Effect of silicon and potassium on tomato anthracnose and on the postharvest quality of tomato fruit (Lycopersicon esculentum Mill.)

The resistance against anthracnose was investigated in tomato cutivars ‘Thilina’ and ‘Maheshi’ by soil application of silicon (Si) at 0 (control), 50 and 100 mg/L during the growth stage, flowering stage and both growth and flowering stages. It showed a reduction of lesions by 80 % in ‘Maheshi’ and 87 % in ‘Thilina’, respectively compared to the control irrespective of the cultivar and stage of the plant at which the treatment was given. Application of potassium (K) at twice (X2) and thrice (X3) the recommended dose to the plants reduced lesion size by over 30 % or 85 % in ‘Thilina’ and ‘Maheshi’ cultivars, respectively. In ‘Maheshi, Si applied at 50 and 100 mg/L at all stages showed a significantly higher (p ≤ 0.05) fruit size compared to the control. Plants treated with higher doses (X2 and X3) of K also showed significantly higher fruit sizes compared to the control. Fruit firmness significantly increased in ‘Maheshi’ treated with 50 and 100 mg/L Si applied at the growth or flowering stage. A significantly lower percentage of total acidity (TA %) was observed in ‘Thilina’ treated with 50 or 100 mg/L Si irrespective of the stage of plant. ‘Thilina’ treated with X2 or X3 doses of K showed significantly higher (p ≤ 0.05) total soluble solid (TSS). Also, the percentage number of appressoria formed (number of spores with appressoria/total number of spores × 100) on areas inoculated with the fungus were significantly higher in fruits treated with X3 K dose and all Si treated fruits compared to the control.

J.Natn.Sci.Foundation Sri Lanka 2015 43 (3):273-280