UTILIZATION OF WILD TOMATO RELATIVE FOR THE DEVELOPMENT OF IMPROVED TOMATO LINES FOR HIGH HUMIDITY ENVIRONMENT
An effort to obtain a tomato cultivar that would adapt to high temperature and high humiditycondition in the southern part of Nigeria in order to increase tomato yield in this partof the country has been in progress for the past nine years (2000-2008).The researchwas carried out at the Faculty of Agriculture Research Farm, University of Nigeria,Nsukka located in the derived savanna zone latitude 0.6o52, N, longitude 07o 24, E,447.26 m altitude. Three cultivated tomato varieties (Solanum lycopersicon) RomaVF, Tropica (Derica), Nsukka Local and a wild relative, Solanum pimpinellifoliumand their progenies were used in the study for the development of a novel tomatocultivar for commercial production. The results of the frequency distributions of theparents and progenies showed continuous variation in fruit size thus suggesting fruitsize in tomato as a polygenic trait that is controlled by multiplicative gene action.Genetic progress made over the generations equally revealed that highest genetic gainwas obtained at the F11 generation over all the generations studied with a decline atthe F12 generation.Correlation coefficients revealed positive associations betweenyield and all the yield components in all the generations. Path coefficient analysisshowed that number of flowers per plant had the highest direct effect on yield.Principal component analysis had number of flowers per plant and fruits per plant asthe highest weighting factors. Genotype by trait (GT) biplot analysis revealed thatRoma x Wild out performed the other hybrids for the yield traits measured. Theresults of different statistical analyses performed rated Roma x Wild as the bestgenotype among the three cross combinations (Roma x Wild, Local x Wild andTropica x Wild) that will replace the original parents for adaptability under highhumidity environment. Among the agronomic traits studied, number of flowers perplant and number of fruits per plant were of considerable importance, thus selectionbased on these traits will enhance yield in tomato. The genotype (Roma x Wild) gavehigher yield and was more tolerant to high humidity conditions.