Water requirements and irrigation of mature mango trees

Due to the existing uncertainty of producers concerning the importance of water stress of mango trees during winter months (flower bud development period), an irrigation trial was started in 1988 on twelve year old Fascell mango trees to determine the seasonal water requirements of mature trees. The experiment was conducted over six consecutive years in the Nelspruit area which is situated in the Eastern Lowveld of South Africa. (30 degrees 58'E, 25 degrees 33'S). Irrigation scheduling was done with the aid of tensiometers placed at 300, 600 and 900 mm soil depth while the quantity of water applied was measured with flow meters. Stressed treatments were not irrigated during the winter months (May to August) and little rainfall occurred during this period. Results showed that by not irrigating during winter months, annual production could be increased by 9 % and water use decreased by 20 %. Results also showed that the stress period did not reduce fruit size. Total seasonal water requirement of these mature mango trees under optimal irrigation was approximately 11 976 m(3)/ha/year. Furthermore, the seasonal water use of trees not subjected to water stress, varied from 20 to about 44 m(3)/ha/day during winter and summer, respectively.