Field performance of processing tomato hybrids under bacterial spot and begomovirus pressure

Begomoviruses and bacterial spot are examples of important limiting yield factors for the processing tomato crop in Brazil in which the availability of resistant cultivars is strongly welcome. Three field trials were carried out in 2010 and 2011 to evaluate commercial and experimental processing tomato hybrids under begomovirus (trial 1) and bacterial spot (trials 2 and 3) pressure. Blocks at random were used in trials 1 and 2 (2010), while trial 3 (2011) was carried out in a split-plot randomized blocks design, where Xanthomonas perforans and/or X. gardneri inoculation (yes or no) was tested in main plots and hybrids, in sub-plots. Begomovirus infection was natural. Both diseases were assessed independently by using visual severity rates. Whenever diseases were assessed in a single evaluation (trials 1 and 2), we estimated the treatment relative effect for disease severity; while for multiple evaluations (bacterial spot, trial 3), we calculated the Area Under the Bacterial Spot Progress Curve (AUBSPC). Yield data were also taken. Significant differences were detected for disease severity in the three trials and for yield in trials 2 and 3. Hybrids BRS Sena, HF1-50, and BQ-210 performed better for resistance to begomoviruses in trial 1. For bacterial spot (trial 2), seven hybrids had estimated relative effet lower than 0.50, but with intense confident interval overlapping among hybrids. Yields varied from 33.7 (BQ 145) to 56.5 t/ha (BRS Sena). In trial 3, BRS Sena performed again among the most resistant to begomovirus, and along with CVR 54, BA 5446, and HMX 7889 showed an AUBSPC significantly lower than those of the most susceptible hybrids. In six hybrids the bacterial spot significantly reduced yield (41.4% in average), which varied from 95.8 (AP 533) to 138.0 t/ha (BA 5446).