Floral biology and reproductive effort of Aesculus indica (Wall. ex Camb.) Hook: An andromonoecious species in temperate region of Garhwal Himalaya, India.

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Date
2017-07
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College of Forestry, Ranichauri Campus , V.C.S.G. Uttarakhand University of Horticulture and Forestry
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Aesculus indica a large deciduous tree is widely distributed along the Himalayan lowlands. The studies in relation to floral biology and reproductive effort of A. indica conducted at Ranichauri exhibited that the sex expression of A. indica is andromonoecious. Total number of flowers per inflorescence was 341.9 ± 65.67 to 441.4 ± 74.62 of which13.3 ± 3.19 to 20.15± 6.68 flowers were with developed style. An average duration of 7.5 months is required for the completion of one reproductive cycle. The flowering pattern of A. indica was asynchronous. The peak period of anthesis was recorded between 06:00 to 08:00 hrs in a day. Pollen production (2016) per tree varied from 1010008499 ± 26217045 to 8078958841 ± 97679046. Viable pollen of 87.54 ± 4.02% to 90.04 ± 0.82% and 85.34 ± 3.23% to 89.57 ± 3.65% were observed in flowers with developed and underdeveloped style respectively. Maximum germination was observed in 20% sucrose concentrations. The pollen ovule ratio varied from 8855 ± 65.38 to 9078.61 ± 198.43 (developed) and 8863.95 ± 107.17to 9029.61 ± 198.23(underdeveloped) flowers supporting xenogamy. Pollination observations have shown that A. indica being pollinated by wind while insects also play a major role in performing pollination. Major visitors were Bombus spp. and Tagiades menaka. The study demonstrates that A. indica donot have much difference on fruit set between the cross pollination and the open cross pollination but it possesses a type of barriers to selfing. The average seed set per fruit is one in all the pollination treatments. The seed set and fruit set varied for different canopy layers, i.e., 0.53% to 0.63% (lower canopy), 0.68% to 0.84% (middle canopy) and 0.82% to 1.01% (upper canopy). The reproductive success in canopy layer showed marked variations. Therefore, the current findings may be useful in studying breeding system, pollination ecology, pollen – pistil interactions, distribution and composition of the A. indica populations in future.
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