Impact of Irrigation Water Quality on Yield and Concentrations of Some Heavy Metals in Rice.

Abstract

The available water resources in Egypt are limited so; the concept of lowquality irrigation water in such location is dramatically and caused pollution by heavy metals in soils and plants. More solutions have to use to face the problem of using wastewater. The present field experiments were conducted during 2010 and 2011 summer seasons at farm of Rice Research and Training Center, Sakha, Kafr El-Shiekh, Egypt to, investigate the effect of water quality during nursery period on production of rice cultivars; Giza177 (V1) and Giza178 (V2) irrigated with drainage water (DW), agronomic traits, as well as concentrations of cadmium (Cd), lead (Pb) and Ni (nickel) in rice grains and straw. Two nurseries were performed for each cultivar; the first nursery was irrigated by fresh water (FW) and the second nursery by drainage water (DW). Seedlings from each cultivar (30 days) transplanted under two levels of urea 0 kg N/fed (T1) and 69 kg N/fed that recommended for their cultivars (T2) then irrigated with DW two weeks before harvest. The results revealed that among the eight treatments, DwV2T2 (Drainage water + Giza178 + recommended of N fertilizers) gave the highest values of chlorophyll content in flag leaf, number of tiller, number of panicle, grains and straw yields (t/fed). Moreover, concentrations of studied heavy metals were higher in rice straw than in grains in both rice cultivars for all water quality treatments. The Cd and Ni concentrations in rice grains exceeded the permissible limits according to World Health Organization (WHO, 1992) at DWV1T1 (Drainage water + Giza177 + untreated control) and DWV1T2 (Drainage water + Giza178 + recommended dose of fertilizers) treatments. Pb concentration exceeded safety limits at DwV1T2 (Drainage water + Giza177 + recommended dose of fertilizers) in both seasons. However concentration of these metals in grains of Giza178 rice cultivar didn't exceed permissible limits with all treatments in both seasons. The obtained results also, showed that utilization of fresh water during nursery period for both rice cultivars; Giza 177 and Giza178 led to decrease the concentrations of studied heavy metals (Cd, Pb and Ni) in grains.