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Title
CERTIFICATE
DECLARATION
ABSTRACT
Preface
ACKNOWLEDGEMENT
CONTENTS
List of symbols/notations used and their descriptions
List of Tables
List of Figures
1 Introduction
1.1 Historical perspectives
Fig.1.1. Main natural rubber producing countries of the world
Table 1.1. Area under natural rubber in the main producing countries (‘000 hectares)
Table 1.2. Production of natural rubber in the main producing countries during 2004 (‘000 tonnes)
Table 1.3. Productivity of natural rubber in the main producing countries during 2004 (kg ha-1)
1.2 Indian scenario
Table 1.4. State-wise total area and production of natural rubber in India during 2003-04
1.3 Importance of growth measurements
1.4 Weather and Hevea trees
1.5 Problem statement
1.6 Objectives of the study
2 Review of Literature
3 Materials and Methods
3.1 Study locations and their site features
3.2 Planting material and experimental layout
Table 3.1. Geographical, weather and soil characteristics of the study location
Table 3.2. Basic details of the clones planted in the trials at the study locations
3.3 Field planting and crop management
3.4 Measurement of tree growth
3.5 Errors in girth measurements
3.6 Time scale of girth measurements
3.7 Period of data collection
3.8 Delimitation of annual period into seasons
3.9 Growth analysis parameters
3.10 Expression of relative growth rate
3.11 Monthly growth pattern and culmination girth increments
3.12 Seasonal trends in absolute and relative growth rate
3.13 Annual growth pattern
3.14 Tree growth and assessment of maturity
3.15 Clustering of clones based on growth parameters
3.16 Influence of weather factors on growth
3.17 Modelling immature growth and inclusion of weather factors into growth functioins
3.17.1 Overall modelling approach
3.17.2 Growth functions used
3.17.3 Incorporating seasonal growth pattern into growth functions
3.17.4 Developing modifier functions to incorporate seasonal influence of weather factors into growth functions
Fig.3.1. Relationship curves of modifier functions for afternoon relative humidity (a), vapour pressure deficit (b)and rainfall (c) .
3.17.5 Incorporating modifier functions of weather factors into growth functions and modelling tree growth development
3.17.6 Fitting of functions
3.18 Weather data and statistical analysis
4 Results
4.1 Weather at the study locations
Table 4.1. Monthly pattern of rainfall (mm) at L1
Table 4.2. Average meteorological conditions and their statistical features at L1 during the study period
Table 4.3. Water balance conditions at L1 (based on the data of 1989 to 1996) *
Fig.4.1. Climatic water balance of L1
Table 4.4. Monthly pattern of rainfall (mm) at L2
Table 4.5. Average meteorological conditions and their statistical features at L2 during the study period
Table 4.6. Water balance conditions at L2 (based on the data of 1991 to 1996)
Fig. 4.2. Climatic water balance of L2
4.2 Growth analysis
4.2.1 Monthly growth patterns and culmination increments
Fig. 4.3. Monthly girth increment variations in clones at L1 during the immaturity period in 1989-90 (0), 1990-91 (●), 1991-92 (□) and 1992-93 (■)
Fig.4.4. Monthly girth increment variations in clones at L2T1 during the immaturity period in 1993-94 (○), 1994-95 (●), 1995-96 (□) and 1996-97 (■)
Fig.4.5. Monthly girth increment variations in clones at L2T2 during the immaturity period in 1993-94 (○), 1994-95 (●), 1995-96 (□) and 1996-97 (■)
4.2.2 Seasonal variations in growth and its rate
Fig. 4.6. Mean (○) and generalized (smooth curve) girth increment curves of Hevea at L1 (a), L2T1 (b) and L2T2 (c)
Table 4.7. Culmination girth increments (cm) in L1 clones at different ages during immature phase
Table 4.8. Culmination girth increments (cm) in L2 clones at different ages during immature phase
Table 4.9. Seasonal changes in mean, minimum and maximum Ig, Rg and coefficient of variation in clones at L1
Fig.4.7. Seasonal variations in g R s of the clones at L1 from age 4 to 11 during the immature phase
Fig.4.8. Seasonal trend in growth of Hevea trees at L1
Table 4.10. Seasonal changes in mean, minimum and maximum g g R, I and coefficient of variation in clones at L2
Fig. 4.9. Seasonal variations in g R s of the clones at L2T1 from age 3 to 8 during the immature phase
Fig. 4.10. Seasonal variations in Rgs of the clones at L2T2 from age 3 to 8 during the immature phase
Fig. 4.11. Seasonal trend in growth of Hevea trees at L2 (a, Trial 1; b, Trial 2)
4.2.3 Annual trends and overall performance
Table 4.11. Annual variations in Ig and Rg in clones of Hevea at L1
Table.4.12. Annual variations in Ig and Rg in various clones of Hevea at L2
Table 4.13. Variations in absolute girth (cm) in March 1991 and 1997, seasonal Ig, seasonal Rg, annual Ig and Rg in various clones of Hevea at L1
Table 4.14. Variations in absolute girth (cm) in January 1991 and 1997, seasonal Ig, seasonal Rg, annual Ig and Rg in various clones of Hevea at L2.
