This book highlights the multifunctional role of the ubiquitous molecule, melatonin, in crop plants. The major focus of this edition is to provide detailed insights into morphophysiological, biochemical, and molecular responses of melatonin in the growth and development of the plant. The inception of melatonin as an animal hormone and the subsequent discovery of its multifaceted function in the animal system has triggered the research on this pineal gland hormone. During the last decade, the discovery, quantification and functional studies of melatonin as phytohormone has emerged at a rapid pace. Recently, this phyto-protectant has become an integral component of lab and field-based research on the mitigation of adverse effects of climate-driven abiotic stresses and postharvest biology and technology. The book explores various biosynthetic pathways and detection of melatonin covering its role in flowering, fruit development, photosynthesis, respiration, hormonal crosstalk, post-harvest biology and reactive oxygen species and nitrogen cycles. This book is of high interest to postharvest industries, horticulturists, scientists, researchers, and students.