Tillering behavior in Oryza sativa L. V. Analysis of varietal differences in tillering patterns.

Abstract

In our previous papers, we reported methods of growth analysis in relation to the tillering behavior of a rice plant. Using these methods, we analyzed tillering patterns of 6 rice cultivars, Akihikari (AK), Aikawa 1 (A1), Khao Keo (KK), Dawn (DW), North Rose (NR), Palmyra (PL). These cultivars are produced a relatively small number of tillers per plant (it is therefore called types). Three factors were considered to be the major components in the analysis of rice plant tillering patterns : i.e. (1) the leaf emergence rate on the main stem, (2) emerged tiller percentage of each tillering position on a stem, and (3) the difference between the growth curve of the tiller number (from actual measurement) and the theoretical synchronous growth curve. We compared the tillering patterns of the cultivars used and tried to apply the above 3 factors to tillering behavior analysis. Factor (1) was directly confirmed by the comparison of tillering patterns between AK and A1, factor (2) was confirmed directly by the comparison of AK and DW, but factor (3) was not confirmed directly. But in the comparison of PL and KK or NR, factor (3) was recognized indirectly (i.e. the tiller number in actual measurement of PL, KK and NR were nearly equal, and also amounts of factor (1) of these 3 varieties were nearly equal, but values of factor (2) of PL was smaller than that of KK and NR. It was therefore concluded that factor (3) affected the tillering pattern). On the basis of these results, we discussed tillering behavior of small-tillering type rice cultivars, and considered how to mathematically express factor (3).