ALLELOPATHIC EFFECTS OF SOME WEEDS ON GROWTH AND YIELD OF PADDY RICE (TAROM VARIETY) IN NORTHERN IRAN

Allelopathic effects of aqueous whole plant leachates ofdominant weed (Cyperus difformis and Echinochloa crusgalli)and non dominant weed (Paspalum paspaloides and Sagittariatrifolia) were examined by foliar application on biochemicaland physiological growth and yield parameters of paddy rice(Tarom variety) of northern Iran. Spraying aqueous wholeplants leachates (5%) showed that the content of phenols inflag leaf of treated crop was significantly increased by wholeleachates of Cyperus difformis and Echinochloa crusgalli atP=0.05 by ANOVA. The content of total chlorophyll in flag leafof treated crop was significantly decreased by whole leachatesof Cyperus difformis and Sagittaria trifolia. This study alsoshowed that whole plant leachates of selected weeds did notshow much inhibitory effect on growth parameters (number oftotal tillers pot-1, plant height and elongation of flag leaf). Onthe contrary, elongation of panicle and total grain fill panicle-1were inhibited by foliar application of whole selected weeds.In case of number of effective tillers pot-1, Cyperus difformisalong with Sagittaria trifolia significantly hampered thenumber of effective tillers pot-1 only; while 1000 grain weightand the number of grain panicle-1 were not affected by wholeleachates of all treatments. However, whole plant leachates ofCyperus difformis and Sagittaria trifolia strongly hamperedgrain yield of Tarom variety as compared with control by 30.4and 29.6%, respectively.