Speed-bred crops for food security and sustainable agriculture.

Overcoming the existing barriers of speed breeding and its integration with modern genetic technologies will be crucial for its widespread adoption in plant breeding programs. Safeguarding global food security calls for a steady stream of climate-smart crop varieties delivered in less time with fewer agricultural resources. In this context, speed breeding (SB) was introduced as a shortening practice in modern agriculture through innovative solutions that promote rapid growth and development in plants. Since then, SB application has led to significant increase in yield and climate-resilience traits of modern crop varieties. SB protocols optimized for long-day and day-neutral plants have witnessed great success, and research on optimizing SB for short-day plants (e.g., rice, soybean, pigeonpea) has also been encouraging. Most interestingly, SB offers ample scope for integration with modern breeding methods like genomic selection, haplotype-based breeding and genome editing, which further enhances its capacity to deliver new crop varieties with enhanced stress adaptation and yield potential. While significant progress has been made in uncovering genetic loci associated with SB-relevant traits such as flowering time and maturity, the broader genetic basis of photoperiod response remains understudied in food crops. Despite its transformative potential, SB faces several limitations such as high energy demands, risks of genetic bottlenecks, and difficulties in applications at field scale, thus underscoring the need for continuous improvements. Our review offers the most updated overview of SB applications in crops plants, the genetic mechanisms underlying photoperiod response. We also present prospects for combining SB with evolving technologies for rapid and better breeding outcomes. We advocate that while transformative, SB still faces a set of challenges that must be carefully addressed to realize its full potential for future food supply.