RESPONSE OF SUMMER ONION TO METHYL JASMONATE AND CHITOSAN

Abstract

The field experiment was conducted at the Horticulture farm of Sher-e-Bangla Agricultural University, Dhaka from March to June, 2021 to find the effect of methyl jasmonate and chitosan on the growth, yield and quality in onion (BARI Piaz-5). The experiment was conducted with two factors; Factor A: Methyl Jasmonate (four levels) i.e., M 0 (Control), M 1 (25 µM), M 2 vi

(50 µM) and M 3 (75 µM) and Factor B: Chitosan (four levels) i.e., C 0 (Control), C 1 (2 µM), C 2 (4 µM) and C 3 (6 µM) followed by Randomized Complete Block Design with three replications. Plant growth, bulb development and their quality attributes significantly improved by the application of methyl jasmonate and 50 µM of methyl jasmonate performed the best for diameter of bulb (3.18 cm), single bulb weight (15.72 g), yield (10.48 t/ha) and β–carotene (12.02 mg/100g) whereas 75 µM of methyl jasmonate is best for length of bulb (4.01 cm) and Vitamin-C (17.24 mg/100g) comparatively than other treatments. Chitosan also increases the vegetative growth, yield and nutritional profile with the application of 4 µM of chitosan performed best for length of bulb (3.98 cm), single bulb weight (16.25 cm), yield (10.83 t/ha), TSS% (9.19) and Vitamin-C (14.83 mg/100g) comparatively than other treatments. For combined effect, 25 µM of methyl jasmonate with 4 µM of chitosan produced the highest length of the bulb (4.35 cm), diameter of the bulb (3.49 cm) and single bulb weight (18.33 g) comparatively than other treatment combinations. Whereas, the amount of β–carotene (14.23 mg/100g) in bulbs enhanced substantially at 25 µM of methyl jasmonate with 6 µM of chitosan application and the amount of Vitamin-C (19.60 mg/100g) increased significantly at 75 µM of methyl jasmonate with 4 µM of chitosan application. Results presume that the highest bulb yield (12.22 t/ha) was obtained by the application of 25 µM methyl jasmonate with 4 µM of chitosan which would be the best option to maintain better growth, yield and quality for cultivating onion in summer season.