THE EFFECT OF INITIAL BULB SIZE ON SNOWDROP (GALANTHUS ELWESII HOOK.F.) BULB PROPAGATION BY CHIPPING

Abstract

Different size (5/6, 6/7, 7/8 and 8/9 cm circumference) of initial bulbs were chipped longitudinally into four equal-sized segments. The bulbil formation and length on the chips after the incubation in perlite at 20°C for 12 weeks were measured. The propagation ratio and the percentage of saleable bulbs were determined after one year growing cycle. The results showed that initial bulb size is critical for rapid propagation of Galanthus elwesii by chipping technique. After incubation, the bulbil formation on the chips was between 91.6 % and 97.5 %. Mean bulbil length on the chips varied from 6.6 mm for the smallest bulbs to 8.6 mm for the largest bulbs. Initial bulb size significantly affected the bulb propagation ratio and harvested bulb size. After one growing season, the number of bulbs obtained per initial bulb varied from 2.6 for 5/6 cm circumference to 5.7 for 8/9 cm bulbs. The ratios of harvested bulbs with a saleable size (larger than 4 cm) for 5/6, 6/7, 7/8 and 8/9 cm circumference were 4 %, 36 %, 59 % and 84 %, respectively. INTRODUCTION The greater snowdrop (Galanthus elwesii Hook.f.) is the most important and endangered species of wild-collected bulbs in Turkey’s flora. It has been collected from the Western Taurus Mountains and exported for more than hundred years. The bulb trade should change away from unsustainable wild collection towards sustainable cultivated propagation in order to protect Galanthus elwesii. Chipping is a good method for Narcissus propagation (Fenlon et al., 1990). The apical dominance is broken by cutting bulb longitudinally into chips. It has been shown that Galanthus nivalis can be propagated successfully by chipping technique (Hanks, 1991; Leeuwen and Weijden, 1997). This study aimed to investigate chipping technique and to determine the effect of initial bulb size on propagation of Galanthus elwesii. MATERIAL AND METHODS Plant Material: The bulbs of snowdrop (Galanthus elwesii Hook.f.) collected from the Western Taurus Mountain were obtained from an exporter company at the end of May. Chipping: In June, after removing the outer scales and outer crust of the basal plate, the top of bulbs were cut off about 0.5 cm. The bulbs were then cut longitudinally by hand into four equal sized segments (chips) as described by Hanks and Phillips (1982). Incubation: The chips later were dipped in a fungicide solution with 1 % captan + 0.4 % benomyl (Benlate) for half an hour. After dipping and draining, the chips were placed in thin polyethylene bags filled with coarse perlite and distilled water (4: 1, v/v). The bags were then shaken by providing a good mixture of chips with perlite and sealed by ensuring air space at top. The bags were stored in single layers in the dark at 20°C for 12 weeks. Growth: After incubation, the chips were dipped in the same solution used before incubation for 15 minutes. Six volumes of loamy soil, 4 volumes of coarse sand, 3 volumes of leaf mould and one volume of farmyard manure were mixed. In addition, 6.6 ml super phosphate per liter of the mixture was added. Growth medium was sterilized by Proc. IS on Sust. Use Of Plant Biodiv. Eds. E. Duzyaman &Y.Tuzel Acta Hort. 598, ISHS 2003 70 steam before planting in September. Growth was in polystyrene box (30x45x16 cm) placed in an unheated glasshouse. At the end of one growing season, the bulbs were lifted at the end of May. Experimental Treatments: The initial bulbs sizes 5/6, 6/7, 7/8, and 8/9 cm circumference were used for the experiment as a variable. Measurements: The bulbil formation (the percentage of chips with visible bulbil) and the length of each bulbil were measured after incubation. Total number and the size (the largest circumference) of bulbs were determined after harvest. The propagation ratio (the number of harvested bulbs per initial bulb) and the percentage of saleable bulbs (larger than 4 cm size) were calculated. Statistical Analysis: The experiments were designed as to randomize blocked with 3 replicates. Each replication included 40 chips from 10 bulbs. The data were statistically analyzed using ANOVA and by Duncan test.