Search

Background: Although hormesis induced by heavy metals is a well-known phenomenon, the involved biological mechanisms are not fully understood. Cadmium (Cd) is a prevalent heavy metal in the environment. Exposure of Cd, via intake or consumption of Cd-contaminated air or food, poses a huge threat to human health. Chinese cabbage pakchoi (Brassica chinensis L.) is widely planted and consumed as a popular vegetable in China. Therefore, studying the response of Chinese cabbage pakchoi to Cd- stressed conditions is critical to assess whether cabbage can accumulate Cd and serve as an important Cd exposure pathway to human beings. In this study, we investigated the influence of Cd stress on growth, photosynthetic physiology, antioxidant enzyme activities, nutritional quality, anatomical structure, and canopy temperature in Chinese cabbage pakchoi. A partial least squares (PLS) model was used to quantify the relationship between physical and chemical indicators with Cd accumulation in cabbage, and identify the main controlling factors. Results: Results showed that Cd stress significantly inhibited cabbage's growth and development. When Cd stress was increased, the phenotypic indicators were significantly reduced. Meanwhile, Cd stress significantly enhanced the oxidative stress response of cabbage, such as the activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), and the content of malondialdehyde (MDA) in leaves. Such a change tended to increase fenestrated tissues' thickness but decrease the thickness of leaf and spongy tissues. Moreover, Cd stress significantly increased soluble sugar, protein, and vitamin C contents in leaves as well as the temperature in the plant canopy. The PLS model analysis showed that the studied phenotypic and physicochemical indicators had good relationships with Cd accumulation in roots, shoots, and the whole plant of cabbage, with high coefficient of determination (R2) values of 0.891, 0.811, and 0.845, and low relative percent deviation (RPD) values of 3.052, 2.317, and 2.557, respectively. Furthermore, through analyzing each parameter's variable importance for projection (VIP) value, the SOD activity was identified as a key factor for indicating Cd accumulation in cabbage. Meanwhile, the effects of CAT on Cd accumulation in cabbage and the canopy mean temperature were also high. Conclusion: Cd stress has significant inhibitory effects and can cause damage cabbage's growth and development, and the SOD activity may serve as a key factor to indicate Cd uptake and accumulation in cabbage. [ABSTRACT FROM AUTHOR]

SUMMARY: Wheat (Triticum aestivum L.) radiation use efficiency (RUE) must be raised through crop breeding to further increase the yield potential, as the harvest index is now close to its theoretical limit. Field experiments including 209 wheat cultivars which have been widely cultivated in China since the 1940s were conducted in two growing seasons (2018–2019 and 2019–2020) to evaluate the variations of phenological, physiological, plant architectural, and yield‐related traits and their contributions to RUE and to identify limiting factors for wheat yield potential. The average annual genetic gain in grain yield was 0.60% (or 45.32 kg ha−1 year−1; R2 = 0.44, P < 0.01), mainly attributed to the gain in RUE (r = 0.85, P < 0.01). The net photosynthetic rates were positively and closely correlated with grain RUE and grain yield, suggesting source as a limiting factor to future yield gains. Thirty‐four cultivars were identified, exhibiting not only high RUE, but also traits contributing to high RUE and 11 other critical traits – of known genetic basis – as potential parents for breeding to improve yield and RUE. Our findings reveal wheat traits and the associated loci conferring RUE, which are valuable for facilitating marker‐assisted breeding to improve wheat RUE and yield potential. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fine roots are essential for water and nutrient uptake in plants, but little is known about the variation in fine root traits and the underlying mechanisms that drive it. Understanding the responses of fine root function traits to changing environmental conditions and the role of fine root traits as drivers of forest ecosystem processes are critical for informing physiological and ecological theory as well as ecosystem management. We measured morphological and physiological traits of fine roots from six soil layers and three diameter classes in Schrenk’s spruce (Picea shrenkiana) forests of the Tianshan mountains, China. We found significant effects of nitrogen addition on these morphological and physiological traits, which varied by soil layer and root diameter. Specifically, specific root length (SRL) was higher in medium N addition group (N2) than in control group (N0). Specific root area (SRA) was higher in the control group (N0) than fertilized groups (N1, N2 and N3). Root tissue density (RTD) was higher in low N addition group (N1) than in the other group. Root dry matter content had no significant difference among four treatment groups. SRL, SRA, and RTD of fine roots in different diameter classes were all significantly different between high N addition (N3) and the control (N0) groups. The physiological characteristics of fine roots showed that soluble sugar (SS), fine root vitality (FRV), and tissue water content (TWC) in different soil layers were higher in the control group than in the fertilized groups. While soluble protein (SP), malondialdehyde (MDA) and free proline (FP) were lower in the control group (N0) than in the fertilized groups. In addition, SS, FRV, SP, TWC, FP, and MDA in all N addition treatments groups were significantly different from the control group. Fine root morphological traits were closely related to physiological traits, and added nitrogen inputs change these correlations. Our study confirms that nitrogen addition has specific effects on the morphological and physiological traits of fine roots of Schrenk’s spruce, and the effects of N addition vary according to the amount added. [ABSTRACT FROM AUTHOR]

