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Thesis Abstracts

  1. Studies on morphological and molecular characterization and conservation of mango germplasm (2010)

  2. Assessment of some cultivars of mango (Mangifera indica L.) for vegetative and fruit characters. (1985)

  3. Irrigation and fertigation studies in high-density mango (Mangifera indica L.) (2002)

  4. Studies on nursery and propagation techniques in polyembryonic rootstocks of mango (Mangifera indica L.) (2002)

  5. Mineral composition and anatomical changes in Alphonso mango during storage with reference to internal breakdown (1992)

  6. Studies on storage of mango (Mangifera indica) (1983)

  7. Studies on packaging of mango (Mangifera indica L.) (1985)

  8. Changes in mineral composition of mango fruits during storage (1991)

  9. Population dynamics, biology and management of Amrasca splendens Ghauri (2004)

  10. Ecology and management of stone weevil (2005)

  11. Physiological and biochemical basis of internal breakdown in Alphonso mango-a study on the roles of ethylene, calcium and oxidative stress (2006)

  12. Role of seed in spongy tissue formation in Alphonso mango biochemical studies (2005)

  13. Persistence and mobility of paclobutrazol in soil (2004)

  14. Factors influencing somatic embryogenesis in mango (Mangifera indica L.) for application in genetic transformation (2005)

DIVISION OF FRUIT CROPS

Ph.D Title: Studies on morphological and molecular characterization and conservation of mango germplasm (2010)

 C.Vasugi, Annamali University, Chidambaram,

 Guide: Dr. M.R.Dinesh

Studies on morphological and molecular characterization and conservation of mango germplasm were carried out in the Department of Horticulture, Faculty of Agriculture, Annamalai University, during December, 2005 to December, 2009. Four systematic experiments were carried out to characterize the variability; to assess the genetic diversity; to evaluate for fruit and pickling characters and to study the effect of cryopreserved pollen. Characterization of 43 accessions maintained in the field gene bank of Indian Institute of Horticultural Research based on IPGRI (Biodiversity International) mango descriptor reveled wide variability for leaf, fruit, flower, inflorescence, pulp and stone characters. Genetic divergence and cluster analysis based on both phenotypic and molecular markers were carried out. Accessions were grouped based on similarity/dissimilarity index. Principal Component Analysis (PCA) indicated that fruit descriptors contributed more towards divergence. Cryopreserved pollen was found to be as good as fresh pollen in the inter-specific and inter-varietal crosses. Comparative evaluation of pickling accessions with the commercial and polyembryonic varieties revealed that Dantimamidi and Kovesara possessed good quality characters and was on par with the commercial varieties used in the study. Based on the evaluation of tender mango pickle quality, Chansi Appe, Dodderi Jeerige, Mani Bhatta Appe, Gorana Appe, isagoor Appe, Malange, Dantimamidi, Gurumurty Appe and Kashimidi were identified as good pickling accessions. Possible gene donors for specific traits like attractive skin colour, pulp colour, fruit weight, pulp per cent and TSS was also observed. The morphological characterization data generated in the present study was used to develop a Mango Information System to run on Windows Operating System for ready retrieval and visual comparison.

 

M.Sc. Title: Assessment of some cultivars of mango (Mangifera indica L.) for vegetative and fruit characters (1985)

