Table 2.

Comparison of results of application of (a) RootGraph, (b) RTipC, and (c) WinRHIZO software, and manual labelling of primary and lateral root numbers extracted from subsets of images of barley (n=20) and wheat cultivar Kukri (n=18)

The columns show primary (Prim), lateral (Lat), and total (Tot) root counts accumulated over all manually labelled images. The inequalities beneath the barley data (only) refer to the relative error in lateral root count for the given method as experienced across the range of images. Negative values refer to underestimated root counts. As WinRHIZO does not explicitly differentiate between primary and secondary roots, a diameter threshold of 0.338mm subjectively applied to differentiate between primary and lateral roots. As WinRHIZO grossly overestimates root numbers generally, no effort was made to categorize the counts in primary and lateral roots.

	Manual			RootGraph			RTipC			WinRHIZO
	Prim	Lat	Tot	Prim	Lat	Tot	Prim	Lat	Tot	Prim	Lat	Tot
Barley	120	1836	1956	120	1888	2018	120	1745	1865	123	4379	4502
				−7%<Δε(lat)<14%			−22.3%<Δε(lat)<20%			63%<Δε(lat)<211%
Wheat	90	2097	2187	91	2321	2412	54	5450	5504			10493