INVESTIGATION OF CHLOROPHYLL CONTENT OF LEAVES, GROWTH AND YIELD OF THREE AROMATIC CULTIVARS UNDER PLANT GROWTH REGULATOR –GIBBERELLIC ACID

Abstract

A field experiment was conducted to study the effect of gibberellic acid (GA3) on morpho-physiological, yield and yield characters of three aromatic rice varieties cv. Kataribhog, Chinigura, and Kalijira. Gibberellic acid (GA3) was applied @ 0, 25, 50 and 75 ppm at vegetative and pre-flowering stages. The growth parameters such as plant height, leaf number, leaf length, leaf width, number of total tiller, number of effective tiller and yield and yield attributes were studied along with biochemical parameters like proline and chlorophyll pigments of flag leaves. The GA3 @ 50 ppm showed the better stimulatory effect on growth parameters. Different levels of GA3 had also positive effect on chlorophyll-a, chlorophyll-b and total chlorophyll contents of aromatic rice flag leaf. The maximum amount of chlorophyll-a 22.8 mg g-1 was found in Chinigura using 50 ppm and the lowest amount of chlorophyll-a was 19.1 mg g-1 produced in Kalijira under controlled condition followed by Kataribhog (19.2 mg g-1). The highest amount of total chlorophyll content was observed (30.55 mg g-1) in Chinigura using 50 ppm treatments while the lowest amount of total chlorophyll content (25.54 mg g-1) was observed in Kalijira followed by Kataribhog (25.58 mg g-1) under controlled condition treatments. Some yield contributing characters of aromatic rice such as grain number per panicle, filled grain per panicle, and 1000-grain weights were significantly increased due to application of different levels of GA3. Effective tiller, panicle length, total grain yield, grain number per panicle, filled grain per panicle, thousand grain weights, and harvest index were also influenced by the different levels of GA3. The maximum number of effective tiller (15.00) was found in Chinigura rice variety at 50 ppm GA3.The highest panicle length (26.50 cm) was recorded in Chinigura rice variety at 50 ppm GA3. The highest grain number per panicle (170.78) was obtained in Chinigura rice variety at 50 ppm GA3.The maximum number of filled grain per panicle was recorded in Chinigura rice variety (165.45) at 50 ppm followed by (162.00) also in chinigura at 75 ppm GA3. The maximum thousand grain weights (12.69 g) were in Chinigura rice variety. The highest grain yield (4.23 t ha-1) was in Chinigura rice variety at 50 ppm GA3. Spraying 50 ppm GA3 at vegetative and pre-flowering stages showed better yield potential in three aromatic rice tested but the variety Chinigura performed the best among the three aromatic rice varieties. Plant growth regulator promotes the growth and yield of aromatic rice varieties which might be an alternative eco-friendly tool for rice production.