1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Pollination ecology of solitary pollen bees(Department of Agriculture Entomology, College of Agriculture, Vellanikkara, 2023-04-24) Anusree Padmanabhan P S.; Mani ChellappanBees are often considered to be effective pollinators in both agricultural and natural ecosystems. The recent declines in feral and domesticated social bee populations have raised serious concerns about their impact on the productivity of ecosystems and this urges the need to explore potential alternate bee pollinators for the future. There are 20,000 known species of bees in seven recognised biological families and more than 90 per cent of them are solitary. Unlike social bees, solitary pollen bees establish and provision nests on their own with no assistance from other individuals. Solitary bees play an immensely important role in the pollination of crop plants as well as wild plants. In India, little attempt has been made in documenting solitary bee species. This study was therefore undertaken to document the diversity of solitary pollen bees in selected cucurbitaceous ecosystems with a major emphasis on determining their peak foraging time, nesting preferences, palynology, and the effect of plant protection practices on pollination.Item Factors affecting yield in cashew (Anacardium occidentale L.)(Department of Horticulture (Pomology & Floriculture and Landscaping), College of Horticulture, Vellanikkara, 1979) Parameswaran, N K; Damodaran, V KInvestigations on the different vegetative, flowering and fruiting characters, influencing yield in cashew, were undertaken at the main campus of Kerala Agricultural University at Vellanikkara. These studies were made during the period from November 1978 to April 1979. Important vegetative characters studied were the percentage of flowered shoots per unit area of tree canopy and the growth parameters of the tree represented by spread and height. The major flowering and fruiting characters studied were the pattern of flower opening, percentage of bisexual flowers, factors affecting pollination, fruit-set, fruit-drop and the mean weight of nuts harvested. The results showed that among the vegetative characters, percentage of flowered shoots per unit area of tree canopy was found to be the most important factor, contributing to yield. Tree-spread was also found to have a positive correlation with yield. The influences of this character on yield was not direct but indirectly through the former character. There was no significant correlation between yield and height of the tree. Pattern of flower opening in cashew panicles was found to have three phases viz., the first male phase followed by a mixed phase which is again followed by a second male phase. The duration of these three phases was found to be varying in the different trees. It was found that some trees had only the mixed phase throughout and those trees yielding above the median had a longer mixed phase as compared to the trees yielding below the median. A positive correlation was found between yield and percentage of bisexual flowers in the tree. Among the flowering and fruiting characters affecting yield, this factor was found to influence yield much more than any other character. Examination of a random number of bisexual flowers revealed that a large proportion of bisexual flowers remained unpollinated in nature. So, lack of pollination was found to be one of the reasons for poor fruit-set and yield in cashew. This was further confirmed from the high fruit-set obtained in the hand pollinated panicles. Receptivity of the stigma was found to be continuing up for 48 hours after flower opening and hence it was not a limiting factor for securing high yield. Supplementing the natural pollination with the help of insect pollinators met with some success. Keeping bee-hives in the orchards during flowering season is advisable for facilitating better pollination. A positive correlation could be observed between yield and percentage of fruit-set but the ultimate yield was found to be adversely affected by the severe shedding of young fruits before reaching maturity. The intensity of fruit-drop was found to be high in the early stages of development but it declined during the later stages. The causes of fruit-drop that could be identified were those resulting from the attack of insect pests, adverse climatic conditions etc. Studies did not reveal any significant correlation between yield and mean weight of nuts harvested.Item Growth, Flowering, Floral biology and spike shedding in pepper (Piper nigrum L.)