GA3 induced changes in slow growing endangered Himalayan plant Podophyllum hexandrum and hastening of vegetative growth

The endangered Himalayan plant Podophyllum hexandrum syn. P. emodi is inherently slow growing. The plants exhibit delayed emergence of functional leaves or hypocotyl dormancy. However, on GA3 treatment the functional leaves were found to emerge at a favorable temperature of 25°C in a higher percentage of seedlings and in a shorter time. Functional leaves emerged even at 10°C, a temperature when hypocotyl dormancy generally prevails. A considerable increase in the biochemical parameters related to carbon and nitrogen metabolism [starch, sugars and soluble nitrates, α-amylase and nitrate reductase (NR) activity], respiration and total dehydrogenase activity in all the seedling parts also indicated an enhancement of metabolic processes as influenced by GA3, for further growth and development. Specific leaf area of the green cotyledonary leaves increased at 25°C, probably to meet the carbon and nitrogen requirements for new structure formation. Higher activity of enzymes involved in carbon and nitrogen metabolism, i.e., NR and α-amylase especially at Hbn, the region of leaf meristematic activity, was further indicative of higher metabolism for earlier initiation of rapid vegetative growth. Initiation of reserve accumulation was also observed at 25°C.