EFFECT OF CHITOSAN WITH DIFFERENT MOLECULAR WEIGHT ON THE GROWTH AND BULB YIELD OF ORIENTAL LILY ‘MONA LISA’

The potential of biodegradable and environmentally friendly substances that exhibit biostimulatory effects on plant growth and yield is now being exploited in horticultural production. This study evaluated the effect of chitosan on the growth, flowering, and yield of bulb of oriental lily ‘Mona Lisa’. Three types of chitosan differing in molecular weight (MW) were used: commercial chitosan (CCh, MW = 50,000–190,000 g/mol) and two forms of depolymerised chitosan (DCh 48, with a MW of ~48,000 g/mol, and DCh 154, with a MW of ~154,500 g/mol). The plants were watered twice with an aqueous solution of chitosan at a concentration of 2 g/l, with 100 ml of solution per pot. The control was plants watered with distilled water. Chitosan had a biostimulatory effect on the growth of lily plants. CCh increased the relative chlorophyll content of leaves (+11.3%), the fresh bulb weight (+11.0%), the bulb diameter (+12.3%) and the number of bulblets (+44.9%) compared with the control plants. DCh 154 significantly increased the fresh aboveground weight of plants (+31.3%), the fresh weight of leaves (+29.0%) and their number (+16.8%), the fresh weight of bulb (+12.3%) and their diameter (+11.0%), and the fresh weight of bulblet (+21.9%). DCh 48 increased the bulb diameter (+12.1%) and the number of bulblets (+45.4%), but decreased the length (-8.6%) and width of tepals (-6.8%) of the lily flowers. Finally, DCh 154 was the most effective in lily production. Using depolymerised chitosan as a biostimulant may contribute to developing new methods to produce high-quality lily plants.