Dietary supplementation of laminarin improves the reproductive performance of sows and the growth of suckling piglets

Background Maternal nutrition is essential in keeping a highly efficient production system in the pig industry.Laminarin has been shown to improve antioxidant capacity,reduce the inflammatory response,and favor the homeostasis of intestinal microbiota.However,the effect of dietary supplementation of laminarin on the reproductive performance of sows and the growth of suckling offspring remains unknown.Methods A total of 40 Landrace×Yorkshire multiparous sows on d 85 of gestation,similar in age,body weight(BW),parity and reproductive performance,were randomly divided into four dietary treatments with 10 sows per treatment,receiving a control diet(basal pregnancy or lactating diets)and a basal diet supplemented with 0.025%,0.05%and 0.10%laminarin,respectively.The experiment lasted from d 85 of gestation to d 21 of lactation.Results Laminarin supplementation linearly increased number born alive per litter(P=0.03),average daily feed intake(ADFI,P<0.01),and total milk yield of sows during the lactation of 1–21 d(P=0.02).Furthermore,maternal laminarin supplementation increased the average daily gain(ADG)of piglets while tending to reduce the culling and death rate before weaning.In addition,alterations to the composition of colostrum and milk,as well as to serum inflammatory cytokines and immunoglobulins of sows were observed.The fecal microbiota profile of sows supported the improvement of reproductive performance in sows and the growth performance in suckling offspring.Conclusions Dietary supplementation of laminarin during late pregnancy and lactation could significantly improve reproductive performance of sows and growth performance of piglets.

Gut microbiota affects the estrus return of sows by regulating the metabolism of sex steroid hormones

Background Sex hormones play important roles in the estrus return of post-weaning sows.Previous studies have demonstrated a complex and bi-directional regulation between sex hormones and gut microbiota.However,the extent to which the gut microbiota affects estrus return of post-weaning sows is largely unknown.Results In this study,we first screened 207 fecal samples from well-phenotyped sows by 16S rRNA gene sequencing and identified significant associations between microbes and estrus return of post-weaning sows.Using metagenomic sequencing data from 85 fecal samples,we identified 37 bacterial species that were significantly associated with estrus return.Normally returning sows were characterized by increased abundances of L.reuteri and P.copri and decreased abundances of B.fragilis,S.suis,and B.pseudolongum.The changes in gut microbial composition significantly altered the functional capacity of steroid hormone biosynthesis in the gut microbiome.The results were confirmed in a validation cohort.Significant changes in sex steroid hormones and related compounds were found between normal and non-return sows via metabolome analysis.An integrated analysis of differential bacterial species,metagenome,and fecal metabolome provided evidence that normal return-associated bacterial species L.reuteri and Prevotella spp.participated in the degradation of pregnenolone,progesterone,and testosterone,thereby promoting estrogen biosynthesis.Furthermore,the microbial metabolites related to sow energy and nutrient supply or metabolic disorders also showed relationships with sow estrus return.Conclusions An integrated analysis of differentially abundant bacterial species,metagenome,and fecal metabolome revealed the involvement of L.reuteri and Prevotella spp.in sow estrus return.These findings provide deep insight into the role of gut microbiota in the estrus return of post-weaning sows and the complex cross-talk between gut microbiota and sex hormones,suggesting that the manipulation of the gut microbiota could be an effective strategy to improve sow estrus return after weaning.

Standardized ileal digestibility of amino acids in soybean meal fed to non-pregnant and pregnant sows

