Age of seedling at transplanting has a direct bearing on the yield of the crop. In general, seedling having 3-4 leaves is considered ideal for transplanting.

The optimum age, however, depends upon the duration of variety, season, date of planting, system of raising nursery, tillering habit, inherent fertility and fertilizer management and cultural practices.

(i)  Age of seedling for timely planting : Pillai (1958) has summarized the results obtained at various research stations on the effects of the age of seedlings on yield of tall indica rice. Seedlings of 3-4 week old in case of short duration varieties and of 5 to 6 weeks old in case of varieties of 5-6 months duration may be considered as the optimum age for transplanting. Aged seedlings of 7-11 weeks old can, however, be used without detriment to yield in the case of long duration varieties, provided the planting is done within the optimum period. In case of short duration varieties it is absolutely essential to use seedlings of optimum age of 3-4 weeks only, irrespective of the time of planting, as the short duration rice are mostly period bound.

Due to aberrant weather conditions and/ or intensive cropping system transplanting of rice is often taken up late even beyond the critical period.

(ii)  Age of seedling for late planting: Under such situation economically viable yield may not be possible without adoption of some special measures to compensate the loss due to delay in planting. Pillai (1958) concluded that for late planting of tall indica rice aged seedlings are better than younger seedlings .Medium and long duration dwarf indica rice also behave in the same way.

 (iii) Age of seedling for rabi season : During rabi season seedlings require more time to come to plant able size because of low temperature. Therefore, the optimum age of seedling for planting is comparative more than that for kharif rice. Thirty to 45 days old seedling for (Table 16.8) are found to perform better than either young or old seedling (Kumar et al. 1995; Singh et al. 1996; 1999; Shekinah et al. 1999).