Two field experiments were conducted during the two summer seasons of
2000 and 2001 at Sharbas Village , Domietta Governorate, Egypt, to study the
effect of some weed control treatments in transplanted rice and nutrients uptake by
rice and weeds. The predominant weeds in the experimental field were Echinochloa
crus-gal/i and Cyperus difformis .The results indicated that when the weeds were
allowed to grow with the crop ,grain yields were reduced by about 62.03 % when
compared with twice hand weeded treatments after 20 and 40 days from
transplanting .The heighest dry weight of weeds (210.34 g/m2) were observed in the
unweeded check. The following treatments were applied: Cinmethylin (Argold) 0.03
kg a.i.lfed, Oxadiazon (Ronstar) 0.19 kg a.i/fed, Thiobencarb (Satrin)1.00 kg a.i Ifed,
Butachlor (Machete) 0.90 kg a.i Ifed, and Bentazon (Basagrane) 0.72 kg a.i Ifed
alone or plus one hand weeding after 40 days from transplanting, hand weeded
treatments twice after 20 and 40 days from transplanting as well as unweeded control
. All herbicides were applied 3 days after transplanting rice, except Bentazon which
was applied 15 days after transplanting .Hand weeded treatment twice as well as all
herbicide treatments plus one hand weeded treatment gave the best weed control
and increased grain yield I fed when compared to herbicid treatments alone .
Bentazon alone gave poor control for Echinochloa crus - gal/i . All weed control
treatments reduced N,P and K uptake by weeds from (12.67 to 0.210 kg N from
0.468 to 0.01 kg P from 7.74 to 0.17 kg k) when compared to the unweeded control
(31.8 kg N, 1.175 kg P and 19.44 kg K )/fed. The greatest uptak of N,P and K by rice
was obtained by all herbicide treatments plus one hand weeded treatment after 40
days from transplanting and by twice hand weeded treatments . From the obtained results it can be concluded that all weed control treatments
increased rice grain and straw yields and decreased dry weight of weeds. All weed
control treatments reduced N, P and K uptake by weeds. The greatest uptake of N ,
P and k by rice was obtained by all herbicides plus one hand weeded treatment after
40 days from transplanting.