Soil temperature rise caused by global warming is one of the most serious threats to crop physiology and production. Straw return is considered as a potential strategy to improve soil health and ...agricultural productivity. However, little is known about their interactive effects on wheat growth and production, which limits the development of strategies and technological innovations for future food security. Therefore, in the two wheat seasons from 2018 to 2020, with or without straw return, the heating cable was laid at a depth of 20 cm to increase the soil temperature by 3.8 ℃, and the phenology, photosynthesis, root growth, and grain yield of winter wheat were studied. Soil warming advanced the anthesis date by one week and promoted pre-anthesis wheat growth and dry matter transportation. However, soil warming decreased post-anthesis duration, leaf area index, SPAD, net photosynthesis, and spectral vegetation indexes. Therefore, post-anthesis dry matter accumulation and grain filling were inhibited, lowering the 1000-grain weight and harvest index. Furthermore, the post-anthesis root weight, length, surface area densities and root to shoot ratio were also decreased under soil warming. Finally, soil warming reduced the grain yield by 35.2% in the dry 2018–2019 year. However, the wheat growth characteristics were considerably higher and no difference in grain yield was detected among treatments in the wet 2019–2020 season, indicating that increased precipitation may offset the adverse effect of soil warming on wheat yield. Straw return increased aboveground biomass, but had no effect on wheat yield, probably because the positive effects were limited in the short experimental duration. The findings suggested that soil warming would promote pre-anthesis wheat growth but accelerate post-anthesis wheat senescence, affect dry matter transportation and accumulation, eventually reducing wheat yield in the NCP, especially under dry condition.
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•Warming shortened pre-anthesis duration and promoted pre-anthesis wheat growth.•Warming shortened post-anthesis length, decreased photosynthetic capacity and root growth, eventually reducing wheat yield.•Straw return increased aboveground biomass but had no effect on wheat yield.
Elevational variation in plant growing environment drives diversification of photosynthetic capacity, however, the mechanism behind this reaction is poorly understood. We measured leaf gas exchange, ...chlorophyll fluorescence, anatomical characteristics, and biochemical traits of Salvia przewalskii at elevations ranging from 2400 m to 3400 m above sea level (a.s.l) on the eastern Qinghai-Tibetan Plateau, China. We found that photosynthetic capacity showed an initial increase and then a decrease with rising elevation, and the best state observed at 2800 m a.s.l. Environmental factors indirectly regulated photosynthetic capacity by affecting stomatal conductance (gs), mesophyll conductance (gm), maximum velocity of carboxylation (Vc max), and maximum capacity for photosynthetic electron transport (Jmax). The average temperature (T) and total precipitation (P) during the growing season had the highest contribution to the variation of photosynthetic capacity of S. przewalskii in subalpine areas, which were 25% and 24%, respectively. Photosynthetic capacity was mainly affected by diffusional limitations (71%–89%), and mesophyll limitation (lm) played a leading role. The variation of gm was attributed to the effects of environmental factors on the volume fraction of intercellular air space (fias), the thickness of cell wall (Tcw), the surface of mesophyll cells and chloroplasts exposed to intercellular airspace (Sm, Sc), and plasma membrane intrinsic protein (PIPs, PIP1, PIP2), independent of carbonic anhydrase (CA). Optimization of leaf tissue structure and adaptive physiological responses enabled plants to efficiently cope with variable climate conditions of high-elevation areas, and the while maintaining high levels of carbon assimilation.
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•Quantified and analyzed the response of photosynthetic capacity of S.przewalskii to elevation.•Climate variation along elevation directly affected leaf characteristics to drive diversity in photosynthetic capacity.•Mesophyll limitation was the main internal limiting factor affecting photosynthetic capacity.•This study revealed the mechanism of photosynthesis fluctuations of S.przewalskii in subalpine areas.
•Plant density alters leaf nitrogen allocation to photosynthetic apparatus and nitrogen partitioning among photosynthetic components.•Cotton optimized photosynthetic nitrogen use efficiency and ...photosynthetic capacity by adjusting leaf mass per area.•Appropriate spatial distributions of leaf N allocation to the photosynthetic apparatus and photosynthetic use efficiency of photosynthetic N contribute to efficient utilization of light and nitrogen.
