Influence of Genotype, Salinity, Sulfur Treatments and Planting Container Size on Growth, Yield and Incidence of Gray Mold in Broccoli Plants with Propolis Extract as Disease Control Treatment

Document Type : Original Article

Authors

1 Department of Horticulture, Faculty of Agriculture, Suez Canal University, Ismailia, Egypt

2 Department of Agricultural Botany, Faculty of Agriculture, Suez Canal University, Ismailia, Egypt

Abstract

A pot experiment was conducted at the Experimental Research Farm, Faculty of Agriculture, Suez Canal
University, Ismailia in Fall 2013 till Spring 2014. The experiment included two broccoli genotypes ("Sultan" and
"Marathon"), two levels of salinity treatments (0, 100 mM NaCl), two levels of sulfur (0, 3 g/L soil) and two different
soil volume containers (2, 4 L), in split-split plot design. The objective was to investigate the impact of genotype,
salinity, sulfur treatments and container size on plant growth, yield and incidence of gray mold in broccoli. In addition,
the effect of propolis extract as a natural mean of disease control was also explored. The results of the experiment
revealed that broccoli genotypes differed in their growth and yield response. Also, salinity treatment adversely affected
the growth and yield of broccoli in both genotypes and sulfur treatments were not able to mitigate the unfavorable
effects of salinity on broccoli plants. As a result of this experiment, gray mold in broccoli was reported for the first
time in Egypt and the fungus w a s identified as Botrytis cinerea based on mycological characteristics. Broccoli
genotypes showed different disease severity as "Marathon" cv. was highly susceptible, while "Sultan" cv. showed
higher degree of resistance. RAPD analysis identified some specific DNA fragments discriminating between the two
genotypes which can explain the different response of both genotypes for yield and disease incidence. Salinity treatment
significantly increased the disease severity by an average of 15.6% and 21.2% when compared to the control for plants
grown in large and in small culture container, respectively, which demonstrate the effect of container size on the disease
response as the larger size promoted the disease severity. Sulfur application was the most effective treatment in
decreasing disease severity by 100% in both genotypes and in both container sizes. In presence of salinity, the
inhibitory effect of sulfur sustained in "Sultan" cv., while sulfur decreased the disease severity in "Marathon" cv. only
by 52.5%. In addition, propolis extract displayed inhibitory effect on Botrytis cinerea growth in both genotypes.
Overall, genotypic differences observed for yield and salinity tolerance suggest that breeding programs to enhance such
important traits are feasible. Soil-supplied sulfur enhanced broccoli defense to disease and can be suggested as mean of
managing nutrition to control plant diseases. Finally, propolis extract can be suggested as a natural mean of gray mold
disease control in broccoli.

Keywords