Background Two studies were designed to determine standard ileal crude protein(CP)and amino acid(AA)digestibility of soybean meal(SBM)from different origins fed to non-pregnant and pregnant sows.Seven solvent-extracted SBMs from soybeans produced in the USA,Brazil,and China were selected.In Exp.1,eight different diets were created:a nitrogen(N)-free diet and 7 experimental diets containing SBM from different origins as the only N source.Eight non-pregnant,multiparous sows were arranged in an 8×8 Latin square design(8 periods and 8 diets).In Exp.2,the diet formula was the same as in Exp.1.Eight gestating sows(parity 3)were assigned to 4 different diets in a replicated 4×3 Youden square design(three periods and four diets)in mid-gestation and again in late-gestation stages.Results When fed to non-pregnant and late-gestating sows,the standardized ileal digestibility(SID)of CP and most AAs from different SBM were not significantly different(P>0.05).When fed to mid-gestating sows,the SID values for Arg,His,Lys,Phe,Cys,Gly,Ser,and Tyr in SBM 1 were lower than in SBM 4 and 5(P<0.05),whereas SID for Leu from SBM 5 was higher than in SBM 1 and 4(P<0.05).SID values for Ile,Ala,and Asp from SBM 4 were lower than in SBM 1 and 5(P<0.05).Sows had significantly greater SID values for Lys,Ala,and Asp during mid-gestation when compared with late-gestation stages(P<0.05).Mid-gestating sows had greater SID value for Val and lower SID value for Tyr when compared with non-pregnant and late-gestating sows(P<0.01),whereas non-pregnant sows had significantly greater SID value for Met when compared with gestating sows(P<0.01).Conclusions When fed to mid-gestating sows,the SID values for most AAs varied among SBM samples.The SID values for Lys,Met,Val,Ala,Asp,and Tyr in SBM were affected by sow gestation stages.Our findings provide a cornerstone for accurate SBM use in sow diets.

Effects of improved amino acid balance diet on lysine mammary utilization, whole body protein turnover and muscle protein breakdown on lactating sows

Background The study objective was to test the hypothesis that low crude protein(CP)diet with crystalline amino acids(CAA)supplementation improves Lys utilization efficiency for milk production and reduces protein turnover and muscle protein breakdown.Eighteen lactating multiparous Yorkshire sows were allotted to 1 of 2 isocaloric diets(10.80 MJ/kg net energy):control(CON;19.24%CP)and reduced CP with“optimal”AA profile(OPT;14.00%CP).Sow body weight and backfat were recorded on d 1 and 21 of lactation and piglets were weighed on d 1,14,18,and 21 of lactation.Between d 14 and 18,a subset of 9 sows(CON=4,OPT=5)was infused with a mixed solution of 3-[methyl-2H3]histidine(bolus injection)and[13C]bicarbonate(priming dose)first,then a constant 2-h[13C]bicarbonate infusion followed by a 6-h primed constant[1-13C]lysine infusion.Serial blood and milk sampling were performed to determine plasma and milk Lys enrichment,Lys oxidation rate,whole body protein turnover,and muscle protein breakdown.Results Over the 21-d lactation period,compared to CON,sows fed OPT had greater litter growth rate(P<0.05).Compared to CON,sows fed OPT had greater efficiency of Lys(P<0.05),Lys mammary flux(P<0.01)and whole-body protein turnover efficiency(P<0.05).Compared to CON,sows fed OPT tended to have lower whole body protein breakdown rate(P=0.069).Muscle protein breakdown rate did not differ between OPT and CON(P=0.197).Conclusion Feeding an improved AA balance diet increased efficiency of Lys and reduced whole-body protein turnover and protein breakdown.These results imply that the lower maternal N retention observed in lactating sows fed improved AA balance diets in previous studies may be a result of greater partitioning of AA towards milk rather than greater body protein breakdown.

Analysis on Absorption,Utilization and Transfer Efficiency of Nitrogen in High-yield Wheat Cultivars at Different Sowing Dates

