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As a native tree species with a strong adaptability, Platycladus orientalis is a species of choice for afforestation and landscaping in northern China. However, it develops mostly male cones and few female cones. In addition, its reproductive characteristics are not yet clear, which limits further breeding work. To systematically clarify the reproductive biology characteristic and fertilization mechanism of P. orientalis, the present study comprehensively investigated the process of micro and macro-sporogenesis in male and female cones from bud initiation to fertilization, and seed development. The specific time in each developmental stage, including bud initiation, microsporogenesis, megasporogenesis, and cone and seed development, was determined, and the abortive phenomenon during development was discovered in both male and female cones. In addition, this research showed that the microspore mother cells were dormant in winter at meiosis stage, and the male gametophyte started to develop when dormancy ended. The tapetum developed normally and belonged to the secretory type. The optimal treatment time for male and female cones transformation by artificial induction was from late June to mid-July. This finding provided a theoretical basis for hybridization, breeding, improvement of seed yield and quality, and artificial induction of male and female cone transformation in P. orientalis. [ABSTRACT FROM AUTHOR]

Study Question: Do sperm-specific phospholipase C zeta (PLCZ1) mutations account for male infertility due to fertilization failure?Summary Answer: Six novel mutations and one reported mutation in PLCZ1 were identified in five of 14 independent families characterized by fertilization failure or poor fertilization, suggesting that these mutations may be responsible for fertilization failure in men exhibiting primary infertility.What Is Known Already: PLCZ1 is essential for the induction of intracellular calcium (Ca2+) oscillations and the initiation of oocyte activation during mammalian fertilization. However, genetic evidence linking PLCZ1 mutations with male infertility remains limited.Study Design, Size, Duration: Fourteen unrelated primary infertility patients were recruited into this study from January 2016 to December 2018; the patients exhibited total fertilization failure or poor fertilization, as evidenced by ICSI and sperm-related oocyte activation deficiencies identified in mouse oocyte activation assays.Participants/materials, Setting, Methods: Genomic DNA samples were extracted from the peripheral blood of patients. The whole exons of PLCZ1 were sequenced by Sanger sequencing. The PLCZ1 sequences were aligned by CodonCode software to identify rare variants. The ExAC database was used to search for the frequency of corresponding mutations. The pathogenicity of identified variants and their possible effects on the protein were assessed in silico. PLCZ1 protein levels in semen samples were evaluated by western blotting. Oocyte activation ability was assessed by the injection of wild-type and mutant PLCZ1 cRNAs into human mature metaphase II (MII) oocytes in vitro.Main Results and the Role Of Chance: We identified six novel mutations and one reported mutation in PLCZ1 among five affected individuals. In addition to four novel missense mutations, two new types of genetic variants were identified, including one in-frame deletion and one splicing mutation. Western blot analysis revealed that PLCZ1 protein expression was not observed in the semen samples from the five affected patients. Microinjection with the PLCZ1 cRNA variants was performed, and a significant decrease in the percentage of pronuclei was observed for four novel missense mutations and one novel in-frame deletion mutation, suggesting that these mutations have a deleterious influence on protein function. By artificial oocyte activation treatment, the fertilization failure phenotypes of four affected patients were successfully rescued and three healthy babies were delivered.Large Scale Data: N/A.Limitations, Reasons For Caution: We screened only the whole exons of PLCZ1. Additional possible mutations in the non-coding region of PLCZ1 should be further studied.Wider Implications Of the Findings: Our study not only further confirms the important role of PLCZ1 in human fertilization but also expands the mutational spectrum of PLCZ1 associated with male infertility, which provides a basis for assessing genetic variation in PLCZ1 as a potential diagnostic marker for infertile men suffering from fertilization failure.Study Funding/competing Interest(s): This research was supported by the National Natural Foundation of China (81 571 486 and 81 771 649). All authors have no conflicts of interest to declare. [ABSTRACT FROM AUTHOR]