 M.C.Subbaiah, UAS, Bangalore,

Guide: Dr. C.P.A.Iyer

Observations were taken on 42 cultivars of mango collected from all over the country on various characters including vegetative growth, flowering and fruit characters, to obtain information on the extent of variability and also to help in selection of cultivars for specific purposes. The data were taken on seven year old trees. Wide variability was observed for number of growth flushes, length of shoots put forward in a year, time of flowering, length of panicles, initial fruit set, fruit number per panicle and date of harvest. The number of fruits per tree ranged from 5.0 in Langra to 247.5 in Pacharisi. In terms of fruit number. Chandrhkaran, Gola, Himayat pasand, Hyder Sahebi, Kallapadi, Kasturimamidi, Lazat Baksh, Neelum, Pacharisi, Padiri and Panakalu were found to be promising. In terms of fruit weight, Amini, Hyder Sahebi, Kallapadi, Kasturimamidi, Lazat Baksh, Neelum, Pacharisi, Padiri and Panakalu were found to be promsing. The weight of the fruit was found vary from 63 g in Chandrhkaran to 647g in Amini. The percentage of pulp in a fruit ranged from 39.7 (Chandrhkaran) to 74.1 (Fazli). It was found that the cultivars Fazli, Himayat Pasand, Kallapadi, Padiri and Panakalu yielded maximum pulp per tree. The pulp : skin + stone ratio (edible to non-edible portion) was found to range from 0.65:1 in Chandrhkaran to 2.86:1 in Fazli. The total soluble ranged from 12.8 in cultivar Amini to 29.2 in cultivar Chandrhkaran. The acidity was found to be the least in cultivars Banganapalli, Imam Pasand, Lazath Baksh and Peddarasam (0.06%), whereas it was maximum in cultivar Suvarnarekha (0.65%). The total sugar content was found to range from 8.03 in Fazli to 20.41 percent in Rataul. Panakalu (17.63%), Amarapalli (17.24%), Langra (15.78%), Kallapadi (15.75%) and Dashehari (15.50%) also had high total sugar content. The sugar: acid ratio was found to range from 16.66:1 in Mohammada Vikarabad to 270.66:1 in Rataul. Cultivars Lazath Baksh (257.3:1) and Rataul (270.6:1) recorded high ratio.

 

M.Sc. Title: Irrigation and fertigation studies in high-density mango (Mangifera indica L.) (2002)

Hanamanth.Y.Asangi, UAS, Bangalore,

 Guide: Dr. K.Srinivas

The investigation on Irrigation and fertigation studies in high-density mango (Mangifera indica L.) var. “Arka Anmol” was carried out at Indian Institute of Horticultural Research, Bangalore during the year 2001-2002. Seven year old mango plants of Arka Anmol was grafted and dwarfing rootstock Vellaikulamban and planted at a spacing of 5 m x 5 m, gives a plant density of 400 plants per hectare. The mango plants were subjected to two levels of irrigation (40% and 80% evaporation replenishment rate) and three level of fertigations (100%, 75% and 50% recommended dose of fertilizer) applied through drip irrigation system. Fruit yield (9.50 t/ha.), number of fruits per plant (99.92) and fruit volume (259 cc) were higher with 80% of evaporation replenishment rate as compared to 40% of evaporation replenishment rate {(fruit yield (7.06 t/ha.) number of fruits per plant (63.58), and fruit volume (232.20 cc)}. The higher fruit yield (10.65 t/ha.) and number of fruits per plant (97.88) at 100% recommended dose of fertilizer, fruit yield (7.92 t/ha.), number of fruits per plant (64.38) were lower under 50% recommended dose of fertilizer. However, the interaction effect of 80% evaporation replenishment rate and 100% of recommended dose of fertilizer reported highest fruit yield (12.50 t/ha.), number of fruits per plant 9113) as compared to other interactions. The acidity (0.40%), peel weight (48.42 g), pulp weight (178.89 g), stone weight (38.05 g), peel to pulp ratio (3.84) and pulp to stone ratio (3.63) were higher at 80% evaporation replenishment rate as compared to 40% of evaporation replenishment rate. Whereas, higher TSS was reported at 40% of evaporation replenishment rate (18.58 oBrix). Similarly, TSS (18.20 Brix), peel weight (48.18 g), pulp weight (182.83 g), stone weight (49.06 g), peel to pulp ratio (3.84) and pulp to stone ratio (3.63) were higher at 100% RDF as compared to 50% of RDF.

 

M.Sc. Title : Studies on nursery and propagation techniques in polyembryonic rootstocks of mango (Mangifera indica L.) (2002)

