Effects of quantity and frequency of irrigation on growth and nutrient uptake in Acacia nilotica seedlings in Indian dry zone

One-year old seedlings of Acacia nilotica planted in 8 m3 lysimeter were maintained by re-irrigating at 36.2 mm (I1), 26.5 mm (I2), 20.2 mm (I3), 18.1 mm (I4) and life saving (I5) when the soil water content (SWC) decreased to 7.56%, 5.79%, 4.44%, 3.23% and wilting condition in respective treatment with views to determine critical level of water use and productivity enhancement. Seedling height and collar diameter decreased (p < 0.01) with irrigation frequency from I1 to I4 level. Growth variables were lowest at I5 but increased by 1.4- and 1.6-fold at I1, 1.2- and 1.4-fold at I2, 1.1- and 1.2-fold at I3 and 1.01- and 1.1-fold at I4 levels, respectively. WUE was highest at I2. Seedlings in I1 accumulated 4-fold K and Fe, and 2-fold P, Ca, Mg, Mn, Zn and Cu than those in I5. Non-linear relations of growth and nutrient uptake with water quantity indicated positive influence of supplemental irrigation. Irrigation at I3 to I4 did not indicate significant growth over I5. Whereas I2 level was the best with highest WUE. Therefore, A. nilotica may be raised for developing greenbelt/woodlots in desert cities by irrigating at I2 and above to provide SWC of ≥5.79% in the loamy sand soil.