**1. Introduction**

Currently, the generation, application, and dissemination of new techniques and technologies in the conservation of fruits and vegetables in post-harvest are of vital importance when considering that 20–50% of the agricultural production obtained is lost [1–4]. The losses of fruits and vegetables are different according to the economic development of the countries, in nations considered developed, from 5 to 35% is lost, and in developing countries from 20 to 50%. In these regions, it is considered that losses of fruits and vegetables occur mainly in the retail and consumption stages, while in countries considered poor or low-income, losses of fruits and vegetables are related to poor pre-harvest handling where low technological levels are applied, harvesting techniques that damage the fruits, poor transport from the orchard to the warehouse, packaging without technical design, and the lack and inadequate infrastructure for storage [1, 2, 5]. On the other hand, fruit and vegetable losses are generally classified into five stages: Stage 1: pre-harvest handling. Stage 2: packing process. Stage 3: post-harvest handling and storage. Stage 4: distribution from the warehouse to the

retail market. Stage 5: consumption [6]. Fruits in post-harvest and without being subjected to any industrial process are living organisms with their own metabolism and enzymatic action, with high percentages of water content and susceptibility to attack by microorganisms, factors that determine the perishability of the fruit, i.e., the shelf life under storage conditions that can last from a few days [6] to years. To prolong the shelf life of fruits, different technologies have been implemented: use of low and high temperatures, refrigeration and freezing, immersion in chemical additives [7], controlled and modified atmospheres, vacuum packaging, and edible coatings [8]. The purpose of post-harvest handling technologies is to preserve fruit quality and minimize losses caused by transport and handling in storage. The quality of harvested fruit is not increased, only preserved; quality attributes are obtained pre-harvest, so it is very important to apply optimal technological levels both pre-harvest and post-harvest [8]. The application of phytohormones, growth regulators, and various chemical calcium compounds in the pre- and post-harvest handling of the fruit constitutes some alternative technologies to increase and preserve fruit quality. In this chapter, pioneering work and recent research on the application of phytohormones, growth regulators, and calcium to pre- and post-harvest fruit will be described in general terms.
