Factors affecting haploid production in wheat using the Hordeum bulbosum system. 2. The effect of the timing of pollination

Summary The effect of manipulating the timing of pollination on the fertilization frequency in wheat × tetraploid Hordeum bulbosum hybridizations was investigated as a possible means of overcoming varietal incompatibility in this cross. Pre- and post-anthesis pollinations were made on previously identified highly crossable and poorly crossable wheat genotypes and the stage of development of the individual florets at pollination was expressed in days from anthesis units.In both crossable and non-crossable wheat genotypes, a significant negative linear relationship was observed between floret age and fertilization frequency. The magnitude of the response of early pollination was dependent on the number of alleles for non-crossability present at the Kr loci. The non-crossable cultivar Highbury, possessing more than one allele for incompatibility, showed a slight response. The greatest response was shown by the highly crossable cultivar Chinese Spring, possessing alleles for crossability at all Kr loci. The single chromosome substitution line, Chinese Spring (Hope 5B), possessing the most potent allele for non-crossability, Kr ₁, showed an intermediate response. The H. bulbosum genotype had no effect on the magnitude of this response, influencing only the mean fertilization frequency.     

中耕深松对不同作物生长发育影响的试验

深松可以打破犁底层,加深耕作层,增加伏雨入渗,达到土壤蓄水保墒的目的,从而改变作物的产量.在辽宁省阜新县马蹄营子村的863项目试验田中,使用1HS-1.2中耕深松机对玉米与谷子等主要作物进行中耕深松试验.其结果表明:中耕深松对不同作物的主要生长发育指标影响程度不同.     

中耕深松的作用及机具发展现状

论述中耕深松对土壤蓄水及作物根系生长、产量影响的研究进展,介绍深松机的分类及型号表示方法,总结国内外深松机具的发展历程及现状,为我国深松机具的研制推广提供有益的参考。     

Effect of no‐tillage vs. conventional tillage on soil organic matter and nitrogen contents

Abstract

Four treatments (no‐tillage plus subsoiling, no‐tillage, conventional tillage plus subsoiling, and conventional tillage) were continuously in place for 6 yr and a second set of no‐tillage plus subsoiling and conventional plus subsoiling treatments were continuously in place for 3 yr to study the long‐term effects of conventional and no‐tillage corn on soil organic matter (OM) and N contents. Soil samples were taken at random between the rows and in the rows to a depth of 60 cm, in 5‐cm increments to a depth of 30 cm, and then in 15‐cm increments from the 30 to 60‐cm depth for OM and N determination. No‐tillage resulted in A3 and 20% more Kjeldahl N than conventional tillage in the 0 to 5‐cm soil depth after 6 and 3 yr, respectively. after 6 yr, the 0 to 5‐cm depth had 36% more OM in no‐tillage treatments than in conventional tillage treatments, and soil from no‐tillage treatments averaged 27% more OM than the conventional tillage plus subsoiling treatment at the 0 to 15‐cm soil depth.     

保护性耕作条件下深松技术的国内外发展现状

近年来,土地过度开垦致使土地沙漠化、干旱等自然灾害问题越来越严重,因此提出了基于保护性耕作的深松技术。以深松技术代替铧式犁翻耕,是利用深松机具的部件在土壤不被翻转条件下疏松土壤、打破坚硬犁底层、加深耕作土层,以此来调节土壤3相(固、液、气态)比,改善土壤内部结构,降低土壤被侵蚀度,提高土壤蓄水保墒的能力,达到高产、少耕、环保的目的,促进农业的可持续发展。为此,主要介绍了基于保护性耕作深松技术在国内外发展现状,旨在为保护性耕作和深松机械的制造和发展提供一定的依据。     

摩托车可变配气正时发动机的循环仿真与分析

针对国内中小排量摩托车发动机的结构特点,研制了切换凸轮型线VVT系统,探讨了基于循环模拟进行VVT系统与发动机热力循环过程合理匹配的途径。建立了嵌入可切换双进气正时VVT系统的发动机循环仿真模型,通过实验测试对仿真模型进行了验证;分析了VVT控制策略和运行模式,对VVT机构配气正时参数进行了优化。实验表明:通过加装这种切换凸轮型线VVT系统能够有效提高JL156FMI型摩托车发动机的动力性和燃油经济性。     

Tillage effects on soil aggregation,organic carbon fractions and grain yield in Eum‐Orthic Anthrosol of a winter wheat–maize double‐cropping system,Northwest China

Conservation tillage has been applied in vast semi‐arid regions of the Guanzhong Plain, Northwest China. The tillage effects on soil aggregation, organic carbon (OC) stabilization and grain yield on this plain have not been fully elucidated. A 9‐year field experiment was established from 2002 on a silty clay loam soil (Eum‐Orthic Anthrosol) growing winter wheat–maize in a double‐cropping system. Six conservation tillage treatments were applied by different combinations of rotary tillage (RT), subsoiling (SS) and no‐till (NT), with or without finely chopped straw retention. Conventional tillage (CT) acted as the control. Results showed that in the surface (0–10 cm) soil, the proportion of water‐stable aggregates (WSA) <0.05 mm was 18% less while that for WSA >2 mm was 98% more under NT treatments compared with CT. Additionally, the oxidizable OC content in WSA 0.25–2 mm was 27% greater under NT treatments compared with CT. The OC stocks increased under SS by 17%, RT by 16% and NT by 15% relative to CT. Grain yield (wheat + maize) showed similar increasing trends in all the tillage treatments compared with CT. Both OC stocks and grain yield were larger in treatments with than without straw retentions. These results indicate that NT is beneficial for OC accumulation in WSA but is limited in its ability to improve soil structure in this region. SS plus straw retention (fine‐chopped or as a mulch) is an effective practice to improve soil structural stability, OC accumulation and soil productivity of Eum‐Orthic Anthrosols in Northwest China.     

深松和秸秆还田对灌耕灰钙土团聚体特征的影响

2015—2017年设置传统旋耕秸秆不还田(RT)、深松35 cm秸秆不还田(ST)及深松35 cm秸秆还田(STS)3个处理,应用干筛法和湿筛法对0～40 cm土层团聚体数量、组成和稳定性进行研究。结果表明,STS能促进土壤大团聚体的形成并促进团聚体的稳定,深松和秸秆还田均可显著影响团聚体数量和大小(P<0.05)、促进不同粒级团聚体更新转化。干筛法下,0～40 cm土层,STS处理最佳,>0.25 mm机械稳定性团聚体含量(DR_0.25)、平均质量直径(MWD)、平均几何直径(GMD)较RT分别增加3.0%、9.5%和15.5%,分形维数(D)降低4.5%。湿筛法下,STS处理的WR_0.25(>0.25 mm水稳性团聚体含量)、MWD、GMD较RT分别增加45.2%、12.0%和9.1%,D值降低1.1%。干筛法和湿筛法下,不同土层均以0～10 cm土层R_0.25(直径>0.25 mm团聚体含量)、MWD、GMD值STS较RT的增幅最大,干筛法下,分别增加8.6%、18.0%、25.3%,湿筛...     

辽西干旱半干旱区免耕行间深松培土对土壤水分及玉米产量的影响

为了探究免耕行间深松培土(集成模式)对辽西干旱半干旱区土壤水分、水分利用效率及玉米产量的影响,依托辽宁省北票市蒙古营乡沈阳农业大学定点试验田,通过监测土壤水分和玉米产量,探讨不同耕作方式(旋耕CK、深松、翻耕、免耕秸秆覆盖、集成模式)对干旱半干旱区春玉米地土壤水分、产量、水分利用效率以及经济效益的影响.结果表明:(1)...