Priming methods affected deterioration speed of primed rice seeds by regulating reactive oxygen species accumulation, seed respiration and starch degradation.

Introduction: Seed priming is a pre-sowing seed treatment that is beneficial for rice seed germination and seedling growth, but the reduced seed longevity after seed priming greatly limited its adoption. The deterioration of primed seeds showed large differences among different studies, and the priming method might play an important role in regulating the deterioration speed of primed seeds. However, whether and how the priming method affected the deterioration of primed rice seeds during storage remains unknown. Methods: In this study, two typical seed priming methods, namely hydropriming (HP) and osmopriming (PEG) were compared under artificially accelerated aging conditions, the changes in germination performance, starch metabolism, seed respiration and reactive oxygen species accumulation before and after accelerated aging were determined. Results and discussion: Hydroprimed rice seeds exhibited significantly faster deterioration speed than that of PEG-primed seeds in terms of germination speed and percentage. Meanwhile, α-amylase activity and total soluble sugar content in hydroprimed seeds were reduced by 19.3% and 10.0% respectively after aging, as compared with PEG-primed seeds. Such effects were strongly associated with the increased reactive oxygen generation and lipid peroxidation, as the content of superoxide anion, hydrogen peroxide and malondialdehyde in hydroprimed seeds were 4.4%, 12.3% and 13.7% higher than those in PEG-primed seeds after aging, such effect could be attributed to the increased respiratory metabolism in hydroprimed seeds. In addition, the simultaneous use of N-acetylcysteine with HP and PEG priming greatly inhibited the deterioration of primed rice seeds, suggesting that the ability to scavenge reactive oxygen species may be the key factor affecting the speed of deterioration in primed rice seeds during storage.

Photomorphogenesis and Photosynthetic Traits Changes in Rice Seedlings Responding to Red and Blue Light.

The purpose of this study is to determine the effects of red and blue lights on the photomorphogenesis and photosynthetic traits of rice seedlings. The rice seedlings were cultured with red light (R), blue light (B), combined red and blue lights (R3B1/R1B1/R1B3), and white light (CK) as the control. The combined application of red and blue lights could promote the growth of rice seedlings to varying degrees; enhance photosynthesis by increasing the seedling leaf area, chlorophyll content, and chlorophyll fluorescence; improve root characteristics by increasing root number, root volume, and root activity; and thus increase the dry matter accumulation of rice seedlings. In addition, the combination of red and blue lights could regulate the expression of genes related to photosynthesis in rice leaves, affect the activity of the Rubisco enzyme, and then affect the photosynthesis of rice seedlings. These results indicate that red and blue lights have direct synergistic effects, which can regulate the growth of rice seedlings and promote the morphogenesis of rice seedlings. The combined application of red and blue lights can be used to supplement the light in rice-factory seedling raising.

Simultaneous Application of Red and Blue Light Regulate Carbon and Nitrogen Metabolism, Induces Antioxidant Defense System and Promote Growth in Rice Seedlings under Low Light Stress.

The purpose of this study is to determine the effect of light quality on growth, carbon and nitrogen metabolism, and antioxidant defense system of rice seedlings. Six light conditions were employed, including white (W), red (R), blue (B), combined LED of R and B at 3:1 (R3B1), combined LED of R and B at 1:1 (R1B1), as well as combined LED of R and B at 1:3 (R1B3). Combined application of red light and blue light could promote the growth of rice seedling leaves and roots under low light stress to varying degrees, increase the photosynthetic area by increasing the leaf area, improve the root characteristics by increasing the root volume, and increase the dry matter accumulation of rice seedlings. In addition, the combination of red light and blue light could increase carbon and nitrogen metabolites in rice seedling leaves, regulate the expression of genes related to carbon and nitrogen metabolism and enzyme activity, and enhance the antioxidant enzyme activity of rice seedlings. These results indicate that red light and blue light directly have synergistic effects which can regulate the carbon and nitrogen metabolism of rice seedlings, promote the morphogenesis of rice seedlings under low light stress, and promote growth, which has never been reported in previous studies. This study is a new discovery in the application of light quality in crop production and provides new avenues to enhance crop stress resistance. However, further study is needed to explore the physio-biochemical and molecular mechanisms of light quality in crop production.