This study aimed to analyze the absorption, utilization and transfer char- acteristics of nitrogen in high-yield winter wheat （Triticum aestivum） cultivars at dif- ferent sowing dates, so as to determine the optimum sowing dates for different high-yield wheat cultivars. A field experiment was conducted in the Shajiang black soil of Anhui Province with Jimai 22, Wanrnai 52 and Zhoumai 22, and the effects of early sowing （October 3）, optimum sowing （October 12） and late sowing （October 30） on wheat plant N content and accumulation, pre-and post-anthesis N accumula- tion （NA） of total plant, nitrogen remobUization to grain （NR）, N remobilization effi- ciency （NRE）, contribution of N remobilized to grain （NRC）, grain yield, N use effi- ciency （NUE） and N harvest index （NHI） of different wheat cultivar were investigat- ed. The results showed that sowing date had an impact on N content, absorption and utilization in wheat plants at various growth stages. The NA, NR and NRC of aboveground vegetative organs of wheat before anthesis were higher than those af- ter anthesis. Under the condition of late sowing, the grain N accumulation mainly depended on the N absorption by vegetative organs before anthesis. Under the conditions of optimum and early sowing, the absorbed N after anthesis accounted for a large proportion in grain N accumulation. The N uptake intensity and relative cumulative rate differed greatly among different growth stages and different-genotype wheat cultivars, and the pre-anthesis NA, pre-anthesis NR, pre-anthesis NRE, post- anthesis N assimilation amount and post-anthesis NRC showed significant differ- ences among different wheat cultivars. The grain yields of different wheat cultivars under the early and optimum sowing were all higher than those under the late sowing. The NHI and grain N accumulation were highest under the optimum sow- ing, and the latter significantly decreased with the delay of sowing dates. In con- trast, the NUE was highest under the late sowing, reaching 35.95%-41.32%. It indi- cated that under the condition of late sowing, most of the nitrogen was not ab- sorbed by wheat, but the use efficiency of the absorbed nitrogen significantly in- creased. In overall, the three high-yield wheat cultivars were all suitable for early and optimum sowing. Under the condition of late sowing, the yield of Zhoumai 22 showed the smallest differences with those under early and optimum sowing, and its NUE was significantly improved. Therefore, among the three high-yield wheat culti- vars, Zhoumai 22 was most suitable for late sowing.

Study on Sowing Date for Mechanicaltransplanting Rice under Wheat-Rice Cropping System in Chengdu Basin

Nurturing sturdy mechanical-transplanting seedlings is the key to achieve high yield using mechanical-transplanting technology under wheat-rice cropping conditions in Chengdu Basin. In this study, super hybrid rice II You 602 was adopted as experimental material, to investigate the effects of sowing date on seedling growth,transplanting quality, growth process and yield of mechanical-transplanting seedlings in wheat-rice cropping region of Chengdu Basin, thus exploring supporting high-yield cultivation techniques for mechanical-transplanting technology in Chengdu Basin, Results showed that the appropriate sowing date for mechanical transplanting in wheatrice cropping region of Chengdu Basin was April 10-15, and the appropriate seedling age was 45-50 d, which led to the highest yield of mechanical-transplanting seedlings. Although postponing sowing was conducive to improving transplanting quality and increasing the percentage of earbearing tillers, it would result in lagged group growth, poor spike quality and reduced effective number of panicles, grain number, seed-setting rate, 1 000-seed weight and other yield components, thus declining the yield. Yield reduction rate would be above 10% with sowing date postponed by 15 d.

Effects of Different Sowing Dates and Sites on Starch RVA Profile Characteristics of Different Ecotypes of Rice (Oryza sativa, L. japonica)

[Objective] This study aimed to investigate the effects of different sowing dates and sites on starch RVA profile characteristics of different ecotypes of japonica rice. [Method] Five different ecotypes of japonica rice were sown at seven different dates in four rice planting regions in Jiangsu Province to analyze the differences in starch RVA profile parameters among different rice varieties. [Result] Among eight parameters of rice starch RVA profile, peak time exhibited no significant differences among different sites, while other seven parameters varied significantly or extremely significantly among different sites, sowing dates and varieties. Specifically, rice variety exerted the most significant effects on rice starch RVA profile parameters. Starch RVA profile characteristics varied significantly among different ecological conditions but exhibited no significant differences among different latitudes. To be specific, in different sites, peak viscosity （PKV）, hot paste viscosity （HPV） and breakdown viscosity （BDV） demonstrated a descending order of Huai＇an 〉 Suzhou 〉 Lianyungang 〉 Yangzhou. Cool paste viscosity （CPV） and consistence viscosity （CSV） were higher in the north than in the south; specifically, CPV and CSV were significantly higher in Lianyungang and Huai＇an than in Yangzhou and Suzhou. Setback viscosity （SBV） showed an increasing trend with increasing latitude; specifically, SBV was significantly lower in Suzhou than in other three sites. Pasting temperature （PAT） and peak time （PET） changed slightly among different latitudes. With the postponing of sowing date, peak viscosity （PKV）, hot paste viscosity （HPV）, cool paste viscosity （CPV） and peak time （PET） showed a decreasing trend, setback viscosity （SBV） and consistence viscosity （CSV） increased, breakdown viscosity （BDV） increased first and then decreased, whereas pasting temperature （PAT） decreased first and then increased. Furthermore, rice starch RVA profile parameters showed the same variation trend with sowing date in different sites; early sowing within suitable sowing dates could effectively improve the parameters of rice starch RVA profile. However, different parameters exerted different variations among different sites and most parameters were higher in the north than in the south, which indicated that starch RVA profile parameters were significantly affected by sowing date in the north of Jiangsu Province. Among eight starch RVA profile parameters, setback viscosity exhibited the maximum variation coefficient, while peak time exhibited the minimum variation coefficient. Among five rice varieties, Nanjing 46 exhibited the highest peak viscosity and breakdown viscosity and the lowest setback viscosity and consistence viscosity, suggesting that Nanjing 46 had the most appropriate starch RVA profile characteristics and the best cooking and eating quality. Lianjing 4 exhibited relatively high peak viscosity and breakdown viscosity, and relatively low setback viscosity and consistence viscosity, suggesting that Lianjing 4 had good starch RVA profile characteristics. Different sowing dates and sites exerted significant effects on starch RVA profiles of different eco- types of japonica rice. Rice starch RVA profile characteristics varied significantly among different sites but exhibited no significant variations among different latitudes. In addition, starch RVA profile characteristics varied significantly among different sowing dates. Therefore, early sowing of the same variety was conducive to improving starch RVA profile characteristics in appropriate planting regions. [Conclusion] This study provided a theoretical basis for producing high-quality rice and improving the eating quality of rice in Jiangsu Province.

