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20204
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Subject: Forest Biology and Tree Improvement × End date: 2020 × Start date: 2020 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Selection for drought tolerance and wood quality traits from selected accessions of Tectona grandis Linn f.
    (Department of Forest Biology and Tree Improvement, College of Forestry, Vellanikkara, 2020) Anjana, C B; KAU; Santhoshkumar, A V
    Teak (Tectona grandis Linn. f.) is an important hardwood timber in the tropic. Most teak-growing countries are now performing tree improvement programs. It mainly aimed at achieving superior growth characteristics. These may have indirect effect on wood properties. So it is essential to include wood quality traits in breeding of teak. As teak requires long nursery period which extends to almost one year and any decline in moisture during this period may cause decline in initial growth and may eventually lead to death of teak.Asstated,mostofthebreedingactivitiesthathavebeendoneonteakinvolvedselecting plustreesbasedonlyonquantitativeandqualitativetraits.Tillnow,veryfewworkwasdone on screening teak for drought tolerance. The study is being conducted at the teak provenance trial plantation established in Livestockresearchstation,Thiruvizhamkunnu.30accessionsofteakwereplantedincompact family block design with 3 progenies each, replicated five times. Out of 30 accessions, eight were completely absent in the field. From the remaining 22 accessions, three were discarded due to the lack of enough number of progenies (minimum 2) per accession. So the 19 accessions were used for the further studies. Growth characters and wood quality traits were observed among these accessions from thefield. Growth parameters like height and girth showed significant variations among 19 provenances.Variationofheightwasintherangeof9.57m(A5)to17.97m(A2).Thevariation in the girth at breast height was in the range of 31.75cm (A5) to 86.07(A29). PPD and SWV showedsignificantvariationsamong19provenances.AccessionsA2,A29,A21,A20,A1,A3 andA22showedbettergrowthparameters.ThevalueforPPDrangefrom20.25mm(A1,A23) to 24.25mm (A20). The value for SWV ranged from 3535 ms-1 (A29) to 4360 ms-1(A30). Specific gravity for the different accessions was calculated from the regression equationusing PPD. Specific gravity range from 0.32 (A20) to 0.44 (A1, A23). Among the accessions, A23, A17, A28, A19, A18, A21 and A22 showed better wood qualitytraits. Eighteen trees belonging to eighteen accessions were then selected using comparison method. These trees were then vegetatively propagated through stem cuttings for further studies. These accessions were then screened for drought tolerance by studying physiological changes in response to imposed drought stress in three stages viz. normal, stress and regain. Kruskal Wallis test showed significant variation among physiological parameters during these three stages of drought. A significant reduction in stomatal conductance, transpirationrate, photosynthetic rate, relative water content, chlorophyll a and chlorophyll b content, total chlorophyll content, membrane stability index, chlorophyll stability index as compared to normal growing conditions among the accessions of teak. A significant increase was observed in the canopy air temperature difference among the accession. A hierarchical cluster analysis was carried out for physiological parameters of the accessionsduringdrought.Theaccessionswhichperformedwellduringdroughtweregrouped in cluster IV. The accessions belonging to this cluster was A21, A6 and A24. During drought, higher values for chlorophyll stability index, membrane stability index, chlorophyll a and chlorophyll b content, total chlorophyll content, relative water content and the photosynthetic rate was observed for A21. In addition to that highest value for stomatal conductance and transpiration was recorded in A21 and A6. Chlorophyll fluorescence was observed highest in A21, A24, A5 and A6. Among the accessions, the lowest value for the canopy air temperature difference was observed inA21. Duringregainrecoveryinphysiologicalcharacterswasobservedamongtheaccessions. A21 showed higher values for physiological parameters like chlorophyll stability index, membrane stability index, chlorophyll a and b content, total chlorophyll content, chlorophyll fluorescence, relative water conductance, transpiration and stomatal conductance. The photosynthetic rate was observed highest in A21, A6, A5 and A24. A13 and A17 found to be least recovered during drought because of prolonged damage to physiological process after imposeddrought.Itcanbeconcludedfromtheaboveresultsthatconsiderablevariationexisted among the teak accessions for wood properties and growth characters. In drought tolerance studies significant variation among the accessions were also observed. A21 is found to be drought tolerant compared with otheraccessions.
