As important yield-related traits, thousand-grain weight (TGW), grain number per spike (GNS) and grain weight per spike (GWS) are crucial components of wheat production.  To dissect their underlying genetic basis, a double haploid (DH) population comprised of 198 lines derived from 8762/Keyi 5214 was constructed.  We then used genechip to genotype the DH population and integrated the yield-related traits TGW, GNS and GWS for QTL mapping.  Finally, we obtained a total of 18 942 polymorphic SNP markers and identified 41 crucial QTLs for these traits.  Three stable QTLs for TGW were identified on chromosomes 2D (QTgw-2D.3 and QTgw-2D.4) and 6A (QTgw-6A.1), with additive alleles all from the parent 8762, explaining 4.81–18.67% of the phenotypic variations.  Five stable QTLs for GNS on chromosomes 3D, 5B, 5D and 6A were identified.  QGns-5D.1 was from parent 8762, while the other four QTLs were from parent Keyi 5214, explaining 5.89–7.08% of the GNS phenotypic variations.  In addition, a stable GWS genetic locus QGws-4A.3 was detected from the parent 8762, which explained 6.08–6.14% of the phenotypic variations.  To utilize the identified QTLs, we developed STARP markers for four important QTLs, Tgw2D.3-2, Tgw2D.4-1, Tgw6A.1 and Gns3D.1.  Our results provide important basic resources and references for the identification and cloning of genes related to TGW, GNS and GWS in wheat.

Inappropriate tillage practices and nitrogen (N) management have become seriously limitations for maize (Zea mays L.) yield and N use efficiency (NUE) in the North China Plain (NCP).  In the current study, we examined the effects of strip deep rotary tillage (ST) combined with controlled-release (CR) urea on maize yield and NUE, and determined the physiological factors involved in yield formation and N accumulation during a 2-year field experiment.  Compared with conventional rotary tillage (RT) and no-tillage (NT), ST increased the soil water content and soil mineral N content (N_min) in the 20–40 cm soil layer due to reduction by 10.5 and 13.7% in the soil bulk density in the 0–40 cm soil layer, respectively.  Compared with the values obtained by common urea (CU) fertilization, CR increased the N_min in the 0–40 cm soil layers by 12.4 and 10.3% at the silking and maturity stages, respectively.  As a result, root length and total N accumulation were enhanced under ST and CR urea, which promoted greater leaf area and dry matter (particularly at post-silking), eventually increasing the 1 000-kernel weight of maize.  Thus, ST increased the maize yield by 8.3 and 11.0% compared with RT and NT, respectively, whereas CR urea increased maize yield by 8.9% above the values obtained under CU.  Because of greater grain yield and N accumulation, ST combined with CR urea improved the NUE substantially.  These results show that ST coupled with CR urea is an effective practice to further increase maize yield and NUE by improving soil properties and N supply, so it should be considered for sustainable maize production in the NCP (and other similar areas worldwide).