Denmark is leading in advanced animal biowaste engineering and management in the world. The comprehensive system of livestock manure utilization in Denmark can achieve planting-breeding balance and the fertilize capacity requirement, which can not only protect the healthy development of animal husbandry, but also promote the development of cropping industry. This review summarized the present situation of animal biowaste utilization technologies, specially the technical proposal of the planting-breeding balance and technologies to reduce ammonia emissions from livestock production in Denmark. The main successful experience of scientific management concept, law and regulation system, advanced technologies and utilization pattern of Danish manure management were also analyzed. The scientific management concept of manure utilization in Denmark is life-cycle pollution control during the manure utilization. Fertilizers and animal manures must be applied in the proper seasons and methods to promote the absorption of nutrients. In areas of intensive animal production, nutrients in the manure may contribute all or a substantial proportion of the local or regional fertilizer demand and some manure nutrients may even be in excess of local demand, requiring the alternative utilization to avoid the environmental overload. The overall objective of the Danish regulations on the livestock production and management of animal manures is to achieve sustainable recycling of manures in order to reduce emissions of nutrients and pollutants to the environment. Since the 1980s, Danish incentives and regulations had reduced losses of nitrogen and enhanced the use efficient of manure nitrogen, which had substituted large amounts of mineral fertilizers. The livestock farms and farmers in Denmark must ensure the amount of nutrients calculated not to exceed the allowed limits for their crops according to Danish harmony rules for the nutrient management. Farms with a livestock herd in excess of this density must have written contracts with neighbouring stockless farms, where the manure could be applied. The advanced technologies and corresponding equipment of animal waste utilization were encouraged for the investigation and application, including the solid-liquid separation of animal slurry, the ammonia and malodorous gases abatement, nutrient leaching from application and measures for reduction, technologies and logistics for handling, the transport and distribution of animal manures. Also, the life cycle assessment methodology had been applied to compare alternative manure management technologies in Denmark. There are a lot of specialists in environmental technologies and management of animal wastes, in industry and consultancy work, the agricultural advisory service and the public service. The mature utilization pattern and strategies for the efficient recycling of manures as a means of reducing leaching and runoff loss of the nutrients were also established. Nowadays, the widely used fertilizer and plenty of animal manures have brought some negative environmental impacts while increasing crop yields in China. The intention of this article is to introduce the biological, physical and chemical processes controlling pollution from the animal production and technologies needed to manage animal wastes in Denmark. Those environmentally friendly technologies for managing animal waste efficiently and in a sustainable manner are worth learning and using for reference for planting-breeding combined circular agricultural development in China. [ABSTRACT FROM AUTHOR]

Water footprint (WF) is a comprehensive measure of water consumption by human activities and can be used to assess the impact on both water volume and quality. This study aims to explore the feasibility of evaluating green, blue and grey WFs of crop production based on field measurements. The irrigated paddy rice grown in three different experimental sites in different typical irrigation districts in Huai'an, East China over 2011 to 2014 was taken as study case. With fixed irrigation and fertilization, on the basis of measuring field water and fertilizer balance at daily step, we calculated WF of crop production under different test treatments. Results show that crop water requirement of rice was measured as 667.1 mm and 6.2% of the total nitrogen (T-N) was washed away from farmland accompany with drainage and percolation. Average annual WF of paddy rice during 2011–2014 in Huai'an was 1.760 m 3 /kg (33.3% green, 25.8% blue and 40.9% grey). The level of WF and blue water proportion in different locations (irrigation districts) and different years changed slightly, while the proportion of green and grey WF changed with the variance of precipitation. Green water proportion was 25.1%, 34.2 and 44.2%, while 48.0%, 40.2% and 31.0% for grey water proportion under precipitation levels of 400, 600 and 800 mm, respectively. The reduced grey WF was due to increased drainage. This study not only proved the feasibility of assessing WF of crop production with field experiments, but also provided a new method for WF calculation based on field water and fertilizer migration processes. [ABSTRACT FROM AUTHOR]

Agricultural management practices play an important role in soil structure and fertility. However, there is a lack of knowledge on the effects of long-term fertilization on aggregate structure in the Loess Plateau region in China. This study was devoted to examining the responses of soil aggregate stability and associated structure to fertilizers over 19 years under a soybean (Glycine max L.)-corn (Zea Mays) rotation. Treatments included unfertilized control (CK); nitrogen (N), phosphorus (P), and NP chemical fertilizers; and manure (M) and MN, MP and MNP organic/chemical combinations. The results showed that the water-stable aggregates, mean weight diameter, geometric mean diameter, aggregate state, and aggregate degree decreased in chemical fertilizers (N, P, and NP). However, it increased in all treatments containing manure (M, MN, MP, and MNP) compared to the CK. The changes in dispersion rate and fractal dimension were opposite to those indicators in all treatments. The applications of chemical fertilizers do guarantee an increase in crop yield, but only organic fertilizers significantly improved soil structure. These results suggest that manure's incorporation into loessial soil is a preferred strategy for sustainable soil management. [ABSTRACT FROM AUTHOR]

