Grain Yield and Nutritional Quality of Commercial Maize (Zea mays L.) Genotypes: Aspergillus Exposure and Aflatoxin Contamination

Abstract

Maize, one of the world’s most important cereals is susceptible to an opportunistic pathogen, Aspergillus flavus and aflatoxin contamination, which ultimately causing both economic and human health related problems. The insufficient understandings of maize resistance to the fungus have made the selection of resistant genotypes difficult for scientists and cultivators. Fourteen different types of maize genotypes were investigated in the fields of Ayub Agricultural Research Institute, Faisalabad, Pakistan. The experiments were conducted in two maize growing seasons i.e., spring sowing (1st experiment) and autumn sowing (2nd experiment). The study was aimed to find out the maize host response to A. flavus exposure and its effect on the grain yield, quality (chemical composition) and aflatoxin accumulation during the spring and autumn seasons. For this purpose, A. flavus inoculum was applied in the cob during seed maturation. A. flavus inoculated plants produced some damage, however, these symptoms were negligible, but inoculated and non-inoculated cob were morphologically different that’s why visible symptoms of fungal infection on maize cob can be related to the infection by the A. flavus in maize genotypes. Fungal inoculation reduced the grains per cob, total grains weight/cob, protein, oil as well as carbohydrate contents of the grains. The maize genotype KSC-9663 produced better yield during spring season among all genotypes, used in this study. Maize genotype, FH1046 overall produced better yield during autumn season and maize genotype YH-1898 was better for chemical/nutritional quality (grain starch, fiber, ascorbic acid and carbohydrate contents) during spring as well as during autumn (grain fat, fiber, ash, carbohydrate, ascorbic acid and total free amino acid) seasons as compared to other genotypes. Maize genotype, KSC9618 produced highest phytochemicals (alkaloids, flavonoids, phenolic, proline, polyphenols) during spring season and R-2207 produced higher concentration of phytochemicals better during autumn season. Maize genotype, FH-1046 produced highest contamination of aflatoxins (AFG1 and AFB1), while, YH-1898 produced highest accumulation of AFB1 and Malka16 accumulated highest concentration of AFG2 in spring sowing experiment. Maize genotype, Pearl produced highest contamination of AFG1 and R-3305 produced highest aflatoxin contamination (AFB1) in autumn season. All genotypes showed resistance to AFB2 in both experiments, as did not produce or its level was lowered than the permissible limit for human consumption. 1st experiment (spring season) produced greater aflatoxin contamination as compared to 2nd experiment (autumn season). It is concluded that non-wounding A. flauvs inoculation could significantly affect the yield of maize genotypes under favorable weather conditions (for A. flauvs), which affected the yield and chemical composition of maize grains.