Effects of seedling age on the growth stage and yield formation of hydroponically grown long-mat rice seedlings

Understanding the characteristics of rice productivity is of great importance for achieving high yield formation.However,such traits have not yet been studied for different ages of hydroponically grown long-mat rice seedlings(HLMS),which constitutes a new method of seedling cultivation.Field experiments were conducted to evaluate the effects of seedling age on the growth stage,photosynthesis characteristics,dry matter production,and yield of HLMS.A conventional japonica rice cultivar(Wuyunjing 24)and an indica hybrid rice cultivar(6 Liangyou 9368)were used as test materials.The results showed that the whole phase was shortened by 13-15 days for young seedlings(13-day-old)compared with old seedlings(27-day-old),which occurred because the growth process accelerated with the transplantation of young seedlings.As seedling age increased,the dry matter weight of stems of individual plants and of the population increased at the transplanting stage but decreased at the maturity stage(MS).Compared with that of 27-day-old seedlings,the average ratio of panicle weight to total plant dry weight of 13-day-old seedlings during a 2-year period increased by 3.71%for Wuyunjing 24 and by 3.78%for 6 Liangyou 9368 at the MS.Moreover,as seedling age increased,the leaf area index and photosynthetic potential decreased for both cultivars,and the photosynthetic rate markedly decreased at the heading stage(HS).With the exception of that of Wuyunjing 24 from the jointing stage to the HS in 2014,the crop growth rate was higher for young seedlings than for old seedlings.Grain yield significantly decreased with seedling age,but no significant difference was detected between the 13-and 20-day-old seedlings for either cultivar.Therefore,equilibrious and high biological yield formation,vigorous growth in the late stages,and high photosynthetic production capacity are important characteristics and causes of the efficient and sustainable output of photosynthetic systems and for achieving high yield formation in young transplanted seedlings(13-20-day-old).

ZmDRR206 functions in maintaining cell wall integrity during maize seedling growth and defense response to external stresses

Plants adaptively change their cell wall composition and structure during their growth,development,and interactions with environmental stresses.Dirigent proteins(DIRs)contribute to environmental adaptations by dynamically reorganizing the cell wall and/or by generating defense compounds.A maize DIR,ZmDRR206,was previously reported to play a dominant role in regulation of storage nutrient accumulation in endosperm during maize kernel development.Here we show that ZmDRR206 mediates maize seedling growth and disease resistance by coordinately regulating biosynthesis of cell wall components for cell-wall integrity(CWI)maintenance.Expression of ZmDRR206 was induced in maize seedlings upon pathogen infection.ZmDRR206 overexpression in maize resulted in reduced seedling growth and photosynthetic activity but increased disease resistance and drought tolerance,revealing a tradeoff between growth and defense.Consistently,ZmDRR206 overexpression reduced the contents of primary metabolites and down-regulated genes involved in photosynthesis,while increasing the contents of major cell wall components,defense phytohormones,and defense metabolites,and up-regulated genes involved in defense and cell-wall biosynthesis in seedlings.ZmDRR206-overexpressing seedlings were resistant to cell-wall stress imposed by isoxaben,and ZmDRR206 physically interacted with ZmCesA10,which is a cellulose synthase unit.Our findings suggest a mechanism by which ZmDRR206 coordinately regulates biosynthesis of cell-wall components for CWI maintenance during maize seedling growth,and might be exploited for breeding strong disease resistance in maize.

BEAR1, a bHLH transcription factor, controls seedling growth by regulating gibberellins biosynthesis in rice

The genetic pathways of rice seedling growth have a major impact on seedling emergence from soil and development.In this study,we identified a new bHLH transcription factor,BEAR1,from rice RNAi mutant library.Both the BEAR1-RNAi and bear1 CRISPR mutants had accelerated seedling growth.Histological section of leaves showed accelerated development of lacuna and vascular bundles in bear1 mutant.GUS staining revealed that BEAR1 was highly expressed in coleoptiles and leaves at seedling stage.Expression analysis of gibberellin(GA)biosynthesis and metabolic genes and content determination of active GAs indicated that the expression of GA biosynthesis genes,especially OsKS4 and OsCPS2,were upregulated and the GAs content were significantly increased in bear1,which correlated with the seedling phenotype of bear1 mutant.Molecular and biochemical assays revealed that BEAR1 directly binds to the promoter of OsKS4,thereby repressing its expression.Haplotypes analysis showed clear differentiation in indica and japonica rice varieties,and a strong correlation with seedling height.These findings provide novel insights into the regulation of seedling growth in rice.