Mineral-associated organic carbon (MOC), that is stabilized by fine soil particles (i.e., silt plus clay, <53 μm), is important for soil organic carbon (SOC) persistence and sequestration, due to its large contribution to total SOC (TSOC) and long turnover time. Our objectives were to investigate how climate, soil type, soil texture, and agricultural managements affect MOC contributions to TSOC in China. We created a dataset from 103 published papers, including 1106 data points pairing MOC and TSOC across three major land use types: cropland, grassland, and forest. Overall, the MOC/TSOC ratio ranged from 0.27 to 0.80 and varied significantly among soil groups in cropland, grassland, and forest. Croplands and forest exhibited significantly higher median MOC/TSOC ratios than in grassland. Moreover, forest and grassland soils in temperate regions had higher MOC/TSOC ratios than in subtropical regions. Furthermore, the MOC/TSOC ratio was much higher in ultisol, compared with the other soil types. Both the MOC content and MOC/TSOC ratio were positively correlated with the amount of fine fraction (silt plus clay) in soil, highlighting the importance of soil texture in stabilizing organic carbon across various climate zones. In cropland, different fertilization practices and land uses (e.g., upland, paddy, and upland-paddy rotation) significantly altered MOC/TSOC ratios, but not in cropping systems (e.g., mono- and double-cropping) characterized by climatic differences. This study demonstrates that the MOC/TSOC ratio is mainly driven by soil texture, soil types, and related climate and land uses, and thus the variations in MOC/TSOC ratios should be taken into account when quantitatively estimating soil C sequestration potential of silt plus clay particles on a large scale. [ABSTRACT FROM AUTHOR]

Soil nutrient is the basis for stable and high crop yield. Mastering soil's nutrient content of cultivated land is the precondition for　implementing soil test and formula fertilization. Investigations of soil's pH value and nutrient of vegetable land, paddy field and fruit land in Guizhou Anshun area were carried out in this paper. The results showed that soil's pH value of cultivated land in Guizhou Anshun area was lower than 7, and the soil was overall acidic; soil nutrient was sufficient, the organic matter, total nitrogen, total phosphorus and total kalium content were in the middle and upper level, but there were significant differences among different districts. The pH value was 5.75 on average and the range of measurement was 4.65-6.2; the value of organic matter on average was 31.13g/kg and the range of measurement was 13.07-94.55g/kg; the value of total nitrogen was 1.74g/kg on average and the range of measurement was 0.73-3.97g/kg; the total phosphorus value was 0.998g/kg on average and the range of measurement was 0.44-1.91g/kg; potassium value was 16.5g/kg on average and the range of measurement was 2.5-42.5g/kg. The soil's pH value for Guanling > Pingba > Puding > Ziyun > Zhenning ≥ Xixiu, the content of organic matter for Xixiu > Puding > Guanling > Ziyun > Pingba > Zhenning, the content of total nitrogen for Xixiu > Guanling > Ziyun > Puding > Pingba > Zhenning, the content of total phosphorus Puding > Guanling > Zhenning > Pingba > Ziyun > Xixiu, the content of total kalium for Puding > Pingba > Zhenning > Guanling > Xixiu > Ziyun. The difference of nutrients in different soil types was significant. The main nutrient content was highest in paddy soil, lowest in fruit land，and vegetable soil's nutrient was in between. There was a significant difference with the same soil type and the same nutrient content. The difference was the largest in organic content and was small in other nutrients. Therefore, this investigation has basically mastered the cultivated land soil's pH value and organic matter, total nitrogen, total phosphorus and total kalium content and distribution in Anshun, which can provide the decision-making reference for soil test and formula fertilization in regional land. [ABSTRACT FROM AUTHOR]

Intrauterine insemination ( IUI) is an effective, noninvasive, relatively simple and cheap method of infertility treatment. Many factors that affect IUI outcomes have been studied. However, there is no consensus about the optimal number of motile spermatozoa inseminated ( NMSI) required for a reasonable chance of pregnancy after IUI. In this retrospective study, we aimed to assess the relationship between NMSI and the pregnancy rate after IUI with husband's spermatozoa. Couples who had either primary or secondary infertility for more than one year were recruited from the Department of Reproduction, Nanjing Maternity and Child Health Hospital, China, between January 2007 and December 2010. Overall, 1153 IUI cycles with husband's spermatozoa were performed in 645 women after ovarian stimulation. Factors that have previously been associated with a successful fertilisation after IUI were assessed. A total pregnancy rate of 13.88% was obtained. The pregnancy rate was only 4.05% if less than 2 × 106 motile spermatozoa were used, but this rose to 14.55% when more than 2 × 106 motile spermatozoa were inseminated. We therefore conclude that IUI can be performed when the NMSI exceeds 2 × 106. With this recommendation, IUI with husband's spermatozoa can be used to treat many more infertile couples. [ABSTRACT FROM AUTHOR]

