The effects of temperature, water content and fungicidal treatment on storage of barley (Hordeum sativum J.) and maize (Zea mays L.) : a dissertation submitted in partial fulfilment of the Diploma of Agricultural Science in the Lincoln University College

Abstract

The principal contaminants found on barley and maize seeds were bacteria and fungi.

Both field and storage fungi were found on barley and maize seeds. The field fungi comprised Fusarium sp. and Alternaria sp. The storage fungi were the species of Aspergillus and Penicillium. On barley seeds, the major fungal flora were genera of Alternaria and Aspergillus. Whereas the principal fungal genera on maize seeds were Aspergillus, Penicillium and Fusarium.

Deterioration of stored barley seeds was due to the attack of Aspergillus sp. And Penicillium sp. Alternaria sp. was not associated with the spoilage of the grains.

Germination of the seeds could be affected by the growth of mould as in the case of barley seeds as well as grain condition as seen in maize seeds.

Moisture content of the seeds and temperature gently influenced the invasion of the stored seeds by the fungi. Between the range of temperature of 10º to 30º and the range of seed moisture levels of 17% to 25%, the greater the temperature and moisture content of the seed, the greater the temperature and moisture content of the seed, the greater the activity of the fungi. The storage fungi grew particularly well at 30º and 25% seed moisture content.

Fungus mycelium was common in the pericarp layers of barley seeds. In the maize seeds, the mycelium was established in the layers between the pericarp and embryo.

The control of mould growth on the seeds by using the three tested fungicides was shown to be unsatisfactory. Benlate (Benomyl a.i. 5%) at a rate of 0.1 g/50 seeds,, Orthocide 75 (Captan a.i. 75%) at a rate of 0.1 g/50 seeds and 0.1% mercuric chloride may have had phytotoxic affects on the trented barley seeds. For maize seeds, the three chemicals gave partial control or the fungal growth. However, they were not efficient in controlling mould growth on the seeds. Of all the three tested fungicides, Orthocide 75(Captan a.i. 75%) gave the best result on barley seeds in controlling fungal growth, whereas there was no significant difference between the fungicides on maize seeds.