Evaluating sweetpotato varieties to meet market needs (VG09009)

What was it all about?

The Australian sweetpotato industry is currently dominated by a single gold cultivar, Beauregard – making the industry vulnerable to pest incursions or changing growing conditions.

This project sought to develop other gold cultivars as well as identify suitable cultivars to drive market demand for red, purple and white sweetpotatoes.

Markets are emerging for red (red skin and white flesh) and purple (purple flesh) categories, whilst sales of traditional white (white skin and flesh) sweetpotatoes are stagnant. Single cultivars dominate each of these categories as well.

The team surveyed growers, market agents and retailers about sweetpotato quality preferences. Common themes were a desire for consistent grades, skin and flesh colour, smooth shapes and small-medium sizes.

To produce more choices for Australian producers, the project team curated germplasm from sweetpotato collections throughout Australia, as well as several newly imported cultivars.

They tested more than 50 cultivars for known viruses and developed a germplasm and mother plant repository for sweetpotato, to support breeding into the future.

A variety of cultivars were planted in trials in Queensland and New South Wales. Cultivars were assessed for plant growth and storage root development, as well as mature sweetpotato quality.

At field days in 2011, commercial sweetpotato growers, allied industry personnel, marketers and retailers reviewed sweetpotato root quality, yields, and taste. The group chose cultivars to continue evaluation in 2012, and that year the process was repeated to distil options to four gold, three red and three purple cultivars, with no white cultivars deemed worth further assessment. In 2013, the project assisted 11 grower evaluations of remaining cultivars, with concluding field days to finalise cultivar assessments.

At the end of the project the following sweetpotatoes had emerged as promising:

• A gold sweetpotato, Evangeline, with size and shape highly desired by consumers, and a strong, gold flesh colour. Evangeline has good nematode tolerance, a very important trait for growers. Evangeline can occasionally split, or develop a confusing red/purple colour skin and yields were less consistent than Beauregard.
• Southern Star was the most promising red cultivar. It occasionally displays a less attractive bronze-hued skin, and can grow too large if not harvested early.
• The purple Eclipse and Philipino White had strongly purple-coloured flesh, and although sometimes shaped unevenly they were no worse than the current industry standard WSPF.
• No obvious white cultivars to replace the industry standard Kestle were found.