Abstract
Post-harvest shelf life of tomato fruit may be increased by deploying mutant alleles which affect the natural ripening process and/or by a favorable genotypic background. Among the several ripening mutant genes, alcobaça (alc) has proved to be highly efficient in increasing shelf life of commercial tomato fruits, especially in heterozygosis, a state at which no limiting deleterious effects upon fruit color occur. The effects of heterozygosity in the alcobaça locus (alc+/alc) on yield and fruit quality traits of tomato hybrids with three genotypic backgrounds. We evaluated three pairs of hybrids obtained from crosses between the near-isogenic pollen source lines Flora-Dade (alc+/alc+) and TOM-559 (alc/alc), and three maternal lines (Stevens, NC-8276 and Piedmont). The six treatments were factorial combinations of two different status in the alc locus (alc+/alc and alc+/alc+) versus three different genotypic backgrounds (maternal lines). Fruits were harvested at the breaker stage of maturation and stored in shelves at 21ºC for 14 days. Yield and fruit quality traits were then evaluated. Regardless of the background, the alc allele in heterozygosis (alc+/alc) did not interfere with the total yield, commercial yield, average mass per fruit, average mass per commercial fruit, fruit shape, or with fruit peduncular scar diameter. The alc+/alc genotype reduced the rate of firmness loss and delayed evolution of the red color of the fruit, thus contributing to an increase of the post-harvest shelf life for all three genotypic backgrounds.
Highlights
Tomatoes (Lycopersicon esculentum Mill.) are grown throughout Brazil and rank as second in order of economic importance among the most consumed vegetables in the country (Filgueira, 2000)
There were no effects of either alcobaça makeup or of the maternal lines utilized, or of the interaction between these two factors
Contrasts involving the hybrids under assessment were non-significant for yield, indicating that the alc allele, in heterozygosity, did not affect total yield, regardless of hybrid maternal line
Summary
Tomatoes (Lycopersicon esculentum Mill.) are grown throughout Brazil and rank as second in order of economic importance among the most consumed vegetables in the country (Filgueira, 2000). In the 1990’s, the cultivation of tomatoes of the extra-firm and long shelf-life types showed increase estimates above 50% This increase happened because of improvements in the quality of fruits considered as firm, which remained suitable for consumption for an extended period of time after being harvested. This material bears genetic traits which interfere with the activity of enzymes that act directly upon the physiological processes related to fruit maturation (Vilas Boas, 1998). These physiological processes can be altered by mutant alleles which, in heterozygosity, extend the post-harvest life of fruits. This is reflected as a higher resistance to transportation and as a longer shelf-life, without loss of their organoleptic characteristics
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