Germination Management Of Pepper And Tomato Seed

A seed is a “living organism” and is sensitive to the environment that it is subjected to. During the germination and subsequent development of the seedling, it is just as important to control the surrounding environment.  In recent years the technology and scientific developments have enabled seedling nurseries to apply this to achieve better results for them and giving the producers stronger seedling, within the timeframes that is required in the well managed production schedules on farms. Many seedling nurseries do just that with heated germination rooms where seedling trays are stacked for a predetermined amount of time to allow germination to occur.  At emergence, the trays are usually transferred out into the nursery where the seedlings are allowed to develop.

Nurseries are these days developing their own programmes for germinating and growing seedlings with excellent results for their local environment, infrastructures and management systems.  It is however always important to remember and adapt some of the basic principles.

The management of the germinating seed is essential to ensure maximum germination and subsequent development of the plant.  Tomatoes require the following temperature conditions for germination:

Table 1: Seed Germination Temperature for Tomatoes (Benton Jones, 1999)

Not only does the temperature impact the actual germination process, but also the rate of seedling emergence:

 Table 2: Days to Seedling Emergence for Tomatoes (Benton Jones, 1999)

This information highlights the importance of temperature on the most important phases of the germination and emergence of tomato seed.  Peppers have a similar sensitivity to temperature and should also be managed accordingly.  During the cooler periods of the year, temperature fluctuations during germination and emergence of the seedlings will result in poor germination, uneven emergence, slow development of seedlings and sometimes a poor pull rate.  This common occurrence is often mistaken for poor quality seed, but the same seed lot will provide almost perfect germination, emergence and development when temperatures rise.

Sakata Seed Southern Africa (Pty) Ltd. provides with their tomato and pepper seed what is termed a range test.  The range test describes the effect of various temperatures on the germination of the particular lot.  Each seed lot responds differently to temperature regimes and therefore, each seed lot is tested accordingly.  The importance of these range tests is that it illustrates how that particular lot needs to be treated to achieve the best germination and emergence of the peppers and tomatoes.

During warmer periods of the year, the relatively higher temperature of the air outside the germination room prevents excessive heat loss from the room resulting in better control of the temperature within the germination room.  However, during cooler periods, the lower ambient temperature makes it more difficult to maintain a constant temperature within the germination room.

There are many methods, varying in expense, used for heating these germination rooms. Some nurseries do not heat; others use simple bar heaters or oil fin heaters or air conditioners. These methods are completely satisfactory if managed correctly.  The size of the room should determine the number of heaters or size of conditioner required to maintain the temperatures required for proper germination and emergence.  Strict control of the room temperature is not possible with a heater, unlike the air conditioners.  If the temperature is maintained within the correct range it should not pose a problem. Nurseries that do not provide any heating should not produce these more sensitive seedlings out of season.  It is recommended that germination rooms be installed to assist in the production of high quality seedlings to their clients.

There are other temperature relating factors that can influence the germination of tomato and pepper seed.

• The temperature of the growing medium in the trays (type of medium)
• The temperature of the water being used to irrigate the trays prior to moving them into the growing room
• The design of the seedling tray
• The number of trays in a stack and within a germination room
• The size of a stack of trays
• The shape of a stack of trays
• The size of the germination room
• The efficiency of the insulation material in the germination room
• The movement of air within the germination room

A good nursery will take note of at all these different factors and adapted where necessary.

When cold medium and cold water are used to fill and water the trays, it will take longer to warm up the medium to reach the optimal range for germination and emergence.  If a large number of trays are stacked together before being put into the germination room, it will take longer for the trays in the centre of the stack to heat up.  If a large number of trays or several stacks are placed into the germination room at the same time, more heat will be required to raise the temperatures of all the trays.

The size and shape of the stack of trays will affect the ability of the warm air to heat up the cells in the centre of the stack.  During the cooler season, smaller stacks should be used to allow for better heating of the trays.  Trays should be arranged into longer thinner stacks to allow for better heat penetration.  A larger germination room will obviously require more heat to raise the temperature to optimum levels, and when a large number of trays are installed into the room, even more heat is required.  Rooms that are not adequately insulated will also require more heat to maintain adequate temperatures, and should a sudden temperature drop be experienced, a large amount of heat may be lost from the room resulting in a reduction in germination and emergence.

The movement of air in a germination room is also extremely important.  Smaller germination rooms may only use a small heater resulting in a large difference in temperature from one side of the room to the other.  Allowing adequate air movement within the room will assist in reducing the temperature gradients that may be present. Adequate ventilation around each stack of trays will also reduce the amount of time taken to raise the temperature of the medium in the cells to optimum levels.

Correct management of the temperature within a germination room is advantageous to any nurseryman.  The result is better germination and emergence of seedlings, higher pull rates and better quality seedlings, all of which will result in better returns and financial stability. The relationship between seed companies, seedling nurseries and producers has become very critical these days, ensuring better results for everyone in the business chain.

DISCLAIMER:  This information is based on our observations and/or information from other sources. As crop performance depends on the interaction between the genetic potential of the seed, its physiological characteristics, and the environment, including management, we give no warranty express or implied, for the performance of crops relative to the information given nor do we accept any liability for any loss, direct or consequential, that may arise from whatsoever cause. Please read the Sakata Seed Southern Africa (Pty) Ltd Conditions of Sale before ordering seed.