• Yellowhorn germplasms showed relatively high genetic diversity. • The core germplasms represent the diversity of the original collected germplasms. • Core and original germplasm are similar in terms of physiological traits. • Core germplasm of yellowhorn represents the original germplasm. Yellowhorn (Xanthoceras sorbifolium Bunge) is an important ecological, economic, and ornamental plant species native to China. However, the physiological diversity, genetic variation, and core germplasms have not been revealed, which hindered the breeding process of yellowhorn. Here, we evaluated the genetic diversity of 155 yellowhorn germplasms using five physiological traits. The content of flavonoids varied significantly in different germplasms, and it was positively correlated with soluble sugar content (P < 0.01). A total of 253, 336 candidate SSR were identified from the whole genome of yellowhorn. A moderate genetic diversity was found in yellowhorn based on the mean values of the number of effective alleles (N e = 2.307), expected heterozygosity (H e = 0.527), and observed heterozygosity (H o = 0.317) with 30 pairs of polymorphic SSR markers. Population structure, Neighbor-Joining phylogeny, and principal coordinates analyses divided all genotypes into two major groups with few admixtures. Meanwhile, we extracted 34 (21.94 %) core yellowhorn germplasms based on the variation in physiological traits (14 germplasms) and genetic diversity (23 germplasms). After multiple different analyses including genetic diversity parameters, coincidence rate of range, variance difference percentage, and coefficient of variation rate of change, there was no obvious difference between core and original germplasm, which indicated that the core germplasm could represent the original germplasm well. Our study will lay a solid foundation for future conservation and management of yellowhorn germplasms and the core collection will be valuable in molecular breeding programs. [ABSTRACT FROM AUTHOR]