Growth changes of tomato seedlings responding to sodium salt of α-naphthalene acetic acid and potassium salt of fulvic acid.

In present study, sodium salt of α-naphthalene acetic acid (NA), potassium salt of fulvic acid (KF) and their combinations were applied to the growth substrates of tomato seedlings (Solanum lycopersicum L.) under chilling stress. The changes in aboveground biomass, root attributes, pigment contents, chlorophyll fluorescence, photosynthesis, osmotic regulation substances, and antioxidant enzymes activity of the tomato seedlings in response to NA and KF were investigated. The application of NA, KF and their combination could promote the growth of plant height and stem diameter of tomato seedlings under chilling stress to varying degrees, and improve root characteristics by increasing root volume, root length and root activity, and increase dry matter accumulation. In addition, the combined use of NA and KF improved the seedling leaf chlorophyll content, qP, Fv/Fm, ΦPSII , Pn and increased the activity of antioxidant enzymes in the tomato plants. The above results suggested a synergistic effect between NA and KF to stimulate the seedlings growth and to enhance the ROS scavenging ability of tomato, which has never been reported in previous research before. However, further researches are needed to explore the physiological and molecular mechanism underlying the synergistic effect between NA and KF.

Cutting time & height improve carbon and energy use efficiency of the forage-food dual-purpose ratoon rice cropping.

Forage-food dual-purpose ratoon rice cropping (FFRR) is used to balance forage demands with ratoon rice grain yields, that is whole plant (stem and sheath, panicles) cuttings in the main season are used as forage, and rice in the regeneration season is used as food. In this study, the local ratoon rice production system as the control, we were carried out the field experiment of cultivation practices (cutting time and cutting height), and investigated the system productivity, economic benefits, carbon footprints and energy use efficiency. The energy use efficiency, energy productivity and energy profitability increased with cutting time delay, and cutting height decreased. Significant differences of these index were observed among the treatments for cutting time and cutting height (p < 0.05). Carbon efficiency and carbon sustainability index was increase with cutting time delay, and there was significant difference among the treatment of cutting time in 2018 (p < 0.05), the minimum carbon footprint of FFRR was 78.6 kgCO2 t-1 averagely at the cutting time of 30 days after the flowering stage. In 2018, the maximum net income of FFRR was 30,577 CNY hm-2 at a cutting time of 30 days after the flowering stage while the stubble height was 10 cm, and dependent on the forage yield of the main crop; in 2019, the maximum net income of FFRR was 27,326 CNY hm-2 at a cutting time of 10 days after the flowering stage while the stubble height was 10 cm, and dependent on the grain yield of the ratoon crop. Therefore, the optimal cultivation practice of the FFRR (cutting at 30 days after the flowering stage and with a stubble height of 10 cm) showed higher carbon and energy use efficiency, economic benefits of the FFRR were fluctuated with the price of forage of the main crop and rice grain of the ratoon crop.

Rice husk biochar mediated red phosphorus for photocatalysis and photothermal removal of E. coli.

The current photocatalytic bactericidal materials in the field of food pathogen control are usually consisted of metals that always suffering from poor stability and possible secondary pollution. Besides, the requirement for high energy excitation also inspires the enthusiasm on exploring non-metallic catalysts. Herein, the non-metallic composite of rice shell biochar loaded with red phosphorus (B@RP) was developed for photocatalysis and photothermal removal of bacteria. The B@RP showed effective photocatalysis performance to stimulate the generation of OH and O2- free radicals for the elimination of Escherichia coli (E. coli). At the same time, the photothermal effect of B@RP can also increase the permeability of cell membrane, which is conducive to free radicals entering the cell interior. Therefore, the non-metallic composite could achieve complete removal of E. coli within 2 h under illumination. Meanwhile, B@RP had excellent stability and the sterilization efficiency maintained 100% after 9 cycles. Hence, B@RP is expected to be a harmless and efficient bactericidal material for food industry.

