IMPACT OF AGRONOMIC MANAGEMENT ON AFLATOXINS CONTAMINATION (Aspergillus flavus) AND CHACOAL ROT (Macrophomina phaseolina) IN CORN

The purpose of this study was to know the maize grain aflatoxin concentration, charcoal rot incidence and production characteristics. Two planting methods (PM) and two irrigation systems (IS) were compared. The evaluated PM were in beds (115 thousand plants ha-1) and rows (85 thousand plants ha-1). The IS were drip and gravity (surface) irrigation. Long ear and grain protein content were not affected by PM or IS. Grain yield was superior in rows (P=0.007) with 46% compared with beds. Between IS, drip irrigation increased yield (P=0.028) in 20% in relation to gravity irrigation. Drip irrigation registered better water irrigation efficiency (P=0.001; 56%) related to gravity irrigation. Aflatoxin level and charcoal rot incidence were not influenced by IS; but between PM, lower aflatoxin concentration (P=0.009; 11.1 µ kg-1) and charcoal rot incidence (P=0.008; 23.7%) were observed in rows. It seems that high population densities in the bed plantings increased water demand, such factor reduced grain yield, increased aflatoxin content, and charcoal rot incidence. Row planting and drip irrigation were the agronomic management that gave greater yields and less risk with A. favus and M. phaseolina in maiz

RADICAL COLONIZATION BY THE MYCORRHIZAL INIFAPMR IN BARLEY TREATED WITH FUNGICIDE

The effect of the treatment with the fungicide chlorothalonil on radical mycorrhizal colonization on barley seed was evaluated. An experiment was performed, the factors were as follows: 1) Mycorrhiza INIFAP® (uninoculated, one, two and three doses) and fungicide (with and without fungicide). Monthly sowings were conducted to determine the degree of colonization in the roots. The results showed that treatment of the seed with chlorothalonil was not significantly decreased by the radical mycorrhizal INIFAP® colonization, chlorothalonil treatment had a mean of 32.63% root infection whereas without chlorothalonil was 36.46%. When the seed was treated with chlorothalonil, the more affected in terms of root colonization by mycorrhizal INIFAP® was a dose, treatment with double and triple doses showed no significant difference between them. Storage of seed infection percentage decreased progressively. Through the time of the inoculated seed storage, root infection by mycorrhizal INIFAP® remained constant and unchanged for the first six months, but then decreased at ca. 50% over a period of 10 months, when treated or not treated with fungicide