Influência dos adubos amoniacais na ramificação da raiz principal da cenoura (Daucus carota L.)

Abstract

Mísshap of carrot roots can be incited by soil agents, like ba­dly prepared soil and nematodes or by ammonium fertilizers. RALEIGH (Knott), cited by SILVA, found that ammonium fertili­zers can kill the root and consequently cause malformation. The pre­ference ot sodlum nitrate ar other non-ammonium fertilizers is wide­ly spread in Brazilian literatura about carrot. MALAVOLTA (1967) even recomends only small quantities of manure to preveni root dammage­REGINA (1964), advises against use of ammonium sulphate and other ammonium fertilizers for the sarne reason. CAMARGO (1963) also pre­fers sodlum nitrate but mentlons the possibllity of substitution by ammonium sulphate, too. Although, it was imposslble to find any origi· na\ experimental information about, in Brazilian literaure. The sodium nitrate is imported by Brazil from Chile and is the­refore almost five times more expensive than ammonium sulphate, in spite oi its \ower nitrogen content. Thls triai investigated four sources of nitrogen: ammonium sulphate, sodium nitrate, urea and manure. The quantities applied were higher than MALAVOLTA recomends for carrot. The results don't show any significant difference between treatments, neither in ramification frequence nor in yield. The varlety used was a cone-shaped carrot, named London. Other varieties pos­sibly are•susceptible to malformation of root by ammonium fertilizers. This will be investigated in further experiments.