Abstract
Tillering of the 2nd to 11th main stem nodes in potted directed-seeded rice plants was artificially controlled by the removal of tillers on specific nodes. Treatments consisted of limiting tillering on one main stem node only, on two or four consecutive main stem nodes at lower (L), middle (M) or upper (U) positions with the same 20 panicles and the constituents of each order tiller per plant. Under these conditions, grain productivity of each order tiller at different nodal positions on the main stem was investigated accurately. 1) Main stem flag leaf number, leaf emergence rate and panicle weight etc. increased as the number of tillering nodes decreased and tillers shifted higher on the main stem. 2) In the plots of the same number of tillering node (s), the mean panicle weight of the primary tiller was greater in the order U > M > L, and those of secondary and tertiary (quaternary) tillers were greater in the order M > U > L and M > L > U for one or two tillering node (s) plots, respectively, and U = M > L and M = U > L for four tillering nodes plot, respectively. Consequently, the mean panicle weight of whole tillers was greater in order M > L > U, M > U > L and U > M > L for one, two or four tillering node (s) plots, respectively. These results showed that lower nodal tillers on the main stem, which emerged earlier and having more number of leaves, do not necessarily produce a higher grain yield than middle or upper nodal ones. 3) The panicle weight of each nodal primary tiller was closely correlated with number of spikelets and it showed highly significant positive correlation with the leaf blade elongation rate from the leaf sheath (cm/day), which might directly mean the physiological activity of the tiller stem.
