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Theses

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2011 - 20153
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Subject: Tree Improvement and Genetic Resource × End date: 2015 × Start date: 2011 × Type: Thesis ×
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    ThesisItemOpen Access
    Dendroclimatological investigations on teak (Tecctona grandis L.F.) in Thrissur forest division of Kerala
    (Department of tree physiology and breeding, College of forestry, Vellanikkara, 2011) Sreejith Babu; KAU; Anoop, E V
    In a study entitled “Dendroclimatological investigations on teak (Tectona grandis L. f.) in Thrissur forest division of Kerala, conducted in the College of Forestry, Kerala Agricultural University, Vellanikkara, Thrissur, the dendroclimatic potential of ring width and mean vessel area of teak was assessed at four study sites. The ring width index chronologies were positively correlated with the previous year south west monsoon, previous year north east monsoon, annual rainfall, whereas negatively correlated with summer rainfall, October-November temperature, previous June-September and current June- September temperature. The mean vessel area index (MVA) chronologies showed significant positive correlation with the previous year south west monsoon, north east monsoon, annual rainfall, previous October-November temperature, October-November temperature and annual temperature whereas a significant negative correlation was observed between mean vessel area index chronology and March-May temperature. In conclusion the tree ring chronologies of teak have good dendroclimatic potential in Thrissur and Chalakudy experiencing typical tropical climate.
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    ThesisItemOpen Access
    Enhancement of storage life of cocoa (Theobroma cacao L) seeds through encapsulation and germination inhibition
    (Department of Tree Physiology and Breeding, College of Forestry, Vellanikkara, 2012) Shiran, Kalappurakkal; KAU; Santhoshkumar, A V
    Studies on enhancement of storage life of cocoa (Theobroma cocoa L.) seeds through encapsulation and germination inhibition were carried out at the Department of Tree Physiology and Breeding , College of Forestry, Kerala Agricultural University, Vellanikkara, during 2010-12. 100-120 days old cocoa pods of, collected from polyclonal cocoa garden of Kerala Agricultural University were utilized for the standardization of microencapsulation techniques. To enhance longevity, germination inhibitor, osmoticum and desiccation were used and longevity of embryonic axes and synthetic seeds were observed. Cotyledon attachment on embryonic axis influenced the germination of embryo. The absence of cotyledon had checked the shoot regeneration of embryonic axes. Embryonic axes with ¼ cotyledon had good root and shoot regeneration with higher germination percentage. The storage medium influenced the longevity of embryonic axes. Higher longevity and viability was observed in ½ MS media while least longevity was observed in dry cotton. The presence of 10-3M coumarin in the basal media ( ½ MS) retarded the root growth of embryonic axes. ABA added to media in 10-4M concentration had increased the longevity of embryonic axes up to 56 days. Cycocel did not have influence on longevity of embryo. No combination effect by the germination inhibitor was seen in the experiment. Osmotic concentrations had positive influence on enhancing longevity of embryonic axes. Media with 250 mM sorbitol enhanced the longevity of embryonic axes to 65 days. Mannitol added media had crystallization during the storage which resulted in low longevity. Sodium chloride in higher concentration had checked the growth of embryonic axes and had shorter longevity. The encapsulation of embryonic axes had increased the longevity of seeds to 40 days while embryonic axes had longevity of 29 days. Maximum longevity of 70 days was observed in synthetic seeds stored in 250 mM sorbitol added media. Longevity was found less than 10 days in dry cotton due to absence of moisture content. The incorporation of MS media in the encapsulation, reduced the longevity of synthetic seeds. In addition, MS media and inhibitor combination in the encapsulation did not have influence on longevity. The MS media reduced the activity of inhibitor action. The 10-3M ABA, 250 mM sobritol and 500 mM sobritol in the encapsulation enhanced longevity to 65 days. Desiccation had a little effect on longevity and it had a negative correlation between RH level and longevity. Longevity had a positive correlation with duration of desiccation. The maximum longevity was possible by storing synthetic seeds in 250 mM sorbitol added media for 55 days and transferring to wet cotton for germination. It had a longevity of 89 days with 80 percent germination. The results of present study indicated that it is possible to store recalcitrant seeds by encapsulation and altering surrounding condition of embryo. The storage potential can be increased up to 3 months by the encapsulation and osmotic environment.