• Genetic gain in wheat yield was 47.4 kg ha−1 yr−1 in Hebei Province during 50 years. • Yield progress in wheat yield was mainly due to the increase of harvest index. • Kernels per spike and thousand kernel weight were main contributors to genetic gain. • The increase of grain filling rate improved kernel weight. • The increase of water-soluble carbohydrate in stem and chlorophyll of flag-leaf benefited to gain in kernel weight. Understanding the key characteristics associated with genetic progress is essential to future wheat breeding strategies. Our objectives were to investigate the genetic progress in grain yield (GY) and key characteristics in wheat (Triticum aestivum L.) cultivars released from 1964 to 2007 in Hebei province, China. Field experiments including 9 milestone cultivars were conducted during three growing seasons (2010–2011, 2011–2012, and 2012–2013) at Shijiazhuang of Hebei. Grain yield is significantly increased by the linear rate of 47.4 kg ha−1 yr−1 or 0.717% (R 2 = 0.909, P < 0.001) and mainly attributed to the increase of harvest index (HI) (r = 0.927, P < 0.01), kernels per spike (Skernel) (r = 0.919, P < 0.01) and thousand kernel weight (TKW) (r = 0.869, P < 0.01). Aboveground biomass (AGBM) has also important contribution to genetic gain in yield before 1997 (r = 0.838, P < 0.05). Although there is decline tendency in spikes m−2 due to decreased maximum tiller numbers (Mtiller) and increased percentage of ear-bearing tiller (ET%) after 70 s, changes of spikes m−2 have no significant effect on yield improvement. Grain yield has positive correlation with kernels m-2 (r = 0.767, P < 0.05) in spite of slower increasing rate of kernels m−2 after 1970s. Genetic gain of GY has close relation with decreased plant height (PH) (r = −0.811, P < 0.01), and PH of stone cultivars after 1970s were 70–80 cm which was optimum for grain yield. Days to heading (DH), days to anthesis (DA) and days to maturity (DM) of stone cultivars have no significant correlation with genetic gain. The significant HI increase mainly results from a significant increase in TKW (r = 0.811, P < 0.01) and Skernel (r = 0.919, P < 0.01). The increased TKW is positively associated with the maximum filling rate (Rmax) (r = 0.720, p < 0.05), average filling rate (Ra) (r = 0.836, p < 0.01), water-soluble carbohydrate (WSC) at anthesis in stem (WSC0) (r = 0.820, p < 0.05), Stem WSC 10 d after anthesis (WSC10) (r = 0.861, p < 0.01) and chlorophyll content (Chl) (r = 0.783, p < 0.05). Thus the physiological traits of Chl of flag leaf, stem WSC and high filling rate can be used to select criterions for further improving yield potential. [ABSTRACT FROM AUTHOR]

Understanding the interactions of genotype (G) × environment (E) × management (M) and their impact on crop yield enables prediction of the performance of genotypes across environment. It can help select the most suitable cultivars in target regions and identify contributions of novel traits in crop breeding. In this study, we used the process-based APSIM-Canola model to investigate the G × E × M interactions for the purpose of increasing canola yield in contrasting climatic regions of China. A dataset with observations for nine cultivars and 30 site-years was used to test the performance of APSIM-Canola model. Two representative genotypes (as base cultivars) were used to simulate canola potential yield and evaluate potential contributions of putative traits to increase canola yield at three representative sites. Our results show that APSIM-Canola was able to simulate seed yield of both spring and winter canola cultivars across contrasting climatic regions with acceptable accuracy. In the Upper and Middle Yangtze River Basin where rainfall is sufficient or irrigation is available, the yield potential of current winter canola cultivar was simulated to be 6.4 and 4.8 t ha −1 , respectively. In the Northern Region with limited rainfall, the yield potential was only 1.1 t ha −1 due to severe water stress. Traits that extended the grain filling duration by 20% could increase potential yield by 10% for winter canola, but 5% for spring canola. A 20% increase in radiation use efficiency (RUE) would increase yield by 10–20% in Yangtze River Basin, but had no impact on yield in the Northern Region. Traits that increased transpiration efficiency (TE) had the opposite impact, with 20% increase in TE leading to 30% increase in yield in the Northern Region, but with no significant yield increase in wet areas. A 20% increase in harvest index (HI) increased potential yield by nearly 20% across contrasting environments. A much larger yield gap for winter canola in the Yangtze River Basin was also found, indicating a much greater potential to increase canola seed yield there than in the Northern Region. This study highlights that very different traits need to be targeted for canola breeding across the contrasting climatic regions of China. [ABSTRACT FROM AUTHOR]

