ENSO Cycle Effects on Rainfed Wheat of Pakistan.

Global climate patterns unpredictability are related to a large-scale phenomenon known as the El Niño/ Southern Oscillation (ENSO) cycle. The terms El Niño and La Niña represent two opposite extremes of the ENSO cycle. To study impact of ENSO cycle on rainfall distribution from October to April (Rabi season) on wheat, data was collected from three locations of rainfed areas of Pakistan viz; National Agricultural Research Centre (NARC), Islamabad, Barani Agriculture Research Institute Chakwal (BARI) and at farmer field Talagang for two environments i.e. 2008-09 and 2009-10. Experiments using Randomized Block Design was conducted using three wheat genotypes, five planting times as PW’s (started from mid of October and extended until the start of December). The results revealed that during El Niño years the rainfall distribution at the time of sowing of Rabi crop was very low especially in 2009-10 resulted in very low yield of wheat (1400 Kg ha-1). Similarly long term data of rainfall elaborated that El Nino year (1957-2010) have significant effect on crop yield and almost 50 % rainfall departure took place starting from 1957-2010 with standard deviation of 24.3. The results further showed that changing planting windows changed the adaptability pattern of wheat crop at three locations because of change in the rainfall over the phenological stages of wheat switching to early maturity due to skipping of growth stages which therefore affected total productivity i.e. biomass and yield. So to mitigate dry spell period due to El Nino management needs to be opted. Key words: ENSO; El Niño; La Niña; Phenology; Planting Windows (PW’s)