For the study, which appears today in Nano Letters, Marelli and researchers from SMART applied small patches of the microneedles containing melatonin to the base of the leafy vegetable pak choy. After application, the researchers found the melatonin was able to extend the vegetables’ shelf life by four days at room temperature and 10 days when refrigerated, which could allow more crops to reach consumers before they’re wasted.

A simple technique to save a lot of wasted food.

Very interesting, but it's wild to me that needles made from silk proteins are the first choice here. Surely there's gotta be some plant protein or cellulose or such that's a lot cheaper.

I do also wonder, if they looked at bringing out melatonin onto the fields before the harvest, in hope of the plants picking it up via their roots.
The article makes it sound like they had a solution (microneedles) in search of a problem, so maybe they didn't even really look at other solutions. Which is fine, other studies can do that, but yeah, we should do that.