Effect of Different Sowing Dates and Densities on Individual Morphological Development of Super Short-season Insect-resistant Cotton

[Objective] The paper was to explore the effect of different sowing dates and densities on individual morphological development of super short-season insect-resistant cotton,confirm their effects on vegetative and reproductive growth of cotton,so as to provide theoretical and practical guidance for sowing date and density management of cotton planting in Jidong cotton growing region in Yellow River Basin.[Method] With super short-season insect-resistant cotton＂546＂as materials,the effects of different sowing dates（sowing dateⅠ：May 20;sowing dateⅡ：June 2;sowing date Ⅲ：June 14）and densities（low density：120 000 plants/hm2;middle density：150 000 plants/hm2;high density：180 000 plants/hm2）on individual morphological development of super short-season insect-resistant cotton were explored.[Result] Different sowing dates and density treatments significantly affected the individual morphological development of super short-season insect-resistant cotton＂546＂.The effectiveness of sowing date was higher than the effectiveness of density,and the effectiveness of sowing date on development of number of individual fruit branches was higher than that on plant height and stem diameter.[Conclusion] The regulation of sowing date and density during the cultivation process of super short-season insect-resistant cotton ＂546＂ in Jidong cotton growing region in Yellow River Basin could effectively promote vegetative and reproductive growth of cotton,strengthening its production base.

播期和播量对超晚播冬小麦基部节间显微结构及抗倒伏指数的影响

为筛选北疆超晚播小麦高产抗倒伏的播期和播量组合,明确小麦基部茎秆显微结构变化特点及其与抗倒伏指数的关系,采用裂区试验设计,主区设3种超晚播期:S1(10月25日)、S2(11月4日)、S3(11月14日),副区设4个播量:P1(337.5 kg·hm^(-2))、P2(450 kg·hm^(-2))、P3(562.5 kg·hm^(-2))、P4(675 kg·hm^(-2)),以当地适宜播期和播量(9月25日、270 kg·hm^(-2))为对照(CK),研究播期和播量对超晚播小麦开花期、乳熟期及蜡熟期的基部节间显微结构和抗倒伏指数及产量的影响。结果表明,开花后,随着小麦生育进程的推进,抗倒伏指数逐渐降低,基部自下而上节间显微结构质量变差,且第1、2、3节间变化规律一致。与CK相比,超晚播小麦茎秆显微结构各项指标(机械和薄壁组织层数和厚度、大小维管束个数、大维管束周长和面积)降低,显微组织变小,抗倒伏指数降低。同一播量不同播期小麦基部茎秆显微结构各项指标和抗倒伏指数均表现为S3>S1>S2;同一播期下,随着播量的提高,显微结构各项指标和抗倒伏指数降低;播期与播量对各指标不存在互作效应。抗倒伏指数与基部节间小维管束个数呈极显著负相关,与其余显微结构指标呈极显著正相关,以薄壁组织对提高小麦抗倒伏作用最强。超晚播条件下提高小麦播量有利于增加穗数,弥补穗粒数和千粒重的损失,进而提高产量,以S2P2穗数最高,产量最佳。综上,北疆超晚播小麦于11月4日播种450 kg·hm^(-2)可获得高产且抗倒伏植株。本研究结果为超晚播小麦稳产丰产提供了理论依据.

