South Perth, Western Australia
June 4, 2010
New research by the Department of Agriculture and Food could lead to savings for the broccoli growers.
Trials at Medina Research Station have shown that planting only uniform-aged seedlings results in both higher marketable yields and a more even harvest.
Development officer Helen Ramsey said the key to success was uniformity in vigour and seedling age at planting, which were influenced by germination and growth rates in the nursery.
“Harvesting of cauliflower crops can take from three to five passes and broccoli two to three passes,” she said.
“Reducing the number of passes to only one or two would cut labour costs significantly and also lead to the possibility of mechanical harvesting. Improving seedling uniformity is one way to reduce the number of harvests in broccoli, although it is yet to be proven for cauliflower.”
Gavin D’Adhemar and Roy Bosworth from the Department of Agriculture and Food harvest broccoli by hand over several passes.
In department trials during 2009, only broccoli seedlings that germinated over a single day were selected for planting. This contrasted with normal commercial practice where seedlings might germinate over a spread of four to six days. Planting the uniform seedlings resulted in more even initiation of the broccoli heads and more even maturity.
At harvest, the uniform broccoli plants produced a marketable yield of 16.2 tonnes per hectare, of which 89 per cent was harvested in one pass (14.4 t/ha). By comparison, commercial plants produced a marketable yield of 10.6 t/ha, of which 78 per cent came from one-pass (8.3 t/ha).
“That’s a 5.6 t/ha or 52 per cent increase in total marketable yield with the uniform broccoli plants over the normal commercial ones,” Ms Ramsey said.
“If you compare the one-pass harvest of the uniform plants at 14.4 t/ha with the total yield (over two harvests) of the commercial plants at 10.6 t/ha, that’s a 3.8 t/ha or 35 per cent increase in marketable yield. Even without mechanical harvesting, the gains and savings made using uniform seedlings are considerable.”
Most of the difference in marketable yield between the commercial and uniform plants was due to head shape, which can determine whether it is suitable for domestic market requirements.
The research was funded by Horticulture Australia Limited and the Australian vegetable industry through its national levy, the department and the Warren Cauliflower Group.
Trials with cauliflower were also less conclusive than with broccoli.
“For a research trial, selection of seedlings with uniform germination was possible,” Ms Ramsey said. “But this is not practical in a commercial situation.
“Genetics is one influence on seedling uniformity and to translate these findings into gains for industry, we need to encourage plant breeders to select for more uniform seed germination in new varieties.
“Another option might be pre-germination treatment or priming of seed, but that is an avenue for more research.”
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