Proteomic analysis of salt and osmotic-drought stress in alfalfa seedlings

Alfalfa is widely grown and is one of the most important forage crops in the world, but its growth and biomass production are markedly reduced under salt and drought stress, particularly during the early seedling stage. To identify the mechanisms behind salt and drought responsiveness at the alfalfa seedling stage, the proteins expressed were analyzed under no-treatment, 200 mol L–1 Na Cl and 180 g L–1 PEG treatment conditions during the seedling stage. Out of more than 800 protein spots detected on two-dimensional electrophoresis(2-DE) g els, 35 proteins showed statistically significant responses(P<0.05) to Na Cl and PEG stress, which were selected for tandem mass spectrometric identification, owing to their good resolution and abundance levels, and 32 proteins were positively identified. The identified proteins were divided into seven functional categories: photosynthetic metabolism, protein biosynthesis, folding and assembly, carbohydrate metabolism-associated proteins, stress defense related protein, metabolism of nucleic acid, other function categories and unknown proteins. Our results suggested that these proteins may play roles in alfalfa adaptation to salt and drought stress. Further study of these proteins will provide insights into the molecular mechanisms of abiotic stress and the discovery of new candidate markers in alfalfa.

Allelopathic Effects of Cedrus deodara Needle Extracts on Seed Germination and Early Growth of Three Turfgrasses

[Objectives]This study was conducted to provide reference for plant landscaping,optimization of planting structure and rational allocation of species in Cedrus deodara gardens.[Methods]With three common garden plants in northern China,Trifolium repens L.,Poa pratensis L.and Trifolium pratense L.,as receptors,the effects of four concentrations(0.025,0.05,0.075 and 0.10 g/ml)of C.deodara needle extract on seed germination and early seedling growth of the three turfgrasses were studied by the Petri dish filter paper method,using a clear water treatment(0 g/ml)as control check(CK).Data were subjected to analysis of variance(ANOVA)and multiple comparisons(Duncan)using SPSS16.0.[Results]Different concentrations of C.deodara needle extract had significant inhibitory effects on seed germination,radicle and seedling height growth of T.repens,T.pratense and P.pratensis(P<0.05),and the inhibitory effects increased with the increase of concentration.When the concentration reached 0.075 g/ml,seed germination and seedling growth of T.repens stopped,and radicle and seedling growth of T.pratense and P.pratensis also stopped.When the concentration was equal to 0.10 g/ml,germination of T.pratense and P.pratensis seeds was inhibited,and the absolute values of allelopathic index was the largest,that is,the inhibitory effects were the largest.And with the increase of concentration,the absolute value of synthetical allelopathic index also increased.The extract of C.deodara needles contained main allelochemicals leading to the scarcity of understory vegetation.[Conclusions]This study provides a theoretical basis for reasonable garden plant configuration during C.deodara greening and garden landscaping.

Research on the Effects of Light Intensity and Seeding Density on the Seed Germination and Seedling Growth of Liriodendron chinense

