EFFECT OF MEPIQUAT CHLORIDE AND GIBBERELLIC ACID ON LODGING RESISTANCE CHARACTERISTICS, FLAG LEAF COMPOSITION AND YIELD OF AROMATIC RICE CV. KALIJIRA

Abstract

Lodging in local aromatic rice variety is a very common scenario in Bangladesh and consequently farmers face losses and feel discouraged to grow aromatic rice though it has very high economic value compared to non-aromatic variety. A field experiment was conducted at the field of the Department of Agricultural Chemistry, HSTU, Dinajpur from July to December 2023 to evaluate the use of two PGR mepiquat chloride and gibberellic acid, which are synthetic crop growth regulators that showed reliable results on the aromatic rice cv. Kalijira. The experimental design was carried out in Randomized Complete Block Design (RCBD) with three replications, comprised of twelve treatments, and the results were observed both individually and interactive way. The first (PGR), mepiquat chloride consisted of eight different levels namely: M1 (control, no MC), M2 (50 ppm), M3 (75 ppm), M4 (100 ppm), M5 (125 ppm), M6 (150 ppm), M7 (175 ppm) and M8 (200 ppm). The second, gibberellic acid was applied at four distinct levels namely: G1 (control, no GA3), G2 (25 ppm), G3 (50 ppm), and G4 (75 ppm). The experimental design followed a morpho-physiological characteristics such as plant height, leaf and node number, internodal length, leaf blade length, leaf blade width, tiller number, stem width, chlorophyll, carotenoid; yield attributes such as panicle number, panicle length, effective and non-effective tiller number, filled and non-filled grain, total grain panicle-1, TGW, grain yield, straw yield, biological yield, harvesting index and nutrient content of flag leaf such as protein, nitrogen, phosphorus, potassium, sulfur, calcium and magnesium were assessed during this experiment. morphological data were collected at three different stages that such as pre-vegetative stage, tillering stage and reproductive stage. MC had shown inhibitory effect on the growth of the rice plants. At reproductive stage, positively the lowest plant height (130.58 cm), internodal length (15.45 cm) and the highest tiller number (22.041/hill) were found significant in M8 (200 ppm) over control but number of filled grain panicle-1 (218.08) in M4 (100 ppm), panicle length (38.417 cm) and 1000 grain weight (11.83 g) were found the highest in M6 (150 ppm). The highest grain yield plot-1 (1.340 kg) in G1×M8 (control, 200 ppm), straw yield (2.645 kg) in G2×M7 (25 ppm, 175 ppm), biological yield (3.683 kg) and HI (35.404) in G1×M8 (control, 200 ppm) were obtained and the application of GA3 has partially counteracted the impact of MC but its performance was not satisfactory increasing the yield of Kalijira variety. One of the main purposes of the investigation was to keep the plant height short to augment the yield proved to be an effective management strategy indeed. Now a range of doses of MC can be recommended to our farmers for practical use. Further studies are necessary to increase the production level which can be very beneficial to our farmers and our economy.