RESPONSE OF TUBEROSE (POLIANTHES TUBEROSA L.) PLANTS TO CHITOSAN AND SEAWEED FOLIAR APPLICATION

Chitosan and seaweed extract are natural stimulants that are used to improve plant growth and flowering. Therefore, two pot experiments on tuberose plants were conducted during the two consecutive seasons of 2017 and 2018 at Horticulture Research Station at Mansoura, Dakahlia Governorate, Egypt. The aim of the study was to evaluate the response of tuberose plant (single flowers known as Balady variety) to different concentrations of chitosan (CHT) and seaweed extract (SWE) rates on growth, flowering, bulb production and some chemical constituents. Tuberose plant was sprayed six times per season with different concentrations and rates of natural stimulants under study i.e. T1 (control), T2 (20 ppm CHT), T3 (40 ppm CHT), T4 (60 ppm CHT), T5 (0.5 cm³/l SWE), T6 (1.0 cm³/l SWE), T7 (1.5 cm³/l SWE), T8 (20 ppm CHT + 0.5 cm³/l SWE), T9 (40 ppm CHT + 1.0 cm³/l SWE) and T10 (60 ppm CHT + 1.5 cm³/l SWE). These ten treatments were laid out in a randomized complete block design (RCBD) with three replicates. Generally, chitosan or/and seaweed extract treated tuberose showed significant increase (p<0.05) in plant growth, flowering and bulb production. Chitosan at higher concentration plus the higher rate of seaweed extract T10 (60 ppm CHT + 1.5 cm³/l SWE) increased the plant height, leaf number per plant and leaf width as well as number of florets/spike, spike length, rachis length and spike fresh weight. In confirmation of this, the same treatment (T10) resulted in higher values of bulb diameter and dry weight of bulb compared to the other treatments under study and unsprayed plants. In most cases, total nitrogen, total phosphorus and potassium percentages in the leaves and bulbs as well as total chlorophyll in the leaves were significantly increased by using T10 followed by T4 and T9 compared to the other ones under study. Moreover, natural stimulants (chitosan and seaweed extract) should be frequently applied in the farms to get the best growth and flowering of the tuberose plants.