Venkata Rao, UAS, Bangalore,

Guide : Dr. Y.T.N.Reddy

The investigation on “Studies on nursery and propagation techniques in polyembryonic rootstocks of mango (Mangifera indica L.)” was carried out at the Indian Institute of Horticultural Research, Hessaraghatta, Bangalore-89 during the period 2001-2002. Fourteen polyembryonic varieties along with one monoembryonic Alphonso studied for seedling attributes related to germination, growth and vigour. Earliest germination was noticed in Muvandan and whereas the maximum germination percent and rate of germination was in Muvandan and Olour respectively. With regard to seedling growth characters like, seedling height, number of leaves and leaf area was maximum in Alphonso. In osmopriming treatments, the variety Alphonso recorded the maximum seedling height, girth, number of leaves and leaf area in treatment GA3 at 100 ppm concentration. Bark and stem percent was maximum in varieties Vellaikolumban and Bappakai in treatment GA3 at 100 ppm concentration. In media and biofertilizer experiment, the seedling height, girth and number of leaves were maximum in variety Alphonso and Muvandan in treatment comprising of potting mixture (1:2:1 proportion) + cocopeat + VAM. The bark inverted variety Olour recorded the minimum graft height and sprout length whereas the seedling girth was maximum in variety Alphonso where bark inversion was carried out. Thus based on the different seedling growth and vigour characters, the monoembryonic varieties Alphonso, Totapuri and polyembryonic varieties Muvandan, Bappakai, E.C-95862 and Mylepelian were highly vigorous, whereas Kurukkan, Nekkare, Chandrakaran, Olour, Peach and Kensington varieties as vigorous and the Kitchner, Starch, Prior and Vellaikolumban varieties could be placed under less vigorous group.

 

DIVISION OF POST-HARVEST TECHNOLOGY

 

Ph.D Title: Mineral composition and anatomical changes in Alphonso mango during storage with reference to internal breakdown (1992)

 K.Haribabu, UAS, Bangalore,

Guide: Dr. Shantha Krishnamurthy

 The investigations were made on (i) Physico-chemical changes, mineral composition, histological and histochemical changes, during growth, development, storage and ripening and (ii) the effect of pre-harvest spray and post harvest spray and post harvest infiltration with calcium chloride on the above mentioned changes and also on the occurrence of internal breakdown (spongy tissue) in Alphonso mango. Fruit length, diameter, weight of fruit, pulp and peel increased gradually up to 45 days, followed by a sudden increase to maximum of 90days and pre harvest spray of calcium at 5000 and 10000 ppm significantly enhanced this increase. The effect of post harvest calcium infiltration was more prounced in delaying ripening, reducing the weight loss and firmness, increase of peel colour, pulp colour (carotenoids), sugars and decrease of acidity during storage as compared to pre harvest sprays. Analysis of calcium (Ca), Potassium (K), Sodium (Na) and Phosphorus (P) during growth and development, in general indicated reduction in the concentrations from 15 days to 90days after fruit set both in the peel in the pulp. The distribution of minerals in 6 different pulp tissues during ripening indicated that Ca content was maximum in the basal pulp portion as compared to middle and apical parts. The distribution of minerals in 6 different pulp tissues during ripening indicated that Ca content was maximum in the basal pulp portion as compared to middle and apical parts. Further, the pulp towards the peel showed more Ca than in the pulp towards endocarp. In case of K & P, it was more in the pulp nearer to endocarp and no change was seen from base to apical portion of the pulp. Spongy tissue affected pulp showed low Ca (19.25 mg), high K (726 mg), P (135.6 mg) & Na (45 mg) as compared to 41.8 mg Ca, 501 mg K, 85 mg P & 37 mg Na in the healthy tissue. Both the pre & post harvest Ca treatments had no effect on spongy tissue development. Histochemical studies indicated the appearance of starch granules after 60 days of fruit set in all the tissues of the fruit & maximum accumulation was found after 90 days of fruit set. In pre harvest sprays of Ca, the cell of the fruit were bigger in size with more starch grains & degradation of these grains was delayed during ripening. Ripening process was initiated in mesocarp region. Development of spongy tissue was found in pulp near endocarp. The cells in this were small, globular & thick walled with numerous starch grains.