Plant population density (PPD) is an important practice for optimizing canopy structure and improving canopy photosynthetic capacity of field-grown cotton (Gossypium hirsutum L.). A 2-yr field experiment was conducted to determine if and how PPD (7.5, 19.5 or 31.5 plants m−2) affects the light-saturated photosynthetic rate and photosynthetic nitrogen use efficiency in cotton leaves, with a focus on the key canopy characteristics for efficient utilization of light and nitrogen. The results showed that leaf N allocation and partitioning among different components of the photosynthetic apparatus were significantly affected by PPD. As PPD changed, cotton optimized photosynthetic N use efficiency and photosynthetic capacity by adjusting leaf mass per area, which in turn affected leaf N allocation to the photosynthetic apparatus. In the upper canopy layer, leaf N allocation to the photosynthetic apparatus increased as PPD increased, resulting in an increase in leaf photosynthetic N use efficiency. In contrast, in the mid- and lower-canopy layers, leaf N allocation to the photosynthetic apparatus decreased as PPD increased, resulting in declines in leaf light-saturated photosynthetic rate and photosynthetic N use efficiency. The overall results indicated that high photosynthetic capacity of leaves in the upper-canopy layer and high leaf N allocation to the photosynthetic apparatus and photosynthetic use efficiency of photosynthetic nitrogen in the mid- and lower-canopy layers were two key canopy characteristics for efficient utilization of light and nitrogen by cotton. The medium-PPD is the optimum plant density due to high light utilization efficiency, superior spatial distribution of leaf N allocation to the photosynthetic apparatus and photosynthetic use efficiency of photosynthetic N in leaves within the canopy.
•The improved intercropping system integrated with straw and plastic mulch in each intercrops.•The improved management practices serve as a promising farming system in an arid conditions.•This system ...maintained high physiological activity of crops at their reproductive growth period.•This system is beneficial to maintaining the stability of crop water demand and soil water supply.•This system can coordinate the contradiction between water shortage and high yield in arid areas.
Strip intercropping is a feasible cropping pattern to improve crop productivity via enhancing the stability of farmland ecosystem. Straw returning and plastic film mulch are effective and valuable measures to boost crop productivity in arid or semi-arid regions. It is unknown whether the yield advantage of strip intercropping can be further enhanced by improving photosynthetic characteristics when applied synchronously with straw returning and plastic film mulch measures. A field experiment on wheat-maize intercropping system was conducted at strip management with straw and plastic film, and photosynthetic characteristics, leaf and soil water potential, and grain yield were determined. The results showed that the SPAD value of wheat and maize leaves with NTSM/NTP (no-tillage with wheat straw mulch in wheat strips and previous residual plastic film mulch in maize strips) was decreased at the vegetative growth period, a higher SPAD value was maintained at the reproductive growth period, compared to CT/CTP (conventional tillage with no straw returning in wheat strips and annual new plastic film mulch in maize strips), it indicated that NTSM/NTP treatment can maintain high physiological activity of intercropped wheat and maize at their reproductive growth period. NTSM/NTP treatment raised net photosynthetic rate (Pn) and leaf water use efficiency (WUEL) of wheat by 9.0–15.8 % and 4.9–8.8 % from filling (Feekes 11.0) to doughing (Feekes 11.2) stage, and raised both indexes of maize by 11.5–25.5 % and 4.7–14.8 % from milking (R3) to doughing (R4) stage, with little effect on transpiration rate (Tr), in comparison to CT/CTP, respectively. NTSM/NTP treatment kept relatively high leaf and soil water potential of intercropped strips, and favorably created a suitable soil moisture environment for enhancing the drought resistance on intercrops. In addition, the value of difference between leaf and soil water potential of wheat and maize in NTSM/NTP treatment was lower than that in CT/CTP treatment at given determining stages, it indicated that NTSM/NTP treatment was beneficial to maintaining the stability of crop water demand and soil water supply for growth of two intercrops. Thus, NTSM/NTP treatment obtained high grain yields, increased by 8.6–11.1 % for intercropped wheat, increased by 16.0–20.2 % for intercropped maize, and increased by 13.8–17.1 % for intercropped wheat plus maize, in comparison to CT/CTP treatment. The improved photosynthetic capacity, optimized leaf and soil water potential, and increased grain yields for intercropped wheat and maize in NTSM/NTP treatment. Therefore, strip intercropping integrated of no tillage with wheat straw and previous residual plastic film mulch can be recommended as the excellent technique to coordinate the contradiction between water shortage and high grain yield in arid irrigated regions.
