Summary and Conclusions

Transcription

1 6 Summary and Conclusions

2 Conclusions 111 Summary and Calicut University campus covers an area of about 500 acres and the flora consists of naturally growing plants of different habits and also species planted by people. Systematics and phenological aspects of reproductive development of the flora have not yet been carried out. Objectives of the study include a phylogenetic classification and phenology of flowering and fruiting of the angiosperm flora of Calicut University Campus. Phenology of flowering/and fruiting are correlated with meteorological data particularly rainfall of the campus area. Along with the phenological observations of flowering /fruiting, morphological studies also are conducted on fruits and seeds collected from 92 species. Seed germination behaviour, classification, distribution of dormancy and their relationship with rainfall also are investigated. A classification of seedling types based on seedling emergence, morphology and establishment and modifications of cotyledons also become the part of the study.

3 Conclusions 112 Systematics was done as per APG II phylogenetic classification. Standard methods of fruit/seed collection and post harvest technology were followed for seed drying, storage and germination. Germination percentage, mean time germination etc. were calculated using routine methods/formulae. Morphology of seedlings and cotyledons was represented by photographs and camera lucida drawings. Based on monthly rainfall, three periods - low, average and high rain fall were categorised and flowering/fruiting phenology was correlated to these three rainfall periods. Systematics studies revealed that majority of plants out of the 92 taxa come under advanced clades/families, whereas a few plants/families were fallen under primitive clades also. More numbers of plants showed flowering/fruiting under average rainfall. The flora consisted of trees, shrubs and herbs, which are annuals and/or perennials showing annual flowering. Fruits and seeds of different morphology and various seed-dispersal mechanisms also were observed. Germination studies led to a classification of seeds into readily germinable and dormant types. Drying and storage showed increased rate of germination in many species but seeds of a number of species lost their viability due to drying/storage. Based on storability or desiccation sensitivity,

4 Conclusions 113 orthodox, intermediate and recalcitrant seeds were found to be existed. Variations of seedling morphology enabled to classify them into different functional types. Modification of cotyledon morphology was another important character of the Campus flora. These observations and their correlations or comparison with the phenology of flowering/fruiting and rainfall are discussed with current literature and the following conclusions are made. 1. Phylogenetic classification, as per APG II scheme, of 92 species reveals that more numbers of plants/families come under advanced clades, whereas primitive families are represented by a few members. 2. Flowering phenology showed more number of plants flowered during average rainfall which has been reported as a character of Indian as well as other tropical forests. Annual flowering of many herbs as well as shrubs with short life-span and perennials with annual flowering are dependant on rainfall and these features are typical characters of tropical flora. 3. Seed dispersal mechanism is found to be directly related to rainfall in such a way anemochory is more common in plants which fruit during low rainfall and zoochory is maximum in average and heavy rainfall.

5 Conclusions Seed size/weight is an important feature in determining dispersal distance and the variation in seed size is very high in the flora and so also the dispersal mechanism. 5. Recalcitrant and intermediate seeds are characterised by large size, very high MC, low MTG and short storability and their fruiting phenology is directly related to high rainfall. 6. Difference in germination rate and MTG leading to the classification of seeds into readily germinable and hard types is an important ecological character for germination and/or survival of seedlings, which depend on rainfall. 7. Distribution of dormancy - mainly morphological - observed in many of the species is an important ecological character or adaptation for survival and this observation also is a feature of tropical flora. 8. Difference in the germination rate and MTG between Petri dish- and field- germination is indicative of the requirement of some soil/ other ecological factors that might control the germination behaviour. 9. Air-drying and sun drying of seeds imposed dormancy in some species and loss of viability in others revealing some sort of sustenance of the taxa depending upon the climatic conditions.

6 Conclusions Variation of seedling morphology is another manifestation of the diversity in the Campus flora and some seedling types are unique to this flora. Phanerocotylar epigeal foliaceous (PEF) type of seedlings, occur abundantly. 11. Diversity in the morphology and modifications of cotyledons is remarkable and this character also is another aspect of the diversity of the flora. 12. Sets of morphological characters that exist in the various taxa of the flora differ so widely that generalities are often difficult to discern. 13. This diversity may be due partly to the broad range of characters/parameters that have been taken into consideration for the investigation. 14. In cognizant of the reality that the data from a relatively small area and small fraction of the plant species, the author has tried to avoid generalizing the statements too broadly, on the basis of the observations. 15. Nevertheless, correlations between flowering/fruiting phenology and rainfall which controls/affects all other climatic factors are found to be related to the variations in habit, fruit/seed morphology and their

7 Conclusions 116 dispersal mechanism. Seed germination behaviour, desiccation sensitivity, dormancy, seedling emergence/ establishment and variations and/ or diversity of seedling types and cotyledons also are found to be the characteristic features of the flora of tropical region to which category the Calicut University Campus belongs.