Abstract: Microbial residue represents a significant amount of soil organic matter, and its component amino sugar can serve as time-integrated indicators that reflect chronic effects of agricultural management. We evaluated the influence of different land-use and fertilization treatments on the amounts and patterns of amino sugars (glucosamine and galactosamine) and muramic acid in a Mollisol (Udolls, USDA Soil Taxonomy System) in northeastern China. The treatments included: BL, bareland, without any vegetation; GL, restored grassland which allows plants to re-vegetate naturally; AL, arable land without any fertilizer; ALF, arable land with chemical fertilizer; and ALMF, arable land with chemical fertilizer and pig manure. The amino sugar concentrations differed significantly between various treatments after 26 years, with the order of ALMF>GL>ALF>AL>BL. This suggests that long-term contrasting management changed microbial residue accumulation in soil, which is strongly related to soil organic carbon content. The larger ratios of glucosamine to muramic acid in the GL plots than the AL and BL plots indicated a shift toward fungal-derived residues after 26 years of natural restoration. Our results suggested that different land-use and fertilization treatments clearly influenced amounts and patterns of microbial residues and their contribution to SOM accumulation, primarily due to differences in organic C inputs. [Copyright &y& Elsevier]

Soil organic carbon (SOC) stock can be improved through the return of crop residues. However, the efficiency of C sequestered in soil (i.e., ΔSOC/ΔC input) might differ among crop systems. In this paper, we investigated the C input and SOC stabilization in paddy soil and upland soil under different long-term fertilization practices. Our objectives were to determine (i) the response of SOC stock to C input under different fertilization practices, and (ii) C sequestration efficiency in the two contrasting agroecosystems. The long-term fertilization experiment in paddy soil started in 1981, while the adjacent upland soil experiment commenced in 1986. Each experiment consists of 9 treatments: CK (no fertilization), N, P, K, NP, NK, NPK, 2NPK (double dose), and NPKOM (NPK plus organic manure). Physical SOC fractions (cPOM, silt+clay_f, fPOM, iPOM_m, silt+clay_m) were isolated by sieving, dispersion, and density flotation. Fertilization increased crop yield and C input, but it did not change the quality of SOC as revealed by CPMAS-13C NMR spectra. During the period of the experiment, SOC stock was improved by 6.7–15.3Mgha−1 in paddy soil for all fertilization practices, while in upland soil the CK, N, P, K, and NP fertilizations reduced the SOC by 1.2–3.8MgCha−1 and the other four fertilizations increased it by 0.5–7.4MgCha−1. The change in SOC was mainly ascribed to the POM fraction, whereas the two silt+clay sized fractions were independent of fertilization practice except the NPKOM treatment. At a given C input, the C sequestration efficiency was greater in paddy soil than in upland soil, which may be attributed to lower microbial activity but greater chemical (i.e., oxalate-soluble Fe) and physical stabilizations (i.e., soil structure) in paddy field. Our results indicate that paddy soil may sequester more SOC, with higher efficiency, than upland soil does. [ABSTRACT FROM AUTHOR]

The genetic diversity of 85 isolates of Phytophthora infestans collected in 2007 from Gansu province in China was determined and compared with 21 isolates collected before 2004. Among them, 70 belonged to the A1 mating type and 15 were self-fertile ( SF). The mitochondrial DNA haplotypes revealed both Ia (25%) and IIa (75%) haplotypes. Metalaxyl resistance occurred with high frequency (54%) in Gansu. Simple sequence repeat ( SSR) genotyping revealed 26 genotypes (13 from the Tianshui region) among the 85 isolates, and 18 genotypes among the 21 isolates collected before 2004, without overlap in genotypes detected in the two groups. Cluster analysis showed clear subdivisions within the different mating type isolates. Among Gansu's isolates, Nei's and Shannon's diversity indices were highest in isolates collected in Tianshui where both A1 and SF isolates were found. Analysis of molecular variance of isolates from Gansu indicated that 51% and 49% of the variance was explained by within-area and among-area variance, respectively. The results suggest that the occurrence of SF isolates increases the risk of sexual reproduction, the formation of oospore as initial inocula in the field, and affects the genotypic diversity in the population. [ABSTRACT FROM AUTHOR]