 

M.Sc. Title: Studies on storage of mango (Mangifera indica) (1983)

C.M.Kala, UAS, Bangalore,

 Guide: Dr. Shantha Krishnamurthy

An investigation on the effect of using skin coating waxol, in combination with heat treatment and fungicides on ripening and keeping quality of the important cultivar ‘Alphonso’ mango was made. The experiment had 10 treatments with replicates for each treatment. The effects of treatments on physicochemical changes, ripening and spoilage were observed during a storage period of 20 days. Post harvest hot water treatment of Alphonso mango at 52+ 1 C for 5 minutes resulted in hastening of ripening process, reduced spoilage and development of uniform orange surface colour of the fruit. The use of Benlate at 500 ppm reduced the spoilage and the extent of reduction was on par with hot water treatment. Further reduction of spoilage by combination of hot water and fungicides (Benlate and T.B.Z. at 500 ppm) was not evident. Waxol treatment retarded ripening by 5 days as compared to the control, and retained freshness of the fruit up to 20 days of storage. Waxol treatment combined with (i) hot water alone and (ii) with fungicides Benlate and T.B.Z. at 500 ppm were the best, with reference to the quality of ripe fruits and control of spoilage after 20 days of storage at ambient conditions. Organoleptic quality of the fruit was not affected by post harvest treatment.

 

M.Sc. Title: Studies on packaging of mango (Mangifera indica L.) (1985)

V.R.Prasad.S, UAS, Bangalore,

Guide : Dr.Shantha Krishnamurthy

An investigation to compare the effect of combination of post harvest dip treatments with waxol (3%) and hot water with waxol, with or without wrapping in tissue paper and polyethylene film on physic-chemical changes and keeping quality of Alphonso mangoes during storage at room temperature was made. It was observed that combination treatment of hot water alone followed with wrapping in polyethylene (HDPE) delayed ripening as compared to the unwrapped fruit of the corresponding treatment. Weight loss was reduced by more than 50% in the wrapped fruits. Spoilage was high (20%) in polyethylene wrapped fruits. Wrappers had to be removed after 10 or 15 days of storage for further ripening of the fruit at ambient conditions of storage. Organoleptic evaluation of the ripe fruits in waxol with hot water treatment showed good colour, texture and taste as compared to the control fruits which had shriveled by 15th day of storage.

 

M.Sc. Title: Changes in mineral composition of mango fruits during storage (1991)

R.A.Reena, UAS, Bangalore,

Guide: Dr. Shantha Krishnamurthy

Changes in weight loss, firmness, moisture, dry weight, surface colour and minerals were studied at 5 stages of ripening in four cultivars of mango namely Alphonso, Bangapalli, Rasapuri and Totapuri. The weight loss during ripening ranged from 13.4 to 17.4%. The loss of green colour was accompanied by appearance of yellowish orange colour. At the ripe stage, ‘L’ values ranged from 44.7 to 67.9, ‘a’ and ‘b’ values ranged from 4.0 to 8.1 and 23.4 to 34.9 respectively. Moisture content decreased with an increase in dry weight of the fruits during ripening. Alphonos mango recorded the lowest Ca content in both pulp (8.2 mg) and peel (73.9 mg), lowest peel Na content (6.0 mg) and highest P (112.4 mg) and Fe contents (100.2 ppm) in the peel and K content in the pulp (828 mg). Bangapalli recorded the highest of (466 mg) in peel, Fe (99 ppm) in the pulp, K (986 mg) in the peel and lowest K of 598 mg and Na content of (5.6 mg) in the pulp. Rasapuri recorded the low contents of all the minerals. Calcium content in the peel and pulp were 245.9 mg and 9.4 mg. Fe content was the lowest (5.8 ppm) in the pulp and in the peel (3.5 ppm), highest Na content in the pulp (11.2 mg) and in the peel (12.6 mg). Totapuri showed the highest Ca-content of 13.3 mg in pulp, P content of 78.4 mg & the lowest peel K content of 676.7 mg. these changes have been correlated with the shelf life of the cultivars.

 

DIVISION OF ENTOMOLOGY & NEMATOLOGY

M.Sc. Title: Population dynamics, biology and management of Amrasca splendens Ghauri (2004)

