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Item Standardisation of grafting in bitter gourd (Momordica charanita L.)(Department of Vegetable Science, College of Agriculture,Vellayani, 2020) Aiswarya V Dev, K P; Rafeekher, MThe study entitled "Standardisation of grafting in bitter gourd{Momordica charantia L.)" was conducted in the Department of Vegetable Science, College of Agriculture, Vellayani during 2017-2019 in order to identify suitable rootstocks, standardise grafting techniques and evaluate growth and performance of grafts in bitter gourd. The study was conducted in two parts. Standardisation of grafting in bitter gourd using four rootstocks was done in part I and evaluation ofthe grafted bitter gourd for growth, yield and quality was attempted in part II. Bitter gourd scion (Preetlii) and four rootstocks (sponge gourd, pumpkin, bottle gourd and bittCT gourd) were raised in protrays. Separate experiments for each roolstock, were laid out in CRD, replicated thrice for standardization of grafting. Growth regulators (alar and cycocel) at two different concentrations /.e.,10 mgL"' and 50 mgL*' were sprayed at second leaf stage forreducing seedling height of rootstocks and then grafted using three methods (hole insertion grafting, one cotyledon grafting and cleft grafting). Alar @10 mg L*' reduced plant height(7.50 cm) and enhanced diameter (2.97 mm) in sponge gourd rootstock. Faster graft union(4.11 days) was recorded forfiole insertion grafting withhighest success percentage (77.07 %). Spraying of cycocel @ 50 mg L ' resulted in the highest success percentage of 56.44 per cent. Combination of cycocel @ 50 mg L"'+ hole insertion grafting recorded highest success percentage of 86.67 when bitter gourd grafted onto sponge gourd. Though cycocel @ 10 mgL"'and 50 mgL"'improved the diameter of pumpkin rootstock, alar@ 10 mgL"' and 50 mgL'reduced the height ofthe rootstock. New leaf emerged faster (3.51 days) in hole insertion grafting but one cotyledon grafting recorded the highest success percentage (68.60 %). Cleft grafting not only took more days for graft union but also recorded least success percentage (11.20 %). Though alar @ 10 mgL*^ alar@50 mg L'* and cycocel @10 mg L'' were equally effective to improve success percentage but the combination of alar @ 10 mg L'^ + one cotyledon grafting recorded the highest success percentage of 81 per centwhen bitter gourd was grafted onto pumpkin. Application of alar @ 10 mg L'onto bottle gourd rootstock improved diameter (4.65 mm) and @ 50 mg L"'reduced height (12.61 cm). Among the grafting methods, graft united faster (3.69 days) in hole insertion method, while success percentage was tlie highest (86.40 %)for one cotyledon grafting. Growth regulator had no role in days taken for graft union and could not improve success percentage over distilled water. Application of alar @ lOmg L*' cycocel @ 10 mg L*' and 50 mg L*' were equally effective in reducing the height of bitter gourd rootstock. Alar @ 50 mg L"\ cycocel @ 10 mg L'and @ 50 mg L ' improved the diameter of the rootstock. Among grafting methods, hole insertion grafting exhibited faster union (3.57 days) with highest percentage of success (68.13 %). Cycocel @ 50 mg L"' recorded the highest percentage success among growth regulators. Based on the results of part I, grafts produced by cycocel @ 50 mgL*^ + hole insertion grafting in sponge gourd, alar @ 10 mgL'^ + one cotyledon grafting in pumpkin, distilled water (control) + one cotyledon grafting in bottle gourd and cycocel @ 50 mg L*^ + hole insertion grafting in bittergourd were selected and planted in main field along witli non grafted control in randomised block design replicated four times for evaluating growth, yield and quality of grafted bitter gourd. All grafts exhibited lower establishment over non grafted control.Bitter gourd grafted onsponge gourd andbottle gourd rootstocks as well asnon grafted control had similar vine length. Inlemodal length was more in non grafted control (6.00 cm). More branches were produced when bitter gourd and sponge gourd were used as rootstocks.Pumpkin rootstock produced longer primary root, higher root volume and root weight. Early appearance of first male and female flowers at lower nodes was also recorded in bitter gourd grafted on pumpkin rootstock. Though grafting did not significantly influence number of male flowers, the number of female flowers was higher in non grafted control and bitter gourd grafted on sponge gourd. Non grafted control, bitter gourd grafted on sponge gourd, bottle gourd and bitter gourd rootstock exhibited on par sex ratio.Non grafted control, bitter gourd grafted on pumpkin and bitter gourd recorded early harvest but bitter gourd grafted on sponge gourd and bottle gourd rootstock extended duration of the crop. Non grafted control and bitter gourd grafted on sponge gourd rootstock recorded more fruits per plant and yield per plant. Non grafted control, bitter gourd grafted onto bitter gourd and bitter gourd grafted on to sponge gourdexhibited on par fmit length. Bitter gourd grafted onto pumpkin, bitter gourd grafted onto sponge gourd, non grafted control and bitter gourd grafted onto bitter gourd had similar flesh thickness. Bottle gourd and bitter gourd rootstock enhanced fruit weight (181.50 g). Grafts did not differ for fruit girth, vitamin C content and organoleptic properties. Nongrafted control recorded highest B:C ratio (1.67)followed by sponge gourd (1.50). In conclusion, grafts of bitter gourd variety Treethi' can be produced with highest success percentage by cycocel @ 50 mgL'' + hole insertion graftingusing sponge gourd as rootstock, alar @ 10 mgL"' + one cotyledon grafting using pumpkin as rootstock, one cotyledon grafting without growth regulator using bottle gourd as rootstock. Among these grafts, sponge gourd as rootstock produced longest vine, more branches, longer crop duration, on par female flowers, sex ratio, fruits per plant and yield per plant compared to control. However, cultivation of non grafted plants recorded higher B:C ratio which necessitate further evaluation of biotic and abiotic tolerance of grafts for benefitting farming community.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 Characterization, host range and management of papaya ringspot virus (PRSV)(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2018) Atheena Harish; Anita Cherian, K