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ThesisItem Open Access Evaluation of propagation techniques and rootstock studies of mango (Mangifera indica L.)(Department of Pomology and Floriculture College of Agriculture, Vellayani, 2019) Reshma, U R; KAU; Simi, SAn investigation entitled “Evaluation of propagation techniques and rootstock studies of mango (Mangifera indica L.)” was carried out during 2016– 2019 at Department of Pomology and Floriculture, College of Agriculture, Vellayani. The investigation aimed to screen local mango varieties/ collections for polyembryony, to study the pre-sowing treatments, sowing positions and age of stone after extraction from fruit on germination of mango stones, to screen local mango varieties for use as dwarfing rootstocks and to study the effect of two propagation methods in three modified environments on three varieties of scions. Out of twenty local mango varieties collected from different parts of Thiruvananthapuram district of Kerala, seventeen were polyembryonic while three were monoembryonic. The mango var. Kappa Manga (T19) recorded the highest germination per cent (73.33 %), germination index (2.41) and seedling vigour index on growth basis (2795.20). The mean germination time (17.50 days) was the least in Vellari Varikka (T18). Kotookonam Varikka recorded the highest per cent polyembryony (65.13 %) and produced the highest number of plantlets per stone (5.00). Microsatellite analysis of all the plantlets from two varieties viz., Kotookonam Varikka and Kochu Kilichundan that exhibited the highest percentage of polyembryony were done using 20 SSR primers and the products were compared with their respective mother plants. All the seedlings obtained from the respective stones had identical SSR profile to the mother plant, which indicated nucellar origin of seedlings having similar genetic composition to the mother plant. The zygotic seedling might have degenerated at very early stage of growth and the remaining nucellar seedlings were all vigorous. To study the effect of pre-sowing treatments, sowing positions and age of stone after extraction from the fruit on germination of mango stones, an experiment was laid out in completely randomized design with 42 treatment combinations replicated thrice. The treatments comprised two sowing positions viz., flat (S1) and stalk end up (S2), three age of stones after extraction from fruit, viz., freshly extracted (A1), 10 days (A2) and 20 days after extraction (A3) and seven pre-sowing treatments viz., 100 ppm GA3 (T1), 200 ppm GA3 (T2), 1 ppm KNO3 (T3), 2 ppm KNO3 (T4), cow dung slurry(T5), water (T6), control [without treatment (T7)] and their combinations. The variety Kotookonam Varikka was utilized for the study. The stalk end up sowing method and freshly extracted stones proved to be the best with respect to germination and vigour of mango seedlings. The stones treated with 200 ppm GA3 required minimum number of days for initiation of germination (22.62 days), 50 % germination (31.78 days), exhibited the highest germination percentage (62.59 %), rate of germination (0.48), vigour index on growth basis (2310.02) and weight basis (657.09). Treatment with 100 ppm GA3 produced the highest seedling length (35.70 cm) and dry weight (10.39 g) at 4 month after sowing (MAS). Interaction effects also indicated that the freshly extracted stones sown by stalk end up method after treatment with 200 ppm GA3 for 24 hours resulted in significantly the highest germination rate (0.74) and the least number of days for initiation of germination (13.00 days). An attempt was made to identify the local mango varieties for use as dwarfing rootstock based on morphological, physiological and anatomical features. The experiment was laid out in completely randomized design (CRD) with ten genotypes replicated thrice. At 4 MAS, the lowest seedling length (29.48 cm) was noticed in Kochu Kilichundan (T4), followed by Unda Varikka (T10) and the highest seedling length (56.11 cm) was in Kappa Manga (T8). Moreover, the germination percentage of Kochu Kilichundan (46.67 %) was on par with all the varieties except Kappa Manga (71.11 %) along with the lowest vigour index-I and vigour index- II was on par with Unda Varikka. However, the least dry matter of seedling (9.66 g) was recorded in Unda Varikka. At 6 MAS, majority of the morphological features were the highest in Kappa Manga. The highest starch content (8.53 %) was estimated to be in Kasthuri (T2). Kochu Kilichundan and Unda Varikka exhibited