Although gross primary production (GPP) is an essential proxy for reflecting terrestrial ecosystem function, GPP estimation at regional scale on the Tibetan Plateau (TP) is constrained by the lack of ...ground observations. Moreover, how climate-induced phenological and physiological change further affects carbon uptake in this region remains unclear. In this study, we first estimated GPP at 8-day intervals and a 0.5° resolution from 2007 to 2015 over the TP based on an improved approach and GOME-2 sun-induced fluorescence (SIF) retrievals. The obtained SIF-based GPP coincided well with flux observations and two state of the art GPP products, with a regional carbon uptake of 0.62 ± 0.04 PgC year−1 or 307 ± 22 gC m−2 year−1. With the SIF-based GPP, two phenological indicators (start and end date of the growing season, i.e., SGS and EGS) and one physiological indicator (maximum photosynthesis capacity, GPPmax) were identified and their relative contributions to inter-annual GPP variability were further quantitatively separated using a multiple regression model. Advanced SGS, delayed EGS, and increasing GPPmax can all enhance carbon uptake and a combination of the three indicators can explain 72 ± 20% of GPP inter-annual variability. The response of annual GPP to phenological and physiological variations has significant altitude dependence, as the decline of annual GPP in most of the area is dominated by the GPPmax decline, while the increase of annual GPP in the high-altitude area is dominated by the advanced SGS. The response of all three indicators to both temperature and precipitation variation has great spatial heterogeneity. Our study suggests that remote sensing of SIF can provide a unique opportunity to estimate GPP in regions with a lack of ground observations and that our enhanced understanding of the impact of the climate-induced phenological and physiological change on GPP variability in alpine ecosystems can improve GPP estimation in a changing climate.
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•Gross primary production (GPP) is estimated with SIF space observations on the TP.•An assemble of SGS, GPPmax and EGS can explain 72 ± 20% of GPP inter-annual variability.•GPP variability is dominated by physiology in the most areas of the TP.•The response of GPP to phenological and physiological change has altitude dependence.•The response of phenology and physiology to climate variations has spatial heterogeneity.
Poor grain filling of inferior kernel of summer maize is a major challenge restricting grain yield of summer maize, especially under higher plant densities. Much work so far has proved that tillage ...practices could regulate soil properties and grain yield of maize effectively. In order to explore the effect of tillage practice on grain filling of inferior kernel of summer maize, field experiments were conducted over two consecutive years (2016–2017), and three tillage practices (T1, no tillage; T2, no tillage with subsoiling; T3, deep horizontal rotary tillage) were assessed. The grain filling parameter showed that final grain weight (A), the time reaching the maximum grain filling rate (Tmax), the dry matter accumulation under the maximum grain filling rate (Wmax), the mean grain filling rate (Gmean), and the active grain filling period (D) of T2 were usually higher than that of T1 and T3, and significant difference was observed between T2 and T1. Compared with T1, T2 and T3 reduced the soil bulk density and increased the soil porosity, and significantly increased the root dry matter accumulation in the 0–40 cm soil profile by 13.4% and 28.7%, respectively. Soil water content decreased among tillage practices in the order T2 > T1 > T3. However, T2 and T3 increased the water consumption, compared to that of T1. Moreover, T2 and T3 increased post-anthesis photosynthetic capacity, including the photosynthetic rate, leaf area duration, and chlorophyll content, and further improved the post-antheisis and total dry matter accumulation. The enzyme activities of SuSase, StSase, and ADPG-PPase of inferior and superior kernel in T2 and T3 were also higher than that of T1. In conclusion, the present results indicate that subsoiling could promote the grain filling of inferior kernel of summer maize by regulating soil water content, soil water consumption, and photosynthetic capacity.
•Tillage practices affected the grain filling of inferior kernel of summer maize.•Subsoiling significantly improved the soil water content in maize production.•Subsoiling or deep horizontal rotary tillage increased post-anthesis photosynthate capacity.•Subsoiling is an optimal tillage practice in promoting the grain filling of inferior kernel of summer maize.
Plant photosynthetic capacity directly determines crop yield. Light quality regulates photosynthetic capacity. This review discusses plant responses to far-red light from the phenotypic to the ...molecular level, focusing specifically on the improvement of photosynthetic capacity by adjustment of photosynthetic electron transport and the path of light energy. Far-red light can also regulate leaf angle and increase plant height and leaf area, via expression of associated genes, to capture more light energy. Thus, far-red light regulates plant morphology and photosynthetic capacity. Identifying the mechanism of this regulation may lead to increased crop yields.
•Inter- and intra-sexual competition patterns affected eco-physiological responses of P. cathayana to EC, ET and ETC.•Carbon-related metabolites of females were most strongly affected by ET under ...inter- and intra-sexual competition.•Males exhibited strongest responses of water and nitrogen use efficiencies to EC and ETC.•Competitive pressure of females on males was intensified by ET but alleviated by ETC.
