PG Thesis

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Author: search.filters.author.Santhosh Kumar, A VHas files: Yes

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    Impact of ecorestoration on soil seed bank in eastern Attappady, Kerala
    (Department of Tree Physiology and Breeding, College of Forestry, Vellanikkara, 2014) Fredy C Timy; Santhosh Kumar, A V
    A study was conducted to find impact of eco restoration on soil seed bank in Eastern Attappady and relate it to the structural attributes of vegetation in the area. Fifteen sites were randomly selected, which includes three biomass conservation areas (BCA), seven plantation and five non ecorestored sites (NER). From each site, 10 quadrates of size 20 X 20 m2 were selected and vegetation attributes of trees and regeneration enumerated. Soil seed bank sampling was done at an interval of four months in a year. Five soil samples of 30 X 30 cm2 surface area to a depth of 5 cm were collected. To assess the seed density and species composition in the seed banks, seedling emergence technique was used. Sorensen similarity index were calculated to find similarities in species composition between soil seed banks, aboveground vegetation and regeneration. Rainfall regimes of the region were observed as one of the main driving forces for the vegetation structure. Cluster analysis of above ground vegetation revealed that Palliyara and Sambarcode BCA’s and Agali plantation, which fall in the wetter region of the study area were clustered together. Pattimalam, Kottathara and Vellamari plantations which were in drier tract, were proximal to NER clusters. Floristic diversity studies revealed that species richness was higher in biomass area compared to plantation area. Species richness between plantations varied significantly. Simpson index obtained varied from 0.73 to 0.86 in plantations. Floristic diversity of the area was maximum in BCA's of wetter areas, followed by BCA of drier tracts, plantations and non-ecorestored areas. Regeneration study revealed that average regeneration in plantation was 2.42 individuals/m2, while in biomass areas it was 2.11 individuals/m2. In non-eco-restored (NER) areas, the regeneration was found to be low (0.47 individuals/m2). Cluster analysis revealed that Agali, Palliyara and Sambarcode plantations along with Sambarcode BCA had higher overall regeneration. Plantations like Pattimalam, Vellamari and Melechavadiyoor had low regeneration. The reason for lower regeneration can be attributed to edaphic and biotic constraints probably due to their location closer to human settlements. Soil seed bank study revealed that mean seed density in the study area was 153.3 seeds/m2. Leucaena leucocephala, Albizia odoratissima, Senna siamea, Santalum album, Samanea saman and Erythroxylum monogynum were the tree species represented in the soil seed bank. Seed bank was predominated by herbs and shrubs. Seed bank density was observed to be lower in the NER regions, where the degradation is maximum and highest in the BCA regions where the degradation is less. Study revealed that mean seed density of plantations area was 176.8 seeds/m2. Seed density for BCA was estimated to be 247.4 seeds/m2 while that for NER was 35.6 seeds/m2. In soil seed bank, Leucaena leucocephala was dominating and with potential to destroy species diversity of the area. Study revealed that seed bank differs with season. In the present study, most of the seeds germinated in pre monsoon followed by monsoon periods. Soil seed bank diversity (Shannon Weiner index) of study area was found to be ranging from 0 to 0.98. Sorensen similarity index between aboveground vegetation and soil seed bank were low ranging from 0 to 0.14 for study area. Seedling bank resulting from seed rain seems to be a major role player in vegetation establishment than seed bank. The study concluded that evidences of a viable seed bank were not visible as a result of ecorestoration efforts.
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    Influence of host, light and mineral nutrition on the growth of sandal seedlings ( santalum album L)
    (Department Of Tree physiology & Breeding,Co Forestry, Vellanikkara, 2008) Samom Khelen Singh; Santhosh Kumar, A V
    Studies on the effects of light quality, quantity and nutrient deficiency on the growth of sandal seedlings were conducted in College of Forestry, Kerala Agricultural University, Vellanikkara, Thrissur during the year 2006-2008. Radioisotopic study to understand the transfer of photosynthates from the host plants to sandal seedlings and anatomical studies of sandal haustoria were also taken up during the investigation. Sandal seedlings had better shoot growth parameters (viz. shoot length, collar diameter and leaf number), root growth parameters (viz. root length and number of secondary roots), biomass production and chlorophyll content under shaded condition and green light quality when different light qualities and quantities are taken into consideration individually. Sandal seedlings also had better rate of photosynthesis under shaded condition. As far as different light qualities are concerned, rate of photosynthesis was better under red and green light qualities. Generally, the combination of 50 per cent shade and green light quality was found to give the maximum values of different growth parameters and chlorophyll content in leaves of sandal seedlings. The combinations of 50 per cent shade and red light quality and 25 per cent shade and blue light quality were found to be the best with regard to rate of photosynthesis in sandal seedlings at the end of the study period Characteristic deficiency symptoms produced by seedlings due to deficiency of N, P and K include yellowing of older leaf tips, formation of brown spots in leaves and change in leaf colouration, curling of leaves and stunting of growth. The seedlings that received complete nutrient solution were healthy with dark green foliage. Vegetative growth of the seedlings was also found to be affected due to the nutrient stress. Nitrogen deficient seedlings showed a decline in all the fractions of chlorophyll during the study period. Visual deficiency symptoms of the nutrient elements also coincided with a corresponding reduction in foliar levels of the concerned element. Radioisotopic study showed that transfer of photosynthates takes place from the host plants to sandal seedlings and the amount of transfer varies from one host species to another host species. Anatomical studies showed that sandal roots can establish close vascular connections with host roots through haustoria.
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    In vitro propagation of bijasal (Pterocarpus marsupium Rxob.) through tissue culture
    (College of Forestry, Vellanikkara, 1993) Santhosh Kumar, A V; Vijayakumar, A V
    The present investigation was carried out at the College of Forestry, Vellanikkara during 1991 – 93 with an objective of making a protocol for micropropagation of bijasal (Pterocarpus marsupium). Axillary buds obtained from mature trees were used as the explants. During the study it was found that nodal segments of size about 1 cm was ideal as the explants. Prophylactic spraying of mother trees with mixture of Bavistin and Indofil m-45 coupled with surface sterilization of explants with 0.1 per cent mercuric chloride for 10 minutes could control culture contamination to the greatest extent. However, systemic bacterial infection in explants could not be controlled. Murashige and Skoog (MS) medium was noted to be suitable for primary culture establishment. Woody plant medium (WPM) supplemented with 2.0 ppm kinetin and 0.1 ppm IAA was the best for inducing multiple shoots from primary explants. The various growth regulator combinations however, failed to induce leaf morphogenesis in shoots. Among the various media additives tested, CCC had a beneficial role in leaf production in culture. Case in hydrolysate, adenine sulphate, coconut water, silver nitrate, cobalt chloride and activated charcoal were the other additives tried without having any significant beneficial effect on culture of bijasal. Sucrose at two per cent or three per cent sucrose with one per cent maltose were noted to be ideal carbon sources in culture. Semi – solid medium having 0.8 per cent agar was found to be best for culturing the nodal segments. The culture did not show any difference in growth in a range of pH from 5 to 6. An illumination of 2000 Lux light was most ideal for incubating the cultures. All attempts to establish continuous cultures failed due to the sudden loss of morphogenetic potential of cells on culture.