J. Hortl. Sci. Vol. 4 (2): 128-133, 2009 Effect of paclobutrazol and benzyl adenine on oriental lily hybrids Puja Sharma, Y.D. Sharma and Y.C. Gupta Department of Floriculture and Landscaping Dr. Y.S. Parmar University of Horticulture and Forestry Nauni, Solan, H.P.-173230, India E-mail: pujasharma03@gmail.com ABSTRACT Studies on the effect of growth regulators viz., Paclobutrazol and Benzyl Adenine (PBZ and BA, respectively) on Oriental Lily Hybrids, ‘Star Gazer Pink’ and ‘Star Gazer White’ in the second year were carried out at Department of Floriculture and Landscaping, Dr. Y.S. Parmar University of Horticulture and Forestry, Nauni, Solan (H.P). The effect of growth regulators applied in the first year, was studied on growth and flowering of Oriental lily hybrids in the second year. Plant height and number of leaves plant-1 were recorded maximum when PBZ 25 ppm was applied in the first year. Maximum plant height and number of leaves plant-1 were found in ‘Star Gazer White’ (84.46 cm; 35.04 cm). Bulbs of ‘Star Gazer White’ when dipped in PBZ 25 ppm for 12 h in the first year resulted in maximum plant height (102.50 cm) in the second year. Leaf area in the second year was recorded maximum in ‘Star Gazer White’ (34.40 cm2) when PBZ 50 ppm was applied as bulb dip in the first year. Flower buds were initiated earlier in ‘Star Gazer White’ (84.48 days) as compared to ‘Star Gazer Pink’ (85.90 days). Days to bud initiation were also recorded minimum (75.81 days) when PBZ 25 ppm was applied as pre-plant bulb dip. More number of flowers plant-1 was recorded in ‘Star Gazer White’ (5.42) which lasted longer on stems (16.77 days). Bulbs dipped in growth regulators in the first season produced maximum number of flowers plant-1 (5.72) and duration of flowering was also maximum (18.28 days). Key words: PBZ, BA, Lilium, Star Gazer Pink, Star Gazer White INTRODUCTION Lilium is one of the most beautiful geophytes in the flower world and ranks among the top ten traded cut flowers. Oriental lilies occupy a prestigious position among the group owing to its large fragrant flowers and long vase life. The size of bulbs reduces after flowering in Lilium. These bulbs cannot be reused for commercial flower production due to their small size which subsequently produces poor quality flowers. Although, Lilium cultivation is gaining popularity among the farmers in India but one of the major bottlenecks in large scale cultivation is the high cost of planting material which has to be purchased every year. The present investigation was therefore planned to increase the size of Lilium oriental hybrid bulbs by using growth regulators (PBZ and BA) for the production of commercial flower crop. MATERIAL AND METHODS Studies on two oriental lily hybrids, viz. ‘Star Gazer Pink’ and ‘Star Gazer White’ were carried out at the experimental farm of Department of Floriculture and Landscaping, Dr. Y.S. Parmar University of Horticulture and Forestry Nauni, Solan (H.P) during 2000-2001. Bulbs of uniform size (10/12 cm) were planted in January and growth regulators viz., Paclobutrazol (PBZ) and Benzyl Adenine (BA) were applied (at two levels each i.e., 25 ppm and 50 ppm). As treatment, 3 methods of application were selected i.e., pre plant bulb dip (12h), foliar spray (up to the level of droplet formation) and soil drench (200 ml around stem base). Foliar spray and soil drench applications were made when plants attained a height of 15 cm. The plants were raised as per standard cultural practices. Plants were debudded and the bulbs were harvested after drying