Descrição
Keywords: Chelidonium majus oil extract, Powdery mildew, Sugar beet yield.
Powdery mildew (Erysiphe betae) is one of the most important fungal diseases in sugar beet fields, causing reductions in root yield and sugar content. This study investigated the effect of greater celandine (Chelidonium majus) oil extract as a natural agent for controlling the disease and improving root yield and sugar content under North-East Iranian conditions. The experiment was carried out on the susceptible sugar beet cultivar Efesos from Denmark using a randomised complete block design with three treatments-1% Ch. majus oil extract, distilled water as a negative control, and the fungicide Tridemorph 75% EC (Calixin) as a positive control-each replicated three times. Foliar spraying was carried out manually in two applications, initiated upon the appearance of the first disease symptoms on the leaves, with a 20-day interval between sprays. The disease severity index (DS) was assessed using the four-point visual rating scale of Whitney (1983) from the International Institute of Sugar Beet Research (IIRB) at four time points. The efficiency percentage of each treatment was calculated based on the area under the disease progress curve (AUDPC of DS), in comparison with the negative control, and according to Abbott’s formula (1928). The harvest was carried out at the appropriate time. After removal from the soil, the roots were topped by eliminating the crown and neck from the upper part and the tail from the lower part, and were cleaned of soil and debris. The roots were then weighed in the field using a digital balance to determine root yield, expressed in tonnes per hectare. In addition, the harvested roots were delivered to the sugar factory located in the research area to determine the recoverable sugar percentage or sugar content of each root. The results of the ANOVA revealed a significant difference at the level (p<0.01) for efficiency, root yield, and root sugar content. The maximum efficiency was 85.17% for Tridemorph and 70.23% for Ch. majus treatment. The highest root yield (66.38 t/ha) was obtained with Tridemorph, while the lowest (30.17 t/ha) belonged to the negative control. Ch. majus treatment showed a root yield of 57.45 t/ha. The highest root sugar content (15.42%) was recorded for Tridemorph, while the lowest (14.02%) belonged to the negative control. The Ch. majus treatment exhibited a root sugar content of 14.95%. In conclusion, Ch. majus oil extract demonstrated considerable potential as a natural control agent against powdery mildew in sugar beet, markedly enhancing both root yield and sugar content relative to the untreated control.
Agradecimentos
Os autores agradecem o apoio financeiro das agências FAPEMIG e CAPES.
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