It provides a theoretical basis for the artificial promotion of the reproduction and regeneration of Liriodendron chinense through exploring the effects of light intensity and seeding density on the seed germination and seedling growth of this rare plant. Controlled experiments were conducted by setting different seeding densities and shading intensities to observe and detect the seed germination and seedling growth under different experimental conditions. The data were analyzed by SPSS and the model was fitted to calculate the seed germination rate, seedling emergence rate and seedling growth parameters of Liriodendron chinense, which were used to analyze the effects of seeding density and light intensity on the seed germination and seedling growth of Liriodendron chinense. Light has a significant impact on the seed germination and seedling growth of Liriodendron chinense (P P > 0.05). High density promotes the seedling height (the seedling height showed a rising trend with the increase of seeding density, reaching the highest at 500 seeds/m2. “3-stitch + 300 seeds/m2” combination is an appropriate condition for Liriodendron chinense reproduction since it can realize higher germination rate and better seedling growth potential. The seedling height and basal diameter growth curve of Liriodendron chinense fits well to the Logistic equation (R2 ≥ 0.977). Light has a significant impact on the seed germination and seedling growth of Liriodendron chinense, and appropriate shading treatment can increase the seed germination rate and seedling emergence rate of Liriodendron chinense. Seeding density has little influence on the seed germination rate of Liriodendron chinense, but high density will promote seedling height.

Two chemical mutagens modulate the seed germination,growth,and phenotypic characteristics of Chinese fir(Cunninghamia lanceolata)

Chinese fir(Cunninghamia lanceolata(Lamb.)Hook),a fast-growing and economically important timber tree species in China,is widely used in construction,furniture,and paper manufacture but has a long breeding cycle.Chemical mutagens,such as ethyl methane sulfonate(EMS)and sodium azide(SA),are widely used in crops such as rice,wheat,cotton,soybean and sugarcane but their utility for tree breeding is unknown.In this study we examined the effects of EMS and S A on Chinese fir seed germination and growth.Chinese fir seeds were treated with the two chemical mutagens;were planted in Jiangle County,Fujian Province,China;and their heights were measured from 2011 to2017.The concentrations and durations of treatment with the two chemical mutagens were significantly associated with the Chinese fir seedling and mortality rates,as well as with the heights of trees from the seedling stage to 3 years old.We also generated 127 mutants with abnormal branches and reproductive growth.We report here the effects of two chemical mutagens on Chinese fir breeding;our data will contribute to knowledge of the utility of EMS and SA in forestry.

Transpiration and growth responses by Eucalyptus species to progressive soil drying

The regulation of plant transpiration is a key factor affecting transpiration efficiency, growth and adaptation of Eucalyptus species to limited water availability in tropical and subtropical environments. However, few studies have related this trait to the performance of Eucalyptus seedlings and none have investigated the influence of vapor pressure deficit (VPD) on transpiration rates and growth. In this study, the transpiration and growth responses of seedlings of Eucalyptus urophylla (S.T. Blake) and Eucalyptus cloeziana (F. Muell.) to progressive soil water deficits were evaluated under semi-controlled conditions using the fraction of transpirable soil water (FTSW) method. In addition, the influence of VPD on seedling transpiration, development and growth was also investigated. The FTSW threshold ranged from 0.40 to 0.99 for the transpiration rate and from 0.32 to 0.97 for the development and growth variables. Little or no changes in the FTSW threshold were detected in response to changes in atmospheric VPD. Both Eucalyptus species presented a conservation strategy under drought stress. In addition, water-conserving mechanisms during the seedling phase were related to rapid stomatal closure, reduced leaf area, and number of leaves.

Allelopathic Effects of Extracts from Three Asteraceae Plants on Seed Germination and Seedling Growth of Four Plants