4.2.4 Growth performance and immature phase
4.2.5 Clonal groupings based on growth attributes
Table 4.15. Proportion of rubber trees attaining tappable girth in the terminal years of immaturity at L1
Table 4.16. Proportion of rubber trees attaining tappable girth in the terminal years of immaturity at L2
Fig.4.12. UPGMA cluster pattern of clones at L1 based on growth attributes
Fig.4.13. UPGMA cluster pattern of clones at L2 based on growth attributes
4.3 Influence of weather factors on growth
4.3.1 Simple correlations
Table 4.17. Correlations coefficients between girth increments and weather factors in immature rubber trees at L1.
Table 4.18. Correlations coefficients between girth increments and weather factors in immature rubber trees at L2.
Fig.4.14. Pooled data scatter plots showing the relationship between weather factors and girth increments of clones at L1.
Fig.4.15. Polled data scatter plots showing the relationship between weather factors and girth increments of clones of T1 at L2.
Fig.4.16. Pooled data scatter plots showing the relationship between weather factors and girth increments of clones of T2 at L2.
4.3.2 Path analysis results
Table 4.19. Results of stepwise regression analysis between weather factors and girth increments in the trial clones at L1.
Table 4.20. Results of stepwise regression analysis between weather factors and girth increments in T1 clones at L2.
Table 4.21. Results of stepwise regression analysis between weather factors and girth increments in T2 clones at L2.
Table 4.22. Pooled data path analysis direct (diagonals) and indirect effects (off diagonals) between weather factors and girth increments in the trial clones at L1.
Table 4.23. Pooled data path analysis direct (diagonals) and indirect effects (off diagonals) between weather factors and girth increments in T1 clones at L2
Table 4.24. Pooled data path analysis direct (diagonals) and indirect effects (off diagonals) between weather factors and girth increments in T2 clones at L2.
4.3.3 Multiple regressions
Table 4.25. Results of multiple regression analysis between weather factors and girth increments in the trial clones at L1.
Table 4.26. Results of multiple regression analysis between weather factors and girth increments in T1 clones at L2.
Table 4.27. Results of multiple regression analysis between weather factors and girth increments in T2 clones at L2
4.3.4 Stepwise regressions
4.4 Growth modelling without and with weather variables
4.4.1 Growth modelling
Table 4.28. Results of stepwise regression analysis between weather factors and girth increments in the trial clones at L1.
Table 4.29. Results of stepwise regression analysis between weather factors and girth increments in T1 clones at L2.
Table 4.30. Results of stepwise regression analysis between weather actors and girth increments in T2 clones at L2.
Table 4.31. Parameter estimates of the fitted functions and residual mean square error (RMSE) of the predicted values
Fig.4.17. Plots of observed and predicted values applying the fitted models of Chapman-Richards (a), Weibull (b) and Schumacher (c)
4.4.2 Growth models incorporating seasonal term
4.4.3 Growth models incorporating modifier functions of weather factors
Table 4.32. Parameter estimates of the fitted functions including seasonal term in the models and residual mean square error (RMSE) of the predicted values
Fig. 4.18. Plots of observed and predicted values applying the fitted models of Chapman-Richards (a), Weibull (b) and Schumacher (c) including seasonal term
Table 4.33. Parameter estimates of the fitted models including modifier functions of RH2, VPD and RF with common slopes and intercepts for both site
Fig.4.19 Plots of observed and predicted values of the fitted models of Chapman-Richards (a), Weibull (b) and Schumacher (c) including modifier function of RH2 with common slopes and intercepts for both sites
Fig.4.20. Plots of observed and predicted values of the fitted models of Chapman-Richards (a), Weibull (b) and Schumacher (c) including modifier function of VPD with common slopes and intercepts for both sites.
Fig.4.21. Plots of observed and predicted values of the fitted models of Chapman-Richards (a), Weibull (b) and Schumacher (c) including modifier function of RF with common slopes and intercepts for both sites.
Table 4.34. Parameter estimates of the fitted models including modifier function of RH2, VPD and RF with separate slopes and intercept for each site
Fig.4.22. Plots of observed and predicted values of the fitted models of Chapman-Richards (a), Weibull (b) and Schumacher (c) including modifier function of RH2 with separate slopes and intercepts for each site
Fig.4.23. Plots of observed and predicted values of the fitted models of Chapman-Richards (a), Weibull (b) and Schumacher (c) including modifier function of VPD with separate slopes and intercepts for each site
Fig.4.24. Plots of observed and predicted values of the fitted models of Chapman-Richards (a), Weibull (b) and Schumacher (c) including modifier function of RF with separate slopes and intercepts for each site
5 Discussions and Conclusions
5.1 Weather conditions
5.2 Growth analysis and immature phase
5.2.1 Monthly growth patterns
5.2.2 Seasonal growth
5.2.3 Annual growth trends, overall performance and immaturity period
5.3 Influence of weather factors
5.4 Growth models and weather factors
5.5 Conclusions
References