Seed Physiology: Part I - Seed Formation and Germination

Abstract

The seed is a mature ovule that plays a pivotal role in plant propagation. Within the seed resides a miniature plant (embryonic axis - cotyledon), with the potential to develop into an adult plant under favorable conditions. Germination, for viable and non-dormant seeds, commences with seed imbibition, i.e., the rehydration process. The germination process entails an ordered sequence of metabolic activities, culminating in the resumption of embryo growth and development. The initial phase involves the reactivation of processes attenuated during the late stages of maturation, accompanied by an increased respiratory activity in the seed embryo. Imbibition ensures tissue hydration, activation, synthesis, and enzymatic action. Phytohormones such as gibberellins, auxins, and cytokinins play fundamental roles in promoting cellular division, elongation, and differentiation within the embryonic axis. Additionally, the supply of oxygen is essential for the oxidation of reserves stored in seeds, generating ATP, heat, and intermediary products necessary for the maintenance and continuity of the germination process. Throughout this process of embryonic growth and development leading to plant formation, the continuous availability of water is absolutely indispensable. This article aims to provide a comprehensive overview of the processes involved in seed formation and germination, emphasizing the significance of imbibition, enzymatic activity, and phytohormones in this context, while highlighting the critical requirements of oxygen and water for the success of this fundamental aspect in plant life.