Breeding of blocky type pepper varieties adapted for production in greenhouses and net houses in mild winter regions

The production areas of pepper in greenhouses and net houses in regions with mild winter conditions are expanding very rapidly. A typical crop in simple plasticcovered greenhouse structures is planted at the end of the summer and ripe fruits are harvested during the fall, winter and spring seasons. Environmental conditions inside such structures are more extreme than those prevailing in either outdoor production in regular crop season or in climate-controlled greenhouses. During the beginning and the end of the production season, plants in simple structures are exposed to extremely high day temperatures, up to 45°C. In the middle of the season, during the winter, minimum night temperatures are in the range of 4-10°C. Varieties suitable for such conditions should be bred for adaptation to such harsh conditions. The first limiting factor in pepper production is fruit set under low temperatures. The minimum night temperature known to allow fruit set of blocky pepper was 18°C. Selection genotypes from a wide range of genetic variation under low night temperatures, led to the development of varieties that can set normally shaped fruits even under night temperatures of 8-10°C. This in turn extended the period of fruit setting, leading to a longer production season and higher yields. A common phenomenon during the spring period is fruit cracking, a physiological disorder associated with large differences between minimum and maximum night temperatures. Repeated selections against this disorder, both in the Arava (southern Israel) and Almeria (southern Spain) were successful. Varieties such as Cannon and Melchor, which possess both good fruit set under low temperatures and resistance to fruit cracking, are grown successfully in many semi-arid zones with mild winters. It can be concluded that in the case of simple structures, appropriate genetic advancement through breeding can be combined with suitable technological means to provide farmers with sustainable production systems.