. We tested four elevated temperature treatments on four rice cultivars under paddy field conditions and measured yield and its components. Heating convection air directly, the facility could increase the temperature of the rice canopy up to 1–2 °C, which could properly simulate global warming. Considering the costs, the HBWF reduced the operating costs because of its relatively lower power consumption (0.164 kW/m2), which was 80% lower than that of Free Air Temperature Increase. Our results demonstrate that the HBWF could build a 25 m2 homogeneous heating area and had little effect on the relative humidity under a paddy field environment. Warming treatments significantly reduced the grain yield by 4.4–22.7% in 2015, and 30.8–61.9% in 2016, compared to the control. The main contribution to the significant decrease of the grain yields was the decrease in seed setting rate. Moreover, a reduction of 1000-grain weight led to the decline in grain yield. The increasing ranges of the temperature simulated by HBWF were stable in different years, however, whether the elevated treatments demonstrated significant difference on rice growth mainly decided by the basic atmospheric temperature (as the control) during the growth period.ConclusionsThe new warming facility is suitable for field trials to assess elevated temperature combinations and provides an extra equipment option for use in elevated temperature research in the future.

Elevated CO2 and temperature influence key proteins and metabolites associated with photosynthesis, antioxidant and carbon metabolism in Picrorhiza kurroa

Global warming is currently one of the most serious issues in ecology. Rising CO2 level and temperature have begun to impact life cycles, distribution and yield of various plants yet, how medicinal plants will respond to changing environment is largely unknown. Picrorhiza kurroa Royle ex Benth. (Plantaginaceae) is a medicinal plant species that has been used for treatment of various diseases, particularly hepatic disease. Here, we have performed leaf and rhizome specific proteomic and metabolomic analysis to investigate the effect of elevated CO2 and temperature on adaptive responses of P. kurroa. We observed differentially abundant proteins related to photosynthesis and carbon metabolism under free air carbon dioxide enhancement, whereas cytoskeleton proteins in free air temperature increase besides signaling, antioxidant, stress-responsive and chromatin remodeling proteins in both conditions. We also found an increased accumulation of metabolites, particularly picroside-I and picroside-II, sugars and sugar alcohol in rhizomes, whereas, decrease in picroside-I and increase in picroside-II content in leaves at FACE condition. Biochemical indices like total protein, phenolics, flavonoids and antioxidant activity were altered in a tissue-specific manner to elevated CO2 and temperature. The results would provide new insights into possible adaptive mechanism, particularly in P. kurroa and medicinal plants in general. SignificancePicrorhiza kurroa is an endangered medicinal plant of Himalayan region having immense medicinal values due to the presence of iridoid glycosides. This endangered plant species is particularly, more vulnerable to climate change. P. kurroa provides an opportunity to investigate the interaction between high altitude plant and their environment. Therefore, it will be essential to elucidate the adaptation mechanism at molecular level under e[CO2] and e[t] conditions. The e[CO2] and e[t] will likely alter the proteome and metabolite composition of plant and thereby, enhance plant adaptation. Proteomic and metabolomic studies would facilitate to explore the adaptive mechanism of P. kurroa which is poorly understood. Collectively, the findings will be helpful for better understanding of plant response to future CO2 and temperature enriched environment and are of key importance to agriculture and ecosystem.

Combined effect of elevated CO2 and temperature on growth, biomass and secondary metabolite of Hypericum perforatum L. in a western Himalayan region

Rising carbon dioxide [CO2] levels and air temperature influence overall growth and production pattern of crop plants, and thus they help in understanding the functional relationship between the environment and crop performance. The present experiment was conducted to study the simultaneous effect of elevated CO2 (550 ± 50 μmol mol−1) and air temperature (2.5 ± 0.5 °C above ambient) on Hypericum perforatum growth, biomass and carbon-based plant secondary metabolite concentrations at free air CO2 enrichment (FACE) and free air temperature increase (FATI) facilities of CSIR-Institute of Himalayan Bioresource Technology, Palampur, India during 2016-2017. Experiment was laid out in factorial CRD (completely randomized design) with five replications. Results showed that the growth and biomass were significantly affected by elevated CO2 and temperature. Plant height at 140 days after exposure (DAE) and 280 DAE was 8.49% and 6.90% higher in FACE + FATI as compared to ambient, respectively. Total dry biomass was 35.70% and 55.20% higher in FACE + FATI as compared to ambient at 140 DAE and 280 DAE, respectively. Application of vermicompost recorded 8.50% higher biomass and 20.65% higher hypericin content as compared to control. Hypericin concentration reduced significantly by 22.00% in elevated CO2, while under combined effect of elevated CO2 and temperature it reduced by 19.30% when compared to ambient. Phenological stages i.e. bud and flower formations were advanced by 4 and 5 days, respectively, under FACE as compared to ambient.

Effects of experimental warming on physicochemical properties of indica rice starch in a double rice cropping system

To evaluate the actual response of rice starch physicochemical properties to climate warming, a field warming experiment was conducted with four indica rice cultivars using free-air temperature increase (FATI) facility in a double rice cropping system. FATI facility increased rice canopy temperature by 1.4–2.1 °C during the entire growth period. The responses of starch physicochemical properties to experimental warming were basically consistent for both early and late rice. On average, experimental warming increased the starch relative crystallinity, granule average diameter, and amylopectin average chain length by 14.3%, 6.9%, and 2.4%, respectively. These resulted in starch with lower swelling power, water solubility, and pasting viscosity, but higher gelatinization temperatures and gelatinization enthalpy. Our study indicated that experimental warming affected the rice starch physicochemical properties, and would provide some useful information on how to guide the rice starch end use in food and non-food industries under climate warming.

Experimental warming reduces fertilizer nitrogen use efficiency in a double rice cropping system

Climate warming significantly affects nitrogen (N) cycling, while its effects on the use efficiency of fertilizer N are still unclear in agroecosystems. In the present study, we examined for the first time the response of fertilizer N use efficiency to experimental warming using &lt;sup&gt;15&lt;/sup&gt;N labeling with a free-air temperature increase facility (infrared heaters) in a double rice cropping system. &lt;sup&gt;15&lt;/sup&gt;N-urea was applied in micro-plots to trace the uptake and loss of fertilizer N. Results showed that moderate warming (i.e. an increase of 1.4°C and 2.1°C in canopy temperature for early and late rice, respectively) did not significantly affect grain yield and biomass. Warming significantly reduced N uptake from fertilizer for both early and late rice, while increased N uptake from soil. The N recovery rate of fertilizer was reduced from 35.5% in the control and to 32.3% in the warming treatments for early rice and from 47.2% to 43.1% for late rice, respectively. Warming did not affect fertilizer N loss rate in the early rice season, whereas significantly increased it from 38.9% in the control and to 42.7% in the warming treatments in the late rice season, respectively. Therefore, we suggest that climate warming may reduce fertilizer N use efficiency and increase N losses to the environment in the rice paddy.