著者

SUZUKI TAKESHI WATANABE IWAO SHIRAIWA TAKUMI

出版者

日本植物分類学会

雑誌

APG : Acta phytotaxonomica et geobotanica (ISSN:13467565)

巻号頁・発行日

vol.56, no.1, pp.71-83, 2005-04-11

被引用文献数

2

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Samples of the aquatic floating fern Azolla japonica and its relatives (sect. Azolla) growing in 73 localities of Japan were analyzed by allozyme electrophoresis. Six allozyme types were recognized: AW, BW, BZ, TA, TO and YA types. Compared to the International Rice Research Institute (IRRI) accessions of Azolla by allozymes, the BZ and BW types had the same allozyme patterns as those of A. caroliniana and an artificial hybrid Azolla, respectively; It was supposed that both types had escaped from Azolla introduced to Japan for agricultural use on rice fields. The YA and AW types had very similar allozyme patterns to those of A. filiculoides and A. microphylla, respectively. The TA and TO types shared all allozyme bands except one. The TA and TO types were suggested to be closely related to A. rubra by allozyme comparison. Morphologically, it was suggested that numbers of septa in glochidia (spikelets on male massulae) differentiates the TA type from A. rubra, although only one sample of the TA type was observed. The TA (and possibly TO) type might be an independent species of genus Azolla, or true A. japonica.

著者

Kushari D.P. Watanabe Iwao

出版者

一般社団法人日本土壌肥料学会

雑誌

Soil science and plant nutrition (ISSN:00380768)

巻号頁・発行日

vol.38, no.1, pp.65-73, 1992-03

被引用文献数

1

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The growth of Azolla in the field is often limited by the phosphorous supply. To develop a screening technique for the ability of Azolla to grow and fix N_2 more efficiently under P-deficient conditions, water culture experiments were conducted under concentration-controlled conditions. Azolla was grown in a 60-liter bucket with a P concentration ranging from 0.02 to 0.06 ppm. At 0.03 ppm, Azolla became P-deficient. Under P-deficient condition, Azolla pinnata strains #5 and #7001 produced a larger amount of biomass and showed a lower tissue P concentration than A. microphylla #4018 and A. mexicana #2026. The P concentration in the culture medium decreased from 0.03 to 0.02 ppm during the growth of Azolla. A device for the supply of acid or alkaline and P solutions was designed to maintain a constant pH and P concentration in the water culture medium. Even when the P concentration was kept at 0.03-0.035 ppm, Azolla suffered from P deficiency. Under this condition, the A. microphylla, A. mexicana, A. filiculoides, and A. nilotica strains produced a smaller amount of biomass and showed a higher tissue P content than the A. pinnata strains. Growth responses of Azolla species under P concentration-limited conditions were, thus, similar to those under quantity-limited conditions. Quantity-limited water culture is more convenient for screening a large number of Azolla strains for their ability to grow under P-deficient conditions.