In China, coal-mining industries are mainly located in the water shortage areas including arid or semiarid areas. Mine wastewater is used for irrigation of agricultural land in these areas. However, few studies have been conducted to address ecological and food safety risks caused by mine wastewater irrigation. In this research, a pot experiment was performed to examine the effects of mine wastewater irrigation on soil enzymes, physiological properties of wheat and potential risks of heavy metal contamination to wheat crop. Plants were subjected to three mine wastewater irrigation treatments: leacheate of coal gangue (T1), coal-washing wastewater (T2) and precipitated coal-washing wastewater (T3). Plants irrigated with well water were taken as the control (CK). The results showed that mine wastewater irrigation caused adverse effects on soil enzymes, physiological properties and grain yield of winter wheat. At anthesis, T1, T2 and T3 treatments significantly reduced the activities of soil enzymes (urease, sucrase and catalase), root activity and net photosynthetic rate of wheat compared to CK. At maturity, grain yield was decreased by 17.8%, 15.4% and 9.8% by T1, T2 and T3, respectively, as compared to that of CK. Importantly, mine wastewater irrigation resulted in accumulation of heavy metals (Cr, Pb, Cu and Zn) in wheat grain. Contents of these heavy metals in grains of winter wheat subjected to mine wastewater irrigation were significantly higher than those in CK. The comprehensive contamination indexes of wheat grain in T1, T2 and T3 all reached high pollution level. Our results showed that mine wastewater irrigation significantly increased the pollution risk of heavy metals, thus unsuitable for crop irrigation. [ABSTRACT FROM AUTHOR]

Abstract: Understanding agronomic and physiological performance of crop high yield is essential to make strategies for breeding and crop management. This study aimed to identify major agronomic and physiological traits associated with high grain yields of rice and wheat in the wheat–rice rotation system in the lower reaches of Yangtze River of China. Two high-yielding cultivars, each for winter wheat and rice, were field-grown from 2008 to 2010 for 3 years. Two crop management treatments, the local farmer''s practice (LFP) and improved high-yielding cultivation (IHC), were used. The IHC adopted two new techniques, i.e., site-specific nitrogen management in both rice and wheat and alternate wetting and moderate drying irrigation in rice and controlled soil drying irrigation in wheat. Across the 3 years, the IHC yielded an average 9.67tha−1 of wheat and 12.55tha−1 of rice with an annual total of 22.2tha−1, an increase of 26.8% when compared with that (17.5tha−1) under the LFP. The increased grain yield under the IHC was mainly attributed to expanded sink size as a result of more kernels per spike or more spikelets per panicle, increased kernel weight of wheat and increased percentage of filled grains of rice. When compared with LFP, IHC showed a greater percentage of productive tillers, more pre-anthesis nonstructural carbohydrate (NSC) storage in the stem, greater leaf photosynthetic rate and concentration of cytokinins in root exudates, higher activities of sucrose synthase and adenosine diphosphoglucose pyrophosphorylase in grains, more dry mater production during the grain filling period, and higher harvest index. We conclude that (1) expanding sink capacity through an increase in kernels per spike or spikelets per panicle, (2) enhancing grain filling efficiency by an increase in pre-anthesis NSC in the stem, and (3) increasing post-anthesis dry mater production by an enhancement in root activity during grain filling should be considered as three major strategies for further increases in grain yields of wheat and rice in the lower reaches of Yangtze River of China. [Copyright &y& Elsevier]

