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Abstract
Rice· Oly::a ativa”) is one of the world’ most importaut cereal crops,
pr viding staple food for nearly one half of the population. In many developing
COTlIltLit!S, rice i the main source of food ecurity and is intiman Iy It ociated
with local life ryle lind cnluue. With rapid increase f global population. much
greater rice production is demanded. (Bao-Rong Lu, 2004 . Rice production will
have t.o increa e by 65% by 2020 to cope wirh the estimated population growth in
rice-consuming countries (IRRI 1989). Rice crop play II significant role ill
Egypt’ strategy for 11 tainmg’ the food self-sufficiency and tor increasing the
export Rice which occupies about 0.65 million hectares. produce approximately
6 railliou metric ton of rough rice annually (national average of about 9.9 ,/ha. in
2004). Farther increase in rice production through incre-ased yield per unit area is
needed. This Can be achieved through varietal impro emeut, optimizing cultural
practice II well a courrolling weed. diseases, u ecrs and improving
producriv ity of aline area (RR! . 2004). eeds compete ’i ith crop plant for
light nutrient , water and ,’pace (Glauninger & Holzuer 1982 and Kropff J993).
III ri e crops worldwide, I .se due to omperitive effect of weed lire timared
at 10 to J5% of potential production {Smith 1983; Zo chke 1990; Baltazar &
Delratta 1992. \ ithout weed control. yield los es ha e been e uimeted to t<’luge
from 16% to 86% or Veil 100% (Zo ehke 1990; Baltazar . Defsarta 199_:
Kropff 1993)
’; eeds contribute from 10-8”% 10 rice yield 10 se (Labrada, 2001), III
hiua, weeds caused from 10-20% annual yield loss 01 10 nillion rons ill 33
million (Zhang 2001. In Egypt weeds competition is the most imp rtant yieldreducing
facror Icau ina from 36-90%yjeld reduction).