Effects of Interaction between Density and Nitrogen Rate on Growth and Yield of No-tilling and Direct Sowing Rapeseed in Chengdu Plain

[Objective] The aim was to explore the optimal density and nitrogen rate of no-tilling and direct sowing rapeseeds in Chengdu plain. [Methods] Effects of in- teraction between density and nitrogen rate on the growth and yield of direct sowing rapeseed under no-tillage condition were investigated with Chuanyou 58 as materials and a split-plot experiment adopted. [Results] In Chengdu Plain, the yields of rape- seed changed from increasing to decreasing with increase of density and nitrogen rate. Both of density and nitrogen rate had significant effects on growth and yield of rapeseed and the latter overweighed in the effect. In addition, interaction of the two had negative effects on rapeseed yield. The yield of rapeseeds achieved the highest at 3 395.25 kg/hm^2 with interaction of density at 30.00×10^4 plant/hm^2 and nitrogen rate at 180.00 kg/hm^2; the theoretical maximal yield was 3 403.41 kg/hm^2 with interaction of density at 40.80×10^4 plants/hm^2 and nitrogen rate at 198.90 kg/hm^2. [Conclusion] In Chengdu Plain, the optimal density and nitrogen rate are 30.00×10^4-45.00×10^4 plant/hm^2 and 180.00-198.90 kg/hm^2, respectively.

The Effect of Sowing Date and Density on the Characters and Yield of Maize in Chongqing

In order to investigate the most suitable sowing period and the optimum planting density of new com variety ‘Yudan 30＇ In Chongqing region, using split plot experiment design, the effect of sowing date and planting density on main a- gronomic characters and yield of maize in the field was studied. The results showed that in Chongqing, the delay of sowing date could shorten the fertility peri- od, and reduce 100-grain Weight and yield, but could increase plant height and ear height, panicle traits did not change significantly. With the density increasing, plant height and ear height also increased, while ear length, ear diameter, stem diameter, row number and kernel number also decreased. 100-grain weight and yield also in- creased with the increase of density, but to a certain threshold, yield and 100-grain weight decreased with the increase of density. The yield of 3 sowing periods pre- sented as AI〉A2〉A3, the yield of 4 kinds of density presented as B3〉EH〉B2〉B1, and the yield under sowing time and density interaction presented as AIB3〉A1B4〉 A2.B3〉A2.B4〉A3B3〉 A3B4〉A2.B2〉A1BI〉A2BI〉A3BI. So proper eady sowing and increase of planting density could raise the yield of maize per unit area, and AIB3 was the optimum planting configuration in Chongqing area.

Effects of Irrigation Quantity and Term on Waterconsumption and Yield of Winter Wheat by Wide Precision Sowing

[Objective] The aim was to research effects of irrigation quantity and term on winter wheat by wide precision sowing and to provide references and technical supports for water-saving agriculture in North China. [Methed] During 2013-2015, Jimai 22, a winter wheat cultivar, was taken as materials to explore effects of irrigation quantity and term on water consumption characters and yield of winter wheat by wide precision sowing. [Result] As irrigation water increased, water consumption and irrigation water＇s proportions were growing, but quantity and proportion of soil water consumption were both diminishing; seed yields all kept increasing upon irrigation, but water use efficiencies were decreasing. Given the same irrigation conditions, water consumption by wide precision sowing was more, but yield and water use efficiency were higher. [Conclusion] The practice of combining wide precision sowing and irrigation in jointing and flowering stages, based on yield, water use efficiency and economic profits, has the potential to create more yields and higher water use efficiency and suitable to be applied and promtoed in North China.