of the plant. Data on bulb size of the harvested bulbs is presented in Table 1. After cold treatment of bulbs at 4ºC for two months in moistened sawdust, planting was done and the crop was grown following standard cultural practices. No growth regulator treatment was applied in the second year. Different vegetative and flowering parameters were recorded from time to time. Overall the experiment consisting of 30 treatment combinations including 2 cultivars, 5 levels parameters were recorded from time to time. Overall the experiment consisting of 30 treatment combinations including 129 2 cultivars, 5 levels of growth regulators and 3 levels of methods of application of growth regulators was conducted in factorial randomised block design. Recorded data was subjected to analysis of variance. RESULTS AND DISCUSSION Bulb circumference was found to be better in PBZ 25 ppm followed by PBZ 50 ppm when compared to other treatments (Table 1). Dipping the bulb gave better results than other methods of application (Table 1). It is evident from the data (Table 2a) that mean height of plants of ‘Star Gazer White’ was more (84.46 cm) as compared to ‘Star Gazer Pink’ (81.38 cm). Bulbs/plants treated with PBZ 25 ppm in the first year produced plants of maximum height in both ‘Star Gazer White’ (93.13 cm) and ‘Star Gazer Pink’ (90.20 cm). The effect of dip and drench treatments did not differ significantly from each other. Interaction data (Table 2b) also shows that maximum plant height (102.50 cm) was recorded when bulbs were dipped in PBZ 25 ppm in the first year. The effect of PBZ in increasing the plant height in second year was due to better bulb size. In a similar study Simmonds and Cumming (1977) found that the inhibitory effects of the retardants CCC and ancymidol on stem elongation were carried over into the replacement stems of Lilium cultivar ‘Enchantment’ in the next growing season but the degree of inhibition was considerably reduced. On the contrary, ethrel, which inhibited stem elongation of cvs ‘Enchantment’ and ‘Harmony’ during the first season’s growth produced a significant increase in stem elongation, during the second season’s growth. More number of leaves per plant (Table 3) was recorded in ‘Star Gazer White’ (35.04) as compared to ‘Star Gazer Pink’ (34.07). Number of leaves was also maximum Table 1. Bulb circumference (cm) of harvested bulbs of Lilium cultivars ‘Star Gazer Pink’ and ‘Star Gazer White’ upon application of growth regulators Growth regulator Cultivar (cv.) Mean Method of Application (M) treatment (ppm) (T) Star Gazer Star Gazer Pink White Dip Drench Spray PBZ 25 16.73 17.30 17.02 18.85 16.60 15.60 50 16.00 16.27 16.13 17.65 16.00 14.75 BA 25 15.57 16.04 15.81 16.90 16.15 14.37 50 14.93 15.90 15.42 16.55 15.15 14.55 Control (distilled water) 13.60 14.10 13.85 13.85 13.85 13.85 Mean 15.37 15.92 16.76 15.55 14.62 CD 0.05 cv. 0.24 T 0.38 M 0.30 T x M 0.66 in ‘Star Gazer White’ (40.22) in PBZ 25 ppm treated plants /bulb in the first year. Plants treated with BA also produced more number of leaves per plant. Number of leaves on a plant could directly be correlated with plant height in the respective treatment, which could further be correlated with their respective bulb size at the time of planting. Data (Table 4a) also shows that more leaf area per plant (28.09 cm2) was produced by plants of cultivar ‘Star Gazer White’ as compared to ‘Star Gazer Pink’ (27.05 cm2). Maximum leaf area per plant (28.81cm2) was also recorded when PBZ 25 ppm was applied in the first year. BA at both the levels also