The relationship between the number of primary roots and yield components in rice plant grown on farmers' paddy fields. III. Variations among paddy fields.

Abstract

The relationship between the number of primary roots and yield components of rice plants was investigated, regarding variations among 4 different farmers' paddy fields. Many characters of panicles and of primary roots showed variations among the paddy fields, whether they were examined on per-hill or on per-unit-area basis. These variations were mostly associated with the number of fertile culms. Increase in the number of elongated primary roots during shoot growth also showed a similar trend to that in the number of fertile culms. However, when the average values of the characters of panicle and the number of primary roots were compared on per-culm basis, another kind of variations was noticed among the paddy fields. It was presumed, therefore, that the amount of various characters per unit area were not only affected by the number of fertile culms. A relatively constant ratio was obtained between the number of elongated primary roots and the characters of panicles; i. e, one elongated primary root corresponds to about two spikelets or 40 mg of ripened rice kernels. Throughout the paddy fields examined, the average value of 15, 000 elongated primary roots corresponded to about 600 g of brown rice yield per square meter.