Variety-specific responses of lettuce grown under the different-coloured shade nets on phytochemical quality after postharvest storage

ABSTRACT

This study illustrates the effects of light quality as influenced by photo-selective shade nets (red, yellow, and pearl with 40% shade) and the widely used commercial black net (25% shade) on overall retail quality and phytochemical contents of three lettuce (Lactuca sativa L.) varieties (two green varieties, Ashbrook and Aquarell, and a red variety, Exbury) at after postharvest storage. Variety-specific responses were observed with respect to different coloured shade nets with regards to the accumulation of β-carotene, ascorbic acid, flavonoids (kaempferol, isorhamnetin, quercetin, myricetin, anthocyanin), and antioxidant activity at harvest. Growing var. Ashbrook under the pearl net improved the ascorbic acid and myricetin contents after postharvest storage. Var. Exbury (red) produced under the black net showed higher retention of ascorbic acid, and anthocyanin contents after postharvest storage. Also pearl net production improved the β-carotene content after postharvest storage in var. Aquarell. All lettuce types produced under the pearl nets showed less weight loss, and overall acceptance after postharvest storage. Spectral quality under the shade nets enabled us to improve the phytochemical content and antioxidant properties in light-sensitive varieties Ashbrook Aquarell and Exbury, during winter season.

KEYWORDS:

• Lactuca sativa L.
• bioactive compounds
• light quality
• myricetin
• anthocyanin
• ascorbic acid

Acknowledgments

The authors wish to thank Hygrotech (Pty) and Seedcor (Pty) South Africa for providing fertilisers and seedlings for these trials.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was supported by the National Research Foundation, South African Research Chair programme [grant number 98352].