In a move designed to increase the UK's supply of donor eggs, the Human Fertilisation and Embryology Authority has recently agreed to a fixed-sum compensation policy for donors "which better reflects their expenses" and inconvenience. Such a policy, however, which is reliant on non-patient donors for its success, is in contrast to what appears the system in China, where egg donors can only be recruited from those having IVF (i.e. patient donors) and on a conditional egg-sharing basis. Commitment to an egg-sharing policy in the UK would provide a more equitable system of egg donation than a compensation policy. [ABSTRACT FROM AUTHOR]

uscular mycorrhizal fungi (AMF) are crucial for ecosystem functioning, and thus have potential use for sustainable agriculture. In this study, we investigated the impact of organic and mineral fertilizers on the AMF community composition and content of Glomalin-related soil protein (GRSP) in a field experimental station which was established in 1979, in the Loess Plateau of China. Roots and soils were sampled three times during the growing period of winter wheat in 2008. The treatments including: N (inorganic N), NP (inorganic N and P), SNP (straw, inorganic N and P), M (farmyard manure), MNP (farmyard manure, inorganic N and P), and CK (no fertilization). AMF communities of root and soil samples were analyzed using PCR-DGGE, cloning and sequencing techniques; and GRSP content was determined by Bradford assay. Our results indicated that spore density, GRSP, and AMF community varied significantly in soils of long-term fertilization plots at three different wheat growing stages. The effects of wheat growing period on AMF community in roots were much more evident than fertilization regimes. However, the diversity of AMF was low in our study field. Up to five AMF phylotypes appeared in each sample, with the overwhelming dominance of a Glomus-like phylotype affiliated to G. mosseae. GRSP content was correlated positively with organic carbon, total phosphorus, available phosphorus, soil pH, and spore densities, but correlated negatively with soil C/N ( P < 0.05). The results of our study highlight that the richness of AMF in Loess Plateau agricultural region is low, and long-term fertilization, especially amendments with manure and straw, has beneficial effects on accumulation of soil organic carbon, spore density, GRSP content, and AMF diversity. Host phenology, edaphic factors (influenced by long-term fertilization), and habitats interacted to affect the AMF community and agoecosystem functioning. Additionally, soil moisture and pH make a greater contribution than other determined soil parameters to the AMF community dynamics in such a special semi-arid agroecosystem where crops rely greatly on rainfall. [ABSTRACT FROM AUTHOR]

The effect of long-term fertilization on soil-denitrifying communities was determined by measuring the abundance and diversity of the nitrite reductase genes nirK and nirS. Soil samples were collected from plots of a long-term fertilization experiment started in 1990, located in Taoyuan (110°72″ E, 28°52″ N), China. The treatments were no fertilizer (NF), urea (UR), balanced mineral fertilizers (BM), and BM combined with rice straw (BMR). The abundance, diversity, and composition of the soil-denitrifying bacteria were determined by using real-time quantitative PCR, terminal restriction fragment length polymorphism (T-RFLP), and cloning and sequencing of nirK and nirS genes. There was a pronounced difference in the community composition and diversity of nirK-containing denitrifiers responding to the long-term fertilization regimes; however, less variation was observed in communities of nirS-containing denitrifiers, indicating that denitrifiers possessing nirK were more sensitive to the fertilization practices than those with nirS. In contrast, fertilization regimes had similar effects on the copy numbers of nirK and nirS genes. The BMR treatment had the highest copy numbers of nirK and nirS, followed by the two mineral fertilization regimes (UR and BM), and the lowest was in the NF treatment. Of the measured soil parameters, the differences in the community composition of nirK and the abundance of nir denitrifiers were highly correlated with the soil carbon content. Therefore, long-term fertilization resulted in a strong impact on the community structure of nirK populations only, and total organic carbon was the dominant factor in relation to the variations of nir community sizes. [ABSTRACT FROM AUTHOR]

