Maize gets the wet and dry treatment

Maize growers in the 'wet' and 'dry' production areas of Far North Queensland are about to draw another dividend from their investment in breeding programs — new varieties adapted to their particular growing conditions.

And the potential of the new varieties to improve the profitability of maize growing could help the industry compete with the steadily increasing popularity of sugar cane production.

The varieties — QX5 and QX6 — come from Kairi-based DPI Farming Systems Institute maize breeder Ian Martin, with support from growers through the GRDC's $90,000 Maize Germplasm Improvement project.

The three-year project seeks better and more coordinated use of maize germplasm held by Queensland's Department of Primary Industries and NSW Agriculture.

Mr Martin says there are significant climatic differences between the far north's maize-growing areas, despite their close proximity to one another.

"We are trying to create horses for courses, if you like, splitting the far north maize industry into the 'wet' area, which runs from Atherton, Kairi and Tolga through East and Upper Barron towards Malanda, and the drier parts, where problems are different.

"The drier maize production areas are Kaban, Mareeba, Walkamin — although not a lot of maize is grown there now — and Lakeland Downs, where growers look for varieties to cope with heat and moisture stress."

Mr Martin said the new wet area variety QX6 had shown good standability, coping well when hit by Cyclone Justin during 1997 trials.

Its yield was coming through around 1 t/ha better than QX1, the benchmark hybrid for the wet country (8.9 t/ha against 7.7 t/ha in two trials).

The second new variety, QX5, appeared to yield almost as well as Hycorn 90, the standard for the north's drier growing conditions, with better grain quality.

"QX5 has superior general resistance to leaf diseases, most notably Turcicum leaf blight and brown spot," Mr Martin said.

"The more acute disease problems are in the wetter areas where, besides leaf blight, you have Polysora rust, Gibberella (or pink) ear rot and Gibberella stalk rot.

"The ear rot sometimes produces toxins which can have a bad effect on consuming animals, in particular pigs, in which it affects weight gain.

"Pretty good resistance to pink ear rot is available — and QX6 has a degree of it — but stalk rot is a more complex problem." Mr Martin said release of both hybrids is scheduled for the 1998-99 season, provided seed production proceeds satisfactorily.

The GRDC maize program also was responding to grower requests to look at the potential for growing maize under irrigation and high inputs.

It was actively selecting for hybrids which could produce very high yields (12-12.5 t/ha) under non-limiting conditions — supplementary irrigation and nitrogen input of 200 kg/ha.

"This year we will release inbred lines from the maize program to the private seed companies, which will allow them to combine publicly bred inbreds with their own proprietary ones to produce superior commercial hybrid varieties," Mr Martin said.

Program 2.3.1

Contact: Mr Ian Martin

07 4095 8229

Region North, South, West