In ordinary paddy cultivation the age of the nursery is 24 to 27 days . For example if you take short duration paddy varieties like ADT 43 or any other short duration varieties the total life span ie cultivation period including nursery is 110 to 115 days . When you split this time into various stage of crop growth like seedlings ( 25 days ) Growth and tillering phase phase ( 20 days ) Reproductive phase is 35 days and ripening phase is 30 days …Total 110 days …Growth and Tillering phase form vegetative phase which account for 20 days only in ordinary paddy cultivation method …
In SRI paddy planting method by reducing the nursery phase from 25 days to 8 to 12 days , the vegetative phase in which active tillering (side branching of more panicles ) is formed , the extra 13 days are added to the vegetative phase of 20 days thus increasing the duration to 33 days . Hence in the extended duration of tillering ( side branching ) period the total number of tillers are counted to average of 35 in place of average tillers of 20 in conventional planting method …This is the secret of higher yield in SRI method of paddy cultivation over conventional method.