These researchers found that rice yield was higher when single
seedlings per hill were transplanted, compared with three
seedlings per hill. While they did not examine any concomitant effects of water management, seedling age or
other management parameters seen from SRI experience to
have important impacts, the ceteris paribus effect of having
more or fewer plants per hill is worth considering.
The explanation proposed by San-oh and collaborators
was that single plants per hill have higher cytokinin concentrations
in their roots during the late reproductive stage,
compared to plants grown three per hill