S.Rudresh, UAS, Bangalore,

Guide : Dr. Abraham Verghese

The present investigations were made during 2003-04 on the different aspect of Amrasca splendens Ghauri at IIHR namely, seasonal incidence, biology, extent of damage, management of A . splendens and response of leaf hopper to Alphonso, Banganapalli and Totapuri varieties, All the aspects were summarized below. Seasonal incidence of A. splendens indicated that three population peaks were observed, with the second peak was observed during third week of April (23.20 mean leafhoppers per shoot). The first peak during third week of June (11.05 mean leafhoppers per shoot) and third peak was during last week of November (0.29 mean leafhoppers per shoot). Incidence of A. splendens was found on all the commercial varieties studied namely, Alphonso, Banganapalli and Totapuri from May 2005. On these varieties the incidence gradually increased from February to March and reached its peak during April, from then the population started declining and reached a minimum during July to October, July to March and May to January, in Banganapalli, Totapuri and Alphonso, respectively. The Incidence of A. splendens had showed positive significant correlation with maximum temperature(r=0.38) minimum temp. (r=0.36) and flushing(r= 0.67). Tender leaves were found to have positive effect. Further, the studied showed that co-occurrence of factors like maximum temperature at third week prior to leafhopper incidence and flushing at one week prior to leafhopper incidence explained the leafhopper density up to 65 per cent. Relative humidity and wind speed were not found to have any effect. Studies on the biology of A. splendens on mango were conducted under laboratory conditions, during April 2004. Previposition, oviposition, and post oviposition periods lasted for 8 to 10, 10 to 12 and 4 to 6 days, respectively. The total fecundity based a nymphal emergence ranged from 15 to 26 eggs per female. Eggs were slightly oval and transparent and were laid in the midrib, vienlets and occasionally in leaf lamina. Oviposition per days varied from 1 to 4 during peak season for per female. It took 4 to 5 days for hatching. The nymphs passed through five instars and they lasted for 0.69, 1.25, 1.94 and 2.63 days, respectively. During the course of the study three predators namely Isyndus heros Fab. And Mantis religiosa Lab., were found attacking the different stages of the leafhopper. However these were of no major consequence. The female adults caused the major damage by ovipositing in midrib towards anterior region of tender leaf, which resulted in blockage of phloem tube due to which, drying of leaf apex backward was observed. However in majority of damaged leaves the dried tip just break off leaving a typical “tip cut” symptom. After emergence nymphs cluster on the lower side of the tender leaves and suck sap from midrib and vienlets. Under server infestations, the leaves of sprouting shoots withered and ultimately fell down. The oviposition in the midrib caused anatomical changes in the leaf midrib and as well as in lateral veins of the leaves. The healthy midrib stained in toluidine blue mercuric bromophenol blue and periodic acid Schiff’s reagent has indicated the presence of vascular bundles and other related structures, where as in infested tissue the staining was either blank or very lightly indicated the degeneration of tissue or the presence of chitinaceous materials in the midrib (left out material of chorion). Further, it could be clearly seen that there was an opening in the midrib to indicate the escape of nuymphs by rupturing midrib. Studies were conducted on the management of A.splendens during April 2005. The botanicals namely viz., Pongamia soap 10 g/l, Neem soap 10 g/l, Neemazal 1.5ml/l, Neemark+ 1.5ml/l, Neem oil 10ml/l, NSKE 4% were used for the study. Endosulfan 2ml/l was used to compare the efficacy of botanicals. The results showed that neem oil 10ml/l and NSKE 4% giving 100 per cent control of the leafhoppers.

 

M.Sc. Title : Ecology and management of stone weevil (2005)