[Objectives]This study was conducted to investigate the allelopathic effects of the extracts of Asteraceae plants on plant seeds and seedlings.[Methods]The effects of the extracts of three Asteraceae plants(Erigeron annuus,Bidens pilosa and Inula japonica)on the seed germination and seedling growth of four plants(Setaria viridis,Erigeron canadensis,Chenopodium album and Lactuca sativa)were studied by the Petri dish filter paper method and bioassay method.[Results]Different concentrations(10,20,40,100,200 mg/ml)of the extracts of E.annuus,B.pilosa and I.japonica had different allelopathic effects on the seed germination of the same recipient plant,and with the increase of the concentrations of the extracts,the inhibitory effects were more significant.The extract of B.pilosa had the strongest inhibitory effect.The extracts at the low concentration(10 mg/ml)had no significant effects on the germination rates and germination energy of the four kinds of plant seeds.In terms of root growth and biomass,the extracts of E.annuus and I.japonica showed the effect of low promotion and high inhibition.Under the treatment with high concentrations(100,200 mg/ml)of the extracts from the three Asteraceae plants,the germination of plant seeds,plant root length,stem height and biomass were inhibited.With the concentrations of the extracts of the three Compositae plants increasing,the chlorophyll contents of the four plants showed a downward trend,and the activity of SOD,POD,CAT and other antioxidant protective enzymes showed a trend of first increasing and then decreasing.[Conclusions]These three species of Asteraceae plants had certain allelopathic inhibitory effects on the germination and growth of the four kinds of plant seeds,including S.viridis,E.canadensis,C.album and L.sativa,and they have potential in the development of botanical herbicides or plant protection.

Selection of Optimal Medium for Cultivation of Idesia polycarpa var.vestita Seedlings in the Industrialized Nursery Process

Idesia polycarpa Maxim.var.vestita Diels is an important oil plant with high economic value.In order to improve seed germination and to cultivate high quality seedlings,we set out to identify an optimal medium for its seedling growth in a plastic cave tray(plug seedling).In this study,four different media including M_(1)(soil),M_(2)(peat∶perlite=2∶1),M_3(peat),and M_4(peat∶perlite∶vermiculite=2∶1∶1)were tested in industrialized plug seedlings.The seedling growth of Idesia polycarpa var.vestita including plant height,crown diameter,leaf number,ground diameter,the relative chlorophyll contents of leaves,etc.was measured.The results indicated that the medium M_(2) was the best for increasing seedling height,crown diameter,leaf counts,ground diameter,and the relative chlorophyll contents of leaves.Therefore,medium M_(2) is recommended in the industrialized nursery process for the seedling growth of Idesia polycarpa var.vestita.

Study on the Differences of Antimony Tolerance in Seed Germination and Seedling Growth among Different Maize Cultivars

[Objectives]This study was conducted to investigate the differences in antimony tolerance among different maize varieties.[Methods]The effects of antimony stress(1000 mg/L)on seed germination and seedling growth of 26 maize varieties cultivated in Hunan Province were studied.[Results]The antimony stress had little effect on germination rate and germination index of maize seeds,but a significant effect on seed vigor index and root growth;and the antimony stress inhibited shoots less than roots.The tolerance of different maize varieties to antimony stress was quite different,and cluster analysis could divide the tested varieties into three types:susceptible type,intermediate type and tolerant type.Among them,Zhaoyu 999,Huayu 130,Changyu 1,Qingqingyu 800,Qiandan 12 and Huangdan 008 had strong antimony tolerance.[Conclusions]This study is of great significance to the screening of antimony-tolerant maize varieties for breeding research and the planting and application in antimony-contaminated areas around mining areas.

Effect of biochar application on rice,wheat,and corn seedlings in hydroponic culture

In recent years,biochar has attracted considerable attention for soil quality improvement and carbon sequestration due to its unique physicochemical properties.However,the mechanism by which biochar application negatively affects the growth of crop seedlings has not been fully investigated.In this study,a hydroponic experiment was conducted to evaluate the response of rice,wheat,and corn seedlings to biochar application(CK,0 g/L;BC1,0.5 g/L;and BC2,1.0 g/L).Compared with the CK treatment,the BC1 and BC2 treatments decreased the fresh shoot and root weights of rice and corn seedlings(P<0.05),but there was no significant effect on wheat seedlings(P>0.05).For the contents of nutrient elements in seedlings,both BC1 and BC2 treatments hindered the roots from absorbing Fe and Cu and increased the uptake of Ca and Mn.Compared with the CK treatment,the translocation factor(TF)values of Ca,Mn,and Zn were significantly decreased especially in rice seedlings(35.3%-36.8%,68.7%-76.5%,and 29.8%-22.0%,respectively)under the BC1 and BC2 treatments,while only Mn was significantly decreased in wheat and corn seedlings(P<0.05).Transmission electron microscope(TEM)analysis of root cross-sections showed that nano-sized biochar particles(10~23 nm)were found in the root cells under BC2 treatment conditions.Our findings reveal that a large amount of biochar application can reduce nutrient absorption and translocation,and hinder rice,wheat,and corn seedlings,particularly rice seedling,in hydroponic system.

