Most of the current tomato varieties bred in temperate countries do not set fruit well when night and day temperature are higher than 23 and 30 deg.C, respectively. A breeding program was carried out in order to obtain heat and humidity tolerant genotypes with large fruits and diseases resistance. Intercrossing technique was used with mixtures of pollen from F1 hybrids between heat tolerant cuban varieties (L72, HC 108; HC 25/80) and INRA-France line (Fline; Camboline, Pormor) with diseases resistance and high fruit qualities.
The variability found for several characters in this original population (Gomez and Laterrot, 1988) let us develop breeding program. Selection was carried out in Cuba, during the hot and wet season (May-October) in which maximum annual mean temperature (28 deg.C) takes place and humidity is 60-70% during the day and up 80-90% during the night. Annual mean rain fall is 1300- 1400 mm and annual golbal radiation is 180 kilocalories/cm^2^ (Rey and de la Hoz, 1979).
The S1 generation, high significant positive correlation was found between yield per plant and its component, the number of fuits per plant (r^2^=0.6348***), as well a correlation (r^2^=0.1455*) between yield per plant and the mean fruit weight. The correlation between number of fuits per plant and mean fruit weight was low, but positive. In the S3 the values were higher for the correlation between yield and mean fruits weight (r^2^=0.6625 ***) than between yield and number of fruits per plant (r^2^=0.5022***), both which are significant.
According to Principal Components Analysis in the S1 genration: number of fruits per plant; fruit setting; yield per plant and mean fruit weight gave the major contribution to total variation; while in the D=S3 fruit shape (height/diameter); mean fruit weight; pericarpe thickness; number of fruit locules and fruit setting gave the major contribution to total variation. Narrow sense heritability was high (0.8860) for mean fruit weight; intermediate (0.5144) for nubmer of fruits per plant and low (0.1460) for yield per plant.
According to the observations, six heat tolerant tomato lines were found (1.34 kg mean yield per plant and 145 g mean fruit weight). These results let us prescribe selection based on number of fruits per plant in first generations and then on mean fruit weight in more advanced generations.
Literature cited:
Gomez O. and H. Laterrot 1988 Uso de la tecnica de intercruzamento pro mezcla de polen en la creacion de variabilidad en el tomate. Agrotecnica de Cuba (Cub.) 20 (1) 109-113.
Rey, R.A. and L.O. de la Hoz 1979 Manual de regimen de riego de la pricipales cultivos de Cuba. Ed. Orbe, C. Habana.