dwarfism with less plant height (38.77 cm and 40.20 cm respectively), but the former had the least internodal length (3.16 cm). The highest values for number of leaves (23.20), leaf length (12.59 cm), leaf width (4.07 cm) and average leaf area (22.57 cm2) were recorded in Unda Varikka compared to Kochu Kilichundan. However, the highest number of roots (28.53), root length (35.02 cm), dry weight of root (3.10 g), dry weight of shoot (1.46 g) and stomatal density (51.68) were recorded in Kochu Kilichundan while total leaf area of the two varieties were on par. Moreover, Kochu Kilichundan had the highest phenol content in apical bud (60.57 mg/g) and leaves (29.03 mg/g) and bark percentage of root (23.69 %) and shoot (34.02 %) of all the varieties. Membrane stability index, relative water content, transpiration rate and leaf temperature were non-significant. The anatomical studies revealed the highest phloem-xylem ratio both in stem (0.99) and root (1.35) and the least total conduit area of root (6.38 mm2) in Unda Varikka while the least total conduit area of stem (5.42 mm2) was in Kochu Kilichundan, indicating the dwarfing potential of both Kochu Kilichundan and Unda Varikka. To study the effect of propagation methods and modified environments on different varieties of scion, an experiment was laid out in completely randomized design with eighteen treatment combinations replicated thrice. The treatments comprised two propagation methods viz., epicotyl (P1) and softwood grafting (P2), three modified environments viz., climate controlled [fan and pad (M1)], humid chamber (M2) and natural shade [75 % shade (M3)] and three varieties of scions, Kalapady (V1), Neelum (V2) and Kotookonam Varikka (V3) and their combinations. The grafts produced by epicotyl grafting resulted in significantly higher scion length (15.80 cm), had the least number of days for leaf opening (15.07days) , first (12.19 days) and last sprouting (22.02), higher number of grafts sprouted at weekly intervals, higher initial success percentage (83.21 %), graft establishment percentage (72.22 %), number of leaves per graft (15.40), leaf length (15.27 cm), leaf width (3.36 cm), leaf area (41.69 cm2), number of nodes on scion (21.63), internodal length (5.20 cm), number of growth flushes per graft (1.76), lower number of days taken between grafting to first vegetative flush (26.06 days) as well as to second vegetative flush (44.98 days) and higher final survival of grafts (65.19 %). The micro climate controlled by fan and pad system produced most conducive conditions for vegetative growth of mango grafts. Among the different varieties of scions, Kotookonam Varikka recorded the highest girth of rootstock, girth of scion, length of scion, graft height, spread of plant in N-S direction and E-W direction, number of grafts sprouted at weekly intervals, initial success percentage, percentage of graft establishment, leaf width, number of nodes on scion, internodal length, number of growth flushes per graft and the lowest number of days taken between grafting and second vegetative flush. Kalapady recorded the least number of days for first and last sprouting, leaf opening and for first vegetative flushing. The greatest sprout length, number of leaves, leaf length and leaf area were recorded in Neelum. The scion did not influence the final survival of grafts. The treatment combinations had no influence on root length. Interaction effects also confirmed that epicotyl grafting method with Kotookonam Varikka variety as scion under controlled conditions using fan and pad system resulted in grafts with higher scion length (16.80 cm), sprout length (6.05 cm), more number of growth flushes per graft (2.33) and earlier second vegetative flush (40.87 days). Based on the above findings it could be concluded that the highest percentage of polyembryony was in Kotookonam Varikka and microsatellite analysis revealed the nucellar origin of plantlets and confirmed higher vigour of nucellar seedlings over sexual seedling. Stalk end up sowing of freshly extracted stones treated with 200 ppm GA3 for 24 hours recorded better germination and vigour of mango seedlings. The mango variety Kochu Kilichundan and UndaVarikka were identified as promising rootstocks to impart dwarfness and Kochu Kilichundan was superior in most of the morphological and physiological characters. The epicotyl grafts of Kotookonam Varikka under controlled climate by fan and pad system recorded better graft establishment, survival, vegetative and growth parameters.