DENSITY STUDIES ON Stevia rebaudiana (BERTONI) IN EGYPT

Abstract

The fresh leaf yield and quality i.e. total soluble carbohydr-ates and stevioside (the main sweetening agent) of stevia under six plant densities of 24000 to 48000 plants/fed. resulted from the treatment combinations of three inter-row spacing (58.3, 70.0 and 87.5 cm) and two intra-row spacing (15 and 20 cm) using two seed types (seedlings resulted from tissue culture and root rizomes) of the variety Spanti from Spain imported were evaluated in Giza Experimental Station, Agricultural Research Center during the period of September 1998 to July 2000, where a ten successive cuts were carried out. Results revealed that:For seedlings, plant population density of 40000 plants/fed (70x15 cm) gave the highest leaf yield (4.304 tons/fed.). However, for rizomes planting, plant population of 36000, 40000 and 48000 plants/fed.( 58.3 x 20cm, 70 x 15cm and 58.3 x 20cm), respectively, yielded the highest leaf yield (7.158, 7.226 and 7.793 tons/fed.).For both seedling types, increasing or decreasing the population density beyond that induced significant reduction in fresh leaf yield.Total soluble carbohydrate and stevioside content in the leaves were not significantly affected by either inter or intra row spacing or their interaction with cutting times.Fresh Leaf yield was increased gradually and significantly in successive cuts for both seed types and this increased was more pronounced in summer cuts and in the latest cuts. On the other hand, cutting time insignificantly affected leaf content of total soluble carbohydrate and stevioside.