肉苁蓉种子离散元仿真参数标定

为寻求肉苁蓉种子离散元模型的物料特性参数,采用物理和仿真试验相结合的方法,以不同物性参数组合下肉苁蓉种子休止角为响应值,采用Plackett-Burman试验对参数进行筛选,获取显著性参数,即肉苁蓉种间静摩擦因数、肉苁蓉种间动摩擦因数、肉苁蓉种子-钢板静摩擦因数、肉苁蓉种子-钢板恢复系数。通过Box-Behnken试验建立休止角与显著性参数回归模型并优化,获取接触参数最优值,即肉苁蓉种间静摩擦因数为0.65、肉苁蓉种间动摩擦因数为0.07、肉苁蓉种子-钢板恢复因数为0.54、肉苁蓉种子-钢板静摩擦因数为0.43。通过仿真与物理试验对比验证,得到二者相对误差为2.05%,表明标定参数可为肉苁蓉种子播种机械仿真提供数据依据。

Application Effects of Ultra-fine Powder Shaped Maize Seed Coating Agent in Spring Sowing areas in northeast China

The research explored adaptability maize seed coating agent in spring sowing and effects of ultra-fine powder shaped areas in northeast China. The results showed that germination potential and rate both improved around 5% and the num- ber of root increased by 4% in the treatments with ultra-fine powder shaped maize seed coating agent compared with the control group without seed coating. What＇s more, the treatments with ultra-fine powder shaped maize seed coating agent took advantages in terms of fresh weight of seeding, stem diameter, and dry weight. It is notable that control effects on underground insects performed the best, with per- centage over 94%, which is more excellent relative to other agents in markets. Therefore, ultra-fine powder shaped maize seed coating agent can be widely applied in spring sowing areas in northeast China, without side effects.

Effects of Different Sowing Dates and Sites on Grain Quality and RVA Profile of Nanjing 46,a Popular Cultivar of Japonica Rice(Oryza sativa L.)

[Objective] This study was performed to determine the effects of sowing dates and sites on grain quality and Rapid Viscosity Analyzer （RVA） profile of Nan-jing 46. [Method] The field experiments were carried out at five sites in Jiangsu Province, and in every site, the seeds were sowing on seven different dates. RVA related indices were measured after harvest. [Result] Along with the delay of sowing date, the mil ing quality of Nanjing 46 increased at first and then reduced, while its appearance quality went up and the cooling and edible quality decreased. With the sowing sites moving southward, the rice mil ing quality, appearance quality, and cooling and edible quality of Nanjing 46 decreased at first and then increased. Grain traits responded variably to the sowing dates and sites. The brown rice rate, grain width, grain length, length/width, mil ed rice rate and head mil ed rice rate were less affected, while the chalky rice rate and chalkiness degree were more af-fected. The gelatinization temperature, protein content, amylose content, gel consis-tency and eating value were in-between. The RVA profile analysis revealed that the breakdown value, setback value and pasting temperature were affected by the sow-ing date and geographical environment. The peak viscosity, hot viscosity, cool vis-cosity and peak time were influenced more by geographical environment. With the delay of the sowing date, peak viscosity, hot viscosity, cool viscosity, setback value and pasting temperature decreased at first and then increased, while the breakdown value changed inversely, and the peak time did not exhibit a regular trend. With the decrease of latitude, the peak viscosity, hot viscosity, breakdown and cool viscosity declined at first and then increased, the setback value and peak time decreased, while the pasting temperature increased. [Conclusion] This study wil provide refer-ences for the effective production of Nanjing 46.

安徽省10-12月积温时空变化特征及冬小麦适宜播期分析

为确定安徽省冬小麦适宜播期,利用1971-2021年安徽省分布于淮北、江淮及沿江麦区的50个气象站点观测数据,分析了10-12月积温时空变化特征,并基于叶龄积温法分析了前30 a(1971-2000年)与后21 a(2001-2021年)各地冬小麦冬前生长至不同叶龄对应的播期。结果表明,1971-2021年,安徽省及其各麦区10-12月每月积温及总积温均呈显著或极显著线性增加趋势,安徽省10-12月每月积温及总积温上升速率分别为8.6、9.6、7.8和26.1℃·(10 a)^(-1),安徽省及其各麦区10-12月每月积温上升速率呈现出11月>10月>12月规律;沿江麦区12月积温上升速率[6.5℃·(10 a)^(-1)]明显低于淮北[8.4℃·(10 a)^(-1)]及江淮[8.3℃·(10 a)^(-1)]麦区;淮北和江淮麦区10-12月总积温上升速率均为26.6℃·(10 a)^(-1),沿江麦区略低[24.9℃·(10 a)^(-1)]。安徽冬小麦冬前生长至相同叶龄时,后21 a播期比前30 a总体推迟1~4 d。淮北、江淮和沿江麦区后21 a适宜播期比前30 a分别平均推迟2.61、2.86和2.07 d。后21 a淮北麦区半冬性、弱冬性品种适宜播期分别为10月16-21日、10月12-16日,江淮麦区春性、半冬性品种适宜播期分别为10月25-30日、10月21-25日,沿江麦区春性品种适宜播期为10月30日-11月4日。

