An investigation was conducted on the standardization of plant growth regulators on growth and flowering of spider lily (Hymenocallis speciosa L.) in Department of Floriculture and Landscape Architecture, College of Horticulture, Mudigere (Under the University of Agricultural and Horticultural Sciences, Shivamogga) during the academic year 2019-2020. The experiment was laid out in Randomized Completely Block Design (RCBD) and replicated thrice with nine treatments viz., Gibberellic acid (150 and 200 ppm), Naphthalene acetic acid (150 and 200 ppm), Chlroemquat Chloride (500 and 1000 ppm) and Benzyl Adenine (100 and 200 ppm) along with the control (water spray). The plants were sprayed with different plant growth regulators thrice at 45, 75 and 105 days after planting.The results revealed that GA3 @ 200 ppm recorded maximum plant height (69.67 cm), number of leaves (40.92), leaf length (60.67 cm), leaf breadth (6.67 cm), leaf area (5789.51 cm 2 ), plant spread (E-W) (70.75 cm) and plant spread (N-S) (55.57 cm), minimum days taken for spike emergence (91.33), minimum days taken from bud initiation to harvesting of a flower spike (9.47) and the maximum flowering duration (30.00). The treatment NAA @ 200 ppm recorded maximum chlorophyll a (2.84 mg/g), chlorophyll b (2.87mg/g) and total chlorophyll (5.71 mg/g) content of the leaves.

The plant growth regulators consist of a large group of naturally occurring or synthetically produced organic chemicals and considered as helping tool in the modern production system of flowering plants. Plant growth regulators are being used by the commercial growers of ornamental plants as a part of cultural practice. Plant growth regulators have quicker impact on vegetative as well as flower yield of flowering crops. Among them, Gibberellic Acid (GA3) plays important role in flower production, quality and yield of the flower crops. The Gibberellic Acid (GA3) is a tetracyclic di-terpenoid compound and a plant hormone stimulating plant growth and development. GAs stimulate seed germination, trigger transitions from meristem to shoot growth, juvenile to adult leaf stage, vegetative to flowering, determines sex expression and grain development along with an interaction of different environmental factors viz., light, temperature and water. The production of flower with good quality flowers has greater importance. Their exogenous application helps to improve the different economically important and market desirable characteristics of flower plants. As it have various advantages like less time consuming to treat the plant and environment friendly. Use of growth regulators in flowering crops must be specific their action and toxicologically and environmentally safe. The physiological activities of flowering crops regulate by the application of growth regulators like GA3 has finally affect the growth and flower production in flowering crops. There are various factors contributing to the efficacy of plant growth regulators among them the method of application plays a key role in determining the effectiveness of plant growth regulators, as they can be effective if properly absorbed by plants. The physiological activities of flowering crops regulate by the application of growth regulators and finally affect the growth and flower production in flowering crops. In this review, we have summarised critically on the role and use of Gibberellic Acid (GA3) on flower production of commercial crops.

An experiment on "Influence of benzyl adenine and gibberellic acid on morphological behaviour of Asiatic lily" was conducted at experimental block (protected condition) in the Department of Floriculture and Landscape Architecture, College of Horticulture, Mudigere (under University of Agricultural and Horticultural Sciences, Shivamogga), during 2019-2020. The experiment comprises of 16 treatments alone and in combinations of benzyl adenine (50, 100 and 150 ppm), gibberellic acid (100,150 and 200 ppm) and control (water soaking) replicated thrice in Randomized Complete Block Design (RCBD). The GA3 @ 200 ppm exhibited earlier sprouting (6.00 days), maximum sprouting per cent (99.03), plant height (83.13 cm), number of leaves (67.25), leaf length (10.27 cm), leaf breadth (2.51 cm), leaf area (1139.00 cm 2 ) and leaf area index (3.80). The Basal stem diameter (18.06 mm), chlorophyll-a (1.31 mg/g), chlorophyll-b (0.36 mg/g) and total chlorophyll (1.94 mg/g) recorded maximum in BA @ 150 ppm. While maximum days taken for bulb sprouting (12.12), minimum plant height (36.72 cm), number of leaves (29.33), leaf length (7.11 cm), leaf area (518.33 cm 2 ) and leaf area index (1.71) recorded in the BA @ 150 ppm.