The relationship of various agroecological regions and their key factors (ecosystem, growth period, soil type, precipitation) to the yield of neem oil, its key meliacins (azadirachtin-A, nimbin, salannin), and the total as well as the key fatty acids (oleic, stearic, palmitic) is reported. Moderate climate with moderate growth period, the Indo-Gangetic alluvium soil and 400–1600 mm precipitation appeared to be the most conducive for higher oil yield. Oils from the trees grown in desert-saline soil with hot arid climate revealed the highest azadirachtin-A content. The black and Indo-Gangetic alluvium soils with moderate hot semi-arid and hot sub-humid climate with GP 90–180 d were conducive for salannin and nimbin. The coastal ecosystem, coastal alluvium and red soils, GP > 210 d and 2000–3200 mm precipitatton generally favoured oleic, stearic, palmitic and the total fatty acid content of the oils.
Neem oil, agroecological regions, agroecological factors, meliacins, fatty acids
