Abstract
In the present paper it was made clear that the occurrences of the panicles with twin or triplet rachis-branches born on their neck-node are due to the cohesion of 1st and 2 nd or 1st, 2 nd and 3 rd bract, and they occur most frequently under sunny and well-fertilized conditions at the differentiation stage of 1st bract primordium, and the length of inter-node of primary rachis-branches (especially the length of lower 5 inter-nodes) becomes short under favorable (sunny and well-fert-ilized) conditions and becomes long under unfavorable conditions at the differentiation stage of 1st bract primordium, while it becomes long under favorable conditions and becomes short under unfavorable conditions at the reduction division stage of pollen mother cell. These characteristics on adult panicles were considered to be of good use to diagnose the nutritive or environmental conditions of rice plants in the period from the differentiation stage of 1st bract primordium to the end stage of reduction division of P. M. C.
