Mechanism on the Development of Deformed Spikelets in Oryza sativa L. : IV. The relationships between form and structure in both the compound 2-flowered and the double-ovaried spikelets

[摘要] In the present report, firstly the vascular courses were investigated in both materials, the compound 2-flowered spikelet with one ovary and the double-ovaried spikelet. The one is caused by gibberellin treatment in var. 'Vialone nano' and the another is the typical spikelet of the double-kerneled rice. Secondary the breadthes of the main vascular bundles were compared each to each among three kinds of spikelet in 'Vialone nano'; the compound 2-flowered spikelet with one ovary, another one with two ovaries and the normal spikelet, and also the breadthes of the main vascular bundles of the double-ovaried spikelet were compared with those of the normal spikelet of 'Vialone nano'. The results are as follows. As regards the vascular courses, the, compound 2-flowered spikelet with one ovary is got different in quality from another one with two ovaries. But between both the main vascular bundles of floret axis, the lower one, which diverges from the main vascular bundle of spikelet axis at the axil of the first lemma, is ordinarily smaller than the upper one, which does in like manner at the axil of the second lemma and always connects with the dorsal vascular bundle of the ovary. Likewise as regards the vascular courses except that of pistil, there is no difference between the double-ovaried spikelet and the normal spikelet, and also between each the compound 2-flowered spikelet, which is caused by gibberellin treatment in the double-kerneled rice and 'Vialone nano'. The conclusions to be reached from these results and the previous informations (Matuba, 1973 and 1974) are as follows: 1) The compound 2-flowered spikelet with one ovary too has two florets, the lower one is male or non-sexual at the axil of the first lemma and the upper one is bisexual at the axil of the second lemma. 2) The double-ovaried spikelet has only one floret at the axil of the lemma in spite of the external appearance of multi-ovaries. 3) The number of ovaries is not always correspond to that of florets. In other words, there are two developmental mechanisms under multi-ovaried phenomena. These conclusions are. supported by the measurements of the breadthes of both the main vascular bundles, that of spikelet axis and that of floret one, and are in good accord with the foreknowledges deduced from a hypothesis (Matuba, 1971) shown previously. The hypothesis is thus confirmed.

[学科分类] 农业科学（综合）