Achieving high maize yields and efficient phosphorus (P) use with limited environmental impacts is one of the greatest challenges in sustainable maize production.  Increasing plant density is considered an effective approach for achieving high maize yields.  However, the low mobility of P in soils and the scarcity of natural P resources have hindered the development of methods that can simultaneously optimize P use and mitigate the P-related environmental footprint at high plant densities.  In this study, meta-analysis and substance flow analysis were conducted to evaluate the effects of different types of mineral P fertilizer on maize yield at varying plant densities and assess the flow of P from rock phosphate mining to P fertilizer use for maize production in China.  A significantly higher yield was obtained at higher plant densities than at lower plant densities.  The application of single super-phosphate, triple super-phosphate, and calcium magnesium phosphate at high plant densities resulted in higher yields and a smaller environmental footprint than the application of diammonium phosphate and monoammonium phosphate.  Our scenario analyses suggest that combining the optimal P type and application rate with a high plant density could increase maize yield by 22%.  Further, the P resource use efficiency throughout the P supply chain increased by 39%, whereas the P-related environmental footprint decreased by 33%.  Thus, simultaneously optimizing the P type and application rate at high plant densities achieved multiple objectives during maize production, indicating that combining P management with cropping techniques is a practical approach to sustainable maize production.  These findings offer strategic, synergistic options for achieving sustainable agricultural development.

Sex determination in plants gives rise to unisexual flowers.  A better understanding of the regulatory mechanism underlying the production of unisexual flowers will help to clarify the process of sex determination in plants and allow researchers and farmers to harness heterosis.  Androecious cucumber (Cucumis sativus L.) plants can be used as the male parent when planted alongside a gynoecious line to produce heterozygous seeds, thus reducing the cost of seed production.  The isolation and characterization of additional androecious genotypes in varied backgrounds will increase the pool of available germplasm for breeding.  Here, we discovered an androecious mutant in a previously generated ethyl methanesulfonate (EMS)-mutagenized library of the cucumber inbred line ‘406’.  Genetic analysis, whole-genome resequencing, and molecular marker-assisted verification demonstrated that a nonsynonymous mutation in the ethylene biosynthetic gene 1-AMINOCYCLOPROPANE-1-CARBOXYLATE SYNTHASE 11 (ACS11) conferred androecy.  The mutation caused an amino acid change from serine (Ser) to phenylalanine (Phe) at position 301 (S301F).  In vitro enzyme activity assays revealed that this S301F mutation leads to a complete loss of enzymatic activity.  This study provides a new germplasm for use in cucumber breeding as the androecious male parent, and it offers new insights into the catalytic mechanism of ACS enzymes.