Measurement of nitrogen content in rice plant using near infrared spectroscopy combined with different PLS algorithms.

Nitrogen plays an important role in rice growth, and determination of nitrogen content in rice plants is of great significance in assessing plant nutritional status and allowing precision cultivation. Traditional chemical methods for determining nitrogen content have the disadvantages of destructive sampling and lengthy analysis times. Here, the feasibility of rapid nitrogen content analysis by near-infrared (NIR) spectroscopy of rice plants was studied. Spectral data from 447 rice samples at several growth stages were used to establish a predictive model. Different spectral preprocessing methods and characteristic selection methods were compared, such as interval partial least-squares (iPLS), synergy interval partial least-squares (SiPLS), and moving-window partial least-squares (mwPLS). The SiPLS method exhibited better performance than mwPLS or iPLS. Specifically, the combination of four subintervals (7, 26, 27, and 28), with characteristic bands at 5299-4451 cm-1 and 10445-10423 cm-1, resulted in the best model. The optimal SiPLS model had a correlation coefficient of 0.9533 and a root mean square error of prediction (RMSEP) of 0.1952 on the prediction set. Compared to using the full spectra, using SiPLS reduced the number of characteristics by 87 % in the model, and RMSEP was reduced from 0.2284 to 0.1952. The results demonstrate that NIR spectroscopy combined with the SiPLS algorithm can be applied to quickly determine nitrogen content in rice plants. This study provides a technical framework to guide future precision agriculture efforts with respect to nitrogen application.

Ratoon rice with direct seeding improves soil carbon sequestration in rice fields and increases grain quality.

Increasing both carbon (C) sequestration and food production is essential for a sustainable future. However, increasing soil C sequestration or graining yield/quality in rice (Oryza sativa L.) systems has been a tradeoff in that pursuing one goal may compromise the other goal. Field experiments were designed to evaluate methane emission and grain yield in two rice systems in southern China, including the traditional double rice with a seedling transplanting system and innovative ratoon rice with a direct seeding system. Grain yield, grain quality, methane (CH4) emission, and total organic carbon (TOC) loss rate were investigated, and yield-scaled CH4 gas emission was assessed. It is found that double rice has a higher grain yield than ratoon rice. However, the grain quality (processing, appearance of chalkiness degree and chalky grain percentage, and nutritional quality) of ratoon rice is superior to double rice, especially the ratoon crop. The yield-scaled CH4 emission of ratoon rice (0.06 kg kg-1) decreased by 49.29% than double rice (0.12 kg kg-1) throughout the growth period. Compared with the TOC loss rate of double rice (2.95 g kg-1), the rate of ratoon rice was lower (1.97 g kg-1). As a result, ratoon rice with direct seeding can not only improve grain quality but also mitigate yield-scaled CH4 gas emission and TOC loss rate of rice fields. Therefore, we suggest to use ratoon rice with a direct seeding technique to promote agricultural C sequestration.

Estimating and evaluating the rice cluster distribution uniformity with UAV-based images.

The uniformity of the rice cluster distribution in the field affects population quality and the precise management of pesticides and fertilizers. However, there is no appropriate technical system for estimating and evaluating the uniformity at present. For that reason, a method based on unmanned aerial vehicle (UAV images) is proposed to estimate and evaluate the uniformity in this present study. This method includes rice cluster recognition and location determination based on the RGB color characteristics of the seedlings of aerial images, region segmentation considering the rice clusters based on Voronoi Diagram, and uniformity index definition for evaluating the rice cluster distribution based on the variation coefficient. The results indicate the rice cluster recognition attains a high precision, with the precision, accuracy, recall, and F1-score of rice cluster recognition reaching > 95%, 97%, 97%, 95%, and 96%, respectively. The rice cluster location error is small and obeys the gamma (3.00, 0.54) distribution (mean error, 1.62 cm). The uniformity index is reasonable for evaluating the rice cluster distribution verified via simulation. As a whole process, the estimating method is sufficiently high accuracy with relative error less than 0.01% over the manual labeling method. Therefore, this method based on UAV images is feasible, convenient, technologically advanced, inexpensive, and highly precision for the estimation and evaluation of the rice cluster distribution uniformity. However, the evaluation application indicates that there is much room for improvement in terms of the uniformity of mechanized paddy field transplanting in South China.

