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• Skin colour and softening synchronization during ripening of three avocado cultivars

  126-133.

  Kagiso Florance Ledwaba

  Kingsly Shikwambana

  Tieho Paulus Mafeo

  Thabiso Kenneth Satekge

  Nhlanhla Mathaba

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  0

  Skin colour-softening de-synchronization during the early season remains a major quality concern in ‘Hass’ avocado, leading to consumer dissatisfaction and market losses. This study evaluated whether Hass-type cultivars ‘Carmen’ and ‘Maluma’ exhibit de-synchronization between skin colour and mesocarp softening as compared to ‘Hass’ avocado. The study was conducted using fruit harvested from a ZZ2 Moeketsi commercial farm in Tzaneen, Limpopo, South Africa. The ‘Carmen’ and ‘Maluma’ cultivars were harvested in April 2024, while the ‘Hass’ cultivar was harvested in May 2024. The harvested fruits were stored at 5.5 °C for 28 days. After cold storage, fruit were held at ambient temperature to induce ripening. Firmness declined significantly in all cultivars (p < 0.001), with ‘Carmen’ softening earlier and ‘Maluma’ showing a gradual softening pattern.  Skin colour changed from green to purple and black; however, colour development was more pronounced and closely aligned with softening in ‘Carmen’ and ‘Maluma’. Chlorophyll and carotenoids decreased, whereas anthocyanin increased during ripening, with a stronger correlation between colour, firmness, and pigment changes in ‘Carmen’ and ‘Maluma’. These results indicate better skin colour-softening synchronisation in ‘Carmen’ and ‘Maluma’, supporting their suitability for early season export programs.

• The effects of ACS (1-aminocyclopropane-l-carboxylate synthase) gene down regulation on ethylene production and fruit softening in transgenic apple

  65-70.

  Zs. Galli

  E. Kiss

  G. Hrazdina

  L. Heszky

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  265

  A detailed examination of the production of ethylene and other ripening parameters during storage period has been undertaken in transgenic apple fruits, where the ethylene biosynthesis was inhibited by antisense ACS (l-aminocyclopropane-l-carboxylate synthase) gene. Data indicate down regulation of ethylene production, softening and spoilage in some transgenic lines. In some cases ethylene production was inhibited for over 90 percent, considerable reduction of softening and spoilage was observed probably due to the reduced activity of cell wall degradable enzymes. ACS activity was also monitored during ripening. The fruits of the best transgenic lines could be stored for minimum 4-5 months longer under 5 °C cold room storage conditions and one month longer at normal room temperature. This molecular approach can provide an alternative way to replace the commonly used and costly atmospheric storage of fruits.