RESISTANCE OF TOMATO (Lycopersicon esculentum Mill.) TO THE Stemphylium solani Weber

Abstract

In the climate conditions of the Brazilian central west regions, tomato can be cultivated the whole year. However, the production is low and quite onerous in function of different factors Besides, different diseases affect the crop. Among the most being the fungal important is the fungi Stemphylium solani, responsible for damages of qualitative and quantitative nature in tomato. With the objective of finding a way to minimize the effect of these pathogen, an experiment was conduced at the experimental fields of the Federal University of Goiás, Goiânia-GO, Brazil. It is located at an altitude of 730 m, latitude of 16° 41’S and longitude of 49° 17’W, with temperature varying among 20 to for 40ºC, relative humidity (average of the month) of 80% in August, 83% in September and 85% in October. Precipitation in August, September and October of 1999 was respectively 0.0 mm, 69.6 mm, and 118.4 mm. The main objectives were to test levels of resistance of commercial varieties, genotypes belonging to the bank of germoplasm of Embrapa-CNPH and F1 generations of tomato Lycopersicon esculentum in field conditions to S. solani. The evaluations were accomplished at the 36, 43, 50, 57, 64, 71, 78 and 85 days after the seedlings planting combining diagramatic scale and grades. Was considered the percentage of infected area on the leaf (PIAL) and the also grades: 1 – without symptoms; 2 – spraid lesions; 3 – gathering lesions; 4 – partial dryness of the leaf; 5 – death of the leaf and 6 – death of the plant. The differentiation among genotypes was made through analysis of variance of the values of area under disease progress curve and by of Tukey’s test at the level of 5% of probability and also the logistic model. Regarding resistance to S. solani, Ohio 4013, Yoshimatusu and TSW-10 behaved as resistant, among the indeterminate. Among the determined ones, F1 (Hawaii 7998 x Monense) showed higher resistance. The genotypes Ohio 4013 and the F1 (Hawaii 7998 x Monense) were the ones that more stood out for resistance to these pathogens and could be suitable for future breeding programs.

KEY-WORDS: Tomato; resistance; Stemphylium solani.