Special focus: Nutrient management improves yield, quality and nutrient use efficiency of crops: theory and application

Nitrogen (N) and phosphorus (P) are essential for the normal growth and development of plants. To obtain high yields, excessive N and P fertilizers were applied in the agricultural production system, leading to ecological deterioration of the environment. With increased demand a for higher crop quality in addition to increased yield,  understanding the mechanisms of N and P balance in plants, as well as that of other mineral nutrient elements, to improve nutrient use efficiency (NUE) in the agricultural system is vital. This special focus issue: Nutrient management improves yield, quality and nutrient use efficiency of crops: theory and application, reports the recent progresses in this area. It showcases the responses and improvement of tolerance to nutrient-deficiency stresses in wheat, maize, rice, rapeseed, and millet. The topics include not only molecular technologies but also cultivation methods for improving NUE. These papers enhance our understanding of crop responses to nutrient-deficiency stresses and benefit crop breeding and production for better nutrient management.

• Brassinosteroids modulate nitrogen physiological response and promote nitrogen uptake in maize (Zea mays L.)
  Jiapeng Xing, Yubin Wang, Qingqing Yao et al.
• TaNRT2.1-6B is a dual-affinity nitrate transporter contributing to nitrogen uptake in bread wheat under both nitrogen deficiency and sufficiency
  Mengjiao Li, Tian Wang, Hui Zhang et al.
• Rice transcription factors OsLBD37/38/39regulate nitrate uptake by repressing 1/2.2/2.3 under high-nitrogen conditions
  XinxinZhu, Dujun Wang, Lijuan Xie et al.
• OsNPF5.16, a nitrate transporter gene with natural variation, is essential for rice growth and yield
  Jie Wang, RenjingWan, Haipeng Nie et al.
• Increased nitrogen use efficiency via amino acid remobilization from source to sink organs in Brassica napus
  Guihong Liang, Yingpeng Hua, Haifei Chenet al.
• TaMADS2-3D, a MADS transcription factor gene, regulates phosphate starvation responses in plants
  Yingchun Han, Na Liu, Chuang Li et al.
• The boron transporter SiBOR1 functions in cell wall integrity, cellular homeostasis, and panicle development in foxtail millet
  Hailong Wang, Sha Tang, Hui Zhi et al.
• Single-cell RNA sequencing reveals the landscape of maize root tips and assists in identification of cell type-specific nitrate-response genes
  Xuhui Li, Xiangbo Zhang, Shuai Gao et al.
• Genome-wide association study and transcriptome analysis reveal new QTL and candidate genes for nitrogen-deficiency tolerance in rice
  Qing Li, Xueli Lu, Changjian Wang et al.
• Integrated linkage mapping and genome-wide association study to dissect the genetic basis of zinc deficiency tolerance in maize at seedling stage
  Jianqin Xu, Zhongfu Ni, Fanjun Chen et al.
• Imbalance between nitrogen and potassium fertilization influences potassium deficiency symptoms in winter oilseed rape (Brassica napus L.) leaves
  Jing Li, Wenshi Hu, Zhifeng Lu et al.
• Delaying application time of slow-release fertilizer increases soil rhizosphere nitrogen content, root activity, and grain yield of spring maize
  GuanghaoLi, Pengxiao Fu, Guigen Cheng et al.
• Low N apparent surplus with higher rice yield under long-term fertilizer postponing in the rice–wheat cropping system
  Yan Zhou, Lei Xu, Jianwei Zhang  et al.
• Effects of increasing panicle-stage N on yield and N use efficiency of indicarice and its relationship with soil fertility
  Chang Ye, Hengyu Ma, Xiu Huang et al.
• Foliar applications of various nitrogen (N) forms to winter wheat affect grain protein accumulation and quality via N metabolism and remobilization
  Xiaokang Lyu, Yang Liu, Na Li et al.
• Contrasting patterns of accumulation, partitioning, and remobilization of biomass and phosphorus in a maize cultivar
  Weina Zhang, Haigang Li, Junling Zhang et al.
• Agronomic and physiological traits associated with genetic improvement of phosphorus use efficiency of wheat grown in a purple lithomorphic soil
  HongkunYang, Renhua Chen, Yufeng Chen et al.
• Effects of water deficit and high N fertilization on wheat storage protein synthesis, gluten secondary structure, and bread-making quality
  Junxian Liu, Junwei Zhang, Gengrui Zhu et al.