Studiu privind influenţa aplicării îngrăşămintelor cu azot asupra helmintosporiozei orezului

Abstract

Rice brown spot produced by Cochliobolus miyabeanus (Ito&Kuribayashi) fungus is the most frequent rice disease in Romania. In this paper authors collective has followed influences urea and complex NPK fertilizer applied in different doses concerning this disease. Experience has located in green house, been organized in 10 variants of 3 repetition each variant. Six variants has represented different urea doses (50 kg active ingredient./ha, 100 kg a.i /ha, 150 kg a.i /ha, 200 kg a.i /ha, 250 kg a.i /ha, 300 kg a.i /ha), three variants has represented different NPK 15:15:15 doses (100 kg a.i /ha, 150 kg a.i /ha, 200 kg a.i /ha), in time of one variant has represented unfertilized variant. After fertilizer applying at rice plants it has effected three notations. It has noted Cochliobolus attack frequency and intensity at all experimental variants, on this base it has calculated attack degree (GA %). At first notations attack frequency has values between 33,33 % and 65 %. Attack degree (GA %) has low values. At second notations, attack frequency has bigger values then 60 %. Both attack intensity and degree has bigger values at variants with maximum fertilizer (urea and NPK). At last notations, variants fertilized with maximum dose of urea and NPK have the bigger values of attack degree, from all experimental variants. The attack degree (GA %) ranged from 1,34 % at variant fertilized with 150 kg urea a.i./ha and 3,28 % at variant fertilized with 300 kg urea a.i./ha. The control variant has an attack degree by 1,69 %