1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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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 Characterisation of pumpkin (Cucurbita moschata duch.) varieties through morphological and molecular markers(Department of Seed Science and Technology, College of Horticulture, Vellanikkara, 2019) Agina Gopan; Rose Mary FranciesPumpkin (Cucurbita moschata Duch.), a crop of Central Mexican origin belonging to the family Cucurbitaceae, is popularly cultivated and valued in Kerala as a vegetable. The tender, large and often round immature fruits of pumpkin with a thick, smooth to slightly ribbed skin, which is mostly deep yellow to orange in colour, is an integral part of the Kerala cuisine. Despite its popularity in the state, few high yielding varieties are in cultivation. To ensure increased production, availability of high quality seeds of improved varieties or hybrids has to be guaranteed. Pumpkin being a cross pollinated crop, occurrence of cross contamination during its seed programme cannot be overruled. Hence, ensuring the purity and identity of seeds of the variety before sale becomes inevitable. Considering the importance of varietal identification in maintaining the genuineness and quality of seeds in seed production programmes, the present investigation envisaged to characterise six pumpkin varieties in the seed chain using morphological and molecular markers, and to generate fingerprints or molecular ID’s of the six varieties using selected polymorphic Inter-simple sequence repeats (ISSR) and Simple sequence repeats (SSR) markers. Characterisation of pumpkin varieties based on 28 quantitative and 16 qualitative traits was done using DUS and NBPGR descriptors. Qualitative vegetative traits like tendril characteristics (presence or absence of tendril, nature of coiling and branching) and leaf shape were not useful for grouping the varieties. Similarly, among the qualitative fruit characteristics, waxiness of mature fruit skin also proved insufficient to distinguish the varieties. Fruit shape was round flat in varieties Ambili, Suvarna and CO-2, while it was elongate/oblong in Saras, club shaped in CO-1 and flattish round in Arka Chandan. Based on qualitative traits, variety Arka Chandan could be clearly distinguished from the other varieties based on poor early growth vigour, moderately incised leaf blade margin, absence of silver patches on leaf blade, flattish round fruit shape, light green immature fruits and dark orange fruit flesh colour. In addition, the seeds of the Arka Chandan had a characteristic marking on the dorso-ventral surfaces unlike other varieties. Quantitative traits proved to be more useful than the qualitative traits for effective identification and categorisation of varieties. Results revealed that among the quantitative traits studied, leaf dimensions (blade length and width) and length of petiole could not be employed for distinguishing the six varieties. Variety Ambili flowered the earliest (49.25 days) and also possessed highly pubescent leaves, while variety Arka Chandan was late flowering (68.00 days). Peduncle length, fruit length and most of the seed dimensions (seed count per fruit, 100 seed weight, width and thickness of seed) was the least in this variety. In general, the size of seeds in varieties CO-1 and CO-2 was higher than those of others. Cluster analysis grouped Arka Chandan (Cluster V) and varieties CO-1 and CO-2 (Cluster IV) the farthest with an inter-cluster distance of 212.25. Principal component (PC) analysis indicated that trait components in PC1 registered an Eigen value of 16.79 and the traits in PC1 contributed 58 per cent to the variability among the varieties, emphasising their utility in identification of varieties. Among the 33 ISSR markers, 28 exhibited polymorphism. The total number of amplicons detected by an individual primer ranged from 4 in UBC-818 to 18 in UBC-847. High polymorphic information content (PIC) value was observed in UBC-809, whereas, low PIC was recorded in UBC-818. The six varieties grouped into four clusters based on ISSR binary data. Out of 20 SSR markers used for genotyping, only five showed polymorphism. The highest Jaccard’s similarity value (1.00) was observed between Saras and Suvarna. The most dissimilar varieties were Saras and Arka Chandan, and Suvarna and Arka Chandan, with a similarity coefficient of 0.12 each. The clustering algorithm grouped the varieties into four clusters. The polymorphic SSRs could be efficiently utilised for distinguishing Arka Chandan and therefore can prove useful for testing the genetic purity of this variety. Unique bands producing ISSR markers were used to generate variety specific DNA fingerprints. No single primer per se proved useful in distinguishing all six pumpkin varieties. However, ISSR primer UBC-822 could distinguish four out of six varieties studied. It produced unique amplicons of size 473 bp, 552 bp, 1403 bp and 517 bp, respectively in Ambili, Saras, CO-1 and Arka Chandan, proving its utility in testing for genuiness and purity of seed lot. In general, it can be concluded that the correlation that existed between morphological and molecular assessments was of medium magnitude. The absence of high consensus between the assessments should not be considered a limitation of these tools to characterize and quantify variability. It only indicates that both morphological and molecular characterisation is important and play a complementary role in providing a better understanding and differentiation of the pumpkin varieties.