Variation for Composition and Quality in a Collection of the Resilient Mediterranean 'de penjar' Long Shelf-Life Tomato Under High and Low N Fertilization Levels

The 'de penjar' tomato (Solanum lycopersicum L.) is a group of local varieties from the Spanish Mediterranean region carrying the alc mutation, which provides long shelf-life. Their evolution under low-input management practices has led to the selection of resilient genotypes to adverse conditions. Here we present the first evaluation on nutritional fruit composition of a collection of 44 varieties of 'de penjar' tomato under two N fertilization levels, provided by doses of manure equivalent to 162 kg N ha-1 in the high N treatment and 49 kg N ha-1 in the low N treatment. Twenty-seven fruit composition and quality traits, as well as plant yield and SPAD value, were evaluated. A large variation was observed, with lycopene being the composition trait with the highest relative range of variation (over 4-fold) under both N treatments, and significant differences among varieties were detected for all traits. While yield and most quality traits were not affected by the reduction in N fertilization, fruits from the low N treatment had, on average, higher values for hue (5.9%) and lower for fructose (-11.5%), glucose (-15.8%), and total sweetness index (-12.9%). In addition, lycopene and β-carotene presented a strongly significant genotype × N input interaction. Local varieties had higher values than commercial varieties for traits related to the ratio of sweetness to acidity and for vitamin C, which reinforces the appreciation for their organoleptic and nutritional quality. Highest-yielding varieties under both conditions displayed wide variation in the composition and quality profiles, which may allow the selection of specific ideotypes with high quality under low N conditions. These results revealed the potential of 'de penjar' varieties as a genetic resource in breeding for low N inputs and improving the organoleptic and nutritional tomato fruit quality.

Variation in flavonoids in a collection of peppers (Capsicum sp.) under organic and conventional cultivation: effect of the genotype, ripening stage, and growing system

BACKGROUND

In recent years, the acreage used for organic agriculture and the demand for organic fruit and vegetables have increased considerably. Given this scenario, landraces, such as Capsicum landraces, can provide valuable germplasm. Capsicum peppers are very interesting because of their high phenolic content, and particularly their flavonoid content, which provides a high added value. Moreover, the broad genetic diversity in local varieties expands the opportunities for adaptation to organic production and for exploiting genotype × environment interactions to select peppers with the highest phenolic content.

RESULTS

In this work, the main flavonoids of peppers were exhaustively evaluated over 2 years in a wide collection of heirlooms, both unripe and fully ripe, under organic and conventional cultivation. The genotype and ripening stage contributed to a high degree to the variation in flavonoids. The growing system influenced this variation to a lesser extent. Luteolin and quercetin showed the highest contributions to total phenolic content (70% and > 20%, respectively) at both ripening stages, while myricetin, apigenin, and kaempferol showed lower contributrions. The average flavonoid content was higher in ripe fruits, and organic management significantly increased the accumulation of total flavonoids and luteolin. Positive correlations between flavonoids were found at both ripening stages, especially between main flavonoids luteolin and quercetin and between kaempferol and quercetin (ρ > 0.7).

CONCLUSION

Genotype × environment interaction enabled the identification of accessions with high flavonoid content grown under organic conditions at both ripening stages, particularly total flavonoids and luteolin at the fully ripe stage. Our results reinforce the importance of a wide genetic variation and of considering different ripening stages and growing conditions for breeding high-quality peppers. © 2020 Society of Chemical Industry.