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    ThesisItemOpen Access
    Modeling carbon dynamics in teak plantations of Kerala
    (Department of tree physiology and breeding, College of forestry, Vellanikkara, 2015) Manjunatha, M; KAU; Santhoshkumar, A V
    The study on “Modeling carbon dynamics in teak (Tectona grandis Linn. F) plantations of Kerala” was carried out in teak plantations of Kerala Forest Department during 2011-2015. The study attempted to estimate the carbon stocks in teak plantations and model the soil carbon using ‘Century’ soil carbon modelling tool. The modelling tool was used to analyze the soil carbon under different scenarios. The study also developed of a system dynamic model for carbon prediction for teak plantations. Teak plantations were divided into five strata based on age (0-5, 6-10, 11-20, 21-30 and >30 years). Thirty samples were selected at random for each stratum. Quadrants of 50 m x 50 m size were established in each sample for vegetation analysis. Fifty samples among the 150 samples so selected were used for the validation of the developed model. Ten plantations each from each age class (50 samples) were selected at random for soil studies. Pits of 1m x 1m x 1 m were dug in each sample plot and soils were collected at 0-20, 20-40, 40-60 and 60-100 cm depths. The total litter was collected from each plot at an interval of three months to estimate diurnal litter fall. Soil C, N, S was estimated along with the N, P, K and lignin of litter. Biomass of the study site was estimated using allometric equations. Secondary data on weather parameters were collected from appropriate sources. Significant differences were not observed among the different age classes and soil depths in case of sand and silt content of soil. However, clay content varied between the different age classes and soil depths. Although water holding capacity did not vary among the plantations of different age class in the surface layer (0-20 cm), it varied among the age classes at 20-40 cm. The bulk density did not differ between age classes, while it was higher in deeper layer of the soil (1.1 to 1.36 g/cm3). Soil pH was moderately acidic (5.1 to 6.0). The soil N varied from 0.07 to 0.34 % in plantations, while the values ranged from 0.43 to 1.23 % in natural forests. Nitrogen content was highest in the surface and decreased with the depth in both teak plantation and natural forest. The mean values of available P in the teak plantations and natural forest varied from 1.0 to 4.81 g/kg and 3.16 to 4.82 g/kg respectively. Significant differences in soil C was noticed between plantation and natural forest. While the soil C did not vary between various age classes, it was higher in surface layers compared to deeper layers. Simulation by CENTURY model in teak plantation indicated decline in total SOC up to 50 per cent by 30th year from the initial value of 6168 g C m-2. There after SOC pool declined at a slower rate till 45 years and reached 2702 g C m-2 by 80 years. There was rapid decrease in active carbon pool in teak plantations from 6.25 g C m-2 to 2.88 g C m-2 initially (up to 3rd year) and slow increase to 10.17 g C m-2 by 9th year. By the end of 80th year, the active pool almost doubled to 12 g C m-2. Slow carbon pool in teak plantations reduced from 3700 g C m-2 to 1224 g C m-2 by 22 years and reached 920 g C m-2 at an age of 80 years. Passive carbon pools in teak plantations more or less remained stable (2150.84 to 1912 g C m-2). Analysis indicated that the model was able to predict the values with high efficiency (0.922) and accuracy (R² = 0.9156) Fire reduced total SOC in teak plantation. The study found a 20 per cent decline in the total SOC by the 22nd year of plantation establishment. The SOC reached at 2343 g C m-2 at the age of 30 year of teak plantation compared to 2702 g C m-2 in a normal plantation. Teak plantation converted to natural forest resulted in an increase of SOC pools by 163 g C m-2 compared to that of the teak plantation. Conversion of teak plantation to agroforestry system resulted in marginal decline of 156 g C m-2 in SOC by 30 years. The SOC in teak plantation converted to ginger cultivation declined by 39 per cent at 30 years after ginger cultivation. Conversion of teak plantation to agriculture (pulses and tuber) resulted in significant reduction all the carbon pools. The SOC declined to 43 per cent at 30 years. A system dynamic model of soil carbon dynamics was developed using STELLA software. It was observed that the model was able to predict the total SOC with high precision (ME=0.69). The present study indicated that modelling is suitable for studying C dynamics in soils under teak plantations. Present results highlight the potential of using these tools for reliable evaluation the carbon sequestration potential of management interventions at plantation as well as landscape level.