A non-invasive model for predicting liver fibrosis in HBeAg-positive patients with normal or slightly elevated alanine aminotransferase.

ABSTRACT: Early and accurate diagnosis of liver fibrosis is necessary for HBeAg-positive chronic hepatitis B (CHB) patients with normal or slightly increased alanine aminotransferase (ALT), Liver biopsy and many non-invasive predicting markers have several application restrictions in grass-roots hospitals. We aimed to construct a non-invasive model based on routinely serum markers to predict liver fibrosis for this population.A total of 363 CHB patients with HBeAg-positive, ALT ≤2-fold the upper limit of normal and liver biopsy data were randomly divided into training (n = 266) and validation groups (n = 97). Two non-invasive models were established based on multivariable logistic regression analysis in the training group. Model 2 with a lower Akaike information criterion (AIC) was selected as a better predictive model. Receiver operating characteristic (ROC) was used to evaluate the model and was then independently validated in the validation group.The formula of Model 2 was logit (Model value) = 5.67+0.08 × Age -2.44 × log10 [the quantification of serum HBsAg (qHBsAg)] -0.60 × log10 [the quantification of serum HBeAg (qHBeAg)]+0.02 × ALT+0.03 ×  aspartate aminotransferase (AST). The area under the ROC curve (AUC) was 0.89 for the training group and 0.86 for the validation group. Using 2 cut-off points of -2.61 and 0.25, 59% of patients could be identified with liver fibrosis and antiviral treatment decisions were made without liver biopsies, and 149 patients were recommended to undergo liver biopsy for accurate diagnosis.In this study, the non-invasive model could predict liver fibrosis and may reduce the need for liver biopsy in HBeAg-positive CHB patients with normal or slightly increased ALT.

Initial whole-genome sequencing and analysis of the host genetic contribution to COVID-19 severity and susceptibility.

The COVID-19 pandemic has accounted for millions of infections and hundreds of thousand deaths worldwide in a short-time period. The patients demonstrate a great diversity in clinical and laboratory manifestations and disease severity. Nonetheless, little is known about the host genetic contribution to the observed interindividual phenotypic variability. Here, we report the first host genetic study in the Chinese population by deeply sequencing and analyzing 332 COVID-19 patients categorized by varying levels of severity from the Shenzhen Third People's Hospital. Upon a total of 22.2 million genetic variants, we conducted both single-variant and gene-based association tests among five severity groups including asymptomatic, mild, moderate, severe, and critical ill patients after the correction of potential confounding factors. Pedigree analysis suggested a potential monogenic effect of loss of function variants in GOLGA3 and DPP7 for critically ill and asymptomatic disease demonstration. Genome-wide association study suggests the most significant gene locus associated with severity were located in TMEM189-UBE2V1 that involved in the IL-1 signaling pathway. The p.Val197Met missense variant that affects the stability of the TMPRSS2 protein displays a decreasing allele frequency among the severe patients compared to the mild and the general population. We identified that the HLA-A*11:01, B*51:01, and C*14:02 alleles significantly predispose the worst outcome of the patients. This initial genomic study of Chinese patients provides genetic insights into the phenotypic difference among the COVID-19 patient groups and highlighted genes and variants that may help guide targeted efforts in containing the outbreak. Limitations and advantages of the study were also reviewed to guide future international efforts on elucidating the genetic architecture of host-pathogen interaction for COVID-19 and other infectious and complex diseases.