Abstract: Knowledge of the changes in agronomic and photosynthetic traits associated with genetic gains in grain yield potential is essential for an improved understanding of yield-limiting factors and for determining future breeding strategies. The objectives of this study were to identify agronomic and photosynthetic traits associated with genetic gains in grain yield of facultative wheat (Triticum aestivum L.) between 1981 and 2008 in Henan Province, the most important wheat producing area in China. During the 2006–2007 and 2007–2008 crop seasons, a yield potential trial comprising 18 leading and new cultivars released between 1981 and 2008 was conducted at two locations, using a completely randomised block design of three replicates. Results showed that average annual genetic gain in grain yield was 0.60% or 51.30kgha−1 yr−1, and the significant genetic improvement in grain yield was directly attributed to increased thousand grain weight which also contributed to the significant increase in harvest index. The genetic gains in rates of net photosynthesis at 10, 20 and 30 days after anthesis were 1.10% (R 2 =0.46, P <0.01), 0.68% (R 2 =0.31, P <0.05) and 6.77% (R 2 =0.34, P <0.05), respectively. The rates of net photosynthesis at 10 (r =0.58, P <0.05), 20 (r =0.59, P <0.05) and 30 (r =0.65, P <0.01) days after anthesis were closely and positively correlated with grain yield. A slight decrease in leaf temperature and an increase in stomatal conductance after anthesis were also observed. Grain yield was closely and positively associated with stomatal conductance (r =0.69, P <0.01) and transpiration rate (r =0.63, P <0.01) at 30 days after anthesis. Therefore, improvement of those traits was the likely basis of increasing grain yield in Henan Province between 1981 and 2008. The genetic improvement in yield was primarily attributed to the utilization of two elite parents Yumai 2 and Zhou 8425B. The future challenge of wheat breeding in this region is to maintain the genetic gain in grain yield and to improve grain quality, without increasing inputs for the wheat–maize double cropping system. [Copyright &y& Elsevier]

Abstract: Selecting more water efficient cultivars is an important way to reduce water use in a water-scarce region. The objectives of this study were to measure the grain yield and water use efficiency (WUE) of winter wheat (Triticum aestivum L.) cultivars to understand the genetic gains in yield and WUE and their associated physiological and agronomic traits in Hebei province, North China Plain (NCP). Two groups of winter wheat cultivars were tested. Group 1 included 16 winter wheat cultivars that were released between 1998 and 2002 and were tested during the 2002/2003 and 2003/2004 seasons under two water regimes. Group 2 included 10 cultivars released between 1970 and 2000, and were tested during the 2005/2006 and 2006/2007 seasons under three water regimes. Results showed that WUE increased substantially from 1.0–1.2kgm−3 for cultivars from the early 1970s to 1.4–1.5kgm−3 for recently released cultivars. There was also a variation in yield and WUE of about 20% among Group 1 cultivars. Most of the cultivars in both groups had similar responses to water supply. WUE was greater for less irrigated treatments and maximum grain production was achieved with moderate water deficit. The genetic gains in grain yield were associated with increasing in biomass, harvest index and kernel numbers per spike for cultivars released in different years. Among the Group 1 cultivars, the ones with higher yield generally had higher WUE. No significant correlations were found between WUE and physiological traits such as ash content, chlorophyll content, or relative water content among the cultivars released recently. However, a significant relationship was found between stomatal conductance or ash contents and WUE or grain yield among the Group 2 cultivars. Relationships were apparent between WUE and date of anthesis and harvest index (P <0.05) in Group 1. Earlier flowering cultivars tended to have higher grain yield. In Group 2, flowering date was advancing by about 4 days over the 30 years of crop breeding. The positive relationship between grain yield and WUE for all the cultivars indicated that using a higher yielding cultivar has the potential to improve WUE and thereby to save water. [Copyright &y& Elsevier]

