"The role of big retailers is very visible and they have broad sustainability goals on energy, waste and on sourcing products. But it's our suppliers who affect the environment through things like water use," he said.
The supermarket's Sustainable Agriculture initiative, launched last year, aimed to support farmers and communities to produce more food using fewer resources and with less waste, he added. Asda also collaborated with LEAF on a guide to sustainable soil management, published in May.
However, Potato Council chair Allan Stevenson of Luffness Mains farm in East Lothian said: "The sustainability message is getting stronger and customers are looking for it more, but we don't feel it down the supply chain. There's no pull from the supermarkets, just a price war between them which is leading to rigorously price-driven sourcing."
Brown added that awareness of regional provenance was also on the rise. "There is strong support for Scottish-grown among Scottish customers - although strong antipathy to English-grown that you don't find the other way round," he said.