Shorter incubation period is associated with severe disease progression in patients with COVID-19.

The diagnosed COVID-19 cases revealed that the incubation periods (IP) varied a lot among patients. However, few studies had emphasized on the different clinical features and prognosis of patients with different IP. A total of 330 patients with laboratory-confirmed COVID-19 were enrolled and classified into immediate onset group(IP<3 days, I group, 57 cases) and late onset group(IP>10 days, L group, 75 cases) based on IP. The difference of clinical characteristics and prognosis of the two groups were compared. There were more patients with fever in I group than in L group(P = 0.003), and counts of all the total lymphocytes, total T lymphocytes, CD4 + and CD8 + T lymphocytes were significantly different between the two groups(all P < 0.01). Besides, patients in L group had more GGOs in CT scan than I group and there were more patients in I group receiving antibiotic treatment than in L group(P < 0.001). For disease aggravation, the median CT scores were comparable between the two groups, but individually, there were more patients with increased CT score during hospitalization in I group than in L group. The aggravation incidence of CT presentation was 21.1% in I group, significantly higher than L group(8.0%, P = 0.042). Multivariable COX models suggested that IP was the only independent factors for CT aggravation. Conclusively, patients with different IP were different in clinical symptoms, laboratory tests, and CT presentations. Shorter IP was associated with the aggravation of lung involvement in CT scan.

Telomere and ATM Dynamics in CD4 T-Cell Depletion in Active and Virus-Suppressed HIV Infections.

CD4 T-cell depletion is a hallmark of HIV/AIDS, but the underlying mechanism is still unclear. We have recently shown that ataxia-telangiectasia-mutated (ATM) deficiency in CD4 T cells accelerates DNA damage, telomere erosion, and cell apoptosis in HIV-infected individuals on antiretroviral therapy (ART). Whether these alterations in ART-treated HIV subjects occur in vitro in HIV-infected CD4 T cells remains unknown. In this study, we employed a cellular model of HIV infection to characterize the mechanisms underlying CD4 T-cell destruction by analyzing the telomeric DNA damage response (DDR) and cellular apoptosis in highly permissive SupT1 cells, followed by the validation of our observations in primary CD4 T cells with active or drug-suppressed HIV infection. Specifically, we established an in vitro HIV T-cell culture system with viral replication and raltegravir (RAL; an integrase inhibitor) suppression, mimicking active and ART-controlled HIV infection in vivo We demonstrated that HIV-induced, telomeric DDR plays a pivotal role in triggering telomere erosion, premature T-cell aging, and CD4 T-cell apoptosis or depletion via dysregulation of the PI3K/ATM pathways. This in vitro model provides a new tool to investigate HIV pathogenesis, and our results shed new light on the molecular mechanisms of telomeric DDR and CD4 T-cell homeostasis during HIV infection.IMPORTANCE The hallmark of HIV infection is a gradual depletion of CD4 T cells, with a progressive decline of host immunity. How CD4 T cells are depleted in individuals with active and virus-suppressed HIV infection remains unclear. In this study, we employed a cellular model of HIV infection to characterize the mechanisms underlying CD4 T-cell destruction by analyzing the chromosome end (telomere) DNA damage response (DDR) and cellular apoptosis in a T-cell line (highly permissive SupT1 cells), as well as in primary CD4 T cells with active or drug-suppressed HIV infection. We demonstrated that HIV-induced telomeric DDR plays a critical role in inducing telomere loss, premature cell aging, and CD4 T-cell apoptosis or depletion via dysregulation of the PI3K/ATM pathways. This study sheds new light on the molecular mechanisms of telomeric DDR and its role in CD4 T-cell homeostasis during HIV infection.

Cover crops and chicken grazing in a winter fallow field improve soil carbon and nitrogen contents and decrease methane emissions.

