Strigolactones (SLs) are newly discovered plant hormones which regulate the normal development of different plant organs, especially root architecture.  Lateral root formation of rapeseed seedlings before winter has great effects on the plant growth and seed yield.  Here, we treated the seedlings of Zhongshuang 11 (ZS11), an elite conventional rapeseed cultivar, with different concentrations of GR24 (a synthetic analogue of strigolactones), and found that a low concentration (0.18 µmol L^–1) of GR24 could significantly increase the lateral root growth, shoot growth, and root/shoot ratio of seedlings.  RNA-Seq analysis of lateral roots at 12 h, 1 d, 4 d, and 7 d after GR24 treatment showed that 2 301, 4 626, 1 595, and 783 genes were significantly differentially expressed, respectively.  Function enrichment analysis revealed that the plant hormone transduction pathway, tryptophan metabolism, and the phenylpropanoid biosynthesis pathway were over-represented.  Moreover, transcription factors, including AP2/ERF, AUX/IAA, NAC, MYB, and WRKY, were up-regulated at 1 d after GR24 treatment.  Metabolomics profiling further demonstrated that the amounts of various metabolites, such as indole-3-acetic acid (IAA) and cis-zeatin were drastically altered.  In particular, the concentrations of endogenous IAA significantly decreased by 52.4 and 75.8% at 12 h and 1 d after GR24 treatment, respectively.  Our study indicated that low concentrations of exogenous SLs could promote the lateral root growth of rapeseed through interaction with other phytohormones, which provides useful clues for the effects of SLs on root architecture and crop productivity.

 

With an increasing population and changing diet structure, summer maize is increasingly becoming an important energy crop in China.  However, traditional farmer practices for maize production are inefficient and unsustainable.  To ensure food security and sustainable development of summer maize production in China, an improved, more sustainable farmer management system is needed.  Establishing this system requires a comprehensive understanding of the limitations of current farming practice and the ways it could be improved.  In our study, 235 plots from three villages in the North China Plain (NCP) were monitored.  Maize production on farms was evaluated; our results showed that the maize yield and nitrogen partial factor productivity (PFPN) were variable on smallholder farms at 6.6–13.7 t ha^–1 and 15.4–88.7 kg kg^–1, respectively.  Traditional farming practices also have a large environmental impact (nitrogen surplus: –64.2–323.78 kg ha^–1).  Key yield components were identified by agronomic diagnosis.  Grain yield depend heavily on grain numbers per hectare rather than on the 1 000-grain weight.  A set of improved management practices (IP) for maize production was designed by employing a boundary line (BL) approach and tested on farms.  Results showed that the IP could increase yield by 18.4% and PFPN by 31.1%, compared with traditional farmer practices (FP), and reduce the nitrogen (N) surplus by 57.9 kg ha^–1.  However, in terms of IP effect, there was a large heterogeneity among different smallholder farmers’ fields, meaning that, precise technologies were needed in different sites especially for N fertilizer management.  Our results are valuable for policymakers and smallholder farmers for meeting the objectives of green development in agricultural production.