Abstract
Crown rust caused by Puccinia coronata f.sp. avenae is the most damaging disease on oat. This work analyzed the effects of temperature and illumination regime during different time of incubation on both spore germination and germ tube growth, using both analysis of variance (ANOVA) and response surface methodology (RSM). This study reveals that the maximum of germination approached 95% under dark conditions at 20°C. Similarly, the maximum germ tube length was 125±23 µm under dark conditions at the same temperature after 18 h. Both spore germination and germ tube growth were observed over a wider temperature range of 5 to 30°C. The darkness conditions seem to enhance significantly (P < 0.05) both the germination and germ tube growth. After 4 h of incubation, germination was significantly higher under darkness regime at 15, 20 and 25°C than under light conditions. The effect of darkness conditions on germ tube growth paralleled its effect on germination. Furthermore, the response surface methodology (RSM) was applied to determine the optimal conditions of temperature, time and illuminations conditions for both the germination process and germ tube growth of urediospores for P. coronata f.sp. coronata. Values for the optimal germination and germ tube growth were 20°C and 8 h under darkness conditions. Moreover, urediospores of P. coronata f.sp. coronata germination and germ tube growth had followed a quadratic response function on temperature (R² = 0.94 and 0.97). On the other hand, the experimental values were in good agreement with the predicted ones and the model was highly significant with the correlation coefficient R being 0.97 and 0.98, respectively for germination and germ tube growth. Key words: Puccinia coronata f.sp. avenae, temperature, time, illuminations conditions, germination process, germ tube growth, urediospores.
Highlights
Oat crown rust, caused by Puccinia cornata Cda. f. sp. avenae Eriks has become an important limiting factors for Oat (Avena sativa) for both grain and forage production in Algeria
response surface methodology (RSM) was adopted to measure the optimal conditions of germination and germ tube growth of urediospores, in which the effects and interactions of temperature, illumination conditions and time was evaluated
Temperature plays a key role in spore germination, germ tube growth and eventual establishment of infection
Summary
Oat crown rust, caused by Puccinia cornata Cda. f. sp. avenae Eriks has become an important limiting factors for Oat (Avena sativa) for both grain and forage production in Algeria. Many authors suggested that the interaction between temperature and light influence the spore germination and germ tube growth and subsequently, infect the host plant by numerous rust pathogens (Givan and Bromfield, 1964; Kramer and Eversmeyer, 1992; Sood and Wiese, 1974; Subrahmanyam et al, 1988). RSM is a compilation of statistical and mathematical techniques widely used to determine the effects of parameters and measure the optimum conditions for any biological phenomenon (Margarida et al, 2009) This techniques gives contours plots from linear, interaction and quadratic effects of two or more parameters and fits the experimental data to calculate the optimal response. RSM was adopted to measure the optimal conditions of germination and germ tube growth of urediospores, in which the effects and interactions of temperature, illumination conditions and time was evaluated
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