The physiological degeneration of potato seed tubers and its control

Abstract

1. After starting independent life, the potato tuber exhibits its own growth characteristics according to each stage in the life cycle. The term “proper age” denotes the stage at which the seed tuber performs the highest function. When the seed tuber is planted before or after the proper age degeneration is proportionate to the time interval. This is known as physiological degeneration. 2. Degeneration that occurs before the proper age is reached, is termed juvenile degeneration and senile degeneration that occurring after the proper age (Figs. 2 and 3). 3. The age is calculated in months. Taking into consideration varieties, cultural practices, type of crop season, etc. (Table 1), the proper age is considered to be 4–6 months. 4. In most areas the time of year selected for potato growing often proves unfavourable for the use of seed tubers at the proper age (Fig. 1 andTable 2). This is because physiological degeneration is extremely widely distributed and the loss is also large, and special measures have to be taken to obtain seed tubers of the proper age. 5. In order to control physiological degeneration it is advisable to grow seed tubers that can be lifted 4–6 months before planting, or the seed tubers should be obtained from areas in which seed is grown during the appropriate crop season (Fig. 4).