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M. Sc. Dissertations

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Subject: Zoology × Author: Monika × End date: 2009 × Start date: 2006 ×
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    ThesisItemOpen Access
    Floral biology, mellitophily and pollination ecology of tulsi (Ocimum sanctum Linn.)
    (CCSHAU, 2007) Monika; Sihag, R.C
    An abstract of the dissertation submitted to the Chudhary Charan Singh Haryana Agricultural University, Hisar in partial fulfillment of the requirements for the degree of Masters of Science in Zoology. Medicinal and aromatic plants have become an important part of daily life world over despite significant progress in modern medical and pharmaceutical research (Singh and Somadey, 2005). Tulsi (Ocimum sanctum Linn.) is worshiped for its role in maintaining general peace in the house. This is one of the most important medicinal and aromatic plants of the biosphere. The main chemical ingredients in this plant are eugenol, carvacrol, methyl eugenol and caryophyllene. The study was made on floral structure, floral phenology, mellitophily, pollination ecology and the role of different modes of pollination in seed yield of tulsi. For the study of flower structure freshly opened flowers were taken and studied under dissecting microscope and revealed the protandrous condition of the flower. Fourteen insect species were found to visit the blossoms of tulsi crop. Out of these, six species were the main pollinators i.e. Apis .dorsata, Apis .mellifera, Apis .florea, Mellisodes sp., Halictus sp., Nomia sp. On the basis of foraging rate, A .dorsata was found to be the fastest forager among the pollinators and Mellisodes sp. was the slowest .Abundance of insect visitors was maximum during peak flowering period. Among the hymenopterous insects, A .dorsata was most abundant followed by Nomia sp., Mellisodes sp., A .mellifera, Halictus sp. and then A .florea. Among all insect pollinators, A .dorsata remained active for longest duration followed by Mellisodes sp., Nomia sp., A .mellifera, Halictus sp. and A .florea, respectively. Bee activity followed the same pattern as temperature did; however, humidity followed a reverse trend. Pollinating efficiency of the pollinators derived on the basis of their abundance, foraging rate and activity duration revealed that A. dorsata was the most efficient pollinator of this crop. Differences in different pollination treatments (i.e. insect, open, wind and self-pollination) on different yield parameters (e.g. number of seed set per inflorescence, yield per plant and per plot, test weight of seeds and percent germination) were significant. Seed setting was found to be highest in insect pollination treatment (1045.66 seeds/inflorescence) followed by 565 seeds/inflorescence in open pollination. However, seed set was found to be very low in other two treatments i.e. wind pollination and self-pollination. Similar results were observed in case of yield per plant and yield per plot. Test weight and percent germination was found to be similar for the three pollination treatments i.e. for insect pollination, open pollination and wind pollination respectively but in case of selfpollination it was near about half of the former three due to deformed and under sized seeds in the latter treatment. Pollination experiments clearly revealed that tulsi flowers are highly benefited from insect visits .Its yield parameters showed that it is a cross-pollinated and entomophilous plant .In general, the yield in this plant is pollinator limited i.e. there is scarcity of pollinators to achieve the maximum goal as is evident by yield data in insect pollination treatment. The structure shape and fertility status of the flower clearly revealed that it has bee pollinated flowers and melittophily pollination syndrome existed in tulsi.