(Department of Horticulture (Plantation Crops), College of Agriculture, Vellanikkara, 1981) Rema Menon; Sivaraman Nair, P CThe present studies were carried out in the College of Horticulture, Kerala Agricultural University, during the year 1979-80. The object was to study the pattern of growth and flowering, floral biology and spike shedding in pepper (Pipernigrum L.) . The studies were conducted on four year old pepper vines (c.v. Panniyur-1 and Karimunda) receiving uniform cultural and manurial practices of the Kerala Agricultural University. Shoot growth in pepper was observed during four months of the year, from May to August, with maximum in July and minimum in August. The mean growth and the percentage of shoots that showed growth varied significantly from month to month and standard to standard. The flowering followed a pattern similar to growth. The percentage of aborted spikes ranged from 40.1 to 26.31 per cent.Item Hybridization using promising second generation inbred and molecular characterization of a the third generation inbreds of WCT coconut(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2018) Hassain, N; Sujatha, RThe research project entitled “Hybridization using promising second generation inbred and molecular characterization of the third generation inbreds of WCT coconut (Cocos nucifera L.)” was carried out in the Department of Plant Breeding & Genetics, College of Agriculture, Padannakkad during the year 2016-2018. The major objectives of this study include development of D x T hybrids using promising palms in second generation (S2) inbreds of West Coast Tall (WCT) as male parent and Malayan Yellow Dwarf (MYD) as female parent and characterization of third generation (S3) inbred seedlings of superior S2 palms of WCT using RAPD analysis. For hybridisation, the male parent was selected from the superior inbred family based on the reports on morphological evaluation and estimation of inbreeding depression during the period 2013-2015 (Chethana, 2016). The family IIIS2-1 showed lowest inbreeding depression for yield related traits among 12 families followed by VS2-2. The palm 313 (IIIS2-1) and 225 (VS2-2) were selected as male parents. Superior MYD palm to be used as the female parent was selected from among the MYD palms available at CoA, Padannakkad based on the general features of mother palm selection (Nair et al., 2008). Observations were recorded from these parental palms which included 24 morphological characters. The male parents showed inbreeding depression for several vegetative characters such as stem girth, functional leaves etc and reproductive characters such as number of female flowers per inflorescence, setting percent and nut yield per palm per year, compared to WCT. The results showed that inbreeding depression for these characters was more in palm 313 (developed by selfing) than palm 225 (developed by sibmating). Total five nuts were harvested from MYD (two nuts by using pollen from palm 313 and three nuts using pollen from palm 225) during May 2018 and were sown in the nursery. Molecular characterization of the 15nos of S3 inbred seedlings of IIIS2 family planted in the field in replicated plots were done using RAPD. Genomic DNA was isolated from 15 seedlings of IIIS3 family among which 10 were produced by selfing the S2 palms (IIIS3-1) and 5 were produced by sibmating the S2 palms (IIIS3-2) along with COD, CGD and WCT. After DNA isolation, samples were subjected to RAPD analysis using 10 decamer primers namely OPAU02, OPBA3, OPAW14, OPAW19, OPAW12, OPAW13, OPAW13, OPAW09, OPAU03, OPAW08 and OPAW15 selected based on screening 30 primers. Using primer OPAW08, a band of size of ~400bp was specifically found in inbreds alone while it was absent in dwarfs and WCT seedlings. In OPAU 03 primer, band size of ~1200bp was absent in WCT but present in all inbreds and CGD. The sibmated inbred NL1 showed a distict pattern when amplified with OPAW 09 compared to all other inbreds. The primer produced a specific band of size ~1050bp only in the sibmated inbred CL1 and was absent in all other samples. Amplification with OPAW19 primer produced a banding pattern in which it mainly distinguished CGD from all other seedlings where there were only two bands while others were having six bands. Primer OPAU 02 produced two unique amplicons: 1100bp present in selfed inbred I1M1 TH2 and MYD; 1000bp present in COD and MYD. Genetic similarity among the 15 IIIS3 seedlings, CGD, COD, MYD and WCT was estimated by using of software DARwin (Darwin 6.Ink). The dendrogram indicated three major clusters in which the grouping of several inbreds along with WCT, COD and CGD may be an indication supporting the hypothesis that the dwarfs might have been originated from the talls during the course of evolution followed by selection. The two dwarfs present in the group are COD and CGD which are from Chavakkad area in Kerala and WCT is the most common cultivar of Kerala. As a future line of study, further evaluation of these S3 inbreds regarding the flowering time and yield characters has to be carried out to find out the genetic potential of these inbreds as breeding lines for producing superior hybrids. The seedlings to be emerged from the hybrid nuts produced in the present study, though limited in number, needs to be evaluated for important traits and the hybridisation programme using superior palms in S2 generation needs to be continued for production of more number of hybrid nuts.Item Breeding for shattering resistance in rice (Oryza sativa L.)