PG Thesis
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Item Barcoding and biosystematic studies on Hymenopteran pollinators of cucurbitaceous vegetables(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2019) Erra Harisha; Shanas, S PThe study entitled “Barcoding and biosystematic studies on hymenopteran pollinators of cucurbitaceous vegetables” was conducted during the year 2017- 2019 at the Department of Agricultural Entomology, College of Agriculture, Vellayani with an objective to study the diurnal activity and dynamics of hymenopteran pollinators of cucurbitaceous vegetables and to explore their morphological and molecular diversity. To determine the composition and relative abundance of different hymenopteran pollinators visiting the flowers of five selected cucurbitaceous vegetables viz., culinary melon (Cucumis melo var. acidulus), bitter gourd (Momordica charantia L.), ash gourd (Benincasa hispida Thunb. and Cogn.), pumpkin (Cucurbita moschata L.) and ridge gourd (Luffa acutangula (Roxb.) L.) collections were made throughout the blooming period in Thiruvananthapuram and four other districts of Kerala viz., Kollam, Pathanamthitta, Alappuzha and Kasaragod from 06:00 h to 18:00 h of the day with a cone type hand net. Among the above mentioned vegetables, culinary melon was selected for detailed study on diurnal activity at College of Agriculture, Vellayani. The study on composition and relative abundance of hymenopteran pollinators revealed that, A. cerana indica was the dominant pollinator in culinary melon (42.51 %), pumpkin (38.76 %) and ridge gourd (35.16 %) whereas, T. travancorica was the dominant pollinator in bitter gourd (31.86 %) and ash gourd (33 %). Observations on diurnal activity were carried out at College of Agriculture, Vellayani in culinary melon during two crop seasons for 3 weeks at weekly intervals. For foraging rate, the number of flowers visited by each bee for 1 minute and for foraging speed, time spent by each bee per flower were observed respectively. During two seasons, the foraging speed of A. cerana indica, T. travancorica and Halictus sp. was found to be highest during 10:00-11:00 h (10.61 and 10.63, 11.23 and 11.46, 10.26 and 10.40 seconds) respectively. The foraging speed of C. hieroglyphica and Lasioglossum sp. was found to be highest during 09:00-10:00 h (9.02 and 9.11, 11.06 and 11.30 seconds) respectively. The foraging rate of T. travancorica, C. hieroglyphica and Lasioglossum sp. was found to be highest during 10:00-11:00 h (9.16 and 9.23, 4.83 and 4.85 flowers/m2/5 min) respectively. The foraging rate of A. cerana indica and Halictus sp. was found to be highest during 11:00-12:00 h and 09:00-10:00 h (10.60 and 10.88, 4.03 and 4.13 flowers/m2/5 min) respectively. Samples which were unidentified through morphological characterization were given for DNA barcoding. The sequence of 2 samples viz., Tetragonula sp. nov.1 and T. travancorica were obtained. Among these, new species (Tetragonula sp. nov.1) of stingless bee, based on adult worker specimen is described. Differences in morphology and genetic analysis based on partial sequences of the mitochondrial COI gene barcode region support the recognition of the new species. The above results revealed that A. cerana indica was dominant in culinary melon, pumpkin, and ridge gourd and T. travancorica was dominant in bitter gourd and ash gourd. The foraging speed during two seasons in the descending order was T. travancorica > Lasioglossum sp. > A. cerana indica > Halictus sp. > C. hieroglyphica. The foraging rate during two seasons in the descending order was A. cerana indica > T. travancorica > C. hieroglyphica > Lasioglossum sp. > Halictus sp. Among the pollinators, five species viz., P. phalerata phalerata, C. annulata annulata from ash gourd, M. disjuncta from bitter gourd, C. simillima, and C. unimaculata javanica from culinary melon were reported for the first time pollinating cucurbitaceous vegetables. Tetragonula sp. nov.1 of stingless bee, collected from pumpkin flower, is the new species report from the study and it is morphologically characterised.Item Development of tropical gynoecious lines in cucumber (Cucumis sativus L.)(Department of Olericulture, College of Horticulture, vellanikkara, 2016) Karthika, A K; Pradeepkumar, TThe present study ‘Development of tropical gynoecious lines in (Cucumber sativus L.) was carried out at Department of Olericulture, College of Horticulture, Kerala Agricultural university, Vellanikkara, Thrissur during August - November 2014 and February - May 2015 to evaluate the F1 hybrids and their F2 population for identifying stable tropical gynoecious lines of salad cucumber. Twelve hybrids produced by crossing gynoecious line EC 709119 with selected tropical monoecious parents were evaluated for gynoecy under rainshelter. Observations on important quantitative and qualitative characters were recorded. These hybrids were selfed to generate F2 population. F2 population was evaluated for expression of gynoecious character, viz., days taken for female flower anthesis, node at which first female flower emerged and total number of female flowers. The data was subjected to analysis of variance and variability among the genotypes was calculated. Most of the characters exhibited high heritability except for fruit parameters like fruit length, fruit girth and flesh thickness. For gynoecy F2 population from the cross EC 709119 x IC 538186 was observed as the most promising one. This population took only minimum days to form female flower and took minimum number of nodes to form female flower with