Vladimír Kren, Ladislav Cvakа

Ergot: the genus Claviceps

ÉVA NÉMETH

PARASITIC PRODUCTION OF ERGOT ALKALOIDS

ENVIRONMENTAL REQUIREMENTS. Abiotic Factors

11.3. ENVIRONMENTAL REQUIREMENTS

11.3.1. Abiotic Factors

The optimal ecological conditions for the development of ergot vary in the course of its onthogenesis. For vernalization of the sclerotia winter

PARASITIC PRODUCTION OF ERGOT ALKALOIDS

temperatures around 0°C (Chapter 3). Germination starts only when the average daily temperature reaches 9-10°C in the springtime. However, optimal temperature for this process lays as high as 18-22°C.

During the time of infection by conidia the optimal weather conditions are characterised by moderately warm temperatures (about 18-20°C), high air humidity (near saturation) or drizzling rain (Golenia et al., 1961; Ruokola, 1961). Low temperatures up to 12°C - especially during the night 3-4 weeks prior to flowering may have an advantageous effect on the infection efficacy because of the stronger degeneration or abnormal development of anthers (McLaren and Wehner, 1992; Watkins and Littlefeld, 1976). At the time of the mycelia development similar ecological conditions are considered to be optimal. In warm and windy weather the risk of drying out of the conidia increases, the flowering period of the rye becomes shorter decreasing the possibility for a successful secondary infection.

The best sclerotia growth is assured by dry, constantly moderate weather conditions. In hot weather, the growing period of sclerotia is shortened causing less developed sclerotia of lower alkaloid content. According to the experiments of Kiniczky (1992) under controlled conditions, the alkaloid level of the sclerotia at 22°C was 5.1% , while the rising the temperature to 25°C decreased the alkaloid content to 2.7% . Higher temperature (up to 30°C) had a significant effect also on the individual sclerotium mass, but their number in the ear was not influenced.

In general, ergot may be grown in the areas, where the annual amount of precipitation is over 500mm and the conditions are considered as advantageous also for the rye. It is desirable to protect the plot against strong and drying wind so that it has a humid climate and regular early morning mist (Kybal and Strnadova, 1968).

Ergot: the genus Claviceps. Volume 6 of Medicinal and aromatic plants. CRC Press, 1999.