Potentiality of Different Seed Priming Agents to Mitigate Cold Stress of Winter Rice Seedling

Seed priming has proved to be an effective pre-germination seed invigoration technique for different crops to improve seed and seedling performance under different abiotic stresses.In Bangladesh,winter rice is very often exposed to cold waves just after sowing in the nursery bed resulting in poor seed germination and seedling emergence,yellowish and thin seedlings production,and a very low survival rate.Seed priming may mitigate the cold stress during seed germination and seedling emergence and helps in the quality seedling production of winter rice.To evaluate the efficacy of different seed priming techniques in increasing seedling emergence,growth,vigor and survivability of winter rice cultivars under cold stress,a pot experiment was conducted at the Department of Agronomy,Bangladesh Agricultural University during December 2018 to January 2019.The experiment comprised two factors,(A)Winter rice variety namely,(i)BRRI dhan29 and (ii)BRRI dhan36;(B)Seed priming agent namely (i)Control(no priming),(ii)20000 ppm NaCl,(iii)30000 ppm NaCl,(iv)20000 ppm KCl,(v)30000 ppm KCl,(vi)20000 ppm CaCl2,(vii)30000 ppm CaCl2,(viii)50 ppm CuSO4,(ix)75 ppm CuSO_(4),(x)10000 ppm ZnSO4,(xi)15000 ppm ZnSO4,(xii)2 ppm Na2MoO4,(xiii)3 ppm Na2MoO4,(xiv)100 ppm PEG(Polyethylene glycol 4000)and (xv)150 ppm PEG.Seeds were sown on two different dates viz.,1st December and 1st January so that seedlings are exposed to cold stress at different stages.The experiment was laid out in a completely randomized design(CRD)with three replications.Results indicated that(in most of the cases)seed priming has a positive impact on seedling emergence rate(%),root length,shoot length,root shoot ratio,root dry weight,shoot dry weight,seedling dry weight and survival rate(%).Among the priming agents,KCl and CaCl2 performed best;while priming with NaCl and PEG showed no advantages over no priming for both the sowing dates.In general,BRRI dhan36 performed better than BRRI dhan29 in terms of seedling growth because of its higher tolerance to cold stress.But,both the varieties performed similarly in terms of emergence rate and survival rate.Thus,priming is an effective tool to increase seed germination,better seedling growth,and higher seedling survivability of winter rice under cold stress,and KCl(20000 ppm)or CaCl2(20000 ppm)can be considered as a viable priming agent.

Growth Promotion Effects of Bacillus subtilis on Bletilla striata Seedlings

Objective:The objective of the study is to study the growth promotion effects of Bacillus subtilis inoculants on the growth of Bletilla striata seedlings.Methods:Various concentrations(1/10×,1/50×,1/100×,and 1/500×dilutions)of B.subtilis inoculants were applied on the B.striata seedlings.Plant height,base diameter,leaf length,leaf width,relative chlorophyll content,tuber diameter,average fibrous root length,number of fibrous roots,and fresh weight were measured after incubation for 50 days.Results:Treatments with different concentrations of B.subtilis significantly increased the number of fibrous roots of the B.striata seedlings and promoted root elongation,and a higher concentration(1/10×dilution)is associated with more significant promotion effects.B.striata seedlings treated with different concentrations of B.subtilis all showed an increase of relative chlorophyll contents in leaves with the increasing inoculant concentration.Only B.subtilis inoculant at a high concentration(1/10×dilution)significantly promoted the plant height and base diameter of B.striata seedlings.The application of B.subtilis did not significantly promote the tuber diameter and fresh weight of B.striata seedlings.Principal component analysis confirmed the maximum growth promotion by B.subtilis inoculant in 1/10×dilution than the other treatments.Conclusions:The application of B.subtilis can increase the relative chlorophyll content,promote growth and development of roots,and increase plant height and base diameter of B.striata seedlings.Therefore,B.subtilis has significant growth promotion effects on B.striata seedlings.These findings provide theoretical basis for the ecological cultivation of B.striata.