showed an increase in leaf area over control. Leaf area per plant was recorded maximum when PBZ 25 ppm was applied as pre plant bulb dip (35.25 cm2) in the first season. Growth regulators applied as bulb dip produced comparatively larger leaf area (29.49 cm2) in the second growing season as compared to drench and spray application. Data in Table 4b also reveals the similar results i.e. leaf area per plant was maximum (34.40 cm2) when PBZ 50 ppm was applied as pre plant bulb dip in ‘Star Gazer White’. Increased leaf area can again be correlated to the increased bulb size and circumference in the respective treatments. Results shows that the application of PBZ in the first year has significantly enhanced all vegetative parameters in the second year. It is apparent from the data that the retardation effect of PBZ was not carried to the next generation. Although the metabolic fate of triazoles has not been studied in great detail but a few studies suggest that root applied PBZ is acropetally transported to the leaves primarily via xylem in apple (Lever, 1986; Richardson and Quinlan, 1986). Further soil applied PBZ is relatively immobile and transpiration by leaves is required to pull the chemical to meristematic region. Only a small portion reaches the J. Hortl. Sci. Vol. 4 (2): 128-133, 2009 Effect of paclobutrazol and benzyl adenine on oriental lily hybrids 130 growing point where it can effectively inhibit the growth (Davis et al, 1988). As far as foliar applications of the PBZ is concerned, Wang et al (1986) reported that foliar applied PBZ was not transported to stem or roots and thus has localized effects. In the light of above studies it could be concluded that in the present experiment the persistence and further movement of PBZ into daughter bulbs is either absent or negligible. Lever (1986) has proposed that a threshold concentration of paclobutrazol is needed in the shoot apex to maintain the GA biosynthesis suppression. It seems that paclobutrazol, if present in the second year bulbs, is in a concentration lower than the threshold for inducing height reduction in the next growing season. Increased plant height, more number of leaves and larger leaf area, may therefore be attributed to larger quantity of food reserves in the bulbs. In Lilium Asiatic Hybrids ‘Elite’ and ‘Jolanda’, Lee and Yang (1997) have found that the stem height, node number and leaf area are positively correlated with bulb circumference. Data in Table 5 shows that flower buds were initiated earlier in cultivar ‘Star Gazer White’ (84.48 days) as compared to ‘Star Gazer Pink’ (85.90 days). In ‘Star Gazer White’, PBZ 50 ppm applied in the first season resulted in earliest flower bud initiation (80.31 days). It has been observed by Table 2 a. Effect of growth regulators applied in the first year on plant height (cm) in Lilium cultivars ‘Star Gazer Pink’ and ‘Star Gazer White’ Growth regulator Cultivar (cv.) Mean Method of Application (M) treatment (ppm) (T) Star Gazer Star Gazer Pink White Dip Drench Spray PBZ 25 90.20 93.13 91.67 98.25 90.95 85.10 50 90.13 90.33 90.23 96.15 92.75 81.80 BA 25 77.40 84.33 80.87 77.40 84.90 80.30 50 83.98 85.68 84.83 84.37 88.32 81.81 Control (distilled water) 65.20 68.80 67.00 67.00 67.00 67.00 Mean 81.38 84.46 84.77 84.78 79.20 Method of application Dip 81.82 87.73 Drench 82.49 87.08 Spray 79.84 78.56 CD 0.05 cv. 0.75 T 1.19 M 0.92 cv. X T 1.69 cv. X M 1.31 T X M 2.08 Table 2 b. Interaction effect of growth regulators applied in the first year on plant height (cm) in Lilium cultivars ‘Star Gazer Pink’ and ‘Star Gazer White’ Growth regulator Star Gazer Pink Star Gazer White treatment (ppm) (T) Dip Drench Spray Dip Drench Spray PBZ 25 95.40 89.20 86.00 102.50 92.70 84.20 50 94.90 91.10 84.40 97.40 94.40 79.20 BA 25 73.40 79.40 79.40 81.40 90.40 81.20 50 80.20 87.53 84.20 88.53 89.10 79.40 Control (distilled water) 65.20 65.20 65.20 68.80 68.80 68.80 CD 0.05 cv. X T X M 2.93 Puja Sharma et al J. Hortl. Sci. Vol. 4 (2): 128-133, 2009 131 Table 3. Effect of growth regulators applied in the first year on number of leaves per plant in Lilium cultivars ‘Star Gazer Pink’ and Star Gazer White’ Growth regulator Cultivar (cv.) Mean treatment (ppm) (T) Star Gazer Pink Star Gazer White PBZ 25 36.60 40.22 38.41 50 35.13 40.10 37.62 BA 25 33.73 32.62 33.18 50 32.77 34.07 33.42 Control (distilled water) 32.10 28.20 30.15 Mean 34.07 35.04 Method of application Dip 36.06 34.77 35.42 Drench 34.16 34.87 34.52 Spray 31.98 35.48 33.73 CD 0.05 cv. 0.96 T 1.53 M 1.18 cv.X T 2.16 cv.X M 1.68 Table 4 a. Effect of growth regulators applied in the first year on leaf area (cm2) in Lilium cultivars ‘Star Gazer Pink’ and `Star Gazer White’ Growth regulator Cultivar (cv.) Mean Method of Application (M ) treatment (ppm) (T) Star Gazer Pink Star Gazer White Dip Drench Spray PBZ 25 28.80 28.82 28.81 35.25 27.43 26.75 50 27.23 29.34 28.29 32.15 26.37 26.35 BA 25 27.63 26.93 27.28 27.65 26.95 27.25 50 27.49 28.97 28.23 30.15 28.20 26.33 Control (distilled water) 24.10 26.40 25.25 25.25 25.25 25.25 Mean 27.05 28.09 29.49 26.84 26.39 Method of application Dip 28.58 30.40 Drench 26.16 27.52 Spray 26.41 26.36 CD 0.05 cv. 0.48 T 0.75 M 0.58 cv.X T 1.07 cvX M 0.83 T X M 1.32 Table 4 b. Interaction effect of growth regulators applied in the first year on leaf area (cm2) in Lilium cultivars ‘Star Gazer Pink’ and Star Gazer White Growth regulator Star Gazer Pink Star Gazer White Treatment (ppm) (T) Dip Drench Spray Dip Drench Spray PBZ 25 31.40 26.70 28.30 33.10 28.17 25.20 50 29.90 25.40 26.40 34.40 27.33 26.30 BA 25 28.40 26.40 28.10 26.90 27.50 26.40 50 29.10 28.20 25.17 31.20 28.20 27.50 Control (distilled water) 24.10 24.10 24.10 26.40 26.40 26.40 CD 0.05 cv. X T X M 1.86 Effect of paclobutrazol and benzyl adenine on oriental lily hybrids J. Hortl. Sci. Vol. 4 (2): 128-133, 2009 132 Table 5. Effect of growth regulators applied in the first year on days to bud initiation in Lilium cultivars ‘Star Gazer Pink’ and Star Gazer White’ Growth regulator Cultivar (cv.) Mean Method of Application (M) treatment (ppm) (T) Star Gazer Pink Star Gazer White Dip Drench Spray PBZ 25 82.56 80.51 81.54 75.81 82.16 86.63 50 84.91 80.31 82.54 79.07 82.67 86.08 BA 25 85.81 85.91 85.86 83.84 85.68 88.05 50 87.11 87.36 87.23 84.95 87.57 89.18 Control (distilled water) 89.12 88.30 88.71 88.71 88.71 88.71 Mean 85.90 84.48 82.48 85.36 87.73 Method of application Dip 84.44 80.51 Drench 86.11 84.61 Spray 87.15 88.32 CD 0.05 cv. 1.26 T 1.99 M 1.54 cv.X M 2.18 T X M 3.45 Table 6. Effect of growth regulators applied in the first year on number of flowers per plant in Lilium cultivars ‘Star Gazer Pink’ and Star Gazer White’ Growth regulator Cultivar (cv.) Mean Method of Application (M) treatment (ppm) (T) Star Gazer Pink Star Gazer White Dip Drench Spray PBZ 25 5.66 6.36 6.01 6.65 5.95 5.45 50 5.56 6.03 5.80 6.50 5.70 5.20 BA 25 5.16 5.66 5.41 5.95 5.25 5.05 50 5.00 5.23 5.11 5.75 4.85 4.75 Control (distilled water) 3.70 3.80 3.75 3.75 3.75 3.75 Mean 5.02 5.42 5.72 5.10 4.84 CD 0.05 cv. 0.098 T 0.15 M 0.12 cv.X T 0.22 T X M 0.27 Table 7 a. Effect of growth regulators applied in the