Background: The decrease in Cunninghamia lanceolata (Lamb.) production on continuously planted soil is an essential problem. In this study, two-year-old seedlings of two cultivars (a normal cultivar, NC, and a super cultivar, SC) were grown in two types of soil (not planted (NP) soil; continuously planted (CP) soil) with three watering regimes, and the interactive effects on plant growth and physiological traits were investigated in a greenhouse experiment. The water contents of the soil in the control (CK) (normal water content), medium water content (MWC) and low water content (LWC) treatments reached 75-80 %, 45-50 % and 20-25 % of the field water capacity, respectively., Results: The results indicated that the CP soil had a negative effect on growth and physiological traits and that the LWC treatment caused even more severe and comprehensive negative effects. In both cultivars, the CP soil significantly decreased the height increment (HI), basal diameter increment (DI), dry matter accumulation (DMA), net photosynthetic rate (Pn), total chlorophyll content (TChl), carotenoid content (Caro) and photosynthetic nitrogen use efficiency (PNUE). Compared to the NP soil, the CP soil also decreased the proline and soluble protein contents, nitrogen use efficiency (NUE) and phosphorus use efficiency (PUE) and increased the nitrogen:phosphorus ratio in roots, stems and leaves. The LWC treatment decreased growth and photosynthesis, changed ecological stoichiometry, induced oxidative stress, promoted water use efficiency and damaged chloroplast ultrastructure. Significant increases in ascorbate peroxidase (APX), peroxidase (POD), soluble protein and proline contents were found in the LWC treatment. Compared with the NC, the SC was more tolerant to the CP soil and water stress, as indicated by the higher levels of DMA, Pn, and WUE. After exposure to the CP soil and watering regimes, the decreases in biomass accumulation and gas exchange were more pronounced., Conclusions: The combination of drought and CP soil may have detrimental effects on C. lanceolata growth, and low water content enhances the impacts of CP soil stress on C. lanceolata seedlings. The superiority of the SC over the NC is significant in Chinese fir plantation soil. Therefore, continuously planted soil can be utilized to cultivate improved varieties of C. lanceolata and maintain water capacity. This can improve their growth and physiological performance to a certain extent., (© 2021. The Author(s).)

Leaves of trees experience the maximum brunt of exposure and undergo certain changes in physiological traits responding to air pollution, and then, the specific leaf traits can be the indicators of air pollution in an area. However, due to the diversity of sources, the composition of air pollutants is very complex. This makes it difficult to predict air pollution using physiological differentiation of leaves. The purpose of this investigation was to examine potential of Ligustrum lucidum Ait. leaf measurement as a method to predict the air pollutants in Luoyang, China. Leaves of roadside L. lucidum were studied from the city center with serious air pollution to relatively unpolluted areas. Leaf size, stomatal traits, and non-structural carbohydrate were measured. The particulate and gaseous pollutants (including sulfur dioxide, nitrogen dioxide, carbon monoxide, and ozone) were investigated too. The results showed that the leaf area and soluble sugar content decreased, while the aspect ratio of leaves increased in heavily polluted areas. As pollution increased, the stomatal traits in different crown positions were changed differently. No significant correlation was found between ozone content and the measured traits of leaves. The responses found in the physiological differentiation of the leaves reflect acclimation to air pollution. The soluble sugar content of the leaves could be used to indicate the short-term stress of air pollution, the area, and aspect ratio of leaves are indicative of the long-term stress due to air pollution. Therefore, physiological traits of L. lucidum leaves appeared to be significant predictive factors for the air pollutants in urban areas., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Drought and nitrogen (N) deposition are important components of global climate and environmental change. In this greenhouse study, we investigated the ecophysiological responses of the seedlings of three subtropical forest plant species (Schima superba, Castanopsis fissa, and Michelia macclurei) to short-term experimental drought stress, N addition, and their interaction. The results showed that drought stress reduced the activities of antioxidant enzymes [superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)] and total antioxidant capacity (T-AOC), but increased the malondialdehyde (MDA), abscisic acid (ABA), and proline (PRO) contents in plants. The PRO content, T-AOC, and antioxidant enzyme activities were increased, and ABA and MDA contents were decreased by N addition alone. Furthermore, N addition under drought stress increased antioxidant enzymes activities, PRO content, and T-AOC. The treatments, however, did not significantly affect the chlorophyll fluorescence parameters of the species. T-AOC was positively correlated with antioxidant enzyme activities in each species, indicating that antioxidant enzymes were important for plant resistance to oxidative stress. MDA content increased with the increase of ABA content, indicating that ABA may help regulate stomatal movement and drought-induced oxidative injury in plants. T-AOC was positively correlated with PRO content, probably because PRO participated in osmotic regulation of cells and increased osmotic stress resistance. These results indicate that N addition can reduce drought stress of subtropical forest plants and will help researchers predict how evergreen broad-leaved forests will respond to global change in the future., (Copyright © 2019 Elsevier Inc. All rights reserved.)