Using symbiotic farming methods [cover crops and chicken grazing (+ C)] in a winter fallow field, we found that the soil organic matter and total nitrogen of the + C treatment were 5.2% and 26.6% higher, respectively, than those of a treatment with cover crops and no chicken grazing (- C). The annual rice grain yield of the + C treatment was 3.8% higher than that of the - C treatment and 12.3% higher than that of the bare fallow field (CK), while the annual CH4 emissions of the + C treatment were 26.9% lower than those of the - C treatment and 10.6% lower than those of the CK treatment. The 100-year global warming potential of the + C treatment was 6.2% lower than that of the - C treatment. Therefore, the use of winter cover crops and chicken grazing in a winter fallow field was effective at reducing CH4 emissions and significantly improving soil nutrients and rice yield.

The timeline and risk factors of clinical progression of COVID-19 in Shenzhen, China.

BACKGROUND: The novel coronavirus disease 2019 (COVID-19) broke out globally. Early prediction of the clinical progression was essential but still unclear. We aimed to evaluate the timeline of COVID-19 development and analyze risk factors of disease progression. METHODS: In this retrospective study, we included 333 patients with laboratory-confirmed COVID-19 infection hospitalized in the Third People's Hospital of Shenzhen from 10 January to 10 February 2020. Epidemiological feature, clinical records, laboratory and radiology manifestations were collected and analyzed. 323 patients with mild-moderate symptoms on admission were observed to determine whether they exacerbated to severe-critically ill conditions (progressive group) or not (stable group). We used logistic regression to identify the risk factors associated with clinical progression. RESULTS: Of all the 333 patients, 70 (21.0%) patients progressed into severe-critically ill conditions during hospitalization and assigned to the progressive group, 253 (76.0%) patients belonged to the stable group, another 10 patients were severe before admission. we found that the clinical features of aged over 40 (3.80 [1.72, 8.52]), males (2.21 [1.20, 4.07]), with comorbidities (1.78 [1.13, 2.81]) certain exposure history (0.38 [0.20, 0.71]), abnormal radiology manifestations (3.56 [1.13, 11.40]), low level of T lymphocytes (0.99 [0.997, 0.999]), high level of NLR (0.99 [0.97, 1.01]), IL-6 (1.05 [1.03, 1.07]) and CRP (1.67 [1.12, 2.47]) were the risk factors of disease progression by logistic regression. CONCLUSIONS: The potential risk factors of males, older age, with comorbidities, low T lymphocyte level and high level of NLR, CRP, IL-6 can help to predict clinical progression of COVID-19 at an early stage.

Elastic sowing dates with low seeding rate for grain yield maintenance in mechanized large-scale double-cropped rice production.

Elastic sowing dates (ESDs) are correlated with rice grain yield. ESD is the easiest factor for farmers to manipulate in mechanized large-scale farming. In this study, field experiments were conducted over a 2-year period to determine the effects of different sowing dates on growth duration, effective accumulated temperature, and yield attributes in two early- and late-season machine-transplanted rice cultivars. In early rice (ER), a delay in the sowing date led to decreased grain yield and shorter growth duration. In late rice (LR), delayed sowing led to significantly lower grain yield and prolonged growth duration. In LR, significantly positive correlations were detected between effective accumulated temperature in the post-heading stage and both filling ratio and yield. Reproductive redundancy increased markedly in LR, by 7.72% over a 5-day interval. We determined that the ESDs for LR were 10 days later than the control, and that of ER was recommend early sowing rather than late sowing. These findings suggest a new strategy to meet the demands of mechanized large-scale rice farming: the development of thermal sensitive high-yield long-duration ER cultivars and high-yield short-duration LR cultivars.

Seed filling under different temperatures improves the seed vigor of hybrid rice (Oryza sativa L.) via starch accumulation and structure.