It remains unclear how global climate change affects dioecious plants that may be especially vulnerable to climate drivers, because they often exhibit skewed sex ratios and eco-physiological specialization in certain microhabitats. In this study, female and male saplings of Populus cathayana were employed to explore sex-specific responses and the effects of sexual competition under elevated temperature (ET), elevated CO2 (EC) and combination of elevated temperature and CO2 (ETC). The results demonstrated that elevated temperature and CO2 interactively modulated sexual competition and responses of P. cathayana. Moreover, competition patterns affected the eco-physiological responses of P. cathayana to climate change treatments. Under both intra- and inter-sexual competition, biomass components, photosynthetic parameters and carbon-related metabolites of females were most strongly affected by ET, while males exhibited a higher photosynthesis and resource use efficiency, and a better biomass accumulation and carbon balance mechanism when compared to females when experiencing intra-sexual competition under EC. The competitive pressure of females on males in inter-sexual competition was intensified by ET, while it was alleviated by ETC. We conclude that climate change drivers and competition patterns differently regulate the sex-specific responses and competitive intensity of males and females, which may have a crucial effect on sex ratios, spatial sexual segregation, biomass production and carbon sequestration in dioecious species in the future.
The off-flavor compound 2-methylisoborneol (2-MIB) is generally associated with the proliferation and metabolism of filamentous cyanobacteria in shallow freshwater ecosystems. Here field monitoring ...in East Taihu Lake from July to October 2021, along with cultural experiments, was conducted to determine the impact of submerged macrophytes on the growth and 2-MIB production of filamentous cyanobacteria. Pseudanabaena sp. was identified as the 2-MIB producer with the highest detection rate (100%) and correlation coefficient (R=0.68, p < 0.001). The 2-MIB concentration and algal growth in the macrophyte-dominated zones were markedly decreased compared with those in the phytoplankton-dominated zone. Five submerged macrophytes classified into flat-leaf type (Vallisneria natans and Potamogeton crispus) and thin-leaf type (Hydrilla verticillata, Ceratophyllum demersum, and Myriophyllum spicatum) exhibited strong inhibition effects against Pseudanabaena sp.: Overall inhibition efficiencies (IEs) of 92.7% ± 6.8% and 92.7% ± 8.4% for cell growth and 2-MIB production were achieved, respectively. Moreover, the thin-leaf macrophytes exhibited significant higher IEs for cell growth (94.0% vs. 84.7%) and 2-MIB production (99.4% vs. 82.6%) than the flat-leaf macrophytes and can be selected as pioneer species in controlling odor problems. Nutrient uptake, increasing water clarity, shading effects, and allelopathic effects of the submerged macrophytes were found to be the dominant inhibition mechanisms.
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•Pseudanabaena was first identified as the 2-MIB producer in East Taihu Lake.•All submerged macrophytes are effective in the inhibitory process of Pseudanabaena.•The shading effects and allelopathic effects play important role in the experiment.•The thin-leaf types are the optimal submerged macrophytes to minimize odor problem.
The production of high quality liquid nitrogen fertilizer with both nutrient comprehensive and biostimulant properties by alkaline thermal hydrolysis of sewage sludge has shown great potential in ...agricultural production. However, little is known about the effects of sewage sludge-derived nutrients, and biostimulants (SS-NB) on leaf photosynthesis and root growth in rice. Phenotypic, metabolic and microbial analyses were used to reveal the mechanism of SS-NB on rice. Compared to NF treatment, phenotypic parameters (fresh/dry weight, soluble sugar, amino acid, protein) were increased by SS-NB in rice. SS-NB can enhance the photosynthesis of rice leaves by improving the photoconversion efficiency, chlorophyll content, ATP synthase activity, Rubisco and NADPH production. Meanwhile, SS-NB also increased antioxidant capacity (SOD, POD, CAT and proline) in rice leaf and root tissues. Metabolomics revealed that SS-NB application increased the expression levels of metabolites in root and leaf tissues, including carbohydrate, nitrogen and sulfur metabolism, amino acid metabolism, antioxidants, and phytohormone. Most importantly, the regulation of metabolites in rice root tissues is more sensitive than in leaf tissues, especially to the higher levels of antioxidants and phytohormones (IAA and GA) in rice root tissues. Furthermore, SS-NB increased the abundance of photosynthetic autotrophic, organic acids-degrading and denitrifying functional bacteria in rice roots and recruited plant growth-promoting bacteria (Azospirillum and norank_f_JG30-KF-CM45), while the NF treatment group resulted in an imbalance of the microbial community, leading to the dominance of pathogenic bacteria. The results showed that SS-NB had great application potential in crop growth and stress resistance improvement.
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•SS-NB enhanced rice N metabolism and accumulation through microbial transformation.•The indole derivatives in SS-NB may stimulate root hormone activity and root growth.•Amino acid synthesis improves the photosynthesis capacity and sucrose accumulation.•The stimulatory effect of SS-NB on rice root was stronger than that on rice leaf.•Diterpenoid metabolites biosynthesize gibberellin to promote root growth.
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