D.K.Nagaraju, Kuvempu University, Shimoga,

 Guide : Dr.Abraham Verghese

Mango stone weevil, (MSW) Sternochetus mangiferae (Fabricius) (Coleoptera: Curculionidae) is an important monophagous pest of mango, its ecology and ethology have escaped the attention of entomologists, but its effects as a pest of mango fruit is highly pronounced affecting yield and exports. In order to understand the insect better, for better management, there is a need to follow the insect, into its niches like seed and bark in an intensive manner. Hence, the present study was conducted at the laboratory and fields of Indian Institute of Horticultural Research (IIHR), Bangalore (12o 58’N; 77o 35’E) during 2001-2005. The different linear and non-linear models employed could explain the variability in infestation at harvest due to the infestation in fallen fruits to the extent of 57 to 83% in different varieties. Further, per cent infestation at harvest was predicted using polynomial model order 2 equation in Alphonso and Banganpalli, and polynomial model order 3 in Totapuri. An adult infested by Beauveria bassiana (Balsamo) Vuillemin was found. The natural occurrence was < 1%, but under laboratory conditions, the fungus gave 100% mortality of adults in 2-7 days when sprayed at 1.3 x 109 spores per ml concentration. Carbaryl, acephate and deltamethrin with 3.33, 6.67 and 8.15% infestation, respectively were effective. Ethofenprox with 14.82% infestation gave intermediate control. Fish oil rosin soap and azadirachtin were not effective. The study clearly brought out for the first time that infestation begins on fruits of 2-4 cm diameter. This is the time to initiate management interventions. The discovery that majority of the adults eventually rest in junctions of main trunk and primary branches augur well to target spot application of insecticides on the main trunk prior to fruiting, thus obviating full canopy sprays. The fact that older trees harboured more MSW is also crucial in being vigilant to MSW infestation. This is environment friendly cost effective and time saving, as trunk spot application requires only 1/5th of spray liquid. The study showed that prediction of weevil infestation in a variety is possible. As stretches of mango of one variety are common in India, this will be useful in forecast and surveillance. The efficacy of B. bassiana demonstrated that the eco-friendly IPM is a potential future venture.

 DIVISION OF PLANT PHYSIOLOGY & BIOCHEMISTRY

 

Ph.D Title : Physiological and biochemical basis of internal breakdown in Alphonso mango-a study on the roles of ethylene, calcium and oxidative stress (2006)

 J.E.Nagamani, Kuvempu University, Shimoga,

 Guide : Dr.S.Shivashankar

Reduction in ethylene evolution in the spongy tissue was mainly due to the reduced activity of ACC oxidase leading to the accumulation of ACC. This might have led to the reduced ripening of the tissues resulting in sponginess. There are many softening enzymes and the major ones are polygalacturonase, pectin methyl esterase and cellulase. Results indicated the lower softening of the tissues in the spongy tissue when compared to the healthy tissues. In climacteric fruits like mango respiratory raise during ripening is very important for proper ripening and development of good aroma. The ethylene hormone strictly controls this. In this direction an attempt has been made to assess the respiratory enzymes to understand whether they are affected due to the formation of spongy tissue. Activities of starch and sugar metabolising enzymes are decreased in spongy tissue leading to the lower sugar formation. Study of antioxidative enzymes in spongy tissues. Oxidative free radicals have been associated with many membrane related disorders. Lipid peroxidation is one of the important effects of free radicals damage. Oxidative free radicals combined with metallic ions like ferrous results in greater damage due to the production of highly reactive hydroxyl radicals. Free radicals are usually scavenged by the antioxidative enzymes like SOD, catalyse, peroxidase, polyphenol oxidase, ascorbate peroxidase, glutathione reductase etc.,. However, if there is damage to the free radical scavenging mechanism then there will be an accumulation in free radicals resulting in the damage of membrane. As a measure of oxidation products MDA has been analysed and antioxidative enzymes like super oxide dismutase, peroxidase, catalyse, polyphenopl oxidase have been estimated in different samples. Spongy tissue has higher oxidative products and lower activity of antioxidative enzymes indicating the lipid peroxidation of membranes. Minerals are essential for the normal functioning of membranes and also for the maintenance of turgor of the cells and for enzyme activities. In this regard, minerals like Zn, Fe, Ca and Mg are estimated in spongy and healthy tissues. Most of the minerals except Ca did not show any significant differences between the tissues. Calcium showed a marginal reduction in spongy tissue.

 

 M.Sc. Title : Role of seed in spongy tissue formation in Alphonso mango biochemical studies (2005)