Excessive nitrogen (N) application to rice (Oryza sativa L.) crop in China causes environmental pollution, increases the cost of rice farming, reduces grain yield and contributes to global warming. Scientists from the International Rice Research Institute have collaborated with partners in China to improve rice N fertilization through site-specific N management (SSNM) in China since 1997. Field experiments and demonstration trials were conducted initially in Zhejiang province and gradually expanded to Guangdong, Hunan, Jiangsu, Hubei and Heilongjiang provinces. On average, SSNM reduced N fertilizer by 32% and increased grain yield by 5% compared with farmers' N practices. The yield increase was associated with the reduction in insect and disease damage and improved lodging resistance of rice crop under the optimal N inputs. The main reason for poor fertilizer N use efficiency of rice crop in China is that most rice farmers apply too much N fertilizer, especially at the early vegetative stage. We observed about 50% higher indigenous N supply capacity in irrigated rice fields in China than in other major rice-growing countries. Furthermore, yield response of rice crop to N fertilizer application is low in China, around 1.5 t ha-1 on average. However, these factors were not considered by rice researchers and extension technicians in determining the N fertilizer rate for recommendation to rice farmers in China. After a decade of research on SSNM in China and other Asian rice-growing countries, we believe SSNMis a matured technology for improving both fertilizer N use efficiency and grain yield of rice crop. Our challenges are to further simplify the procedure of SSNM and to convince policy-makers of the effectiveness of this technology in order to facilitate a wider adoption of SSNM among rice farmers in China. [ABSTRACT FROM AUTHOR]

Microcalorimetry, plate count and PCR–denaturing gradient gel electrophoresis (DGGE) were employed to investigate microbial diversity and activity in soils from the Red Soil Experimental Station of the Chinese Academy of Agricultural Sciences, Hunan Province, China, where a wheat–corn rotation with 12 fertilization treatments was established in 1990. Fertilization greatly increased microbial biomass carbon (C) and nitrogen (N) (Cmic and Nmic) as well as the activities of phosphatase, urease, invertase, protease, catalase and dehydrogenase. Manure alone (M) enhanced the number of denitrifying and aerobic bacteria by 54.4% and 20.5%, respectively, whereas fallow (H) increased the number of aerobic cellulose decomposing bacteria by 31.4%. Fallow and soils amended with mineral fertilizers plus pig manure or straw increased both the DGGE band patterns and the Shannon index compared with mineral fertilizers or the control. Mineral treatments with lower bacterial numbers enhanced the values of the peak time ( tmax) more than did organic treatments. The peak height ( Pmax) was positively correlated ( P<0.01), with soil enzymes, Cmic and Nmic, and the number of microorganisms, whereas the peak time ( tmax) was negatively connected ( P<0.01) with these parameters. The microbial growth rate constant ( k) was linked to bacteria ( P<0.01), actinomycetes ( P<0.05) and catalase ( P<0.05). The total heat evolution ( Q) had no relationships with any soil microbial properties (except for catalase). We propose that Pmax and tmax could be used as indices of soil microbial activity, while the values of k and Q are poor indicators. [ABSTRACT FROM AUTHOR]

A sampling system for capturing sturgeon eggs using a D-shaped bottom anchored drift net was used to capture early life stages (ELS) of Chinese sturgeon, Acipenser sinensis, and monitor annual spawning success at Yichang on the Yangtze River, 1996–2004, before and just after the Three Gorges Dam began operation. Captured were 96 875 ELS (early life stages: eggs, yolk-sac larvae = eleuthero embryos, and larvae); most were eggs and only 2477 were yolk-sac larvae. Most ELS were captured in the main river channel and inside the bend at the Yichang spawning reach. Yolk-sac larvae were captured for a maximum of 3 days after hatching began, indicating quick dispersal downstream. The back-calculated day of egg fertilization over the eight years indicated a maximum spawning window of 23 days (20 October–10 November). Spawning in all years was restricted temporally, occurred mostly at night and during one or two spawning periods, each lasting several days. The brief temporal spawning window may reduce egg predation by opportunistic predators by flooding the river bottom with millions of eggs. During 1996–2002, the percentage of fertilized eggs in an annual 20-egg sample was between 63.5 to 94.1%; however, in 2003 the percentage fertilized was only 23.8%. This sudden decline may be related to the altered environmental conditions at Yichang caused by operation of the Three Gorges Dam. Further studies are needed to monitor spawning and changes in egg fertilization in this threatened population. [ABSTRACT FROM AUTHOR]

Brachionus calyciflorus individuals collected during March from Lake Jinghu, China were cultured at 7, 13, 19, 25, and 31 °C. None of the collected rotifers survived at 31 °C Between 7 and 25 °C, both culture temperature and rotifer batch and their interaction had significant effects on population growth rate, mixis rate, fertilization rate, and resting egg production. Rotifers collected late in March had the lowest population growth rate but the highest mixis and fertilization rates and resting egg production. [ABSTRACT FROM AUTHOR]