INTISAR ELTERAFI1, AHMED HASSANALI2
1University of Gezira, ESNRD, Sudan
2International Center of Insect Physiology and Ecology (ICIPE), BCED, Sudan
Neem trees (Azadirachta indica A. juss.) growing in different habitats in the Sudan showed variations in azadirachtin (Az) content depending on the climate, rainfall, soil type, latitude and altitude. The Az-content ranged from 1.08 to [2.3] mg g-1 of the seed kernel in the first season and from 0.48 to [3.09] mg g-1 in the second season. The average content of the neem oil (N.O.) was 44.6% in the neem seed kernel (NSK); no variation was found between these regions in the oil- content. Trees growing in regions with moderate climate, average rainfall of 400 mm, and altitude of more 470m asl, proved to be rich in Az"=content. However, trees growing in lower altitudes, alluvial or sandy soil, with hot climate reflected very low Az"=contents. Rainfall was found to be the major factor affecting the level of Az in NSK, and the optimal rainfall is found to be 717 mm. Temperature and relative humidity were found to have no direct effect on the Az"=content. However, the combination of temperature and the rainfall showed a positive correlation with the Az level in NSKs. Latitude and altitude have direct effect on Az level. Seasonal variations were clear over the two seasons, and no relationship was found between the two seasons.
Using the chemical data, metrological data,GIS and remote sensing methods maps were conducted to predict the production of these limonoids from different agro-ecological zones in Sudan. This method is applicable to other regions after the metrological data studied. This will improve the production of safe soft biopesticieds from Neem trees.
Keywords: Azadirachta indica, Azadirachtin, ecological variations, neem seed, Sudan