This tendency may be due to enrichment of the soil with the ash, the effect of which is to stimulate high temperatures in the seeds. The variety Rendidora was formed from the best collections selected in the state of Morelos, where improvement work was carried out. Rendidora mejorada was derived from this variety. In Guatemala, in spite of the wide genetic variation recognized, genetic improvement of this crop is still in its early stages. The characteristics most affected by the environment are leaf size and shape.
Soil fertility stands out as an environmental factor in expression of the phenotype.
Improvement aims in Guatemala should be the same, except regarding fruit colour, since purplish green and yellowish green tomatoes are preferred in that country. Bukasov, S.M. 1963. Lima, IICA, Misc. Callen, E.O. 1966. Analysis of the Tehuacan coprolites.