Environmental Temperature and Relative Humidity, two Key Factors in Maize Technology Affecting Ochratoxin a Production and Growth of Ochratoxigenic Species

Abstract

Ochratoxin A (OTA) is a secondary fungal metabolite produced naturally by filamentous fungi of the Aspergillus and Penicillium genera. The aims of this study were to identify the most relevant OTA producing species in maize in Spain by PCR and to study the effect of environmental conditions (a w , temperature) on the development of these fungi and on OTA production in maize. Eighteen and 20 corn samples harvested in 2014 and 2015, respectively, from conventional farms and 31 and 34 corn samples harvested in 2014 and 2015, respectively, from organic farms located in various Spanish areas were tested for presence of ochratoxin-producing fungi. The most important OTA-producing Aspergillus spp. were isolated and identified by species-specific PCR protocols. The growth rate of the main ochratoxigenic species (A. steynii and A. ochraceus) under different environmental conditions was registered and OTA level in cultures was determined by solvent extraction, immunoaffinity column clean-up and LC-fluorescence detection. The results revealed that A. steynii and A. ochraceus are good indicators of OTA risk in maize. Temperature, a w , and isolate influenced OTA production. The highest OTA levels were found in maize cultures of A. steynii at 0.98 a w and 30 ºC. 

Suitability Evaluation of Crop Variety via Graph Neural Network

“…Secondly, relative humidity directly reflects the soil moisture status. Relative humidity can increase maize leaf area and yield to some extent [ 22 , 23 ]. Then, sunshine time directly determines the time of crop photosynthesis, affecting the various stages of crop growth.…”