first year on duration of flowering (days) in Lilium cultivars ‘Star Gazer Pink’ and Star Gazer White’ Growth regulator Cultivar (cv.) Mean Method of Application (M) treatment (ppm) (T) Star Gazer Pink Star Gazer White Dip Drench Spray PBZ 25 16.83 19.13 17.98 22.25 16.70 15.00 50 16.83 18.10 17.47 20.60 16.30 15.50 BA 25 15.57 15.97 15.77 17.15 15.75 14.40 50 15.93 15.93 15.93 16.90 15.35 15.55 Control (distilled water) 14.30 14.70 14.50 14.50 14.50 14.50 Mean 15.89 16.77 18.28 15.72 14.99 CD 0.05 cv. 0.23 T 0.37 M 0.28 cv.X T 0.52 T X M 0.64 J. Hortl. Sci. Vol. 4 (2): 128-133, 2009 Puja Sharma et al 133 earlier workers also that plants with more vegetative growth initiated earlier flowering, which could be associated with higher plant height, more leaf number and leaf area in this treatment. The decrease in days to bud initiation could therefore be associated to larger bulb size in these treatments. More number of flowers per plant (Table 6) was recorded in cultivar ‘Star Gazer White’ (5.42) as compared to ‘Star Gazer Pink’ (5.02). Maximum number of flowers per plant (6.01) were recorded when PBZ 25 ppm was applied in the first year. Growth regulators applied as bulb dip in the first season produced more number of flowers per plant (5.72). Maximum number of flowers per plant (6.65) were recorded when PBZ 25 ppm was applied as pre-plant bulb dip in the first year. The effectiveness of pre-plant bulb dip in the first year in increasing number of flowers per plant in the subsequent year could be correlated to larger bulb size in these treatments. Misra et al (2000) while studying the effect of bulb size on growth and flowering, flowering behaviour of Tuberose reported that the larger sized bulbs produced the highest number of spikes per plant. Longer duration of flowering (Table 7a) was recorded in cultivar ‘Star Gazer White’ (16.77 days) as compared to ‘Star Gazer Pink’ (15.89 days). Flowers lasted longer (17.98 days) on plants when PBZ 25 ppm was applied in the first season. Both the concentrations of PBZ and BA increased duration of flowering over control. Duration of flowering could again be correlated to the bulb size (Table1) in the respective treatments. Maximum duration of flowering (22.25 days) was recorded when PBZ 25 ppm was applied as bulb dip in the first year. Interaction data (Table 7b) also shows that maximum duration of flowering (24.1 days) was achieved in ‘Star Gazer White’ raised from the bulb which were treated in the first year with PBZ 25 ppm. In cultivar ‘Star Gazer Pink’ also same treatment resulted in maximum duration of flowering (20.4 days). Table 7 b. Interaction effect of growth regulators applied in the first year on duration of flowering (days) in Lilium cultivars ‘Star Gazer Pink’ and Star Gazer White Growth regulator Star Gazer Pink Star Gazer White reatments (ppm) (T) Dip Drench Spray Dip Drench Spray PBZ 25 20.40 15.20 14.90 24.10 18.20 15.10 50 19.90 15.40 15.20 21.30 17.20 15.80 BA 25 17.10 15.80 13.80 17.20 15.70 15.00 50 16.90 15.20 15.70 16.90 15.50 15.40 Control (distilled water) 14.30 14.30 14.30 14.70 14.70 14.70 CD 0.05 cv. 0.90 Treatment of bulbs with PBZ in the first season resulted in the development of bigger sized daughter bulbs and ultimately helped in production of more number of flowers, which flowered for longer duration in comparison to untreated bulbs. Roxas (1986), while working with Lilium regale concluded that quantitative and qualitative flower yield parameters are strongly influenced by bulb size. 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