摘要：Field experiments were performed at the farmof Sakha Agricultural research station,Kafr EL-sheikh,Egypt during 2016 and 2017 summerseasons.This study amid to find out the properharvest date and the effect of potassium fertilizer indifferent ways on grain quality and grain yield ofGiza 179 rice variety.Potassium fertilizer treatmentsnamely: 0,48kg KOl ha and 2%KO spray threetimes at mid tillerring stage,panicle initiation andmid boating stage were studied in this attempt.Harvest dates viz: 8,16,24,32,40 days after heading(DAH) were tested in the study.The trial wasimplemented in splitplot design withfourreplications.Thepotassium treatments weredistributed in the main plot while the sub plots wheredevoted to harvest dates.The main results could besummarized as following; the studied potassiumfertilizer had significant effect positive effect onmeasured grain characteristics in both seasons.Applying potassium significantly increasedhulling%,milling %,protein and amylase contents.At the same time,potassium fertilizer showedapparent effective inimproving both grain ricequality and yields.Potassium foliar spray three times at certain rice growth was detected to be orebeneficial than basal application at the rate of 48 kg KO regarding improving rice grain quality of Giza179,yield components and grain yield.Harvest dateat 30 days after heading and potassium foliar sprayat mid tillering + panicle initiation + mid bootingstage could be recommended to improving rice grainquality of Giza 179 including reducing broken grainand raising rice grain yield.