Allelopathic Potential and Mechanism of Rosebay Willowherb[Chamaenerion angustifolium(L.)Scop.]Demonstrated on Model Plant Lettuce

Allelopathic plants are important resources for the discovery of bioherbicides.Rosebay willowherb[Chamaenerion angustifolium(L.)Scop.syn.Epilobium angustifolium L.]widely distributes in Western Asia,Europe,and North America,and behaves as a dominant species within the community due to the production of substances that restrict growth of other plants.This study aims at investigating the allelopathic potential of rosebay willowherb by evaluation of the effects of aqueous extracts from different parts on seed germination and seedling growth in lettuce(Lactuca sativa L.),as well as measuring the accumulation of reactive oxygen species and structural analysis of root tips via scanning electron and transmission electron microscopy.It was observed that the aqueous extracts from the leaves of rosebay willowherb had the strongest inhibitory effect on the germination index,germination energy and total germination of lettuce seeds,followed by capsular fruits and flowers,and the inhibition effect of stems was the weakest.All aqueous extracts(100 mg/mL)showed a significant inhibitory effect on radicle elongation of lettuce seedlings.Additionally,after treatment with the aqueous extract of rosebay willowherb leaves,accumulation of reactive oxygen species increased in columella cells,which correlated with disruption of root tip structure.

Gap characteristics and their effects on regeneration,dominance and early growth of woody species

Aims We aim to examine the canopy gap characteristics and evaluate their influence on regeneration,dominance and the early growth of woody species in seasonally dry Shorea robusta forests(Sal forests).Methods Sixty canopy gaps were surveyed in six randomly located transects belts in seasonally dry subtropical Sal forests of central Nepal.Each transect belt was followed until 10 gap sites were encountered.The equation for the area of an ellipse was used to calculate the size of canopy gap,measuring the longest axis and its perpendicular shorter axis.Number,sizes,ages and causes of tree falls creating canopy gaps along with number and sizes of border trees were identified and recorded.Detailed gap inventories were carried out using square 25-m2 quadrats placed in the middle of each gap.All individuals>2 m in height within the quadrat were identified at the species level and their diameter at breast height was measured.We assigned a nested 4-m2 quadrat to the corner of each 25-m2 quadrat,within which all woody individuals>10 cm tall were identified at the species level,and counted them and their regeneration mechanisms were identified.The height and collar diameter of the tallest individuals were measured.Descriptive statistics was calculated for the variables of interests and Pearson correlation,linear regression,independent-sample t-test and chi-square test were used to relate them and to test for their associations.Important Findings The study found mean gap size of 283 m2 and;50%gaps of 10–15 years old.Gaps created by natural single-tree falls were significantly more numerous,and their mean size was significantly smaller than those resulting from artificial causes or multiple-tree falls.Gap size correlated with the basal area of felled trees,but it did not correlate with the number of tree falls.While tree fall basal area was significantly positively correlated to the seed-originated seedling to resprout ratio,it was negatively correlated,along with gap area and the basal size of retained trees,to seedling growth.The relative seedling density of Terminalia alata increased with increases in gap areas,while that of S.robusta decreased with increases in tree fall basal area,thereby lowering the plot-level dominance.However,the relative seedling densities of Eugenia operculata and Syzigium cumini were negatively and positively correlated,respectively,with tree fall basal area.