涂料树脂的SOW乳化体系

叙述了SOW(表面活性剂/油/水)体系和用这一体系来乳化的几种方法,以及选用近PIT乳化方法的理由。

Effects of Sowing Rate on Marginal Superiority and Yield of Wheat in Wheat-cotton Intercropping System

In the wheat-cotton intercropping system, total 6 sowing rates （187.5, 225.0, 262.5, 300.0, 337.5 and 375.0 kg/hm2） were arranged, and the effects of sowing rate on marginal superiority and yield of wheat were investigated. The re- sults showed that the effect of sowing rate on inner-line wheat was greater than that on side-line wheat; with the increased sowing rate, the marginal superiority of panicle number was reduced in overall, and the difference in panicle number be- tween inner and side lines was decreased from 9.0×10^5/hm2 （sowing rate of 187.5 kg/hm2） to 7.8×10^5/hm2 （sowing rate of 375.0 kg/hm2）; the marginal superiority of grains per spike was increased first and then reduced, and the largest difference in grains per spike between the inner and side lines reached 4.6 under the sowing rate of 300.0 kg/hm2; the marginal superiority of 1 000-grain weight and yield was gradually increased, and the largest difference in 1 000-grain weight between the inner and side lines reached 3.9 g under the sowing rate of 337.5 kg/hm2, and in yield reached 3 136.5 kg/hm2under the sowing rate of 375.0 kg/hm2. The effects of sowing rate on the three yield factors of intercropped wheat ranked as panicle number 〉 grains per spike 〉 1 000-grain weight. The appropriate sowing rate of wheat was 225.0-262.0 kg/hm2 in the wheat-cotton intercropping system.

High-yield Characteristics of Summer Sowing Soybean Varieties

[Objective] This study aimed to investigate the characteristics of high-yield soybean varieties.[Method] The agronomic traits of six high-yield soybean varieties and other 57 summer sowing ones were investigated from 2007 to 2010.[Result] The higher-yield summer sowing soybean varieties should have higher plants （R=0.551 6＊）,more effective pods （R=0.739 7＊）,more seeds per pod （R=0.318 9）,more flowers per plant （＞130）,higher pod setting rate （＞52％）,smaller ratio of aborted pods （＜40％）,longer tap roots （more than 20 cm） and lateral roots （more than 15 cm）,shorter bottom nodes （the length of six bottom nodes should be less than 25 cm）,lower center of gravity of the plant （＜40 cm）,greater stem dry weight,higher dry matter transformation rate and continuously increasing seed weight in late seed filling stage.The ideal growth stage model for summer sowing soybean was that the durations between adjacent stages of sowing,seedling emergence,flowering,seed setting and maturity stage were 5,29-33,29-33,32-36 d,respectively.[Conclusion] This pattern could not only satisfy the ecological conditions for double cropping system,but also balance the full development of vegetative and reproductive growth,promote the yield formation of summer sowing soybean.

The Development and Application of 2BDQ-8 Rice Direct Sowing Machine

[Objective] The aim was to introduce the development and application of 2BDQ-8 rice direct sowing machine and provide a theoretical basis for rice mechanization production. [Method] 2BDQ-8 rice direct sowing machine was used for the promotion test in field of several cities and counties in Jiangsu Province,and artificial rice planting and mechanization rice planting were compared to explore the production and economic situation. [Result] 2BDQ-8 rice direct sowing machine had advantages such as high efficiency and low cost,the rice direct sowing machine saved about 30% compared to the artificial rice planting and mechanization rice planting,and the overall efficiency was significant. [Conclusion] 2BDQ-8 rice sowing machine was a production technology that had low cost and high efficiency,which should be widely applied.