FOLIAR APPLICATION OF GA3 ON CHLOROPHYLL CONTENT, EFFECTIVE TILLERING AND YIELD OF BRRI dhan34

Abstract

Plant growth regulators play vital roles in coordination of many growth and behavioral processes in rice. A field experiment was carried out to explore the growth and flag leaf chlorophyll and grain yield of BRRI dhan34 under different levels of gibberellic acid (GA3). The experimental materials comprising five concentrations of GA3 (0,50, 75, 100 and 125 ppm) spraying thrice on early vegetative, vegetative and harvesting stages. The parameter was plant height, leaf number, tiller numbers, node numbers, internode length, leaf length, panicle length, effective tiller, filled grain no., unfilled grain, 1000-grain weight, grain yield, straw yield, biological yield and harvest index, chlorophyll a, chlorophyll b and carotenoid. There was a significant effect among different level of GA3 on maximum studied characters. The highest plant height was observed by rice plant spraying 125 ppm GA3 at early vegetative (90 cm), vegetative (133 cm) and harvesting stages (204.68 cm) ,respectively. The minimum plant was 54.8, 70, 82.9 cm at control of the stages. The maximum leaf number 3.6, 5.33 and 5.73 was found in treatment 75 ppm, 50 ppm and 100 ppm GA3, respectively on thrice stages. The minimum leaf number was in control at all thrice stages. The maximum tiller numbers hill-1 which was recorded as 18.66, 15.4 and 17.82 were found with the treatment of 125 ppm. The minimum tiller numbers were at control. At various growth stages, the highest leaf blade length 65.80 cm @ 100 ppm, 78.19 cm was found @ 75 ppm and 98.46 cm at 100 ppm, respectively. The maximum node number and internode length @125 ppm GA3 was 2.1, 4.2, 5 and 4.95 cm, 16.63 cm, 21.25 cm, respectively on all stages. The minimum node number and internode length 2.63, 3.2, 4.1and 4.28 cm, 9.48 cm, 12.48 cm were at control. There was a significant effect of different level of GA3 on the Chlorophyll-a content of leaf of rice cv BRRI dhan34. No significant relationship was found in chlorophyll-b and carotenoid in BRRI dhan34 and the levels of GA3. Different level of GA3 shoewd a significant variation on the effective tiller, non effective tiller, filled grain, unfilled grain, 1000-grain weight, grain yield, straw yield, biological yield and harvest index of rice cultivar. The highest panicle length (28.37 cm), effective tiller hill-1 (20.34), filled grain panicle-1 (206.93) and 1000 grain weight (10.99) was found in treatment 125 ppm GA3 .The highest grain yield (3.41 t ha-1), straw yield (4.28 t ha-1), biological yield (7.69 t ha-1) harvest index (44.37 %) was found in treatment 125 ppm GA3. It was reported that 125 ppm GA3 was performed superior to yield parameter. It is inferred that 125 ppm GA3 may be applied thrice for maximizing yield in BRRI dhan34 for farmers level.