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1985 - 198911990 - 19941
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Subject: Horticulture × Author: Rajan, S × Start date: 1980 ×
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    ThesisItemOpen Access
    Selection efficiency and genetic and biochemical bases of resistance to bacterial wilt in tomato
    (Department of Olericulture, College of Horticulture, Vellanikkara, 1985) Rajan, S; KAU; Peter, K V
    Bacterial wilt (Pseudomona solanacearum E.F. Smith) is a major disease of tomato. Attempts were made to improve a reportedly resistant line CL 32d-0-1-19 GS for higher fruit weight and better plant type through four selection methods – mass, pureline, single seed descent and bulk. Genetic and biochemical bases of resistance were also studied. Resistance of the evolved line was tested in vivo and in vitro. Mass, pureline and SSD methods of selection were effective to improve fruits/plant, locules/fruit, yield/plant and fruit weight. SSD method resulted in higher realized genetic gain for fruits/plant (30.97) locules/fruit (0.5) and yield/plant (1.05 kg). Higher genetic advance and high realized heritability were recorded for days to first harvest in SSD selections. Mass selection had higher realized heritability (0.95) for fruits/plant and high realized heritability (0.65) and realized genetic gain (0.5) for locules/fruit. Fruit weight was improved through pure- line selection. Selections based on trait combination fruits/plant, yield/plant and plant height significantly effected higher locules/fruit (4.2). Selection based on trait combination fruits/plant, yield/plant, locules/fruit and plant height were the earliest to flower (59 days). Days to first harvest were significantly reduced (96 days) through selections based on fruit/plant and yield/plant followed by yield/plant and plant height (98 days). Fruit weight was significantly improved by selections based on yield/plant and locules/fruit (58.5 g). Selections based on yield/plant had high realized heritability (0.59) and realized genetic gain (22.0 g) for fruit weight. Fruit weight was significantly improved by selections based on yield/plant and locules/fruit under SSD method (62.4 g). Transgressive segregants appeared through selection based on yield/plant and locules/fruit. SSD selections had the lowest incidence of wilt (9.86%). Multi- locational trails revealed a survival of 89.5% of plants under normal disease stress. Evaluation of generations from LE79 (CL 32d-0-1-1-1-19GS) x Pusa Ruby Cross indicated a monogenic and incompletely dominant type of gene action for wilt resistance. There was no association between yellow gel colour around the seed and disease resistance. No close linkage between resistance and a fewer locules/fruit was observed. The resistant line (LE79-CL 32d-0-1-1-1-1-19 GS) had higher total and higher root content of Pusa Ruby. - tomatine than the susceptible line - Tomatine content increased and maintained at a higher level in resistant line eventhough the infection progressed consequent to artificial inoculation. Pusa Ruby wilted seven days after inoculation. Total phenol content was higher in roots of Pusa Ruby before and after inoculation. The wilted plants of Pusa Ruby had higher content in root and shoot. The O.D. phenols content was more in the resistant line before and after inoculation. Vitamin C content was also more in roots of LE79 before and after inoculation. A higher ratio of phenols and -tomatine: total phenols, -tomatine: O.D. -tomatine: vitamin C were found in roots of LE79 before inoculation. The wilted plants of Pusa Ruby had lower ration of -tomatine: total phenols and -tomatine: vitamin C. a higher increase in O.D. phenols and vitamin C content on infection was observed in resistant line. The ratio of vitamin C: total phenols was higher in roots of LE79 before infection and the ratio increased in both the lines initially on infection and then decreased but to a greater extent in Pusa Ruby. A higher increase in vitamin C content compared to total phenol was observed in LE79 on infection. A low ratio of total phenol: O.D. phenol was related to resistance in LE79. Inoculation in vitro confirmed the resistance of LE79 to Vellanikkara isolate of Pseudomonas solanacearum E.F. Smith. Grafting of suspectible scion on LE79 delayed wilting of scion even on artificial inoculation.
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    ThesisItemOpen Access
    Leaf litter addition and nutrient recycling in two clones of rubber (Hevea brasiliensis Muell. Arg.) at Vellanikkara estate of Kerala Agricultural University
    (Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 1994) Rajan, S; KAU; Nazeem, P A
    The present study deals with the quantification of leaf litter addition and nutrient recycling in two clones of rubber in the Vellanikkara Estate of kerala Agricultural University , Trichur . Two different methods of collection were adopted for litter collection in both the clones RRII 105 and RRII 118. Wintering was found to start on 23rd November, 1993 for clone RRII 105 and continued till 12th February , 1994 whereas in RRII 118 wintering strated by 25th November, 1993 and continued till 17th February , 1994. Peak leaf fall was noticed in the month of January for RRII 105 whereas it was in the month of February in the case of RRII 118. Thus clonal variation do exist for the wintering pattern. The total leaf litter production was estimated to the 4954.297 kg for RRII105 and 4584.558 kg for RRII 118. The nutrients contributed through leaf litter during wintering in the clone RRII 105 were 72 kg N, 2 kg p, 57 kg K, 59 kg ca and 12kg mg whereas for the clone RRII 118 it was 61kg N, 2kg p, 43kg k , 79 kg ca and 9kg mg . The clone RRII 105 contributed more litter as well as nutrients than the clone RRII 118. Contrary to the previous years the nutrient levels in the leaf litter did not follow a regular pattern during the wintering period . The presence of green leaves shed due to high wind velocity resulted in an increased level of nutrients in some collection s. It was also observed that the contribution of N, K and Ca were more during the wintering period whereas p was more prior to peak wintering and Mg was more after peak wintering. Comparison of nutrient status in soil samples collected from the area enclosed by net and outside sites showed that removal of leaf litter resulted in relatively lower levels of soil nutrients in the top soil . The leaf area worked out during the study was 6.44 for the clone RRII 105 and 5.53 for clone RRII118. The study also revealed that enclosing the trees with net is the best method to quantify the leaf litter addition . The expensive and cumbersome procedure of providing nets cannot be replaced by collecting the leaf litter from a marked area provided with 15 cm high fencing . The leaf litter accumulated in the fenced area was always less and varied from 27 to 71 per cent of the quantity of litter collected by providing net to cover the canopy all around the trees.