[International Journal of Plant Biology 2016; 7:6149] [page 1] Pulasan [(Nephelium ramboutan-ake (Labill.) Leenh.] fruit trees: variations in flower morphology, and associated differences in pollination type Nina Ratna Djuita, 1,2 Alex Hartana, 2 Tatik Chikmawati, 2 D. Dorly 2 1 Plant Biology Graduate Program, Bogor Agricultural University; 2 Department of Biology, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University, Indonesia Abstract Pulasan (Nephelium ramboutan-ake) is a species of Sapindaceae which has hermaphro- dite and staminate flowers on different trees. Morphological flower structures and pollina- tion types of the pulasan fruit tree have not previously been reported thoroughly. This study was undertaken to observe the reproduc- tive structure of flowers, and to examine its correlation with pulasan pollination type. A total of 67 hermaphrodite and 14 male trees of pulasan were observed. Some hermaphrodite inflorescences were covered using cloth bags for between four and six weeks to calculate number of fruit, and to determine their polli- nation system. The number of individual flow- ers per inflorescence on male pulasan trees was higher than for hermaphrodite ones. Panicles and spikes were found on both types of pulasan inflorescence. Flowers having four sepals was the commonest structure in both flower types. However, five stamens were com- monly found in hermaphrodite flowers, while male flowers often had six. In general, stigma were curved in shape, with modification in some flowers. Anther of hermaphrodite pulasan flowers naturally never open, although their pollen is viable, so there is a mechanical barrier for self-pollination. It was concluded that pulasan tends to be an allogamous plant. Introduction Sapindaceous plants have various kinds of reproduction structure. Some of them have paniculate inflorescences, (e.g. Litchi chinen- sis and Pometia pinnata), 1,2 some have com- pound dichasia (e.g. Dimocarpus longan) 3 and some, thyrses (e.g. Cupania ludowigii). 4 Like other members of Sapindaceae, plants of the genus Nephelium vary in reproductive struc- ture, in terms of flower position (axillar, termi- nal, or pseudoterminal) and the number of flower parts. 5 It was known that in N. lap- paceum, male trees produce male flowers, but there are also hermaphrodite trees producing hermaphrodite flowers, some of which func- tion as male, some as female. 6 With a her- maphrodite tree of that type, pollination can take place without the existence of a male tree. Nephelium ramboutan-ake also has male and hermaphrodite trees. However, it was not known whether hermaphrodite flowers of this species can function like those of N. lap- paceum. The flower morphology of N. ramboutan-ake has been described briefly in several academic texts. 5-7 However, research on morphological characteristics and pollination type in respect of pulasan flowers, was still very limited. The hypothesis of this study was that if young inflo- rescences covered with cloth bags produce fruits, then the pollination was autogamous; if not, then the pollination was allogamous. To determine whether a plant is reproducing via autogamy or allogamy, observation of the flower structure is needed. This study was undertaken to observe those characteristics of pulasan flowers which correlate with pollina- tion type. Materials and Methods Plant material and research locations The plant material used in this research involved 81 pulasan trees, consisting of 67 her- maphrodite trees and 14 male trees. From each tree, 100 flowers were taken, giving a total number of 8100 flowers observed. Flowers were taken from pulasan trees in the districts of Bogor, Sukabumi, and Semarang, in Java, Indonesia (Figure 1). Flower morphology Morphological data observed were genera- tive characteristics, including inflorescence type, inflorescence position, and the average number of flowers per inflorescence, as well as sepal number, stamen number, stamen size, ovary number, and stigma type. Numeration of each flower part was carried out to know the incidence of different sepal, stamen and ovary counts. Flower structures were observed under binocular microscope and scanning electron microscope (SEM) type JSM-5310LV (JEOL Ltd., Tokyo, Japan). Pollen viability Pollen was given one or two drops of 1% ani- line blue, 8 for between 15 and 30 minutes, and was then observed under a compound micro- scope. The color of viable pollen is blue. Pollination type The hermaphrodite inflorescences of six trees in Mekarsari Fruit Garden, and of two trees in Cipaku Experimental Garden (Bogor), were observed, (giving a total of eight observed trees). The experimental design used in this study was the posttest-only control design. Two kinds of inflorescences were used in this observation: treated and control. In total, 146 young inflorescences from the eight trees were covered with cloth bags to prevent allogamy. As a control, 53 young inflorescences not encased in cloth bags, were used. Every two weeks, all of the inflorescences were observed to see whether or not fruits were being produced. After four to six weeks, the bags were opened and the percentage of inflo- rescences which had produced fruit were counted. These results were compared to the formation of fruit on the control flowers. International Journal of Plant Biology 2016; volume 7:6149 Correspondence: Tatik Chikmawati, Department of Biology, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University, Bogor, Dramaga Campus, Bogor 16680, Indonesia. Tel.: +62.2518.622833 - Fax: +62.2518.622833. E-mail: tchikmawati@yahoo.com Key words: Flower structure; allogamy; viable pollen. Acknowledgments: the research was partly financed by the Center for Tropical Horticulture Studies, via contract number 208/IT3.41.2/SPK/ BOP/2013 on behalf of Prof Dr Sobir, and in part by the Directorate General of Higher Education, Indonesian Government, with Dr Ir Tatik Chikmawati, MSi as researcher chairperson. We are grateful to PT Mekar Unggul Sari, Mekarsari Fruit Garden, Cipaku Experimental Garden Bogor, PT Zanzibar in Kendal, and Hortimart in Semarang, for the use of their facilities. We are also grateful to Prof Mien A Rifai for his sugges- tions in this research. Contributions: the authors contributed equally. Conflict of interests: the authors declare no potential conflict of interests. Received for publication: 14 August 2015. Revision received: 8 October 2015. Accepted for publication: 8 October 2015. This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0). ©Copyright N.R. Djuita et al., 2016 Licensee PAGEPress srl, Italy International Journal of Plant Biology 20165; 7:6149 doi:10.4081/pb.2016.6149 Non commercial use only