Effect of certain environmental factors on seed germination and seedling growth in four different medicinal plant species
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Date
2008-07
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Herbs have always been the principal form of medicine in India and presently they are becoming more popular throughout the developed world. From the ancient times, herbs have been used for pain relieving and health care needs. They have provided the entire medicament to man and domestic animals for a wide spectrum of ailments and to sooth his aches and pains. The present study deals with the effect of certain environmental factors i.e., light, water and temperature on seed germination and watering frequency and shade on seedling growth of four medicinal plant species viz., Andrographis paniculata (Burm.) ex Nees. Datura stramonium Linn. Psoralea corylifolia Linn., and Withania somnifera (L.) Dunal, the seeds were subjected to different stresses (water, temperature and light quality) and the results indicated that per cent seed germination decreased with increasing water stress. However, germination was absent in W. somnifera at high water stress (-15 bar). With increasing in temperature, seed germination was increased in all species and the maximum per cent seed germination was occurred in high temperature (30/35 0C). The maximum seed germination of all the species occurred in direct light in all the species except W. somnifera, in which it was in both direct light and red light. The seedlings of A. paniculata, D. stramonium, P. corylifolia and W. Somnifera were raised in polyethylene bags and subjected to different watering frequencies (daily, 7, 14 and 21 days intervals) and different light intensities (100%, 86%, 50% and 25% of full sun light) and continued upto four months. The observations (height, number of leaves and branches, root length, dry weight of leaves, stem, shoot, root and total seedling) were made with one month interval either direct measurement or by harvesting seedlings. The values of all parameters decreased with decreasing moisture in all the species i.e., from daily to 21 days watering intervals, except root length, in which it increased with decreasing moisture in all the species. The values of all parameters decreased with increasing light intensity in all the species except W. somnifera, in which the height, number of leaves and branches was decreased with decreasing light intensity (increasing shade level). The root length, showed poor growth with increasing shade in all the species. These results indicated that root length was highly affected by moisture and shade.
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