highest number of female flowers and minimum male flowers. Sex ratio was estimated for parents, F1 hybrids and F2 population. Some of the parents having high sex ratio failed to transmit the same to its hybrid progenies. Among the parents, IC 538186 exhibited highest sex ratio. The highest sex ratio among the F2 population was for EC 709119 x IC 538186. Two populations viz., EC 709119 x IC 527427 and EC 709119 X IC 538186 exhibited a sex ratio of more than 2. The 4 F2 population evaluated for gynoecious trait were classified into monoecious and gynoecious character and tested for goodness of fit based on chi square test with monohybrid ratio of 3:1 being monoecy dominant over gynoecy. Out of the 4 populations, 2 populations were found to express significant value and fit in 3:1 ratio for dominant monoecious trait. The other 2 populations failed to fit in the 3:1 ratio. Bitterness was an important quality character which was absent in most of the parents except three of them during initial harvest. The crosses involving parents prone to bitterness were found to be bitter during later harvest, though all crosses were free of bitterness during initial stage. During later harvests, five parents were found to be bitter. Downy mildew incidence on parents and F1 hybrids were analyzed and Percentage of Disease Intensity (PDI) was estimated. Among parents, IC 538186 exhibited minimum infection and falls under the category of moderate resistance. Hybrid, EC 709119 x IC 538186 exhibited minimum infection and falls under the category of moderate resistance. Among 12 F2 populations, EC 709119 x IC 538186 produced maximum number of true gynoecious plants whereas eight F2 populations failed to produce even one true gynoecious plant. This population also exhibited moderate resistance against downy mildew disease and could be selected for developing true breeding stable gynoecious line for future breeding programme. Present investigation proved the scope of developing tropical gynoecious line from temperate lines by crossing with potential-monoecious lines and making selection in advance segregating generations for gynoecy.Item Breeding for gynoecy in bitter gourd (Momordica charantia L.)(Department of Vegetable Science, College of Horticulture, Vellanikkara, 2019) Minnu Ann, Jose; Pradeepkumar, TItem Characterization, host range and management of papaya ringspot virus (PRSV)(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2018) Atheena Harish; Anita Cherian, KItem Standardisation of grafting in bitter gourd (Momordica charantia L.) and watermelon Citrullus lanatus (Thunb.)(Department of Olericulture, College of Horticulture, Vellanikkara, 2018) Akhila, A N; Sarah T GeorgeItem Effect of growing environment and climate change on growth and yield of cucumber [Cucumis sativus (L.)] under organic management(Academy of Climate Change Education and Research Vellanikkara, 2017) Abishna, P V; Usha, K EItem Cause-consequence analysis of human-wildlife conflict at Nemmara forest division, Kerala(Department of Forest Management and Utilization, College of Forestry, Vellanikkara, 2017) Anand, R; Gopakumar, SA study titled “Cause-consequence analysis of human-wildlife conflict in Nemmara forest division, Kerala” was conducted during 2013-2017. The main objectives of the study were to portray the nature and distribution of human-wildlife conflict, study the land use and land cover change pattern. Another objective of the study was to assess the attitude and awareness of the people including the victims of human-wildlife conflict about forest conservation and human- wildlife conflict. The observations of the study would be made useful to evolve location specific management strategies at Nemmara Forest Division. A detailed pre tested questionnaire was used to gather information regarding socio-demographic details, land use and land cover change patterns, human wildlife conflict data, crop farming details and also attitude and awareness of the people. A total of 398 individuals were surveyed from Alathur, Kollengode and Nelliyampathy ranges of the forest division. Participatory Rural Appraisal (PRA) methods such as oral history, time line and problem tree methods were used to collect additional information. The study found out that major conflict areas were along the fringes of the forest areas. The type of conflict even though was mainly crop raiding, the nature of damage and the animal causing the damage were found to be different in different ranges in the forest division. Over the past 30 years there was significant change in the land use and land cover in the division. Over all, cropping pattern has changed from food crops to cash crops. The number of wild animals has increased and this was portrayed as the main reason for human-wildlife conflict. The people found the forest department as the best responsible agency to look up to take action regarding conflict mitigation and were also ready to join hands with them to resolve such issues. Even though the people had a positive attitude towards forest conservation and wildlife they were not satisfied with the conservation policies and human-wildlife conflict mitigation schemes of the government. The people did not favour compensation or insurance schemes as a mitigation strategy towards crop raiding mainly because of the low compensation amounts and difficulty in applying for such schemes. Site specific plans, based on the data generated from this study can be used to develop not only location specific plans but also both animal as well as people specific plans for conflict management and mitigation.