Relative Yields of Inbred Lines and F1Hybrids of Tomato

Abstract

The yield of ripe tomatoes in those areas having a short growing season can be greatly increased by utilizing F1 hybrids for producing the crop. All the high producing F1 hybrids have at least one parent derived from crosses between Lycopersicon esculentum and L. pimpinellifolium. The most outstanding F1 hybrid yielded by weight three times as much ripe fruit per plant as did Danmark. This increased yield was due primarily to an increase in earliness. The characters studied were yield of ripe fruit, number of ripe fruit, wt. per fruit, period from first bloom to first fruit set, number of days from first fruit set to first fruit ripe, spread of plant, height of plant, number of locules per fruit, and wt. per locule. Considering all characters, the range in expression of dominance and heterosis in this material was from non-beneficial heterosis to beneficial heterosis. The interrelations of the characters were such that any of them could be recombined to some extent. The combining ability of the inbred lines studied is dependent upon genetic diversity and the phenomenon of dominance and heterosis, and the available information concerning these genetic phenomena is sufficient to account for all the known facts concerning combining ability. The induction of [male]$ sterility in inbred lines to be used in making F1 hybrids is of sufficient promise to warrant intensive studies on the production of [male] steriles by irradiation, on determining the value of such inbreds in a tomato breeding program, and on working out methods of utilizing them to obtain F1 hybrid tomatoes for commercial production.