Cultivars of Colocasia esculenta (L.) Schott are well known as one of the very important tropical and subtropical tuber crops, so-called taro. They show many variations not only in size, taste, edible parts, physiology and etc, but also in ploidy, namely diploid and triploid (Hot ta 1971, Ramachandran 1978, cf. Moore 1973, Fedorov 1974 . For improvement of taro it is necessary to understand what phenomena happened in the process of diversity of cultivars. The cytogenetical information is one of the very important aspects for the purpose. Very few cytological approaches, however, have been applied to generate new taro cultivars (Ramach andran 1978).We have carried out the crossing test between Colocasia esculenta and C. gigantea aiming the increase of cytogenetical information of taro, and successfully obtained both diploid and triploid F, hybrids between both species. In this paper we describe the features of the meiotic chromosome behaviors of both diploid and triploid hybrids. Materials and methods Crossing proceduresColocasia esculenta (L.) Schott cultivar "Burkok" and C. gigantea Hook. f. in the living collections of Bogor Botanical Garden, Indonesia, were used for the parental materials. The male part of the protogynous inflorescence of C. esculenta was first removed at anthesis. There is no possibility of self-pollination, because of the protogynous dichogamy of the species. The collected pollen grains of C. gigantea were dusted on the stigmatic surface of the female part of the emasculated inflorescence and bagged. After six weeks the seeds matured. Both diploid and triploid hybrids appeared to be weak and survived only with heavy fertilizer ap plications at Bogor Botanical Garden. We obtained 15 mature individuals. Chromosome observationsThe observations of somatic metaphase chromosome were carried out by the conventional techniques, such as the methods mentioned by Lubis et al. (1981).For the observations of the chromosome behavior at meiosis, young inflorescences were fi xed by the fresh modified Carnoy's fluid, the mixture of 2 parts of absolute EtOH, 1 part of chloroform and 1 part of glacial acetic acid, for more than 30 min. Pollen mother cells (PMCs) were collected on a slide glass and stained with 2% aceto-orcein for over 5 min. They were then squashed gently, and observed. Pollen grain fertility was calculated based on the prepara tions stained with aceto-carmine. Fertile pollen grains stained darkly, and were globular in shape.

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Detached warty lenticellate bark of a mangrove tree species, Bruguiera gymnorrhiza (L.) Lamk. from Iriomote Island, Okinawa, a subtropical region of Japan, showed development of acetylene reduction activity when incubated in a mineral nutrient solution lacking nitrogen under an atmosphere consisting of 5%02, 90% N2, and 5% C2H2. The bacteria responsible for nitrogen fixation were isolated from the bark, and their capacity for acetylene reduction and the incorporation of 15N2 into the bacterial cells was confirmed. Four representative strains of the isolates were subjected to taxonomic classification. Two strains were similar to Enterobacter cloacae, and another resembled Enterobacter aerogenes. The characteristics of the fourth strain were similar to those of Klebsiella planticola (Bagley et al., Curr. Microbiol. 6:105-109, 1981). The results of this investigation suggest that the acetylene reduction activity of lenticellate warts of mangrove trunk bark is due to the presence in the warts of nitrogen-fixing bacteria belonging to the family Enterobacteriaceae.

ABSTRACT. Syzygium jiewhoei Hambali, Sunarti & Y.W.Low, a new species from Western New Guinea, Indonesia, is described and illustrated. It is closely related to Syzygium recurvovenosum (Lauterb.) Diels but differs in a range of vegetative and reproductive morphological characteristics.

Oxygen partial pressure as affecting nitrogen-fixing activity of warty lenticellate tree barks was investigated with detached barks of Mallotus japanicUl Lind!. and Ilex pedunculosa MiQ. Fresh bark pieces were incubated under atmosphere containing 0.1 atm C.H. and varied concentration of 0.. ARA of the tissue and pO. in the vessel atmosphere were measured concomitantly over the incubation period. Results showed that ARA of the tissues only developed when pO. in the vessel atmosphere was below 0.06 atm. The opt. pO. for full operation of ARA lay at 0.0~.05 atm.

HAMBALI, G. G., SULISTIARINI, D. & RUGAYAH. 2020. Dracaena jiewhoei (Asparagaceae), a new endemic species from Sumatra, Indonesia. Reinwardtia 19(2): 75‒79. ‒‒ Dracaena jiewhoei Hambali, Sulistiarini & Rugayah, a new endemic species from Muara Emat, Batang Merangin, Jambi, Sumatra, Indonesia is described and illustrated. It is genetically related to Dracaena cantleyi Baker but differs substantially in a range of morphological and its growth pattern characteristics.