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    ThesisItemOpen Access
    Diversity assessment and selection of candidate plus trees of Ailanthus triphysa (Dennst.) Alston in selected districts of northern Kerala
    (Department of Forest Biology and Tree Improvement, College of Forestry, Vellanikkara, 2020) Jes, Lalnunpuia; KAU; Santhoshkumar, A V
    Matti (Ailanthus triphysa [Dennst.] Alston), belonging to the family Simaroubaceae is a medium to tall evergreen rainforest tree. It is one of the most important and extensively used trees for making match splints in India. The study attempted to determine the diversity and select candidate plus trees from selected districts of Northern Kerala and to evaluate their progeny. Thirty candidate plus trees were selected based on baseline regression of trunk volume to crown volume combined with scoring for qualitative characters. The tree height, GBH, crown diameter and clear bole height of the plus trees varied from 20 m to 37 m, 0.69 m to 2.11 m, 3.5 m and 9.75 m and 7 m to 24 m respectively. The thirty candidate plus trees were grouped into nine clusters through cluster analysis. Cluster I had a maximum number of CPTs with 15 accessions, whereas the least number observed for cluster VII, VIII and IX respectively. Clusters with only one plus tree can either possess superior or inferior quality among the plus trees. The clustering pattern revealed that plus trees from the same geographic sources were grouped into different clusters, while plus trees from different geographic sources were grouped into the same clusters. The highest intra and inter cluster was observed on cluster I (2.07) and cluster III and IV (8.91). This indicates there was greater genetic distance within and between the clusters. Seedling biometric observations for different morphological and physiological characters showed significant differences except for the height of the seedlings. The seedlings height, collar diameter, the number of leaves and biovolume ranged from 8.73 cm (FCV-AT-02) to 11.2 cm (FCV-AT-01), 0.14 mm (FCV-AT-02) to 0.25mm (FCV-AT-16), 4.33 (FCV-AT-02) to 6.53 (FCV-AT-20) and 0.12 cm3 (FCV-AT-02) to 0.32 cm3 (FCV-AT-16). The progenies FCV-AT-21, FCV-AT-33, FCV-AT-36, FCV-AT-37, FCV-AT-39 and FCV-AT-40 were found superior based on overall mean performance of the morphological characters. Hence, seeds of these CPTs can be used in immediate field planting operations. The genetic analysis of the causes of variation for the morphological and physiological traits was studied. The highest phenotypic and genotypic coefficients ii of variation were observed on the character biovolume. For all the characters studied, the phenotypic coefficient of variation was higher than the genotypic coefficient of variations indicating that there were non-additive effects. High heritability coupled with a genetic gain was observed in the number of leaves and collar diameter. Similarly, heritability was high for all the physiological traits with an adequate genotypic variation that can help in the further improvement programme. The correlation studies on morphological and physiological studies showed that positive correlation was observed in the seedlings height and collar diameter of the CPTs. The relation with collar diameter and biovolume, collar diameter and stomatal conductance, biovolume and stomatal conductance of the CPTs were also found positive. A positive correlation was also recorded on the plus trees selected on the characters photosynthesis and transpiration and stomatal conductance and leaf temperature. It can be concluded from the study that considerable morpho-physiological variations exist in selected candidate plus trees of Ailanthus triphysa. These results could help in the future breeding programme as well as efficient management of the trees.
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    ThesisItemOpen Access
    Diversity analysis and selection of candidate plus trees of Swietenia macrophylla from selected districts of north Kerala
    (Department of Forest Biology and Tree Improvement, College of Forestry, Vellanikkara, 2020) Aleena Thomas, Moor; KAU; Santhoshkumar, A V
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    ThesisItemOpen Access
    Drought response in plus trees of teak (Tectona grandis Linn.f.) provenances of Kerala
    (Department of Forest biology and tree improvement, Vellanikkara, 2020) Mohammed Ali Eltoum, Hassan; KAU; Santhoshkuamar, A V
    A study on ‘Drought response in plus trees of teak (Tectona grandis Linn. f.) provenances of Kerala’ was conducted in College of Forestry, Vellanikkara during 2018-2019 to evaluate variability in seedling biometric, physiological and biochemical characters of plant during drought stress and drought recovery. Drought stress was induced by withholding water till leaves exhibited symptoms of wilting. Plantlets were exposed to two consecutive drought treatments with an intervening period of stress relief through rehydration. Seedling vigor was screened at six months. No variability was present in morphometric characters like height, diameter, number of leaves and branches. After inducing drought stress, growth parameters slowed down in all accessions between plus trees. Induction of drought resulted in reduction in most of the physiological parameters of the plantlets of teak plus tree accessions. Relative water content, photosynthetic rate, stomatal conductance, transpiration rate, chlorophyll a, chlorophyll b, total chlorophyll and chlorophyll stability index showed reduction. However, under drought stress, plantlets showed increased of canopy air temperature differences and cell membrane stability index. Most of biochemical parameters like free amino acid, proline, glycine betaine, total soluble sugar, super oxide dismutase, peroxidase and malondialdehyde increased after inducing drought. However, total soluble protein and nitrate decreased under drought induction. After rehydration, most of these physiological and biochemical parameters rapidly returned to the level of normal irrigated condition. The stomatal conductance was only differed in the accessions before stress was induced. However, after stress, it was found that accessions differed in stomatal conductance, photosynthetic pigments and total chlorophyll content. In drought recovery, there was no variation in physiological parameters among accessions. Variability on biochemical characters were observed in nitrate reductase, free amino acid, proline and peroxidase among accessions during pre-stress stage, while in drought stress it was observed that proline, super oxide dismutase, peroxidase and 139 malondialdehyde differed among accession. In drought recovery, characters such as nitrate reductase, free amino acid, proline and peroxidase showed variability. Correlation studies showed that among the physiological and biochemical character only chlorophyll a, chlorophyll b and total chlorophyll showed positive correlation with the number of leaves during drought stress, while in recovery, positive correlation was shown by super oxide dismutase, chlorophyll a, chlorophyll b and total chlorophyll content and negative correlation was observed in photosynthetic rate, transpiration, relative water content and stomatal conductance. Hierarchical cluster analysis was done for the eleven accessions based on the Euclidian squared distance. During drought stress, the accessions grouped into five clusters; cluster III possesses four of accessions whereas the least number observed for the cluster V. In recovery, it was grouped into seven clusters; cluster VII had three accessions, while only one accession was present in cluster I, IV, V and VI. First two components of principle component analysis during drought stress accounted for 41.9 per cent of the total variability, which was mainly contributed positively by relative water content, nitrate reductase, free amino acid, proline and malondialdehyde. In drought recovery, first two components of PCA together accounted for 53.2 per cent of the total variability, which was mainly contributed positively by photosynthetic rate, stomatal conductance, transpiration rate, chlorophyll stability index, glycine betaine and malondiadehyde. Selection index were worked out to select accession tolerant to drought stress and recovery based on biochemical parameter and chlorophyll content using first principle component as index. It was found that KFRI T55 was most tolerant and quickest to recover after reliving stress among accession. It can be concluded from the results that physiological and biochemical variations exist in teak plus tree accessions. These results could be useful in selection of drought tolerant