Magnetically treated water irrigation effect on turnip seed germination,seedling growth and enzymatic activities

Pre-sowing magnetic field seed treatment effects on biological characteristics of vegetables and crops have been studied well.However,studies reporting irrigation with magnetically treated water are scanty.Therefore,the effect of irrigation with magnetically treated water on turnip seed germination,seedling growth and enzymatic activities was evaluated.The tap water was treated at 211 mT for 30,45 and 60 min and used for irrigation of turnip seed and seedlings.Uniform and healthy turnip seed was sown under randomized complete block design(RCBD).The germination,emergence rate index,vigor index I and vigor index II increased up to 28.33%,11.54%,57.59%and 32.26%,respectively.The growth parameters such as seedling lengths,fresh&dry weights,chlorophyll content were also enhanced in response of irrigation with magnetically treated water.The seedlings irrigated with magnetically treated water showed 28.92%,11.36%and 14.76%higher protein content,alpha amylase and protease activities,respectively vs control.Results revealed that irrigation with magnetically treated water has potential to improve turnip germination,seedling growth and enzymatic activities and this study is also extendable to other vegetables and crops for the improvement of germination and growth.

Toxicity evaluation of collagen hydrolysates from chrome shavings and their potential use in the preparation of amino acid fertilizer for crop growth

Resource utilization of chrome shavings(CS)has attracted a lot of attention from scientists and technologists in leather industry.Especially,the collagen hydrolysates extracted from CS are expected to find potential application values in agricultural field.However,there is no biotoxicity analysis of collagen hydrolysates from CS.Herein,the collagen hydrolysates with different molecular weights were produced from CS by three hydrolysis dechroming methods including alkaline hydrolysis,enzymatic hydrolysis and alkaline-enzymatic synergistic hydrolysis,and the optimal hydrolysis process of CS was designed and conducted.To evaluate their toxicity,the three collagen hydrolysates were formulated into a nutrient solution for zebrafish development.The obtained results indicated that the hydrolysates with low concentrations(less than 0.6 mg/mL)were safe and could promote the development for zebrafish embryos.Furthermore,the three collagen hydrolysates were utilized as organic nitrogen sources and formulated into amino acid water-soluble fertilizers(AAWSF)including alkaline type fertilizer(OH),enzymatic type fertilizer(M)and alkaline-enzymatic type fertilizer(OH-M)for the early soilless seeding cultivation of wheat,soybean and rapeseed.It is worth mentioning that the chromium contents in the prepared AAWSF were less than 10 mg/kg,which is far less than the limit value in the standard(China,50 mg/kg).The growth and development of seedlings(germination rate,plant height,fresh weight of leaves,soluble sugar content and chlorophyll content)were investigated.The corresponding results showed that the growth of seedlings watered with AAWSF was better compared with the other treatments,and the OH-M fertilizer had the best promoting effect on the seedlings growth and development,followed by the M and OH fertilizers.The safe toxicity assessment of the collagen hydrolysates will expand their application scope,and the use of collagen hydrolysates extracted from CS for seedlings growth also provides an effective and reason-able way to deal with the chromium-containing leather solid waste,which is an effective way to realize its resource utilization.

Seasonal distribution of increased precipitation in maternal environments influences offspring performance of Potentilla tanacetifolia in a temperate steppe ecosystem

Aims Precipitation is predicted to increase in arid and semiarid regions under climate change,with greater changes in intra-and interannual distribution in the future.As a major limiting factor in these regions,changes in precipitation undoubtedly influence plant growth and productivity.However,how the temporal shifts in pre-cipitation will impact plant populations are uncertain.Methods A 3-year field experiment and a greenhouse experiment were conducted in a temperate grassland in northern China to examine the impacts of seasonal(spring and summer)increased precipitation on offspring performance of a common species,Potentilla tanacetifolia.Important Findings Our results showed that the amounts and timing of increased precipitation both played important roles in regulating offspring performance of P.tanacetifolia in the temperate steppe ecosystem.Increased precipitation in spring at maternal stage stimulated seed production,germination percentage and seedling biomass,whereas increased precipitation in summer at maternal stage stimulated seedling biomass.The timing of increased precipitation influenced seed attributes,whereas the amount of increased precipitation influenced offspring seedling biomass.Our results indicate that population development of P.tanacetifolia may be underestimated under future increased precipitation regime,if the transgenerational effect is not taken into account.