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Thesis Type: Ph.D ×

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    ThesisItemOpen Access
    Reproductive Phenology, Floral Biology and Pollination Mechanisms of Rhododendron arboreum Sm. in a Temperate forest of Garhwal Himalaya, India.
    (College of Forestry, Ranichauri Campus , V.C.S.G. Uttarakhand University of Horticulture and Forestry, 2017-07) Chand, Vaishakhy P.; khanduri, V.P. (Dr.) (Advisory)
    R. arboreum is a medium sized evergreen tree, widely distributed from subtropical to temperate forest. The present study in relation to phenology, floral biology and pollination mechanisms of R. arboreum carried out in two reproductive episodes from 2016 to 2017 in temperate forest of Garhwal Himalayas. Phenological study indicated that beginning and terminations of all the phenological events earlier in 2017 than 2016. Phenological events in R. arboreum varied 44 days to 66 days in 2016 and 37 to 65 days in 2017. Peak flowering in both the year during mid-February to midMarch. Flowers are hermaphrodites, actinomorphic and arranged in a corymbose cluster with the average number of 15.5 ± 1.58 to 19 ± 1.94 flowers. Flowers possess protogyny, showed temporal separations and it retains the receptivity upto 4-5 days. The peak anthesis time was between 6:00 am to 8:00 am of the day. The pollen production within tree ranges between 1574111512 ± 75728849 to 2893516569 ± 88351584 per tree. The average percentage of pollen viability varied between 68 ± 4 to 78 ± 7%. The pollen ovule ratio varies 109.72 ± 2.58 to 113.25 ± 3.45 pollen grains per ovule which fall under facultative autogamy. The major pollinators observed were birds. Black Bulbul, Oriental White Eye and Grey Winged Blackbird were the major floral visitors. Result of the breeding system showed that fruit setting of 74.6%, 73.04%, 76.23%, and 63.33% on natural pollinations, hand self-pollinations, hand cross pollinations, and open cross pollinations respectively. The total fruit formed per tree varied from 6800 ± 1569 to 11356 ± 2011. Mean percent of fruits varied among trees from 61.95 ± 8.9 to 72.66 ± 5.49 %. Mean number of seeds per inflorescence varies from 6904.3 ± 1739.3 to 8633.13 ± 1610.8. This study providing information about phenology, floral biology and pollination mechanisms of R. arboreum, will be helps formulating effective conservations strategy for these threatened populations in the hills.
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    ThesisItemOpen Access
    Floral biology and reproductive effort of Aesculus indica (Wall. ex Camb.) Hook: An andromonoecious species in temperate region of Garhwal Himalaya, India.
    (College of Forestry, Ranichauri Campus , V.C.S.G. Uttarakhand University of Horticulture and Forestry, 2017-07) Pradhan, Priya; Khanduri, Dr. V. P. (Advisor); Gusain, Y.S. (Co- advisor)
    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.