Comparative study ohn the somatic chromosome number, growth, yield and disease incidence of cultivated tomatoes and their wild relative

Abstract

Two Lycopersicon species consisting of one local and two exotic varieties of L. esculentum Mill and one wild variety of L. pimpinellifolium Jusl, were evaluated for chromosome number, growth, flowering and fruiting pattern, yield and susceptibility to tomato disease complex in the rainy seasons (May - September) of 1998 and 1999. The somatic chromosome studies showed that both species have chromosome number of 24. The wild variety showed high tolerance to the disease complex associated with high humidity; had the least incidence of flower and premature fruit drop and highest fruit set as measurable indices of adaptation to high humidity conditions. The two exotic varieties and the local variety on the other hand were severely diseased and correspondingly had poorer fruit set. The high fruiting of the wild variety did not however, translate to higher fruit yield on weight basis because of its small-sized fruits.
The indicators of adaptation of the wild tomato to high humidity conditions afford a potential resource for desirable characteristics especially disease resistance. Therefore its hybridization with the cultivated tomato varieties that are susceptible to stresses associated with high humidity and selection from among the segregating generations may provide opportunities for generating adapted tomato lines for the humid tropics.
Key words: Chromosome number, wild tomato, disease, Lycopersicon esculentum.