Linda Louis, UAS, Bangalore,

Guide : Dr.S.Shivashankar

Biochemical Studies showed that moisture content was significantly higher in seeds from spongy-tissue-affected fruits (STS) than seeds from healthy fruits (HS).Analysis of seed components revealed that STS had significantly lower starch content (33.5%) and higher levels of soluble sugars (27.7%) than HS. The incidence of spongy tissue was associated with increased seed respiration rate and amylase activity indicating that the seed in ST fruits had switched over to germination phase. A substantial increase in the content of soluble protein (43.1%) in STS indicated de novo synthesis of various enzymes associated with germination. There was a significant increase in spongy tissue incidence in preharvest GA3 treated fruits (70.2%), while there was a considerable reduction in incidence in paclobutrazol (16.4%) treated fruits as compared to 51.5% incidence in the control. GA3treatment also resulted in higher intensity of spongy tissue. The seeds from HS and STS fruits were distinctly different in their physiological status and biochemical composition. The data clearly indicated that spongy tissue in Alphonso mango is triggered by the onset of seed germination associated events. These events lead to development of spongy tissue in the pulp close to the stone by the continuous transfer of water from pulp to the germinating seed. This theory of seed origin of spongy tissue is amply supported by experimental data and more importantly this concept is able to explain all the facts known so far about spongy tissue.

 

M.Sc. Title : Persistence and mobility of paclobutrazol in soil (2004)

 L.Shalini, UAS, Bangalore,

Guide : Dr.Debi Sharma

 A field experiment was conducted at IIHR, Hessaraghatta, Bangalore, to study the persistence and mobility of paclobutrazol, a predominantly soil applied plant growth regulator to counter alternate bearing in mango following its application to mango tree basins at the rate of 5 and 10 g as per hectare. Soil, water and mango samples from Konkan region of Maharashtra were also collected in order to assess the extent of paclobutrazol residue contamination in these samples, as this area is the largest consumer of paclobutrazol in India. Sample were collected from both conventional soil cultivated orchards and laterite rock cultivations. The study indicated that paclobutrazol persisted at all soil depths for at least 150 days and reduced to below detectable limit at 210 days. It persisted at the surface (0-15 cm) with half lives of 30.7 and 29.7 days from the lower and higher treatment concentrations respectively. It was also seen that paclobutrazol moved quickly down the soil to reach up to or beyond 60 cm. soon after its application. The residues of paclobutrazol in the conventional soil cultivated mango orchards located at Konkan region of Maharashtra ranged below detectable limit to traces. No detectable residues of paclobutrazol were found in soils from laterite rock cultivated mango orchard from the same region irrespective of the number of years for which paclobutrazol applications had been made. The paclobutrazol residues were either below detectable limit or present in traces in mango whole fruits collected from either type of orchards at harvest, notwithstanding the frequency of its application in the orchard. Water samples collected at the time of fruit harvest from open wells located orchards did not contain detectable residues of paclobutrazol.

 

M.Sc. Title : Factors influencing somatic embryogenesis in mango (Mangifera indica L.) for application in genetic transformation (2005)

Subhasis Samanta, UAS, Bangalore,

Guide : Dr.J.B.Mythili

Mango (Mangifera indica L.), the king of fruits, is a prized summer fruit crop of India and Asia. The use of conventional plant breeding approaches for mango improvement has largely been ineffective because of its long life cycle, allogamous and allotetraploid nature. The present investigation was carried out with the objectives of developing suitable and efficient protocols for regeneration through somatic embryogenesis and to study the feasibility of transformation of mango cv. Vellaikolumban using a reporter gene. Young fruits of 25-30 days of age was found to be ideal for culture initiation. Among the various media tried (MS, B5 and RO) for initial nucellar culture establishment, the best proliferation response was obtained in MS medium supplemented with 2.5 mg/l, 2, 4-D. Induction of somatic embryos from nucellar culture was optimized using B5 medium supplemented with 20% (v/v) coconut water and 250 mg/l of casein hydrolysate. Maturation of somatic embryos of 1.0-1.5 cm. length was obtained best in M3 medium composed of B5 salts, L-glutamine (400 mg/l) and ABA (1 mg/l). The faciation and necrosis of embryogenic cultures could be controlled through the use of salicylic acid at a concentration of 0.1 mg/l. Germination of mature somatic embryos with well-developed roots and shoots was achieved best in semi- solid medium (B5) supplemented with 3.0 mg/l GA3. During Kanamycin sensitivity test, It was found that kanamycin at 200 mg/l inhibited regeneration totally in non co-cultivated embryogenic callus derived from nucellus. Among various stages of nucellar culture tried, it was found that embryogenic callus is amenable for transformation. Among various treatment tried, 150 l acetosyringone activated bacterial culture and a period of 3 days co- cultivation was found to give highest percent transformation response (75%). The presence of transgene was confirmed by GUS assay.