(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2018) Anju M Job; Biju, SItem Induction of genetic variability in phalaenopsis orchids through hybridization and embryo culture(Centre for Plant Biotechnology and Molecular Biology, College of Horticulture, Vellanikkara, 2017) Deepali Rahi; Lissamma JosephItem Breeding for drought tolerance in cocoa (Theobroma cacao L.)(Department of Plant Breeding and Genetics College of Horticulture, Vellanikkara, 2019) Juby, Baby; Minimol, J SItem Development of molecular markers linked to yellow vein mosaic resistance in okra (Abelmoschus esculentus (L.) Moench)(Centre for Plant Biotechnology and Molecular Biology, College of Agriculture, Vellanikkara, 2015) Vinutha, J S; Deepu MathewYellow vein mosaic is the most serious disease leading to 50-94 per cent yield loss in okra. None of the chemical measures are successful to save an infected plant and breeding the resistant varieties is the most accepted strategy in the management of this disease. Molecular breeding through marker assisted selection is more advantageous over the conventional breeding since it will help to assure the presence of the gene in the breeding lines and avoid the selection of pseudo-resistant line. As of now, there are no markers for the identification of YVMV resistance gene in okra. Hence the study was undertaken with the objective to identify ISSR and RAPD markers linked with the gene governing resistance to the yellow vein mosaic virus disease in okra through bulked segregant analysis to enable marker assisted selection. In the present investigation, two okra genotypes namely Parbhani Kranthi (YVMV resistant) and Salkeerthi (YVMV susceptible, early bearing, excellent fruit quality) were used. Field screening of both the parental lines was done simultaneously in the same field during February-May 2014. No artificial inoculation methods were followed since the heavy population of white flies observed in the summer months was sufficient to ensure the disease occurrence and crossing was done between the selected plants (Salkeerthi X Parbhani Kranthi). The seeds were harvested from the crossed plants and subsequently used to raise F 1 population. The raising of F 1 plants was carried out in the month of September- December 2014 and the morphological characteristics and disease response of 180 F 1 plants were recorded. All the F 1 plants were free from disease symptoms. The F 1 plants were selfed to produce F 2 seeds. The F 2 population with 200 plants was field screened during January-April 2015. Seven highly susceptible and 7 highly resistant plants were identified, DNA isolated from each, resistant and susceptible DNAs bulked separately and used for Bulked Segregant Analysis (BSA). For theextraction of good quality DNA, the CTAB method (Doyle and Doyle, 1987) may be modified by avoiding the liquid nitrogen while grinding the plant tissue and additionally washing the DNA pellet with wash buffer to remove the mucilage content. Evaluation of quantitative characters on F 1 in comparison with parental lines showed variation for the traits such as plant height, petiole length, days to flowering, days to first harvest, number of fruits per plant and yield per plant. Two molecular marker systems namely, RAPD and ISSR were employed for identification of markers linked with YVMV resistance. A total of 84 RAPD primers and 82 ISSR primers were initially screened for their ability to amplify the DNA fragments. Out of these, 39 RAPD primers and 24 ISSR primers were selected based on the number of bands and nature of amplification. In BSA, two RAPD primers OPB11 and OPL 18 yielded markers linked with resistance to YVMV. OPB11 produced distinct polymorphic bands of 800, 1000 and 1100 bp sizes whereas, OPL 18 produced polymorphic bands of 1000 and 1100bp. Two ISSR primers ISSR 8 and UBC 873 yielded distinct polymorphic bands in relation to YVMV resistance. The ISSR 8 and UBC 873 yielded the markers at 500 and 900 bp, respectively. Another primer ISSR 22 gave a distinct marker at 1100 bp size, linked to susceptibility to YVMV. Co-segregation analysis was performed using individual DNA of resistant parent, susceptible parent, resistant F 2 and susceptible F 2 using RAPD primers OPB 11, OPL 18 and ISSR primers namely ISSR 8, ISSR 22 and UBC 873. OPB 11 produced three distinct markers in all resistant F 2 individuals. ISSR 8 produced distinct marker of 500 bp in all resistant F 2 individuals. ISSR markers were found to be reproducible and they are recommended for use in marker assisted selection for resistance to YVMV in okra.