Seed filling is crucial for seed vigor and starch accumulation and structure. Differences in hybrid rice seed vigor were evaluated in field experiments, conducted across two sites in 2017 and 2018, under different seed filling temperatures along with the underlying mechanisms related to the seed filling characteristics and starch accumulation and structure. Significant differences in the seed vigor parameters were revealed, with different seed filling characteristics observed under different temperatures. When averaged across cultivars, the seeds with a low seed filling rate and long seed filling duration obsessed 11.9% higher germination percentage (GP) and 22.7% higher vigor index (VI) than those with a high seed filling rate and short seed filling duration. Moreover, a high seed filling rate and short seed filling duration significantly decreased the total starch and amylose contents and increased the amylopectin content. Additionally, when averaged across cultivars, the relative crystallinity and starch granule diameter obtained with a high seed filling rate and short seed filling duration were 3.8% and 15.1% higher, respectively, than those with a low seed filling rate and long seed filling duration. In summary, it can be speculated that seed filling characteristics determine hybrid rice seed vigor by affecting starch accumulation and structure.

Integrating cover crops with chicken grazing to improve soil nitrogen in rice fields and increase economic output.

Winter fallow is important for renewing and improving soil fertility under double-cropping rice systems, such as those in southern China. Using a regenerative farming technology of integrating grass-chicken farming in a winter fallow field, we investigated soil nitrogen conversion and assessed the agricultural economic benefits of the whole farmland ecosystem. To test the effects of chicken grazing on the fallow system, we established field treatments involving adding chickens to a field planted with the cover crops, including cover milk vetch (Astragalus sinicus) with chicken grazing treatment (MC) and cover ryegrass (Lolium spp.) with chicken grazing (RC); cover crops only, including cover milk vetch (Astragalus sinicus) treatment (M) and cover ryegrass (Lolium spp.) (R); and a bare fallow field treatment (CK). We found that both cover crops (M and R) and cover crops with chicken grazing (MC and RC) increased nitrate, ammonium, dissolved organic nitrogen, and total nitrogen contents, and the increase was higher in MC and RC treatments. We also observed increased straw biomass and grain yield in the all four treatments, with more increases with chicken treatments as compared with CK. On the economic profits, MC increased by 101.72% and RC increased by 104.12% as compared with CK, while R increased by 5.19% and M reduced by 1.86% as compared with CK. The nitrogen transfer rate (the output/input ratio) of MC, RC, M, and R increased by 66.71%, 71.50%, 65.97%, and 59.97%, respectively, while the nitrogen accumulation rate (input-output) of MC, RC, M, and R increased by 480.56%, 612.98%, 356.74%, and 267.65%, respectively. Our study demonstrates that retaining nitrogen and gaining economic profit by integrating cover crops with chicken grazing is potentially more sustainable than adding cover crops alone. We further suggest that using the integrated grass-livestock farming technology can reduce environmental damage caused by commercial fertilizers.

Early harvesting improves seed vigour of hybrid rice seeds.

Maturity stage in harvesting time greatly affects seed vigour. This work aimed to scientific harvesting time of hybrid rice for being high vigour with high & stable seed yield. Field experiments of different harvesting time were conducted in 2013-2014, and germination percentage (GP), vigour index (VI), seed moisture content and 1000-grain weight was determined. Both GP and VI progressively increased to peaks and then began to decline with harvesting time delayed, and the regression coefficients of varieties were ranged from 0.7214 to 0.9066. In addition, difference values between tangent points (ΔX) of GP were higher than that of VI according to the quadratic functions. Based on seed vigour through the divided range from 75% to 125% of peak value, optimum harvesting time of IIY-416, JY-167, Yliangyou-1 (YLY-1) ranged from 17 to 27, 15 to 23 and 17 to 23 days after the completion of artificial pollination (DACAP), respectively. Moreover, when seedlots harvested from 17 to 23 DACAP, no significant difference was found on 1000-grain weight and the seed moisture content was kept relatively low (19-25%). Therefore, it can be concluded that hybrid rice seed can be earlier-harvest based on seed vigour, and 17 to 23 DACAP can be recommended as optimum harvesting time during hybrid rice seed production.