1992 Volume 61 Issue 4 Pages 590-596
To clarify the influence of the composition of stems on valuable fruits production of a plant of Trapa bispinosa Roxb. cultivated in paddy fields, the distribution and the number of flower buds, the first flowering time and the number of valuable fruits on each stem were investigated. Their changes by planting density and the timing of shading were also examined. A significant distributing pattern of flowers was observed in every stem where 1 to 2 nodes having flower buds (flower nodes : FN) and 4 to 10 nodes not having flower bud (non-flower nodes : NFN) succeeded alternately. In this pattern, the number of NFN per NFNG (non-flower node group) showed a tendency to decrease at higher parts of a stem. Therefore, the condition for fruit ripening conditions at lower FN, in which the flowers bloom at the early flowering stage, was assumed to be better than that at upper FN. When the fruit productivity of each stem was compared, the lower the nodes along the mother stem from which the stem emerged, the larger the number of valuable fruits produced on the stem, and the higher the productivity. Among these stems, the number of fruits which had started their ripening in the early flowering stage was considered to be larger. Moreover, as a result of low planting density (below 7.1/m2) and early shading in June, the first FN on every stem became higher. Therefore, the percentage of stems of lower branching order and from lower nodes would decrease in the plants. In consequence, it was clarified that the lowering of branching order and the increasing of the stems emerging at an early stage in the stem composition are important factors for the production of a large number of valuable fruits and for the increase in the yield of a plant.
